Guitar Ted's How-To: Rear Derailleur set-Up Basics - Part 2

Welcome to Part 2 of how to set up a rear derailleur from scratch on your bike. Again, this applies to the way I would take a new rear derailleur for a mechanical system and set it up to work properly. This would also work for anyone swapping on a used rear derailleur as well. While this doesn't cover electronic rear derailleurs, many of the same basics still apply. 

Now, if you missed the basics of rear derailleurs, that post is HERE and a link to yesterday's post is HERE. I will assume you have read and understood that previous material. 

Keep in mind that if you have any hesitation at all in doing this task, stop and seek the help of a professional bicycle mechanic. Getting any of this wrong can lead to serious injury, property damage, and even death. So, unless you are confident in your mechanical skills and unless you own the proper tools, don't attempt this! 

Okay, with that out of the way, I will remind you that this post only will deal with how to set up the lower limit screw.  How to set up the "B Tension" screw is best done while doing a tune on the cable and rear shifting, so that will come later. . See that link for the earlier steps in this process which MUST be completed BEFORE you do these steps. Now, on with the show.....

The "LOW LIMIT" screw does not come into play until the rear derailleur is at full extension. This happens in your lowest gear on the cassette, or the "biggest cog" if you think of things in that manner. Its job is to prevent the rear derailleur's travel inboard to the point that the chain goes over the top of that last cog and into the spokes. It also aligns that upper jockey wheel on the rear derailleur so it is perfectly in-line with the last cog of the cassette. 

Above you can see #1 which is the "LOW" screw and where it hits the inner portion of the parallelogram of this Shimano XT rear derailleur at point #2. Remember from yesterday's post that turning that "LOW" screw clockwise prevents travel inboard and turning it counter-clockwise allows that travel to continue further inboard toward the spokes. This assumes that your cable tension is correct, that you have the correct, operational shifter, and nothing is damaged or bent on a complete system. But for this job, we aren't worried about that just yet. 

Now, for a quick diversion...... Since setting the "LOW" limit screw is best done with a chain on, I am going to show you a couple of hacks I use to make chain installation a bit easier. Both of these work best if you have a repair stand, by the way. 

First, you want to get the derailleur in the position I have shown to the left here. This will probably mean that your bike will have its front wheel on the ground and the back one straight, or almost so, above it in the work stand. What you want is to make a straight path downward for the chain toward the ground through the derailleur cage. 

This allows you to use gravity to your advantage, instead of fighting gravity - if you were trying to put the chain through the rear derailleur with the bike in a horizontal position. This technique I am sharing makes the job of threading a chain through a derailleur far easier. But again- it works best with a repair stand. Don't have one? Well, I would guess that if you have read this far, you want to do some of your own work on your bicycles. The best thing you can add to your tool stash is a repair stand. Get one!

Drop the chain in from the top, using gravity to feed it through the cage.

Okay, now on with the show... Tip: Make certain that you have cut your chain to length (use the old one as a guide if you can), and make sure you thread the chain in the right orientation. 10, 11, and 12 speed chains will likely have either a top side or bottom, or a right and left orientaion. Check your chain manufacturer's tech spec guide or ask a mechanic if you are not sure about this. Most 9 speed, 8 speed, and 7 speed chains are not affected by this.

Using gravity, you should be able to drop the chain in from the top, through the cage, and past the upper jockey wheel of the derailleur, (which is the lower one as this is oriented here in the image) , and then pass through at least half the chain. You can even thread the chain through a front derailleur at this time, if that applies to your bike. Then adjust your stand back so the bike sits horizontally again. 

Hack #2: Use a bungee cord to hold the cage forward like this to relieve chain tension for ease of quick link attachment.

Ever had trouble connecting those Shimano quick links? Read on...

Now for Hack #3- This applies mostly to Shimano quick links, but some SRAM 7 & 8 speed links are stubborn to go into place as well. If you have had trouble connecting a quick link like this, here's a quick way to solve the problem. First, carefully attach the link with the chain tension relieved as I have shown with the bungee. Try to get the link as tight as you can first, as I have shown immediately above with this Shimano 11 speed link. 

Then, carefully, slowly pedal the bike forward so the quick link is in the "top run" of the chain as I have shown immediately above here. Get the quick link about midway from the cassette cog and the chain wheel. Then, grab a rubber mallet, (you can use your hand, but it usually hurts if you do!), and apply the rear brake firmly with one hand and then strike a pedal (Usually should be the right side since it is closet to you)  sharply with the rubber mallet, as if you were going to pedal forward. This will snap the link into place. Done! 

Now- On to setting initial "LOW" limit for the derailleur. You'll see why I like to have the chain on for this in a minute.... (Here is a link to yesterday's post for reference if needed)

With the rear derailleur on the smallest cog on the cassette, place your hand as I have shown here on the rear derailleur. Use your left hand, as you'll need your right hand to pedal with. Pedaling slooooowly, push with your thumb on the derailleur's knuckle in the direction shown. (Towards the inboard side of the bike). 

The derailleur should start walking the chain up the cassette toward the biggest cog. You may find that with a new rear derailleur that you can only get so far, then you cannot push the derailleur any further, but you are two, maybe three cogs from the largest cassette cog. Okay, if that is the case, you need to turn the "LOW" limit screw counter-clockwise. Always make small, incremental adjustments. I'd turn it maybe a quarter turn at a time, and recheck how far the derailleur can be pushed up. Repeat the process until you can get the chain to drop into the last gear on the cassette, but no further!

Now, lets say that you can push that chain up and it wants to go over the last cog if you keep pushing. (This is why you want to pedal SLOWLY and be very careful) If that seems to be the case, the "LOW" limit screw needs to be turned clockwise, again a quarter turn at a time, until you cannot push the chain off the last cassette cog. 

Showing the technique at the extreme end of the derailleur's travel here.

Keep in mind that you do not need to use excessive force, or much force at all to manage this technique. The carefully applied force and slow movement of the drive train as you pedal will yield the best results here. 

Now if you've found that point where you can get the chain to drop in the last, largest cog on the cassette and not have the chain go over it, you've got the "LOW" limit in the ballpark. You should be okay as far as a safe system now. I'd recommend doing a finer adjustment if necessary when you get to adjusting the cable for shifting, but that will be for my next post in this series. I'll also show how to set up the "B" tension screw for optimal shifting when I get to how to tune the rear derailleur as well.

At this point, your basic set-up of the rear derailleur is complete. Stay tuned for more "How-To" posts soon.

Guitar Ted's How-To: Rear Derailleur set-Up Basics - Part 2

Welcome to Part 2 of how to set up a rear derailleur from scratch on your bike. Again, this applies to the way I would take a new rear derailleur for a mechanical system and set it up to work properly. This would also work for anyone swapping on a used rear derailleur as well. While this doesn't cover electronic rear derailleurs, many of the same basics still apply. 

Now, if you missed the basics of rear derailleurs, that post is HERE and a link to yesterday's post is HERE. I will assume you have read and understood that previous material. 

Keep in mind that if you have any hesitation at all in doing this task, stop and seek the help of a professional bicycle mechanic. Getting any of this wrong can lead to serious injury, property damage, and even death. So, unless you are confident in your mechanical skills and unless you own the proper tools, don't attempt this! 

Okay, with that out of the way, I will remind you that this post only will deal with how to set up the lower limit screw.  How to set up the "B Tension" screw is best done while doing a tune on the cable and rear shifting, so that will come later. . See that link for the earlier steps in this process which MUST be completed BEFORE you do these steps. Now, on with the show.....

The "LOW LIMIT" screw does not come into play until the rear derailleur is at full extension. This happens in your lowest gear on the cassette, or the "biggest cog" if you think of things in that manner. Its job is to prevent the rear derailleur's travel inboard to the point that the chain goes over the top of that last cog and into the spokes. It also aligns that upper jockey wheel on the rear derailleur so it is perfectly in-line with the last cog of the cassette. 

Above you can see #1 which is the "LOW" screw and where it hits the inner portion of the parallelogram of this Shimano XT rear derailleur at point #2. Remember from yesterday's post that turning that "LOW" screw clockwise prevents travel inboard and turning it counter-clockwise allows that travel to continue further inboard toward the spokes. This assumes that your cable tension is correct, that you have the correct, operational shifter, and nothing is damaged or bent on a complete system. But for this job, we aren't worried about that just yet. 

Now, for a quick diversion...... Since setting the "LOW" limit screw is best done with a chain on, I am going to show you a couple of hacks I use to make chain installation a bit easier. Both of these work best if you have a repair stand, by the way. 

First, you want to get the derailleur in the position I have shown to the left here. This will probably mean that your bike will have its front wheel on the ground and the back one straight, or almost so, above it in the work stand. What you want is to make a straight path downward for the chain toward the ground through the derailleur cage. 

This allows you to use gravity to your advantage, instead of fighting gravity - if you were trying to put the chain through the rear derailleur with the bike in a horizontal position. This technique I am sharing makes the job of threading a chain through a derailleur far easier. But again- it works best with a repair stand. Don't have one? Well, I would guess that if you have read this far, you want to do some of your own work on your bicycles. The best thing you can add to your tool stash is a repair stand. Get one!

Drop the chain in from the top, using gravity to feed it through the cage.

Okay, now on with the show... Tip: Make certain that you have cut your chain to length (use the old one as a guide if you can), and make sure you thread the chain in the right orientation. 10, 11, and 12 speed chains will likely have either a top side or bottom, or a right and left orientaion. Check your chain manufacturer's tech spec guide or ask a mechanic if you are not sure about this. Most 9 speed, 8 speed, and 7 speed chains are not affected by this.

Using gravity, you should be able to drop the chain in from the top, through the cage, and past the upper jockey wheel of the derailleur, (which is the lower one as this is oriented here in the image) , and then pass through at least half the chain. You can even thread the chain through a front derailleur at this time, if that applies to your bike. Then adjust your stand back so the bike sits horizontally again. 

Hack #2: Use a bungee cord to hold the cage forward like this to relieve chain tension for ease of quick link attachment.

Ever had trouble connecting those Shimano quick links? Read on...

Now for Hack #3- This applies mostly to Shimano quick links, but some SRAM 7 & 8 speed links are stubborn to go into place as well. If you have had trouble connecting a quick link like this, here's a quick way to solve the problem. First, carefully attach the link with the chain tension relieved as I have shown with the bungee. Try to get the link as tight as you can first, as I have shown immediately above with this Shimano 11 speed link. 

Then, carefully, slowly pedal the bike forward so the quick link is in the "top run" of the chain as I have shown immediately above here. Get the quick link about midway from the cassette cog and the chain wheel. Then, grab a rubber mallet, (you can use your hand, but it usually hurts if you do!), and apply the rear brake firmly with one hand and then strike a pedal (Usually should be the right side since it is closet to you)  sharply with the rubber mallet, as if you were going to pedal forward. This will snap the link into place. Done! 

Now- On to setting initial "LOW" limit for the derailleur. You'll see why I like to have the chain on for this in a minute.... (Here is a link to yesterday's post for reference if needed)

With the rear derailleur on the smallest cog on the cassette, place your hand as I have shown here on the rear derailleur. Use your left hand, as you'll need your right hand to pedal with. Pedaling slooooowly, push with your thumb on the derailleur's knuckle in the direction shown. (Towards the inboard side of the bike). 

The derailleur should start walking the chain up the cassette toward the biggest cog. You may find that with a new rear derailleur that you can only get so far, then you cannot push the derailleur any further, but you are two, maybe three cogs from the largest cassette cog. Okay, if that is the case, you need to turn the "LOW" limit screw counter-clockwise. Always make small, incremental adjustments. I'd turn it maybe a quarter turn at a time, and recheck how far the derailleur can be pushed up. Repeat the process until you can get the chain to drop into the last gear on the cassette, but no further!

Now, lets say that you can push that chain up and it wants to go over the last cog if you keep pushing. (This is why you want to pedal SLOWLY and be very careful) If that seems to be the case, the "LOW" limit screw needs to be turned clockwise, again a quarter turn at a time, until you cannot push the chain off the last cassette cog. 

Showing the technique at the extreme end of the derailleur's travel here.

Keep in mind that you do not need to use excessive force, or much force at all to manage this technique. The carefully applied force and slow movement of the drive train as you pedal will yield the best results here. 

Now if you've found that point where you can get the chain to drop in the last, largest cog on the cassette and not have the chain go over it, you've got the "LOW" limit in the ballpark. You should be okay as far as a safe system now. I'd recommend doing a finer adjustment if necessary when you get to adjusting the cable for shifting, but that will be for my next post in this series. I'll also show how to set up the "B" tension screw for optimal shifting when I get to how to tune the rear derailleur as well.

At this point, your basic set-up of the rear derailleur is complete. Stay tuned for more "How-To" posts soon.

Guitar Ted's How-To: Rear Derailleur Set-Up Basics - Part 1

 Hey Everyone! This is a follow-up on the series on "How-To" posts and this time I am continuing on with rear derailleurs. The basics on parts of a rear derailleur were discussed in THIS POST. Make sure you are familiar with the parts of a derailleur first as these following posts today and tomorrow will cover basic set-up and adjustments. Following these posts I will get into how to adjust shifting with the cable adjustment feature found on many rear derailleurs- but not all. Stay tuned for more on that coming soon. 

Today's post will get into how one would start to set up a brand new, or new-to-the-bike, rear derailleur. There are certain things you will want to do in a certain order that will make your life a lot easier when replacing one of these mechanisms. Also- while I will not discuss electronic rear derailleurs here, many of these basic principals still apply. Always refer to manufacturer's instructions, or take it to a bicycle technician if in doubt. Getting today's lesson wrong (or tomorrow's) can result in damaged parts and possibly a crash and injury/death. (No kidding!) So, if you have any questions at all about your understanding of these basics, get help! It's not worth it to take a chance here. 

Okay, with that out of the way, I would start this process with the chain off. You should have the rear wheel installed with whatever cassette you are going to use. The rear derailleur can then be mounted to the hangar of the frame (replaceable hangar in most cases, probably) and then we can get started.

First, let's familiarize ourselves with the important parts of today's discussion in regard to setting up a rear derailleur. I'll refer to the image above: Working from Left to Right...

1. The cable fixing bolt, where the cable attaches. To get here, you may have to follow a circuitous path (SRAM) or specific leverage arms may have to be engaged. These are specific to individual derailleurs and may not apply in your case as well. Check manufacturer's manuals on your specific derailleur or consult an expert if in doubt. (This part won't be covered today or tomorrow)
   
2. The "HIGH" limit screw on a Shimano rear mech is almost always the upper of two screws, or as in this case with a GRX rear derailleur, a pair of 2mm hex head bolts. These are used ONLY ONCE and then you should not have to touch them again. 
3. The "LOW" limit screw. Both the "HIGH" and the "LOW" limit screws do what they say- They LIMIT derailleur travel. One on the "high"- or smallest cog of the cassette side, and the "low" is for the lowest gear/largest cassette cog side. These LIMIT the travel of the rear derailleur so your chain does not go off into the spokes or off on the other end into the frame. NOTE- These screws DO NOT AFFECT HOW YOUR BICYCLE SHIFTS, other than in one important way, which I will get to in my follow-up post. 
4. The "B Tension" screw, or as in this case, a 2mm hex head screw. This is the adjustment for the upper jockey wheel's relationship to the cassette. This will be discussed in more detail when I get to the end of this post.

Now, if you have the rear derailleur mounted, with no chain on, and no cable attached, you are ready to set the derailleur's travel limits using the limit screws. First, determine what type of screw/bolt you are looking at. Most of the time these will be JIS/Phillips type screws which have what looks like a "cross" slotted head. Other times you may see Torx/flat blade screwdriver heads. Other times you may see these 2mm hex head bolts, as with the example above. 

Also worth noting is that the "HIGH" and the "LOW" limit screws won't always be arranged in the same manner. Refer to the following images for more...

A typical SRAM MTB set up with the HIGH and LOW screws reversed from the typical Shimano positions.

Another SRAM set-up where the screws are not marked.. Note the interface tool type.

What if, as in the last image above, you don't have any markings to know which is "HIGH" and which screw controls the "LOW" limit? Well, you can visually inspect the rear derailleur for clues. 

Most rear derailleurs (NOT ALL) have a "resting" position. This is the state of the mechanism when there is no cable attached. The rear derailleur is typically in its "collapsed" state, which is when the HIGH limit screw will be in contact with some part of the rear derailleur. Visual inspection should lead you to identify which screw is the HIGH one. That leaves the other screw as being the LOW limit. See the following images...

#1: This screw rests against the derailleur at point indicated by #2 when the rear derailleur has no cable attached. So, this is the "HIGH" limit screw on this derailleur. 

On this SRAM rear derailleur you can see the limit screws protruding from the inside of the parallelogram part of the rear derailleur. The nearest to to foreground is the "HIGH" limit, as can be seen by the indicator on the parallelogram's outer side. But if that marking weren't there, you'd be able to see that this screw would be in contact with the inner part of the front knuckle of the derailleur if it were at rest. I have the derailleur partially actuated for this view. 

Now that you know which screw is which, and how to determine that, you can move on to setting the limits of derailleur travel. Typically, you'd set the "HIGH" limit first, as this is the critical 'starting' point for shifting. If the start point is off, the indexing of your shifter won't place the rear derailleur in the exact position it needs to be in to do its job. So, in a way, this particular screw is crucial to the operation of your shifter, but once it is set, you forget it!

As with either limit screw, clockwise rotation of the screw results in limitation of movement to the "outer-side" of the system. So, in the case of the "HIGH" limit screw, clockwise rotation sets a limit for movement further inboard as you turn that screw. Counter-clockwise rotation of the screw results in setting the limit further outboard, so the derailleur will move away from the center of the bicycle as you make this adjustment. 

Ideally, you want the upper jockey wheel of your rear dérailleur to sit directly underneath the smallest cassette cog when the rear derailleur is at rest. Adjust that limit screw until you see that relationship, and that is your "starting point" to adjusting the shifting. Now when the cable is adjusted correctly, (more on that later on in this series), your shifter will index correctly with the cassette and the rear derailleur will "derail" the chain properly to the next lowest gear, and when coming back again, it won't hesitate or overshoot the last cog and go into the frame. 

Okay, that's enough for today! Tomorrow I will cover the trick I use to set the low limit screw. The "B tension" screw discussion will come later. Also, in a following post, I will get into how to connect the rear cable, how to address cable tension for your rear derailleur, what tricks I use, and that should be all you'll need to set up and adjust most rear derailleurs out there. 

Tomorrow: Rear Derailleur Set-Up Basics - Part 2

Guitar Ted's How-To: Rear Derailleur Set-Up Basics - Part 1

 Hey Everyone! This is a follow-up on the series on "How-To" posts and this time I am continuing on with rear derailleurs. The basics on parts of a rear derailleur were discussed in THIS POST. Make sure you are familiar with the parts of a derailleur first as these following posts today and tomorrow will cover basic set-up and adjustments. Following these posts I will get into how to adjust shifting with the cable adjustment feature found on many rear derailleurs- but not all. Stay tuned for more on that coming soon. 

Today's post will get into how one would start to set up a brand new, or new-to-the-bike, rear derailleur. There are certain things you will want to do in a certain order that will make your life a lot easier when replacing one of these mechanisms. Also- while I will not discuss electronic rear derailleurs here, many of these basic principals still apply. Always refer to manufacturer's instructions, or take it to a bicycle technician if in doubt. Getting today's lesson wrong (or tomorrow's) can result in damaged parts and possibly a crash and injury/death. (No kidding!) So, if you have any questions at all about your understanding of these basics, get help! It's not worth it to take a chance here. 

Okay, with that out of the way, I would start this process with the chain off. You should have the rear wheel installed with whatever cassette you are going to use. The rear derailleur can then be mounted to the hangar of the frame (replaceable hangar in most cases, probably) and then we can get started.

First, let's familiarize ourselves with the important parts of today's discussion in regard to setting up a rear derailleur. I'll refer to the image above: Working from Left to Right...

1. The cable fixing bolt, where the cable attaches. To get here, you may have to follow a circuitous path (SRAM) or specific leverage arms may have to be engaged. These are specific to individual derailleurs and may not apply in your case as well. Check manufacturer's manuals on your specific derailleur or consult an expert if in doubt. (This part won't be covered today or tomorrow)
   
2. The "HIGH" limit screw on a Shimano rear mech is almost always the upper of two screws, or as in this case with a GRX rear derailleur, a pair of 2mm hex head bolts. These are used ONLY ONCE and then you should not have to touch them again. 
3. The "LOW" limit screw. Both the "HIGH" and the "LOW" limit screws do what they say- They LIMIT derailleur travel. One on the "high"- or smallest cog of the cassette side, and the "low" is for the lowest gear/largest cassette cog side. These LIMIT the travel of the rear derailleur so your chain does not go off into the spokes or off on the other end into the frame. NOTE- These screws DO NOT AFFECT HOW YOUR BICYCLE SHIFTS, other than in one important way, which I will get to in my follow-up post. 
4. The "B Tension" screw, or as in this case, a 2mm hex head screw. This is the adjustment for the upper jockey wheel's relationship to the cassette. This will be discussed in more detail when I get to the end of this post.

Now, if you have the rear derailleur mounted, with no chain on, and no cable attached, you are ready to set the derailleur's travel limits using the limit screws. First, determine what type of screw/bolt you are looking at. Most of the time these will be JIS/Phillips type screws which have what looks like a "cross" slotted head. Other times you may see Torx/flat blade screwdriver heads. Other times you may see these 2mm hex head bolts, as with the example above. 

Also worth noting is that the "HIGH" and the "LOW" limit screws won't always be arranged in the same manner. Refer to the following images for more...

A typical SRAM MTB set up with the HIGH and LOW screws reversed from the typical Shimano positions.

Another SRAM set-up where the screws are not marked.. Note the interface tool type.

What if, as in the last image above, you don't have any markings to know which is "HIGH" and which screw controls the "LOW" limit? Well, you can visually inspect the rear derailleur for clues. 

Most rear derailleurs (NOT ALL) have a "resting" position. This is the state of the mechanism when there is no cable attached. The rear derailleur is typically in its "collapsed" state, which is when the HIGH limit screw will be in contact with some part of the rear derailleur. Visual inspection should lead you to identify which screw is the HIGH one. That leaves the other screw as being the LOW limit. See the following images...

#1: This screw rests against the derailleur at point indicated by #2 when the rear derailleur has no cable attached. So, this is the "HIGH" limit screw on this derailleur. 

On this SRAM rear derailleur you can see the limit screws protruding from the inside of the parallelogram part of the rear derailleur. The nearest to to foreground is the "HIGH" limit, as can be seen by the indicator on the parallelogram's outer side. But if that marking weren't there, you'd be able to see that this screw would be in contact with the inner part of the front knuckle of the derailleur if it were at rest. I have the derailleur partially actuated for this view. 

Now that you know which screw is which, and how to determine that, you can move on to setting the limits of derailleur travel. Typically, you'd set the "HIGH" limit first, as this is the critical 'starting' point for shifting. If the start point is off, the indexing of your shifter won't place the rear derailleur in the exact position it needs to be in to do its job. So, in a way, this particular screw is crucial to the operation of your shifter, but once it is set, you forget it!

As with either limit screw, clockwise rotation of the screw results in limitation of movement to the "outer-side" of the system. So, in the case of the "HIGH" limit screw, clockwise rotation sets a limit for movement further inboard as you turn that screw. Counter-clockwise rotation of the screw results in setting the limit further outboard, so the derailleur will move away from the center of the bicycle as you make this adjustment. 

Ideally, you want the upper jockey wheel of your rear dérailleur to sit directly underneath the smallest cassette cog when the rear derailleur is at rest. Adjust that limit screw until you see that relationship, and that is your "starting point" to adjusting the shifting. Now when the cable is adjusted correctly, (more on that later on in this series), your shifter will index correctly with the cassette and the rear derailleur will "derail" the chain properly to the next lowest gear, and when coming back again, it won't hesitate or overshoot the last cog and go into the frame. 

Okay, that's enough for today! Tomorrow I will cover the trick I use to set the low limit screw. The "B tension" screw discussion will come later. Also, in a following post, I will get into how to connect the rear cable, how to address cable tension for your rear derailleur, what tricks I use, and that should be all you'll need to set up and adjust most rear derailleurs out there. 

Tomorrow: Rear Derailleur Set-Up Basics - Part 2

Guitar Ted's How-To: Rear Derailleur Basics

Back again with another post on "How-To" and this time it will help you to understand rear derailleur basics. 

The last How-To post was about tubeless rim taping and can be found HERE. There is a link from that post to another How-To on tubeless tire mounting, by the way. 

Okay, this post will NOT describe every rear derailleur situation, but it WILL describe how almost every rear derailleur on modern bikes works, even electronic ones, to a degree. All rear derailleurs owe there basics to how these devices evolved up to the era of indexed shifting which dawned in the 1980's. 

While variations on the theme have been produced, almost every rear derailleur since the 1980's has basics that are the same in function. That's what this post will help you to understand, and when you understand these basic principles, your understanding of adjustments and care for rear derailleurs should be enhanced. 

Or let's hope so! 

Okay, on with the show here.....

Rear Derailleur Basics: Anti-clockwise from the upper left.....

1. "B" tension screw. This can be a Phillips (It isn't really, but for sake of simplicity here...) head screw or a hex head screw. It determines where in space that the upper jockey wheel (See #7) tracks the cassette or freewheel cogs. Needs only to be set once- then forget it!
2. Outside (or HIGH) limit screw. Can be a Phillips, (again- it isn't really, but..), or a hex head screw. On Shimano rear derailleurs it is almost always the upper/higher screw. On SRAM it is usually the lower one. On SRAM rear derailleurs with screws set side-by-side it is the innermost to the rear wheel screw. Generally marked with an "H", but not always. The function of this limit screw is to keep the derailleur from traveling too far outward and just enough to place the upper jockey wheel underneath the smallest cassette/freewheel cog in the highest gear setting. Set once and forget it!
3. Inner (or LOW) limit screw. Similar to #2 only the opposite is true with regard to which screw it is and what it does. This one is really important to get right or your chain will go over the top of the cassette/freewheel and into your spokes, and likely will destroy the rear derailleur in the process. Limit the travel of the rear derailleur so that this does not happen, but so that the chain will shift into the lowest gear. Set once and forget it!
4. Rear cable adjuster. This tensions the derailleur cable so that the shifter will operate the derailleur correctly. (Not applicable to electronically shifted derailleurs, of course) This should only be adjusted when the derailleur is in its resting position, (almost always in the highest gear, but there are exceptions), and should be adjusted so that when the shifter is activated, the chain moves immediately into the second smallest cog. Counter-clockwise rotation of the adjuster tightens the cable, and clockwise loosens it. The adjustment procedure will be covered in a different "How-To" post. NOTE: Not all rear derailleurs have this. Most notably some SRAM rear derailleurs. 
5. Rear derailleur cable attachment: Not applicable to electronically shifted systems. The big thing here is to make sure you thread the cable past the fixing bolt in the proper manner or the rear derailleur will not operate correctly. SRAM rear derailleurs and some newer Shimano rear derailleurs require a specific, circuitous routing, so be careful when replacing a cable! This matters on ALL rear derailleurs, by the way. 
6. Chain routing: When replacing a chain, be extra careful to route the chain through the rear derailleur properly. It is easy to get this wrong which can lead to noises, poor shifting, and permanent rear derailleur damage. 
7. Jockey Wheels: The arrow points to the lower one here, but there is an upper one as well. Both need to be cleaned and lubricated regularly. Failure to do this will result in excess friction, requiring more watts of work from the rider. Failing to clean and lubricate jockey wheels can also lead to premature wear, poor shifting, noises, and more. If you dare to remove a jockey wheel keep in mind that the upper one cannot be swapped for the lower and vice versa. They have specific design and functions. Also: It is imperative that when you replace the axle bolts that they be treated with thread locking compound to prevent them from backing out while riding and possibly causing a crash. 
8. Rear derailleur attachment bolt. Most often a 6mm hex head, but it can be a Torx bolt on some higher end rear derailleurs. Once attached you generally don't have to ever mess with this bolt.

Even oddball rear derailleurs like this one from Ingid use these same basic mechanical principles.

Okay, so this isn't really a "how-to" so much as it is a "how it is". The thing is, once I do get to the article on how to adjust these, I don't want you to ask me "Hey Ted, What does that screw do?". You should know now because you read this article. 

As you may have guessed the next "How-To" will address setting up and adjusting the rear derailleur. Stay tuned...

Guitar Ted's How-To: Rear Derailleur Basics

Back again with another post on "How-To" and this time it will help you to understand rear derailleur basics. 

The last How-To post was about tubeless rim taping and can be found HERE. There is a link from that post to another How-To on tubeless tire mounting, by the way. 

Okay, this post will NOT describe every rear derailleur situation, but it WILL describe how almost every rear derailleur on modern bikes works, even electronic ones, to a degree. All rear derailleurs owe there basics to how these devices evolved up to the era of indexed shifting which dawned in the 1980's. 

While variations on the theme have been produced, almost every rear derailleur since the 1980's has basics that are the same in function. That's what this post will help you to understand, and when you understand these basic principles, your understanding of adjustments and care for rear derailleurs should be enhanced. 

Or let's hope so! 

Okay, on with the show here.....

Rear Derailleur Basics: Anti-clockwise from the upper left.....

1. "B" tension screw. This can be a Phillips (It isn't really, but for sake of simplicity here...) head screw or a hex head screw. It determines where in space that the upper jockey wheel (See #7) tracks the cassette or freewheel cogs. Needs only to be set once- then forget it!
2. Outside (or HIGH) limit screw. Can be a Phillips, (again- it isn't really, but..), or a hex head screw. On Shimano rear derailleurs it is almost always the upper/higher screw. On SRAM it is usually the lower one. On SRAM rear derailleurs with screws set side-by-side it is the innermost to the rear wheel screw. Generally marked with an "H", but not always. The function of this limit screw is to keep the derailleur from traveling too far outward and just enough to place the upper jockey wheel underneath the smallest cassette/freewheel cog in the highest gear setting. Set once and forget it!
3. Inner (or LOW) limit screw. Similar to #2 only the opposite is true with regard to which screw it is and what it does. This one is really important to get right or your chain will go over the top of the cassette/freewheel and into your spokes, and likely will destroy the rear derailleur in the process. Limit the travel of the rear derailleur so that this does not happen, but so that the chain will shift into the lowest gear. Set once and forget it!
4. Rear cable adjuster. This tensions the derailleur cable so that the shifter will operate the derailleur correctly. (Not applicable to electronically shifted derailleurs, of course) This should only be adjusted when the derailleur is in its resting position, (almost always in the highest gear, but there are exceptions), and should be adjusted so that when the shifter is activated, the chain moves immediately into the second smallest cog. Counter-clockwise rotation of the adjuster tightens the cable, and clockwise loosens it. The adjustment procedure will be covered in a different "How-To" post. NOTE: Not all rear derailleurs have this. Most notably some SRAM rear derailleurs. 
5. Rear derailleur cable attachment: Not applicable to electronically shifted systems. The big thing here is to make sure you thread the cable past the fixing bolt in the proper manner or the rear derailleur will not operate correctly. SRAM rear derailleurs and some newer Shimano rear derailleurs require a specific, circuitous routing, so be careful when replacing a cable! This matters on ALL rear derailleurs, by the way. 
6. Chain routing: When replacing a chain, be extra careful to route the chain through the rear derailleur properly. It is easy to get this wrong which can lead to noises, poor shifting, and permanent rear derailleur damage. 
7. Jockey Wheels: The arrow points to the lower one here, but there is an upper one as well. Both need to be cleaned and lubricated regularly. Failure to do this will result in excess friction, requiring more watts of work from the rider. Failing to clean and lubricate jockey wheels can also lead to premature wear, poor shifting, noises, and more. If you dare to remove a jockey wheel keep in mind that the upper one cannot be swapped for the lower and vice versa. They have specific design and functions. Also: It is imperative that when you replace the axle bolts that they be treated with thread locking compound to prevent them from backing out while riding and possibly causing a crash. 
8. Rear derailleur attachment bolt. Most often a 6mm hex head, but it can be a Torx bolt on some higher end rear derailleurs. Once attached you generally don't have to ever mess with this bolt.

Even oddball rear derailleurs like this one from Ingid use these same basic mechanical principles.

Okay, so this isn't really a "how-to" so much as it is a "how it is". The thing is, once I do get to the article on how to adjust these, I don't want you to ask me "Hey Ted, What does that screw do?". You should know now because you read this article. 

As you may have guessed the next "How-To" will address setting up and adjusting the rear derailleur. Stay tuned...

Guitar Ted's How To: The Rim Taping Reference Post

Okay! You asked for it, now you got it! (Well, a couple of you asked for this) This stems from the comments from my last "How To" post. Anyway, this post will be a reference post more than anything since I have written a bunch already on tubeless tire taping procedures and how I do this.

As with anything, quality materials are everything when it comes to successful outcomes. So, make sure you use a tubeless rim and really high quality rim tape with great valves. Never assume that you can get away with using a not-for-tubeless rim, a duct tape variant, or old, used up valves. 

Want to save money? That's cool. We all do. Read THIS POST for great tips on how to get high-quality rim tape or sealant for your set up. Make sure you read the comments at the bottom for more great tips. 

Side Note: If you are re-using a tire with a lot of old sealant in it, READ THIS POST for tips on how to remove old sealant. 

For more on the preparation of you tire, rim tape installation, and valve core tips, read THIS POST. This is an over-all look at tubeless tire set-up, but the rim taping thing is in there.

More Tips:

Actually putting tape on a rim is an arduous task. My number one tip is to get prepped properly (cleaned rim, great tape, right tools) and use plenty of patience. Taping two rims is not a race. The ordinary rider should expect this to take up to and over a half an hour of your time. I know mechanics that will scoff at that, but they do things trying to be fast and efficient. People that are not mechanics don't have that constraint or need. Take your time taping and get it right.

Tools: I'll say it- a truing stand is your best friend here. You can tape a rim "free style", out of a bike, and you can tape a rim in a bike with it upside down on the floor. But a truing stand, properly affixed to a bench, makes taping a rim waaaaay easier. Obviously a truing stand is good for more than this, so seriously consider that as an upgrade to your shop. 

Technique: The next big thing to add here is technique, and what I do is almost impossible without a truing stand, that's why I recommend a truing stand for your personal shop. I pull the tape gently with my right hand and hold the starting end down with my left thumb in the inner rim well. I pull maybe three inches, carefully align it, and pull it down toward the rim well. At the same time I start sliding my left thumb downward, but this is tricky as you have to not let the wheel rotate. 

Once I lay the tape down on the rim then I use my left thumb or I'll use my right forefinger to press the tape down starting at the furthest point from the roll and working toward the roll. I only push it down in the center of the tape. I don't bother worrying about the edges until later. 

I always put two laps of tape down on a rim. This is to help the tape withstand air pressure at the spoke holes. You could also use something like these Velocity Rim Plugs which would do the same thing. Another product that aims to alleviate the same problem is the WTB Solid Strip. By using these you might get away with one run of rim strip. However; I'd still use two runs of tape, because saving whatever weight using one run would give you, it is not worth it. 

Rim tape should be wide enough that it covers up to where the bead of the tire will sit at a minimum and up to the rim's inner edge if at all possible. Never try overlapping tape to make it "wide enough". Get the right width rim tape instead. 

Other than that, I always start taping at the point 180° from the valve stem. I've seen tape jobs that start near the valve stem, but in my opinion this invites a possible failure. Tape ends are prone to lifting and letting sealant seep between layers of tape or the tape and the rim well. If this occurs near a valve stem, a perfect place for pressure to escape, then you have a big problem. So, why not avoid that possibility and start your tape end at a point the furthest away from that big hole in the rim for the valve? 

That's it. Did I miss anything you wanted to know? (Don't forget to check the links!) Hit me up in the comments.

Guitar Ted's How To: The Rim Taping Reference Post

Okay! You asked for it, now you got it! (Well, a couple of you asked for this) This stems from the comments from my last "How To" post. Anyway, this post will be a reference post more than anything since I have written a bunch already on tubeless tire taping procedures and how I do this.

As with anything, quality materials are everything when it comes to successful outcomes. So, make sure you use a tubeless rim and really high quality rim tape with great valves. Never assume that you can get away with using a not-for-tubeless rim, a duct tape variant, or old, used up valves. 

Want to save money? That's cool. We all do. Read THIS POST for great tips on how to get high-quality rim tape or sealant for your set up. Make sure you read the comments at the bottom for more great tips. 

Side Note: If you are re-using a tire with a lot of old sealant in it, READ THIS POST for tips on how to remove old sealant. 

For more on the preparation of you tire, rim tape installation, and valve core tips, read THIS POST. This is an over-all look at tubeless tire set-up, but the rim taping thing is in there.

More Tips:

Actually putting tape on a rim is an arduous task. My number one tip is to get prepped properly (cleaned rim, great tape, right tools) and use plenty of patience. Taping two rims is not a race. The ordinary rider should expect this to take up to and over a half an hour of your time. I know mechanics that will scoff at that, but they do things trying to be fast and efficient. People that are not mechanics don't have that constraint or need. Take your time taping and get it right.

Tools: I'll say it- a truing stand is your best friend here. You can tape a rim "free style", out of a bike, and you can tape a rim in a bike with it upside down on the floor. But a truing stand, properly affixed to a bench, makes taping a rim waaaaay easier. Obviously a truing stand is good for more than this, so seriously consider that as an upgrade to your shop. 

Technique: The next big thing to add here is technique, and what I do is almost impossible without a truing stand, that's why I recommend a truing stand for your personal shop. I pull the tape gently with my right hand and hold the starting end down with my left thumb in the inner rim well. I pull maybe three inches, carefully align it, and pull it down toward the rim well. At the same time I start sliding my left thumb downward, but this is tricky as you have to not let the wheel rotate. 

Once I lay the tape down on the rim then I use my left thumb or I'll use my right forefinger to press the tape down starting at the furthest point from the roll and working toward the roll. I only push it down in the center of the tape. I don't bother worrying about the edges until later. 

I always put two laps of tape down on a rim. This is to help the tape withstand air pressure at the spoke holes. You could also use something like these Velocity Rim Plugs which would do the same thing. Another product that aims to alleviate the same problem is the WTB Solid Strip. By using these you might get away with one run of rim strip. However; I'd still use two runs of tape, because saving whatever weight using one run would give you, it is not worth it. 

Rim tape should be wide enough that it covers up to where the bead of the tire will sit at a minimum and up to the rim's inner edge if at all possible. Never try overlapping tape to make it "wide enough". Get the right width rim tape instead. 

Other than that, I always start taping at the point 180° from the valve stem. I've seen tape jobs that start near the valve stem, but in my opinion this invites a possible failure. Tape ends are prone to lifting and letting sealant seep between layers of tape or the tape and the rim well. If this occurs near a valve stem, a perfect place for pressure to escape, then you have a big problem. So, why not avoid that possibility and start your tape end at a point the furthest away from that big hole in the rim for the valve? 

That's it. Did I miss anything you wanted to know? (Don't forget to check the links!) Hit me up in the comments.

Guitar Ted's How-To: Mounting Tubeless Tires

 I'm going to start sharing some tips from time to time in a series I'll call "Guitar Ted's How-To". This time I am going to share with you how I mount tubeless tires. 

Now, this isn't the only way to do things. It is the way I do things. So, I'm not implicating anyone else's techniques as being "less than good", bad, or great. Nope! This is how I do it. If you can draw anything good from this, then great.

I will say that I've been a bicycle mechanic off and on for the better part of 30 years and a car mechanic for five and a half years. So, in my opinion I will tell you that this way works well. It's not the only way to mount tubeless tires, but I think it is the easiest way. 

Before You Start: I've done hundreds of tubeless tire set-ups over the last 10+ years. I've made a ton of mistakes. So, when I say "do this before you start.", it probably is me telling you, "Hey! I've tried skipping this step. Don't do it!". But - ya know- I can't make you do anything here. Just don't complain to me when things go pear-shaped on you. 

Use a quality sealant and make sure it is fresh.

Use New Tubeless Compatible Components Wherever Possible: Obviously not everyone can use new stuff, but I will tell you NOT to use non-tubeless stuff. We used to have to do this. Now there is no reason at all to use non-tubeless tires, rim strips, sealant, or rims. It's BEST not to re-use valve stems, old tape jobs, old tires, and old sealant. At a minimum, you should use NEW sealant, NEW valves, and re-tape your rims. Not doing that means a BIG chance for a failure resides in your wheel like a ticking time bomb. 

If you try to re-use old stuff, and there is a failure, you can almost bet it is because your tape failed, a stem leaks due to corrosion, or the sealant was too old. Rarely is it anything else. Well......unless you did something wrong or you punctured beyond the sealant's abilities to repair the leak. 

• Tools & Supplies: With that out of the way, you need to use the following items:
• Work gloves- preferably those annoying, tight fitting rubber ones. 
• Safety glasses 
• Isopropyl Alcohol
• Rags or Shop Towels
• Plastic injector tool or a small scoop.
  
• Valve Core removal tool
• A really good floor pump (One of those tubeless compatible ones is even better)
• Sealant
• Tires
• Tubeless Rim Tape (If you haven't done it already. Taping is a separate task from this post, so I won't get into it here. Skip if this is a new wheel with a new tape job..)
• New valves, or at least new valve cores.
  

Not necessary, but it would make life easier: A small air compressor, a bicycle repair stand, and a truing stand. 

Procedure: I will assume that you've thoroughly cleaned the rim's inner well and that it is free from dirt, adhesive, old tape, and that you cleaned that inner rim well with isopropyl alcohol. I assume then that you installed a quality tubeless compatible rim tape that is appropriately sized for your rims. I also am assuming you are using new valve stems, or at least good valve stems with NEW CORES. 

Now that is a LOT of assuming, and you know what that makes me then right? Okay, carrying on then....

Make sure that your tires do not have big patches of dried up sealant sticking in one end of the tire, and clean off the bead seat, making sure there is no layer of dried sealant sticking to the bead area at all. The rest of the inner tire carcass? I don't care what you do there, just don't leave anything on the bead area or anything in there that could cause a wheel imbalance at high speeds. Best to use NEW tires, but again- not everyone can afford that.

Tire Orientation: This is EASY to miss and get wrong, so pay attention closely to how your tire is supposed to be mounted.  Most tires are "directional", meaning that they are intended to be rotated in one direction for best results. This will be indicated in tiny, hard to read lettering which is molded into the tire sidewall. Sometimes all you get is an arrow. Sometimes words AND an arrow. Just pay attention to this,or you may be sorry later.

For further instructions, read on and refer to the following images.... 

Here is where you start, and if you do it this way, you should not need to use a tool to mount your tires. Place the new tubeless compatible tire so that your wheel rests inside the casing. It should look like this image to the left all the way around. 

Now you can double check your correct rotating direction. Then align the branding patch, or "hot patch" as I was told to do this many years ago, so that it aligns with your valve stem. Yes.....it is a meaningless "Pro" thing to do, only it isn't meaningless and there is a very practical reason for doing this. I don't have the time to get into all of that here. You can accept that or not, but there is a reason for this to be done.

Okay, now you can start moving one side of the tire up and over the rim and into the rim well. I like to start at the valve stem to make sure the tire sits in between the butt end of valve stem and the inner rim wall. Then, look at that grip I use to the left there. This is THE grip you want to use with BOTH hands. (I had to use one to take the image, so....)

Use your thumbs to push the tire up and over, starting with your hands together at the valve stem and working outwards and downwards to the "six o'clock" position as the wheel sits. Use your grip with your other fingers and your palm as a foundation for your thumbs to work from. 

The tire bead can sit in the inner part of the inner rim well which will make this side of the tire easier to get on the rim. Now you are ready to work on the opposite side.

Using The Grip, shown in the previous step, you can again start at the valve stem, making sure the tire bead is exactly in between the valve stem in there and the rim edge. If the tire bead sits up on the valve stem, or if you get two beads on one side of a valve stem, (don't ask.) you may not notice this and setting up the tire will become impossible. So, pay attention here! 

Work the bead of that tire up and over the rim edge using 'The Grip' . You may actually now want to fold the tire over the rim, (see top image in this section), which will allow you maximum grip on the tire, and maximum leverage over that bead. You still want to use your thumbs to push up and over, but by rotating that tire carcass over the rim, you will gain an advantage. 

The next image shows how I stand and use my leg to brace off of as I use my two hands to push the tire over the rim edge. (Again, only showing one hand here as I had to take the image with the other) Now, it is important to note that I do not mount the entire tire. I leave a little bit out over the rim edge and then I inject sealant. You can go ahead and put the tire all the way on here. Sealant can be introduced through the valve with the core removed, but I've found that method to be less than satisfactory for a few reasons. So, I don't do that. 

I use this cheap but effective injection tool.

The red arrows indicate the space I leave to inject sealant into the tire.

Sealant installed and now I am ready to seat the remaining portion of the tire.

A couple of notes on the images above. First, I have gravitated to these smaller, more nimble, but very effective plastic injectors meant for veterinary usage. They have a nipple perfectly sized to fit into a valve with the core removed, fit inside wheel's space between the hub and rim well at full extension, and have excellent sealing properties as far as the plunger goes. This makes these great at sucking up sealant when I want to recover it from a tire I am removing.

The plastic tub is where I keep recovered sealant. While I recommend that you use new sealant, I switch out at least a couple of pairs of tires every month, sometimes more than that. So, it makes sense for me to keep the "old" sealant and reuse it. You? I'm guessing you don't change tubeless tires very often. 

By the way, I use about 100ml of sealant in a gravel tire. Use whatever sealant you believe in. Most are pretty darn good. I use WTB's stuff nowadays. 

Yes, I used an image twice. Deal with it!

That final bit of tire can now be pushed up and over the rim edge and you'll probably have to fold that tire over hard to get it to go. Your thumbs may hate you, but you will be successful without using a tool, and not using a tool is better because it means that you pretty much cannot damage the rim tape, tire, or rim. 

Now you can air up the tire. You may be really lucky and just be able to use a floor pump. You may need to remove the valve core and use a floor pump.These two scenarios are what I see from my experience 90% of the time now. The other ten percent I need a blast from an air compressor, but that is getting more and more rare now days. 

Once you get ALL the tire bead up and into its position on the rim, you are set to go for a short ride to help seal the tire to the rim. It takes about 15 minutes, and then you are good to go. Clean up the tire and rim with isopropyl alcohol and a rag when you are done.

Final notes: Loud snapping and popping when the tire is being aired up is normal. You may think it is a violent, scary sound, (and it is), but it is okay. This is just the bead of the tire finally snapping up into the shelf on the rim's inner wall where it belongs. You can check for this after you think you are finished by spinning the wheel and watching the line where the tire and rim edge meet. There should be a fine, molded in line on the tire sidewall visible at an equidistant point from the rim edge all the way around on both sides. If the tire is not correctly seated, this will appear - or rather disappear- as the wheel spins, as a low spot in the tire. You just need a bit more air pressure to POP! that out. 

The red arrows point to the "line" I am referring to in the previous paragraph.

Typically I find that tires will sit into place at about 40psi. However; sometimes I have had to go as high as 50+ psi, but those times are getting rarer as tubeless stuff gets more dialed in. Oh, and if you had to remove the valve core, make sure you don't let all the air out. Be like the Dutch boy with his finger in the dike until you get the core snuck back up in there. Snug the core up- don't crank on it. Refill to the desired pressure. Ride.... 

Hmm.... I think that's about it. Got questions? Have ideas for other posts like this? let me know in the comments, please.