Bicycle Chain Line Nerd-Out

 Last week in my post about the upcoming Singular Gryphon Mk3 build, I received a couple of comments regarding why a triple chain ring crank set would not work on that frame if a double crank set might. The thinking there was that if there is room for two, why not three? 

That's a great question, and I tried my best in the comments to take a stab at answering that. However; there are two problems with that. One: With no visual aids, it gets difficult very quickly to communicate ideas. Two: My answer was in the comments, which means not very many people would see that discussion nor get any benefit from it. Since two folks were wondering what the deal was, I figured perhaps many more of you were as well. So, today I am going to cover this problem and I have some visual aids and extra reading sources for you to explore, should you want a further dive into this subject. 

The area around your bicycle's bottom bracket is a very complex, busy area that has a lot going on in terms of engineering, physics, and mechanically also. It is a lot more than meets the eye. Our problem that we are going to tackle today is one that is confusing for some folks and a mystery to many- That being how one determines what size chain rings work on a given frame. While there are recommendations for chain ring sizing for many bikes, not all examples have that resource. You can check this out for yourself at home with a metric ruler and, if you really want to get nerdy, a plumb bob. But you should be able to do this with a ruler and a good eye.

Illustration from Australian publication, "RideOn"

Chain Line: The big determining factor in sizing chain rings is what is called "chain line", or as it is often shown all run together as "chainline". Chainline is the distance between your bicycle frame's centerline vertically and an imaginary line which runs parallel to that through the centerline of the rear cassette and crank arm chain rings. This helps designers of bicycles and drive train gear to match up the best, optimal shifting drive train with clearances for frame members and rear tires. 

In the illustration above note how the chainline for a triple crank centers on the middle chain ring while the chainline for a double ring crank set falls in between the two rings. You can also think of this as the "space" that a triple carnkset takes up which a double crankset fits within with room to spare because both sets of rings are centered on the chainline. In effect, this double crank set's inner ring actually sits slightly further from the bicycle's centerline than a triple carnkset's granny/inner ring does. That's why a triple might not fit a frame, but a double may fit that same frame. 

Keep in mind also that the bottom bracket spindle measurement is fixed in length and is not changeable. You might  be able to offset your crank a bit using spacers, but this is likely minimal if a possibility at all these days. It used to be that chain lines were adjustable with the use of certain bottom brackets (Phil Wood) or by using different offset length spindles on the old, serviceable bottom brackets, but those days are long gone now. 

Chainline affects three critical areas on a bicycle

The first illustration I used is a bit misleading because nowadays bicycles are cramming a lot more tire into a space that has a shorter distance from the cranks to the rear axle than ever before. The second image here is a bit better look at what most designers are dealing with today. A big tire, a shorter rear/center distance, and drive train constraints which have to all work together in harmony. I've numbered three critical places that can cause issues if everything (all three things) don't work in harmony or within predetermined specs set up by the manufacturers. 

1: Chainring/chainstay clearances. Remembering that our bottom bracket spindle length is fixed, and that is pretty much not a thing we can offset much one way (side-to-side) or at all. So, we have to keep chain ring sizes to a certain range so the frame's chainstay has room to pass the chain rings and the rear tire. This, more than anything else, limits chain ring sizes, and in many cases today, limits you to one chain ring only. 

2: Tire Clearances: Riders today are wanting to slam in the biggest rubber that they can, and even road bike riders are looking at 30+ mm tires these days. Well, you have to allow, by dictate of testing protocol and CPSC rules, 5mm of tire clearance, at minimum, between frame embers and tires. This is a limitation any brand that wants certification and testing in the marketplace has to adhere to. Custom frame makers? Not so much, but the good ones will still hold to this standard. Keeping things to a 5mm clearance limits chain ring possibilities along with tire sizes. 

3: Crank Arm Clearances: The last thing we need to understand is that you cannot just flare out the chain stays on either side to get around tires because your cranks have to have room to spin by frame members as well. Additionally, your feet are swinging around in circles down here also. That only adds to the complexity and all of this relates back to chain line and centerline for frames.

In Conclusion: The complexities of frame/chain line/drive train/tire clearance issues is a thorny problem to solve, but amazingly, designers and engineers are working out new solutions all the time. Boost chain line, for instance, which allows MTB bikes to have bigger tires and room for chain ring, frame members, and works with that wider rear hub spacing which also strengthens rear wheels. Dropped chain stays on gravel bikes which is a ploy to keep chain stays short but allow for big tires as well.

But in terms of what drive train bits will and will not work on your bicycle, well that is something you can measure at home. This article by Sheldon Brown is a gold mine for tinkerers or anyone that wants to nerd-out on the subject. 

I hope that helps you all out there who were wondering how crank set/chain ring choices may or may not work on a particular bicycle. Thanks for reading Guitar Ted Productions!

Bicycle Chain Line Nerd-Out

 Last week in my post about the upcoming Singular Gryphon Mk3 build, I received a couple of comments regarding why a triple chain ring crank set would not work on that frame if a double crank set might. The thinking there was that if there is room for two, why not three? 

That's a great question, and I tried my best in the comments to take a stab at answering that. However; there are two problems with that. One: With no visual aids, it gets difficult very quickly to communicate ideas. Two: My answer was in the comments, which means not very many people would see that discussion nor get any benefit from it. Since two folks were wondering what the deal was, I figured perhaps many more of you were as well. So, today I am going to cover this problem and I have some visual aids and extra reading sources for you to explore, should you want a further dive into this subject. 

The area around your bicycle's bottom bracket is a very complex, busy area that has a lot going on in terms of engineering, physics, and mechanically also. It is a lot more than meets the eye. Our problem that we are going to tackle today is one that is confusing for some folks and a mystery to many- That being how one determines what size chain rings work on a given frame. While there are recommendations for chain ring sizing for many bikes, not all examples have that resource. You can check this out for yourself at home with a metric ruler and, if you really want to get nerdy, a plumb bob. But you should be able to do this with a ruler and a good eye.

Illustration from Australian publication, "RideOn"

Chain Line: The big determining factor in sizing chain rings is what is called "chain line", or as it is often shown all run together as "chainline". Chainline is the distance between your bicycle frame's centerline vertically and an imaginary line which runs parallel to that through the centerline of the rear cassette and crank arm chain rings. This helps designers of bicycles and drive train gear to match up the best, optimal shifting drive train with clearances for frame members and rear tires. 

In the illustration above note how the chainline for a triple crank centers on the middle chain ring while the chainline for a double ring crank set falls in between the two rings. You can also think of this as the "space" that a triple carnkset takes up which a double crankset fits within with room to spare because both sets of rings are centered on the chainline. In effect, this double crank set's inner ring actually sits slightly further from the bicycle's centerline than a triple carnkset's granny/inner ring does. That's why a triple might not fit a frame, but a double may fit that same frame. 

Keep in mind also that the bottom bracket spindle measurement is fixed in length and is not changeable. You might  be able to offset your crank a bit using spacers, but this is likely minimal if a possibility at all these days. It used to be that chain lines were adjustable with the use of certain bottom brackets (Phil Wood) or by using different offset length spindles on the old, serviceable bottom brackets, but those days are long gone now. 

Chainline affects three critical areas on a bicycle

The first illustration I used is a bit misleading because nowadays bicycles are cramming a lot more tire into a space that has a shorter distance from the cranks to the rear axle than ever before. The second image here is a bit better look at what most designers are dealing with today. A big tire, a shorter rear/center distance, and drive train constraints which have to all work together in harmony. I've numbered three critical places that can cause issues if everything (all three things) don't work in harmony or within predetermined specs set up by the manufacturers. 

1: Chainring/chainstay clearances. Remembering that our bottom bracket spindle length is fixed, and that is pretty much not a thing we can offset much one way (side-to-side) or at all. So, we have to keep chain ring sizes to a certain range so the frame's chainstay has room to pass the chain rings and the rear tire. This, more than anything else, limits chain ring sizes, and in many cases today, limits you to one chain ring only. 

2: Tire Clearances: Riders today are wanting to slam in the biggest rubber that they can, and even road bike riders are looking at 30+ mm tires these days. Well, you have to allow, by dictate of testing protocol and CPSC rules, 5mm of tire clearance, at minimum, between frame embers and tires. This is a limitation any brand that wants certification and testing in the marketplace has to adhere to. Custom frame makers? Not so much, but the good ones will still hold to this standard. Keeping things to a 5mm clearance limits chain ring possibilities along with tire sizes. 

3: Crank Arm Clearances: The last thing we need to understand is that you cannot just flare out the chain stays on either side to get around tires because your cranks have to have room to spin by frame members as well. Additionally, your feet are swinging around in circles down here also. That only adds to the complexity and all of this relates back to chain line and centerline for frames.

In Conclusion: The complexities of frame/chain line/drive train/tire clearance issues is a thorny problem to solve, but amazingly, designers and engineers are working out new solutions all the time. Boost chain line, for instance, which allows MTB bikes to have bigger tires and room for chain ring, frame members, and works with that wider rear hub spacing which also strengthens rear wheels. Dropped chain stays on gravel bikes which is a ploy to keep chain stays short but allow for big tires as well.

But in terms of what drive train bits will and will not work on your bicycle, well that is something you can measure at home. This article by Sheldon Brown is a gold mine for tinkerers or anyone that wants to nerd-out on the subject. 

I hope that helps you all out there who were wondering how crank set/chain ring choices may or may not work on a particular bicycle. Thanks for reading Guitar Ted Productions!

Nerding Out On Bikes

I've spent an inordinate amount of time nerding out on bikes, but I'm not the only one.

Bike nerd here. Maybe you are as well? How do you know? Maybe if you cannot keep from constantly thinking about "improvements" to your bicycle. Maybe if you are super curious about "that other guy's rig", or how that set up works. Basically, you think "bike" all day.

If any of that fits you, it may mean that you are a "bike nerd". I am, (big surprise!), so are a lot of other folks. It's okay.

So, to that end I post today about one of the "OG" riders of what is now known as "Tour Divide". Back then, it was "The Great Divide Mountain Bike Race" and one of its pioneers was Mike Curiak. He has been randomly posting his memoirs and images drawn from his experiences racing the Divide in the early 00's. Mike recently posted an article on his bike choices here. It is a fascinating look at the gear and why he chose it. He also goes on to explain what he would use if he were to attempt Tour Divide today. That's "if" as in "never again", according to how I am reading that, but it is a good look into how Mike would choose his bike and basic set up.

This is all especially interesting to me for several reasons. First off, the obvious- it is about bicycles. Then I find it fascinating since Mike has often said that Tour Divide is essentially a gravel race/route. That makes what he is saying about bikes very relevant to my interests. Mike also did the first Trans Iowa, on his Moots YBB, by the way, so there is also that connection. Finally, Trans Iowa drew most of its structure and rules straight from Mike Curiak himself. Even the full, original name of the event I am known for drew its inspiration from the GDMBR- "Trans Iowa Mountain Bike Race". (Jeff Kerkove and I decided to drop off the "Mountain Bike Race" part of the name after V1, but the official name of the blogspot site still includes that bit.)

At any rate, if you enjoy nerding out on bikes as much as I do, check out that link and get ready to go nerdtastic!

Nerding Out On Bikes

I've spent an inordinate amount of time nerding out on bikes, but I'm not the only one.

Bike nerd here. Maybe you are as well? How do you know? Maybe if you cannot keep from constantly thinking about "improvements" to your bicycle. Maybe if you are super curious about "that other guy's rig", or how that set up works. Basically, you think "bike" all day.

If any of that fits you, it may mean that you are a "bike nerd". I am, (big surprise!), so are a lot of other folks. It's okay.

So, to that end I post today about one of the "OG" riders of what is now known as "Tour Divide". Back then, it was "The Great Divide Mountain Bike Race" and one of its pioneers was Mike Curiak. He has been randomly posting his memoirs and images drawn from his experiences racing the Divide in the early 00's. Mike recently posted an article on his bike choices here. It is a fascinating look at the gear and why he chose it. He also goes on to explain what he would use if he were to attempt Tour Divide today. That's "if" as in "never again", according to how I am reading that, but it is a good look into how Mike would choose his bike and basic set up.

This is all especially interesting to me for several reasons. First off, the obvious- it is about bicycles. Then I find it fascinating since Mike has often said that Tour Divide is essentially a gravel race/route. That makes what he is saying about bikes very relevant to my interests. Mike also did the first Trans Iowa, on his Moots YBB, by the way, so there is also that connection. Finally, Trans Iowa drew most of its structure and rules straight from Mike Curiak himself. Even the full, original name of the event I am known for drew its inspiration from the GDMBR- "Trans Iowa Mountain Bike Race". (Jeff Kerkove and I decided to drop off the "Mountain Bike Race" part of the name after V1, but the official name of the blogspot site still includes that bit.)

At any rate, if you enjoy nerding out on bikes as much as I do, check out that link and get ready to go nerdtastic!

Now Is The Golden Age

B+ wheels on the OS Blackbuck

Bike nerds rejoice! You have more crap to play with and occupy your time with these days than ever before. At one time there were only 26" wheels for "serious' off road action, then those pesky 29"ers came about at the end of the century. Next it was the 650B/27.5"ers, and then Surly comes out with 29+! If that wasn't enough, fat bikes get in the act, then Surly does a 26+ wheel, (as seen on the Instigator II), and finally, WTB introduces the B+ concept. Did I mention 36"ers? Yeah....those too!

Look, if you don't like any of these wheel sizes, or want to bitch about any of them just for being, then you don't like bicycles or off road riding. I mean- think about this- There are more ways to satisfy the itch now and probably more than there ever has been in the history of cycling. Now is the "golden age". Don't miss it because you want to argue about a stupid wheel size. Just pick one and ride it already! Again: Bike nerds rejoice!

29+ wheels on a fat bike? Get outta here!

I am amazed at any single one of the many bicycles I own now days. I mean- I woulda killed for these wheel size choices in 1995! Back then it wasn't even a thought. Wheel size? Well.......duh! 26 inch! And tires? If you could find anything wider than a 2.25" tire it was a rarity. Rim width? Whatever! There were Mavic rims, and maybe a Campy Thor rim, or Sun Ringle' rims, and Velocity AeroHeat rims. All were skinny, road bike width rims by today's standards.

So, I wince, and chuckle, and smile wryly when I see all this wheel size posturing and arguments going on in forums or in the bike shops. We have it good now- real good, but it seems no one is getting that. "Choices are good", they say. Good for causing negativity, it would seem. Too bad. Some even seem to want to return to that simplicity and lack of choices. Really?

Pfft! I say it's all good. More choices to meet more specific needs and more ways to enjoy the fun of riding a bicycle. Could we have gotten along without it all? Sure we could. We could all "Tom Ritchey Up" and just use a road bike for everything, but isn't it more fun the way it is now?

I'd like to think so.

Now Is The Golden Age

B+ wheels on the OS Blackbuck

Bike nerds rejoice! You have more crap to play with and occupy your time with these days than ever before. At one time there were only 26" wheels for "serious' off road action, then those pesky 29"ers came about at the end of the century. Next it was the 650B/27.5"ers, and then Surly comes out with 29+! If that wasn't enough, fat bikes get in the act, then Surly does a 26+ wheel, (as seen on the Instigator II), and finally, WTB introduces the B+ concept. Did I mention 36"ers? Yeah....those too!

Look, if you don't like any of these wheel sizes, or want to bitch about any of them just for being, then you don't like bicycles or off road riding. I mean- think about this- There are more ways to satisfy the itch now and probably more than there ever has been in the history of cycling. Now is the "golden age". Don't miss it because you want to argue about a stupid wheel size. Just pick one and ride it already! Again: Bike nerds rejoice!

29+ wheels on a fat bike? Get outta here!

I am amazed at any single one of the many bicycles I own now days. I mean- I woulda killed for these wheel size choices in 1995! Back then it wasn't even a thought. Wheel size? Well.......duh! 26 inch! And tires? If you could find anything wider than a 2.25" tire it was a rarity. Rim width? Whatever! There were Mavic rims, and maybe a Campy Thor rim, or Sun Ringle' rims, and Velocity AeroHeat rims. All were skinny, road bike width rims by today's standards.

So, I wince, and chuckle, and smile wryly when I see all this wheel size posturing and arguments going on in forums or in the bike shops. We have it good now- real good, but it seems no one is getting that. "Choices are good", they say. Good for causing negativity, it would seem. Too bad. Some even seem to want to return to that simplicity and lack of choices. Really?

Pfft! I say it's all good. More choices to meet more specific needs and more ways to enjoy the fun of riding a bicycle. Could we have gotten along without it all? Sure we could. We could all "Tom Ritchey Up" and just use a road bike for everything, but isn't it more fun the way it is now?

I'd like to think so.