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!

Lessons Learned From Teaching

Yesterday I just finished up with my last Mechanics Class for the year. I had a four hour class which was held twice with two different groups of cyclists/students. I taught them the basics of bicycle mechanics, how to tune up their bicycle, and some tricks of the trade I've learned and used over almost twenty years of being a bicycle mechanic.

I'm sure the students learned a lot, and if I take their comments after the fact to heart, I would say that they actually did learn something or three along the way. But what they didn't know was how much I learned teaching them.

The classes were attended by more women than I expected. Fully one third of the total number were women. That was very heartening and, I might add, exciting from my viewpoint. I was stoked because it showed me that several women were not intimidated by the shop, or signing up for classes, and that they wanted to learn. I also was stoked on every class attendant's willingness to learn, by the way, but in this day and age where you hear all kinds of chatter this way and that about how shops are or are not doing a good job with women's needs in cycling, well...... I guess the shop I work at is doing a pretty fair job in that arena.

So, I learned that.

I also learned that people around here don't mind getting their hands dirty. That's good to see. The students dug in and worked with their bicycles and were getting knowledge built through doing. But more than that, I learned that there is a certain joy in giving away knowledge and wisdom gained through a lifetime of work.

I could be like so many mechanics who begrudgingly give out snippets of information, or who won't teach the tricks of the trade for fear that they will lose business or......whatever it is they are afraid of. I don't know. I guess I don't see it that way. I learned something quite different, actually. I learned that when you share some good information people actually respect that and trust and relationship in terms of the business actually grows stronger.

So, those are a few of the things I learned from teaching. I hope to continue that and learn even more.

Lessons Learned From Teaching

Yesterday I just finished up with my last Mechanics Class for the year. I had a four hour class which was held twice with two different groups of cyclists/students. I taught them the basics of bicycle mechanics, how to tune up their bicycle, and some tricks of the trade I've learned and used over almost twenty years of being a bicycle mechanic.

I'm sure the students learned a lot, and if I take their comments after the fact to heart, I would say that they actually did learn something or three along the way. But what they didn't know was how much I learned teaching them.

The classes were attended by more women than I expected. Fully one third of the total number were women. That was very heartening and, I might add, exciting from my viewpoint. I was stoked because it showed me that several women were not intimidated by the shop, or signing up for classes, and that they wanted to learn. I also was stoked on every class attendant's willingness to learn, by the way, but in this day and age where you hear all kinds of chatter this way and that about how shops are or are not doing a good job with women's needs in cycling, well...... I guess the shop I work at is doing a pretty fair job in that arena.

So, I learned that.

I also learned that people around here don't mind getting their hands dirty. That's good to see. The students dug in and worked with their bicycles and were getting knowledge built through doing. But more than that, I learned that there is a certain joy in giving away knowledge and wisdom gained through a lifetime of work.

I could be like so many mechanics who begrudgingly give out snippets of information, or who won't teach the tricks of the trade for fear that they will lose business or......whatever it is they are afraid of. I don't know. I guess I don't see it that way. I learned something quite different, actually. I learned that when you share some good information people actually respect that and trust and relationship in terms of the business actually grows stronger.

So, those are a few of the things I learned from teaching. I hope to continue that and learn even more.

Things Are Getting Greener

Sneak preview of the Greener Monkey

This past weekend was a busy one around here. I had two guitar playing gigs at church and an evening over at another couple's home for a dinner. I also had the honor of conducting the Mechanics Class at the shop where I had some enthusiastic students. Friday afternoon/evening, Saturday, and most of Sunday were just too busy to do anything with bikes, for the most part.

I did get in a cardboard recycling run on the Big Dummy. I think the last time I rode that bike was New Year's Day. Things were pretty clear, as far as snow and ice back then and now we find ourselves right back in that same boat again. This time I feel like it just may signal the end of Winter. Anyway, it was fun to get that bike out and use it. I met some younginz at the recycling bins and one of them stopped to compliment me on my bicycle. That was nice of the young whippersnapper!

Sunday afternoon it was really windy, so I decided not to venture out in the country. Instead, I decided to start the greening of the Monkey. I had a little trouble finding the green anodized cog I had, but I did end up finding it. It is a 17 tooth and the drive ring I am using is a 38T. That's the gearing I find most appropriate for a 29"er single speed on gravel.

I have one more green component on the way, and when that arrives, I'll be finished with the "greening of the Monkey".  Stay tuned...........

Things Are Getting Greener

Sneak preview of the Greener Monkey

This past weekend was a busy one around here. I had two guitar playing gigs at church and an evening over at another couple's home for a dinner. I also had the honor of conducting the Mechanics Class at the shop where I had some enthusiastic students. Friday afternoon/evening, Saturday, and most of Sunday were just too busy to do anything with bikes, for the most part.

I did get in a cardboard recycling run on the Big Dummy. I think the last time I rode that bike was New Year's Day. Things were pretty clear, as far as snow and ice back then and now we find ourselves right back in that same boat again. This time I feel like it just may signal the end of Winter. Anyway, it was fun to get that bike out and use it. I met some younginz at the recycling bins and one of them stopped to compliment me on my bicycle. That was nice of the young whippersnapper!

Sunday afternoon it was really windy, so I decided not to venture out in the country. Instead, I decided to start the greening of the Monkey. I had a little trouble finding the green anodized cog I had, but I did end up finding it. It is a 17 tooth and the drive ring I am using is a 38T. That's the gearing I find most appropriate for a 29"er single speed on gravel.

I have one more green component on the way, and when that arrives, I'll be finished with the "greening of the Monkey".  Stay tuned...........

Being A Teacher

I've never been one to shy away from public speaking. (Image by someone at T.I.v4- Thanks!)

So, about every year this time I end up teaching a mechanics class for the shop where I work. It is a small thing, only two sessions, and maybe eight to ten folks get in to it total. It isn't that big of a deal. Not too intimidating, well.....for me, anyway. I can't speak for anyone else.

Ironically, back in my youth, I was strongly considering becoming a teacher. I likely would have ended up becoming an art teacher, although back then I wanted to do Industrial Arts. Then I got into college without any clear plan, found out about beer and bands, and that I could skate through school without much effort. I didn't think anybody cared, so I left the whole teaching thing behind.

I probably wouldn't have made a very good teacher anyway. Not one a "school system" would have liked, at any rate! But that's all old news and water under the dam now. One thing I always did have going for me was a willingness to "step up to the mic". I remember when I kind of realized this about myself.

It was on a group ride very early in the Spring one year when the snow wasn't melted yet. A TV crew was talking to people about the break in the weather, and they asked some of our party to talk. They all came running back to where I was, asking the rest of us if anyone of us would talk to the TV people. No one really felt like doing it and were in "cowering mode". I thought they were all just being silly, and I said, "I'll go do it! They are just people, ya know!"

Anyway, so that was when I realized I didn't mind speaking in front of a camera, mic, or to a big crowd of people. Whether or not I am "informative" and give folks value for their money spent to take a mechanics class is anyone's guess!

Being A Teacher

I've never been one to shy away from public speaking. (Image by someone at T.I.v4- Thanks!)

So, about every year this time I end up teaching a mechanics class for the shop where I work. It is a small thing, only two sessions, and maybe eight to ten folks get in to it total. It isn't that big of a deal. Not too intimidating, well.....for me, anyway. I can't speak for anyone else.

Ironically, back in my youth, I was strongly considering becoming a teacher. I likely would have ended up becoming an art teacher, although back then I wanted to do Industrial Arts. Then I got into college without any clear plan, found out about beer and bands, and that I could skate through school without much effort. I didn't think anybody cared, so I left the whole teaching thing behind.

I probably wouldn't have made a very good teacher anyway. Not one a "school system" would have liked, at any rate! But that's all old news and water under the dam now. One thing I always did have going for me was a willingness to "step up to the mic". I remember when I kind of realized this about myself.

It was on a group ride very early in the Spring one year when the snow wasn't melted yet. A TV crew was talking to people about the break in the weather, and they asked some of our party to talk. They all came running back to where I was, asking the rest of us if anyone of us would talk to the TV people. No one really felt like doing it and were in "cowering mode". I thought they were all just being silly, and I said, "I'll go do it! They are just people, ya know!"

Anyway, so that was when I realized I didn't mind speaking in front of a camera, mic, or to a big crowd of people. Whether or not I am "informative" and give folks value for their money spent to take a mechanics class is anyone's guess!