Thursday, September 28, 2023

Single Speed Questions - Part 3

 Today I am going to try to wrap up answering the questions I received concerning single speed bikes. If you missed yesterday's discussion, you can read that at the following link:

Single Speed Questions - Part 2

Today I want to first tackle the crank length debate for single speed. Although this wasn't a question I was asked, it often comes up in talk about single speed bicycles. It also can affect knee health, so I wanted to add this bit in briefly.

First off, I don't necessarily buy into any of the recent "your crank arms are probably too long" thing that you may be seeing going around the internet sites and forums of late. Here's the bottom line: Humans have a wide variety of types and predisposed ways of moving due to various influences. To say that "this is the way to go" in regard to crank length is too narrow a focus. There are just too many variables in humans to be able to pinpoint some formula or shortcut to crank arm length nirvana. 

Besides, you have to also add in the adaptability humans have. One crank length may work just as well as another after a given amount of time for a person to adapt to that. As an example, I offer up myself! I have tried crank arms on single speed bikes from 170mm to 180mm with stops in between of 172.5mm, 175mm, 177.5mm, and I've demoed a 225mm crank on a single speed, fixed gear bike. All "worked" for me and some of these still do. 

I see longer cranks as something that keeps your legs in the "power stroke" for a longer period of time. Longer cranks also will articulate your knee joint more and you'll have a longer "dead spot" in your stoke. That dead spot can be mitigated depending on momentum that you develop. 

Shorter cranks tend to keep you alternating into a power stroke more often, but that section of your pedal rotation has a shorter time duration. Shorter crank sets don't articulate your knee joints as much, providing less strain on the joint. 

So, you might want to look at shorter cranks if you have a knee issue. Thinking about knee rehab, many places used to do physical therapy on an exercise bike and they would continually lower the saddle height, causing more and more joint articulation as the patient got stronger. So, I think my analysis of short versus long cranks in regard to knees has some credence. But I am not a doctor, so take that with a HUGE grain of salt. Well, not literally a huge grain of salt! You know what I mean! 

But beyond that? Ride what you feel best on. I think you cannot go wrong with a 170mm-180mm crank. Or maybe this is better said by saying, "use whatever crank set you like", as most are between 170mm and 175mm. My only caveat is if you ride fixed gear, (no coasting!) where you may want to err on the side of short cranks to allow for clearance to spin the cranks through corners. 

Are there any significant differences between riding single speed on a flat/riser bar vs a drop bar?

This is a great question, because your handle bar is a big deal when you talk about single speed riding.  Using leverage which can be applied through the handle bar, a rider can engage the upper torso to aid in cranking up and over hills and other obstacles which you may encounter on a ride. 

On the question of drops versus flat/riser bars though, that debate is less of a concern now. This is because back in the day, a 44cm drop bar was considered "pretty wide" while flat bars were creeping outward in width from the upper 600mm's in the 1990's to almost 800mm wide by 2010. Then drop bars started to be available in wider widths, and I daresay that now you could probably buy a drop bar that is actually wider than a lot of flat bars. 

That said, wide flat bars of up to and over 800mm wide can give a single speed rider a lot of leverage. That is, if the bar fits you. Because I feel that ergonomically there is a point where wider bars give you diminishing results. Of course, this depends upon your build and strength. So, there is no "magic width" to look at here. 

Same with drop bars, and as well, I feel that drop bars don't hinder your performance versus flat bars on a single speed. If anything, a drop bar lever can maybe give a rider a better purchase on the bar in terms of grip, so this will likely just fall to preferences. I see no real disadvantage in terms on single speed use to either type of bar, but they will definitely give the rider different experiences in terms of use. 

 Which is better in your opinion, larger chain ring/larger cog or smaller chain ring/smaller cog for less spin and better top end?

Efficiency is increased when you articulate the chain less, so in those terms, running bigger diameter cogs/chain rings would be preferable. (On gravel. MTB users may want smaller combos for better ground clearance.)  What many may not understand is that you can achieve similar gear ratios using smaller rings/cogs as you can with bigger chain rings/cogs. Example: 38 X 20 results in a 55.1" gear inch while a 32 X 17 results in just shy of a 55" gear. (Assuming a 29" wheel diameter with each combination) So, I'd err toward the larger diameter components and run the 38T X 20T combo. 

"Speed" is only affected by changing the ratio from something higher/lower to something lower/higher in ratio. That and cadence determines speed. "Spin" can also be affected by crank arm length. (See above) So, all else being equal, I'd run the largest cog and chain ring I could to achieve the ratio I wanted to have. 

Are there any danger or warning signs that single speeding might not, or no longer, be good for you? 

Yeah, this is a tough question to answer. I definitely can tell you that single speed riding is not for everyone. My friend, Jason Boucher actually asked me when he was down here recently if I was still riding a single speed. He also added that, while he keeps trying a single speed, it just doesn't click with him. And so it may be with many other folks. 

Single speeding on gravel circa 2006
So, one sign may be that you just don't like it! And that's completely okay. No one should look down on you for that, nor should anyone look down on single speeders. It's all good, this riding of bicycles. 

When would you might want to call it quits on single speed use? Well, obviously health issues might come into play here. Overuse injuries can be a big problem, but just general aging can make riding any bicycle a tough ask if there are health concerns. 

Otherwise, if you have followed good bike set up, and don't over-do things, there really isn't any reason a person couldn't ride a single speed well into the proverbial Sunset. Well, as long as you like it and want to do that

Thanks for reading this series! I hope that you enjoyed it. If you have any further single speed questions, feel free to ask in teh comments!


Derek said...

Good info here. One question, do you have/ ride any fixed gear bikes among that stable? Just curious.

Guitar Ted said...

@Derek - Thank you! Currently I do not have a fixed gear bike. I retired my old Raleigh Gran Prix "Rat Rod" fixie last Spring and I am currently searching for a more road bike type frame/fork for fixed gear use.

In the past I have used my Karate Monkey and a Surly 1 X 1 as fixed gear bikes.

I really enjoy riding fixed and I hope to get something up and running fixed gear soon.

Nooge said...

I recently switched from a 175mm crank to 170mm on my road/gravel bike because I have tight hips. With drop bars you need to lean forward pretty far and I don’t have enough hip mobility to do that well. With 170mm cranks I am able to lean further forwards despite needing to raise my saddle a bit to compensate for the shorter cranks. I’m liking it.

That doesn’t apply as much to mountain bikes since you’re not leaning forward as far or as often.

Guitar Ted said...

@Nooge - Yeah, I can totally see the benefit there. Thinking about someone with a bigger abdomen, or a belly that gets in the way, a drop bar bike with shorter cranks may be a great answer for that body type.

Then again, a longer crank does allow a lower saddle position, which sometimes will make a front end feel "taller", more comfortable, and the bike overall may feel more stable due to the slight weight shift rearward.

You can slice it either way. It will just depend on which way is beneficial to the individual rider in question.