Dumb singlespeed(sort of) question. Tire circumference/diameter.
- Thread starter Dave Taylor
- Start date
JonF
Well-Known Member
Dont forget to run a smaller diameter in front so it always feels like you riding downhill.but if the tire rolls faster its like free speed
1speed
Incredibly profound yet fantastically flawed
Every possible assumption that could lead to a notion of some kind of marginal gain from this could only work under the premise of "all else being equal", which is definitely never, never, never ever going to be the case. You're not racing in a vacuum against an atom-for-atom clone of yourself. Any perceived advantage - misplaced as it would be for reasons already mentioned - would be entirely within your head. (That is, perhaps, until someone came along and ruined it for you by asking something like whether or not the marginal gains of fractions of gear inches you added are offset by the fact that to attain them you have to run those tires at a higher tire pressure than what's ideal to maintain a stable contact patch-to-width ratio - which itself is obvious bullshit since stability differences on such a small scale are almost certainly well within the bounds of any rider's bike handling skill. But just pretend no one would ask that and lead you to do something crazy like get your head all wrapped around ridiculously immaterial marginal gains.)
Why not - I don't know - not make this an uber-complicated games of nanometers and instead focus on simplicity? I know that this is going to be kind of blasphemy for the entire religion that worships at the altar of singlespeed gear ratios, but you know in the end they ... kinda ... don't ... really ... matter, right? At least not in the way people seem to think they do. Racing a bike - any bike, SS or geared - is about "work" - in the physics sense of the term. Everyone racing, whether it's W101 or Mohican or Fair Hill or your weekly local world championships, is racing the same course. That means that in the sense of "work", the displacement component is the same for everyone. If you want to lower your workload in a race, there is only one way to do it - lower the mass you're displacing around the course. Two identical riders - same total mass between bike and rider - will always do exactly the same work on a given course. The winner is just the one who does it faster. And that's much more a function of fitness and (in the case of longer efforts) enough time in the saddle to remain comfortable and in control over time so you don't waste time stopping to rest. What conclusive proof has anyone ever presented to show that faster is an objective function of some gear ratio? For every example I pick of someone ripping it up on a 32:20, I can point to someone else beating the field on a 2:1 or greater. My point is not that there isn't some value in choosing a specific gear ratio - it's just that the choice is going to be more about you than any objective advantage of the gear itself. Stop overthinking bullshit and just get yourself as fit as you can with the time you have to train and then ride the equipment and gear you prefer.
Why not - I don't know - not make this an uber-complicated games of nanometers and instead focus on simplicity? I know that this is going to be kind of blasphemy for the entire religion that worships at the altar of singlespeed gear ratios, but you know in the end they ... kinda ... don't ... really ... matter, right? At least not in the way people seem to think they do. Racing a bike - any bike, SS or geared - is about "work" - in the physics sense of the term. Everyone racing, whether it's W101 or Mohican or Fair Hill or your weekly local world championships, is racing the same course. That means that in the sense of "work", the displacement component is the same for everyone. If you want to lower your workload in a race, there is only one way to do it - lower the mass you're displacing around the course. Two identical riders - same total mass between bike and rider - will always do exactly the same work on a given course. The winner is just the one who does it faster. And that's much more a function of fitness and (in the case of longer efforts) enough time in the saddle to remain comfortable and in control over time so you don't waste time stopping to rest. What conclusive proof has anyone ever presented to show that faster is an objective function of some gear ratio? For every example I pick of someone ripping it up on a 32:20, I can point to someone else beating the field on a 2:1 or greater. My point is not that there isn't some value in choosing a specific gear ratio - it's just that the choice is going to be more about you than any objective advantage of the gear itself. Stop overthinking bullshit and just get yourself as fit as you can with the time you have to train and then ride the equipment and gear you prefer.
serviceguy
Well-Known Member
This is the real mind-blowing fact I get from this thread, where did I put those 26" wheels now?!?!
Dave Taylor
Rex kwan Do
It really comes down to can you mash up 12k of grind climbs in a 100 miler without cramping or spin up with the easier gear but higher rpm. Mashing a bigger gear can save you on flat or roller sections but it can make you cramp after miles of grind climbing. I learned this actually doing practice cries. When I did the MAP crate in ocean county(pretty flat) I was able to barely hang on the 1:15 long ride because I was pulling hard on the front and then mashed too big a gear to get back on. I typically don't cramp much in 100 mile races but I was cramping 1 hour crits. I was also averaging over 300 watts for these. Once I taught myself to be in a pretty skinny gear after pulling through it was much easier to "get back on" and my avg power came down into the 260-270 level.
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it was actually pretty good -
mentioned same amount of work, so being efficient made a big difference.
which means you'll be faster with the same amount of energy......(which is the area under the watts curve)
which means............
spit the hook....
🦈
Everything Marty says is usually spot on but I have to take a nap before I can finish reading it. Hence the ZZZZZZZZZZzzzzzzzzzzzz's
serviceguy
Well-Known Member
Dave Taylor
Rex kwan Do
How about doing something like the Pittsburgh Baker's Dozen? How about ORAMM? You're telling me I am going to complete it just as fast on a 34/16 vs 34/22? At Stoopid 50 I can barely grind a 34/21 out of the campground. Where is the harder gear going to make time? Everyone has an "optimal cadence" that works for them. This is what I'm trying to accomplish I guess.
1speed
Incredibly profound yet fantastically flawed
Not what I am saying at all. You might be faster on a 34:22, while someone else might be faster on a 34:20. So ... who wins? You don't know, do you? Of course you don't. Because you don't have the most important piece of information, do you? You don't know who is on that 34:20. I don't (necessarily) disagree that everyone has an "optimal cadence". But so what? You take the best, fittest rider out there and force him to race on something other than his "optimal cadence" while you put all your time and effort into figuring out every marginal gain you can bring to the table, and you know what? He still beats you. Because he's better than you. Which means, sure, work out all the marginal gains you want with your equipment and your tire width and your optimal cadence and all the other secondary or tertiary stuff. Then show up to a race where guys like Wadsworth or Harding are lining up and you're still at best racing for third. Because the factors that really matter (like just plain fitness and skill) operate on a scale all of those things together will never come close to touching.
Marginal gains are marginal
pkovo
Well-Known Member
I know it’s apples to oranges since BMX racing is wildly different, but on the BMX race side of things, tire diameter is definitely considered. The calculater I use for my daughter has all the major bmx race tires plugged in, so for the same size tire you can see how each tire impacts rollout. According to this if I swap out her 1-3/8 DTH tires for her 1-3/8 Holy Rollers, her rollout changes from 55.01 to 54.77. Tire pressure doesnt matter because they are run rock hard, 70psi plus.
Bmx gear calculator
There is also at least one company (Rennan) that makes decimal gears, for finetuning when moving a whole tooth up or down is too much.
Decimal Gearing
Again, it’s a totaly different animal, but still an interesting thought. I sort of laughed at all of this but as my daughter has advanced her skills I’ve been surprised that she can “feel” very minor gearing differences.
Bmx gear calculator
There is also at least one company (Rennan) that makes decimal gears, for finetuning when moving a whole tooth up or down is too much.
Decimal Gearing
Again, it’s a totaly different animal, but still an interesting thought. I sort of laughed at all of this but as my daughter has advanced her skills I’ve been surprised that she can “feel” very minor gearing differences.
this "might" also mean that there is a difference in circumference between manufacturers or models with the same tooth count.
interesting - idnkt
ChrisG
Unapologetic Lifer for Rock and Roll
I’ll throw chain wrap into the discussion as well.
While, say, 32x16 and 34x17 are very close in terms of gear inches, my feet can certainly feel a difference in favor of the larger ring/cog combination.
Even in my current existence as a multi-gear user, I almost immediately ditched the oem 32t on my trail bike for a 34t, because I prefer the increased chain wrap.
I really can feel this on old-school road gearing, going back and forth between a 39t and 53t on the front.
I’m sure the engineer/physicist types among us can better explain why physically larger gears are more efficient.
While, say, 32x16 and 34x17 are very close in terms of gear inches, my feet can certainly feel a difference in favor of the larger ring/cog combination.
Even in my current existence as a multi-gear user, I almost immediately ditched the oem 32t on my trail bike for a 34t, because I prefer the increased chain wrap.
I really can feel this on old-school road gearing, going back and forth between a 39t and 53t on the front.
I’m sure the engineer/physicist types among us can better explain why physically larger gears are more efficient.
My feet can't even feel the difference between a round chainring and an oval one.
ChrisG
Unapologetic Lifer for Rock and Roll
Oval rings drive me crazy. I don’t question their effectiveness for other users, but they’re not for me.