If you could choose any gear ratio for your geared 29er or 36er, what would it be? And why?
Many people are thrilled by their Schlumpf offering 1:1.5. Is this enough or would you prefer more choices?
A 1:2 for the 29er would be awesome, or like 1:2.5.
Lighter, more rim/ tyre combo’s. If somebody made a strong isis hub, worked on any frame pretty much, had 1:2 I would get one for sure. Take me a while to get the cash, but yes, the more options the better.
I want a hub with 1:1, 1.5, 2, 2.5.
While cranking up an incline on the 36 last weekend, I kinda wanted 1:0.5 or something, but I’m not really sure it’d be worth it. Maybe.
So yeah, I’ll take a hub with all of those, please. When can I expect delivery?
Why limit myself to just 2 speeds?
O.7 ; 1. ; 1.5
I am not sure about the 0.7 but I want something to help me climb inclines … so need to experiment; not sure either of the 1.5 I don’t really need big speed but I spin slowly.
Ideal would be a CVT : I will accept some loss but I think the way to go is CVT with smooth rollers …
On the 29er, if I had just two gears I would like to see them at 1:1.3 and 1:1.8 or something like that. You’d have a low gear that’s a little bigger than a Coker, and a high gear that 's bigger than a geared Coker, without all that rotating weight. 1:1 on a 29er is only really useful for MUni and extremely steep hills (>10% grade).
Interesting replies - interesting that one suggestion is to gear a 29er to mimic a geared 36er.
Does this imply that a Schlumpf geared 36er is an ideal set-up?
In gearing, it is pretty close to right, but it is very heavy, which is why a 1.3/1.8 29er would be nice.
It depends on what you’re trying to do. For flat or downhill road riding, the ideal gear would probably be something in the 70-90 gear-inch range; the closest we get is the 2:1 jackshaft design on a 36", but jackshafts aren’t shiftable, so you can’t use that setup for general riding. The Schlumpf 36" setup of 36"/54" is not bad; you get a usable low gear and a decent high gear, though it’s not high enough. The 36" wheel has an enormous amount of rotating weight, so it would be nice to get that level of gearing with a couple pounds less weight.
Really ideal would be about a five-speed, 29/36/44/54/70 or 36/44/54/70/90 or something, with a 29er wheel for light weight.
Tholub - I would agree with you, but I’m not sure about the 90. A virtual 90" on a 29er would be a ratio of roughly 1:3. Would riding this be possible?
Also - what’s your reasoning for the 44?
If we had gearing that high, we would stop running annoyingly short cranks. With 170mm cranks, 90" would be Totally Doable on flats and downhills.
44 is approximate; it just would be good to have smaller gaps in between the gears than we see with the Schlumpf. A 50% jump in gearing makes shifting expensive.
I don’t feel that I need a bigger gear than 54" - as I don’t get to the point of spinning uncomfortably fast even at maximum speed on downhill cruising on my 36" with 150s (at 39kph/24mph). It feels to me that I reach the limit of how fast I want to go without really being limited by that gear size.
1:1 with 150s on a 36 is also about as low as I want to go. It would be nice to have less of a jump between them though, as especially when downshifting it is like dumping straight into a granny gear.
Sam
If it’s not you, it’ll be someone else; our time trial records are going to be set on gears much bigger than 54", by someone who doesn’t mind going 40+kph. Even now I’m pretty sure Chuck would only need a little bit of training to be comfortable pushing a 90" gear with 170mm cranks.
I’ve never ridden a guni, and I have only a few hundred km on a 36. I can only relate to a change of crank length.
My question is with regard to a “point of no return”, or even the point that gearing becomes dangerous?
ie I put 114 cranks on my 36er to try out. Aside from the extra effort starting, the ride with the wind was fun, but not so much fun into the wind. I also found (possibly due to the differences) that I was using quite a lot more energy in balance adjustments, more so into the gusty wind, so overall I felt my speed was not all that much greater and I used quite a lot of energy in comparison to 125cm cranks I thought.
Is there a practical limit to max gearing?
That’s why you have more than one gear. It wouldn’t be feasible to push a 90" gear up a hill or into a headwind, but if you’re trying to set the hour record on a velodrome track, you can probably push it for the entire hour if you’re strong enough.
It also helps to have relatively small steps between gears. On a bike, typically you’ll get up to speed in a lower gear and shift up as you go faster. So you’re not trying to push a 90" gear from a standing start; you’re trying to shift up to it when you’re already moving almost fast enough to ride in that gear.
Quick calculation: A 90" gear at 100 RPM is moving 43.1 kph, 26.7 mph. Unis have already gone that fast; the speed should be sustainable for a strong enough rider on a good setup.
Dangerous? Certainly the faster you go, the higher your kinetic energy. But it also seems that you get more stable at high speeds; I don’t think anyone at RTL had a high-speed fall, except in the criterium. A fall at 40kph+ is relatively likely to cause an injury, but perhaps less likely to occur.
The main training I would need is brainwashing to eliminate my fear of such speeds… 
Having seen Sam ride a 36" Schlumpf, I think his ‘top-out’ cadence is alot higher than most.
For flat speed, the limiting factor currently is not gearing, it’s the wheel. The 36" are still about three or four times heavier than an equivalent track bike wheel.
I can see a lightweight V-frame, very highly geared 28" on a smooth straight track hitting close to 40km/hr though.