Crank length and hill climbs

Do you have a brake? or is your town really flat? because 89mm cranks are really hard to brake with… I say that but I only have like 30 seconds of experience, I rode my 89mm cranks and they stripped after a little loop in the road:( I might try them again though, I haven’t got any problems with them on my 12" uni lately:p

I dont think I’ll even go longer than 114mm cranks on my Coker, I climbed a 20% hill with them so I think they are pretty much perfect for me:)

Joe,
Check out the “Fastest Speed on a Unicycle” thread. Page 10 may be especially helpful. Fastest speed on a unicycle

wherein it is written and graphed what sort of maximum speeds can be achieved on different unicycle set ups (wheel sizes, crank lengths and gears). All hail the uni geeks!
If you’re looking to break speed records you should probably consider a geared 36" with 125 mm cranks, although 150 mm cranks might do it too.

If you’re looking for issues of control, efficiency, likelihood of pedal strikes etc then you might want to check out the “New Concept: Total Gear Ratio” thread. (New concept: Total Gear Ratio) Eric made some beautiful graphs that make me want to laminate them and put them up on the wall.:slight_smile:

My personal preference? For climbing big hills with an 8 to 10% grade I like to ride my 36" guni (in low gear) with 165 mm cranks. That’s the configuration that I rode up the Mt. Diablo Challenge with, including the last super steep part.
For distance riding with less extreme hills I use 150 mm cranks.

Geoff

I thought the geared 36er with 165s was indeed a pretty good climber. I think I have fallen in love with the geared 29er again though as climbing with a geared 29 in low gear with either 125s or 150s is a breeze - and that really comes in handy for road rides out here in Colorado.

Kh29/137 !

Well, I have a long, hilly race coming up (www.blackflychallenge.com), 40 miles, lots of steep, dirt roads. Just a few minutes ago I swapped a pair of 137s (I had 150/125s) onto my KH29/Schlumpf and quick-tested it out in the street. It rides great, and the shifting is the easiest length I’ve tried yet.

I think ungeared KH29/137 will still be fine for climbing (after hearing tholub’s 29/110 climbing feats, I’d be ashamed to think otherwise), and this uni has a brake, to minimize knee-stress on descents.

I’m trying them out on a long ride tomorrow and I’ll report back.

Very cool, I think 137s would be a very good overall crank length on the KH/Schlumpf 29er. I probably won’t be experimenting with swapping cranks, it is more of a hassle with the KH/Schlumpf as it takes a few rides and lots of tightening of the bolts before the cranks become settled and those crank bolts round out too easy, which is why I prefer the dual hole cranks on the guni - no need to mess with all that.

That is the major complaint I have with the KH/Schlumpf, the crank bolts are either made of too soft a metal, or the hex hole is slightly larger than 6mm so those bolts always deform with constant tightening. I wish the bolt was designed differently so it wouldn’t deform.

Oh and let me know how the brake treats you, I always had issues with using a brake correctly on descents.

I’m loving the 137s after the ride. I only did 18 miles, but I did a hard hill, one of the steepest around here, and pretty long, as well.

With the 29er in 1:1, the 137s are a good climbing length, I only had to stand on the steeper parts. I may try some big climb races with that setup. Also the 137s are a good compromise for leverage vs spinning when just riding along in high-gear, and I was able to smoothly run out some hills because they were easier to spin than the 150s.

I also rode several of the miles on a often-rough dirt railbed that still has the rail ballast in places, so big gravelly parts. This is only place I missed the 150s, but it was “totally doable”, just more effort to crank though those bits.

I’m definitely leaving the 137s on this wheel.

I just had a couple new bolts shipped from Schlumpf because I rounded one out. I might have partly been due to my not getting the allen wrench seated in the bolt deeply enough a few times in the past and possibly the upper part of the bolt-hole stripped first, then the whole bolt-hole. I’m being very careful to get the hex-wrench in there all the way now. I hope I don’t strip any more of these suckers. They ain’t cheap.

I really learned to brake on an 8 mile descent down Whiteface and now I never descend a steep hill without it, it’s just much easier on my knees. Especially on a short-cranked guni, a brake is a must-have for me now. I’m putting brakes on my non-guni Coker and KH24 ASAP.