So recently installed 75 and 90mm cranks on my 24" and 29" respectively and holy cow does it make them fly. I was on a ride around my neighborhood and managed to set off one of speed signs at 20kmh. I usually ride with 90 on the 24" and 100 on my 29", and I’ll be building a second 29" with the 90.
I’ve been riding with the tiny cranks for most of my riding experience now that I’ve built up the muscles and technique to climb most of the small hills in my area and somewhat loose terrain decently well.
I find paired with a wide enough tire it handles well on crappy winter terrain and loose Forrest trails, deep snow and sand are not easy though just because of the leverage needed.
I know it’s not the norm, but anyone else love tiny cranks?
Sure, I am a fan. For all commuting I rarely go longer than 100mm and have also tried 75 and 89s. Indeed it is a suprise the speeds that you can maintain on little unis without fancy gearing. 89mm or 100mm would be my preffered choice for my skill level and the conditions around here on a 24” or 26”. There are quite a lot of hills and already at 89mm what I gaining over 100mm on the flats I lose again on the uphills. By 75mm, when you get to 7% or more slopes I feel I lose too much to make an overall net gain. I can get up those and much steeper but it just feels slow.
I recall doing a little tour around Oslo a couple a few years back with traffic lights and other things to deal with (plus 204m of elevation gain) and still managing to average 18.2km/h over the course of a 16km round trip. For 20mins of that I was averaging 18.9km/h and this was with 100mm cranks on a 26”.
With a 24”-75mm I have managed to 17.5km/h for a cycle around town. Faster is possible but it is probably too hilly around here. Also on some of my rides with 24”-89mm I have been similar speeds anyway, so again I am not sure if the trade off works for me much going down a step, e.g. here is one ride with 24”-89mm 20 min cycle around the block. No lights on this one but still 104 m of elevation gain over a relatively short distance (6km).
I can peek into the mid 20s (km/h) on these smaller unis but cannot maintain anything like that over any real distance. I can just blip up to those speeds momentarily.
I should also add that, while I can maintain a relatively fast pace on smaller unis it takes a great deal of concentration and I tend to sweat (a lot), so for for my commutes (in nicer weather), I am usually in the 14-16km/h range and in winter with snow and ice even less.
I’m the opposite as I can’t get on with short cranks, I have 100mm on a 20” and I just don’t like them. I run 125mm on 20”, 145mm on 27.5”and 165mm on a 26” hatchet.
On the 27.5” i average 8mph or 12kph.
Unicycles are most definitely not the most practical forms of transport and there never going to be a threat to the land speed record so why try and make them fast!
I have been thinking a lot about this myself. I have been running 125s on my 29 and it’s a world of difference from the 150s. I have some 75s that I’m dying to play around with when I have some time on my 29 or 26. I already feel like the 75s will be too small lol.
Right now my buddy is drilling and tapping a set of VCX cranks for me. They started as a 150mm but he will be removing the 150mm hole and adding a 125, 100 and 75. I plan to play around with some different lengths and have him make me a set with my ideal lenghts, whatever those turn out to be.
It is satisfying and fun to ride faster and I am only unicycling in the first place to have fun. Also I commute on mine daily and while I tend to go more slowly than my potential (as noted above) it is nice to be able to ride faster if I am running a little late.
P.S. You could argue, humans are not fast in the first place (at least compared with a bike, car, etc.), why try and make them fast by running? And yet… people run all the time, in part at least because they like going “fast”!
Start with 100 on your 29". I find it is a good start for short cranks as going to short can make a genuine safety risk as your not used to stopping it.
Even 100 to 90 feels like a big difference. I highly recommend giving it a try though because you can genuinely get a lot of good speed off it
For me it’s mostly because I ride distance and commute on my Unicycle so for me the speed really helps cut down travel time. Also I do Unipacking on my 29" so it’s like last year I got a 100km ride done in 9 hours with breaks. It’s also a nice goal to push myself.
Of you’ve seen my recent posts in building 2 carbon 29" wheels for speed and with the smaller crank I genuinely think I can beat my 16kmh average and get that up to 18 or 20 this year with enough practice making it closer to bike speed and not slow person on a bike speed.
For reference too, the last time I measured my 24" with the 90s I can doing 14kmh average on rough gravel.
Agree with you here. I commute on my 29" because it’s easier to bring on transit, less falling distance and more nimble in traffic, and easy to bring in the office.
Tiny cranks plus uni are great for my 13km commute or even multi modal days when in visiting a friend.
You’re not alone! I’ve experienced 89mm cranks on my 36er. Damn fast! Great to cruise around or commute with clipless pedals. Not sure I would have tried it otherwise
I’m also thinking about trying 117 and 110mm on my G29. I currently ride with 127 but I find them a bit too long for clipless riding and a bit too short font flat pedals riding. So using 110/137 double holes cranks would be great!
I ride 125mm from 20 to 29er and a friend has a 36 with 125mm that I ride on occasion, so I am just fully in tune with that crank size now. I have hit 17.5 mph on a 24” and 21.4 mph on a 29er with that magical 125mm crank length so no complaints on speed. Also I averaged 12.4 mph at the NAUCC marathon this past summer with that 29er on 125mm cranks. Just what works for me.
Definitely harder to control tiny cranks. I have tried 75mm on 20, 24, and 26 so far and they felt ok on the 20. The 24 and 26 seemed dangerously hard to stop but could cruise quite fast and felt ok until I tried to stop. I might have actually used those cranks on a regular basis if I didn’t have at least a half dozen traffic lights or road crossings on every ride.
I’m with you on that. I wouldn’t go below 90 on my 29 as of right now and even the 75 on my 24 are after a year of riding 90 on them.
I recently built a new carbon 29" from a 3.0" tire build and I did try my 90s on the 3.0 and it was very hard to stop. The new build took 1.5lbs off the wheel weight and 3lbs off the total uni weight so it’s much easier to accelerate and decelerate.
I tried my 100s on a 36 and had the same issue with trying to stop and ended up hurting my ankle. It’s part of why I don’t own a 36" anymore.
