If you’ll be doing both equally go more like 125mm.
All road shorter than 100mm.
OR you can use whatever you’re comfortable with–but for really technical MUni the 150s make a big difference…the problem is that when you’re cruising along on pavement you either have to crank like mad or crawl at a slug’s pace.
You MIGHT want another unicycle for riding around town, highways, to the next city in the mountains, ect, or just another pair of crankarms if you want to save money. Just remember that the tool for trading them out costs too, and you have to make sure that it’s compatible with your axle type.
Qu-ax makes 100mm splined cranks for about 20 bucks–and United makes 89mm square taper for 12 bucks(do NOT buy any other length from them–the longer ones have the same design, and that design can become unpleasant if the cranks are much longer than your shoe)
For tricks and MUni you will definitely want the 150’s (at least until you can get a feel for what you prefer) Longer cranks are more stable and give better leverage for rough technical riding and hills, however they do not spin as smoothly as shorter cranks because they require more leg movement. If you plan to do a lot of cruising, you could pick up an inexpensive pair of 125mm ISIS cranks from udc. These would be fine for cruising, but you want the KH’s for any type of muni or tricks.
Perfect for cross-country, horribly long for distance.
If you email A E Bike
and ask them for their promotional price, they will sell you a KH 24 for about 450 $, and they ship cheap. It comes stock with all the good parts, cranks, seat etc. that most riders upgrade on other munis. It is as strong and 2 lbs lighter then the other 24 muni’s. This is the way to go if you can spare the extra 50 $
The seat post that comes with it is to long for a basketball player, everyone has to cut it to fit themselves.
The cranks that come w/ that Nimbus aren’t that strong for Muni anyways, so I’d get it w/ 100 or 125’s for road + some strong longer ones for Muni.
-KH Moment 125, 137, 150, 165
-Qu-Ax ISIS Cro-mo 100, 125, 145 (lots of q-factor)
-Onza Tensile 140, 165, 170, 170 (others?) (more Q-factor than Moments, but more than Qu-AX?)
-Echo 165, 170
More Q-factor is better for control at slow to moderate speeds, but causes more wobble at high speeds.