As I was riding downhill I got to thinking about adjustable cranks. I am sure many will feel a double-hole crank is enough, but with Cape Town’s different terrain, I disagree. Sometimes I ride offroad, then extreme hills, then flats and everything in between.
I swap between 127, 150 spirit cranks, 145 zero Q or 150 moment cranks as that is what I currently have, but it has left much to be desired.
I was originally inspired by the flip chip on the Columbus forks to change the rake/trail of the bike.
It is no art piece, but at least my 5-minute doodle catches onto the main concept. The aluminium crank would have a slot and teeth of sorts to hook the two-part chip (just what I call the top and bottom piece) onto. The chip is tightened by the back piece compressing against the front and the second bolt is for more clamping force. The teeth would allow 2-3 mm increments to be reached and additionally, if the chip is designed correctly depending on if the pedal hole is flipped to the top or the bottom it makes it so that 60% of the teeth could be used to achieve even smaller increments than the teeth jumps due to offset. Q-Factor
With a second set of chips, you could also change the Q factor using the same crank without any compromise in strength as a washer on a pedal would have.
The ends would be rounded-ish allowing a snug fit and for it to be flipped so that the extra bolt is at the top or bottom allowing a good range.
This would have compromises on strength, so no 10-meter drops, but for distance or the majority of riding, I think this has the potential to be very useful to certain riders.
The actual engineers and experienced riders please chime in. There would of course be a million changes to make to the design, but with today’s CNC manufacturing setups, it is easier than ever to produce them without first creating specific tooling.
it’s adjustable from 65 to 165mm. I thoght about testing that, maybe the best design for variable cranks I have seen so far. Does anyone know that / has ridden it on a unicycle?
It’s a german company, here is a product link:
I’ve been circling around them for a while, so far the price tag stopped me.
Looks great, the only thing that has been left to desire for me is maybe smaller increments. The design however seems like it it could also work with smaller increments if a smaller diameter locating pin is used by the design team.
And if I remember correctly, the Shimano HollowTech interface is the equivalent of the Qaxle, so you only these uni can give it a try (except if they also have an ISIS reference).
Could always be used, but usually these are used on a rental system to customers so that they can test out which crank length they like or used by bike fitters. I would personally say my heal is very likely to hook on a crank like this causing some unnecessary dismounts. Weight would also just have to be taken into consideration especially since it is rotational weight.
@finnspin I have heard that you’ve tested these new cranks in muni. Any chance you could give us a review? How do they behave? Is their weight an issue? Should we buy them right now?
This makes me even more interested in the KH ISIS to Qu-Ax adapters that @danger_uni showed on the forums a few months ago. This would be a game changer in terms of being able to effectively have 10-speed gain ratio on a Schlumpf hub (5 pedal lengths x 2 gear ratios).
I would absolutely not recommend (or trust) them for Muni. I had some on my freewheel Muni, with the intention of subjecting them to a lot of shaking and load changes to see if any issues would develop. Trouble free for my part, didn’t come loose and I did all my adjusting with a small allen key, like most people would. I was worried that you might have to really crank them down for them to not get lose, but that wasn’t the case for me. (Obviously still take care to tighten them well and keep an eye on them after adjustment, as you should with any bolts.)
The adjustment is easy. Timewise it was similar to switching holes in multi-hole cranks in my experience.
Weight wasn’t an issue for me, but then I’m also the wrong person to ask, I tend to not care about weight.. Other than being adjustable in fine steps, they feel like normal cranks. The version I had had a bit more Q- factor than the regular zero-q, if this is a concern you should check where the production version is.
This is the crank for a perfectionist who likes to dial in their unicycle exactly to their riding and to their terrain. Especially on the road the typical gaps between multihole cranks feel massive, getting the chance to play inbetween and truly find an optimum for the gradients you encounter and the speeds you go is fantastic.
Honestly, I’m not that person myself normally, I’m usually a set it and forget it guy as I ride more “enduro style” Muni and terrain is inherently very varied there. But when I was toying with Everesting ideas (I don’t have nearly the fitness or time for that currently), these cranks were definetely included in my mind to be able to adapt the setup to slowing down uphill as I fatigued.
Man… Looks like I’ll need to start gathering Q-axle unis ISIS will definitely be a minimum now in my fleet but I would very much like to toy around with these cranks
I’m not sure to get your first sentence right. Your overall experience seems great but you still don’t recommend them for muni. Do you think they could break?
Yeah, I would be worried about strength for extended Muni use. The pedal axle has a much bigger cross section than the bolts on the adjustment mechanism. For distance this is not a problem, but it would need a lot more testing and probably a redesign to recommend it for Muni. My purpose of testing it on there was just to accelerate the arrival of issues, should there be any.
Thanks for this additional info.
As per my comprehension, the adjustment mechanism would be the part to fail. It doesn’t look really hard to manufacture, so the solution would maybe to offer the mechanism as a standalone product to replace a failing part
It is interesting to see the variation in ways to change the length of the cranks, but does anyone do this during a ride, I mean have short cranks when riding on road on the way to the forest and then getting off and changing to longer off-road cranks until ur done and then back to road length for going home? Even if it takes a few minutes with an Allen key, I would still not bother myself. Just one length is fine for me. I care more for stability and easy mounting than for speed.
It may not be useful for every ride, but I can see an advantage in these for long and hilly rides. When I go for a high pass with dozens of kilometers uphill and then downhill, being able to quickly change gears would be great. As far as I know, that’s what @toutestbon sometimes do when he rides his ungeared 36er in the mountains.
Occasionally in the winter I have done this on my commutes. Where I started off with shortish cranks and decided that the snow was just a bit too much and I need more traction to push through it.
ISIS will definitely be a minimum now in my fleet but I would very much like to toy around with these cranks