So I got my new Qu-Ax 24" Cross, and it’s an awesome bit of kit. But I’ve noticed that the allen bolts that hold the cranks on to the hub keep coming loose. As far as I know the pedals are on the correct sides (they are marked L and R), but even after banging the cranks on with a rubber mallet and threadlocking the bolts, they’re still coming loose after less than an hour of riding.
Could it be possible that Qu-Ax (or Unicycle.com, I’m not sure who assembled it) managed to get the cranks on the wrong sides? How do I tell which side of the Qu-Ax hub is which? I tried to search the forums but couldn’t find anything relevant, maybe I’m rubbish at searching…
As far as I know hubs does not have a Left or Right side… maybe you could put some LockTight on your bolts… I dont know how you could solve that. My KH moment cranks used to get loose after doing alot of big stuff with them, I just tighted them up and now it’s okay.
Hubs don’t have a side. The cranks are are marked near the pedal with RH and LH.
How are you tightening the cranks? With a hex key? It sounds like you just are not getting them tight enough. If you have a socket wrench go buy an 8mm hex socket and use you socket wrench instead of a hex key. (I don’t have Qu-Ax but I’m assuming its the same as a Nimbus)
When my nimbus was new I torqued mine to 35ft/lbs and later to 50 ft/lbs and they still need a bit of tightening every month or so.
Thanks for the replies guys, it seems your suspicions were correct. I’ve brought my unicycle round to a friend’s house who is a much better engineer than I, and he said the same thing as you. For future reference, here are the two things I’ve done to try to alleviate the problem:
Used red Loctite on the bolt threads and where the splines on the hub / cranks meet. Was using green before and only on the bolts.
Tightened the bolts up REALLY tight. I used a small allen key before - my engineer buddy used a big ol' wrench and now they're super tight. Unfortunately he doesn't have a suitable torque wrench so I couldn't tell you the exact torque.
I inspected the splines etc. while it was all apart and it all seems fine - fortunately I’ve probably only ridden for 10 minutes total with the cranks wobbling so hopefully nothing is damaged.
I will let everyone know how I get on. Hopefully this thread will help out other people with wobbly ISIS cranks in the future!
I’m not doing anything too harsh, just some small hops and light off-roading. Hopefully they’ll stay tight now for a while. For the record, I have one of these Qu-Ax multi tools which has pretty much every single tool you could need in a case the size of a small mobile phone (including a 15mm spanner for pedals, puncture repair patches, tyre lever, spoke keys, allen keys, 10mm socket and more) but it doesn’t include an 8mm allen key - I’m guessing because it wouldn’t be possible to get enough leverage on it.
The crank bolts will always come loose on a new build or whenever you take your cranks off. Just keep checking them and tighten regularly. When ever I have replaced my cranks or taken them off to move them I check them before each ride, and they usually need tightening. They will eventually settle and you won’t need to tighten them as often.
hallo, i have a friend who has the same problem and i thought his qu-ax cross was missing the spacers between crank and hub(???) but then realized that apparentely qu-ax doesn’t have/need them.
he also hammered the cranks and tightens the bolts regularly, guess the next step will be locktite
My problem with the cranks was that I let them get loose and because they are aluminum they got worn out by the hub resulting in them not fitting properly anymore. A new set continuously tightened sorted that out. But changing to Moments made a huge difference. Would recommend swapping out to Moment cranks.
My moments never get loose although I changed the cranks quite often. Maybe they had not enough time to get loose but I don’t think so. I just tighten them as much as I can using a socket wrench.
I think that’s the secret… Do them up as tight as you posibly can and then some!
Haven’t had any problems at all since I reassembled it all around 4 weeks ago. I did buy that long allen wrench from UDC in the end, haven’t had a chance to use it yet but it looks like it should be a good bit of kit.
