It’s all broken and I’ve not ridden my bike since before christmas because of it.

Basically, the preload plastic bolt doesn’t seem to be doing anything. It is not putting any pressure on the NDS crank when you do it up tight therefore none on the BB, could it be the wrong kind?. Also when I have done it all up as tight as possible there still seems to be some sideways movemnt, almost as if I haven’t put the NDS crank on far enough. I know the BB is quite bad but I was hoping to make it rideable.

Sorry for all the waffling, it’s quite hard to describe verbally.
Any ideas would be very welcome though. My bike feels alien when I sit on it. I don’t like that.

I’ve searched the forum and found some useful stuff. I think I have a very similar problem to don simon.

Enough spacers for the size of BB?

Yeah, it used to work fine. It just went wrong on a ride one day.

if your bb’s dead anyway buy a new one something like a hope or chris king ie fit and forget for a while and get some alu spacers instead of the plastic ones then buy an alu end cap bolt from crc or someone like that and try again your problem should then be solved 😉

MMM? Not sure then mate?

Have one of the plastic spacers come out?

If not difficult to say….

Maybe the crank has come out slightly and it’s not tightening back up evenly (cross threaded), making it seem like it’s done up tightly, but not really?

Can it be seen with a few different pics? It might help?

I damaged the plastic preload bolt once which meant i couldn’t nip the cranks up tight enough to eliminate all play. A new one solved the problem – I think the threads were damaged on the old one. LBS will have one!

Is the preload bolt snapped? It’s happened to me before

I had a similar problem, which eventually resulted in the crank coming off mid-ride. Problem was that the splines on the axle were worn, so no matter how tight the pinch bolts were, the crank would slip off – only fix was a new axle (which really gave me an excuse to get a new chainset 😉 )

The pre-load cap isn’t there to keep the crank on, it’s purely to get the crank pushed on far enough in the first place – it should only be done up finger-tight, and then maybe even backed off a bit. It’s the pinch bolts that hold it on. I broke a couple of the preload plastic caps as the crank tried to come off whilst it was screwed in.

Have a look at the splines on the axle and the inside of the crank – if they’re shiny, like the finish has come away, that’s probably your issue

I really am not sure and annoyingly I can’t afford to replace everything with expensive stuff.

Top-1 by James F Shaw, on Flickr

Quick diagram. I’ve not labelled the preload bolt. The arrow indicates sideways play, there is also wobble if you move the crank arms.

I think I’m going to have to buy some stuff though.

Goosed splines is my guess too. Seems to happen very easily once the NDS crank initially loosens mid-ride. Doesn’t matter what you try if that’s the issue – the job’s fubarred. Nice new crankset is the answer.

done it all up as tight as possible

I think that’s your problem right there. The plastic adjuster is plastic so that it fails long before it gets to the “tight as possible” phase. The preload should just be “nipped up” then you tighten the crank bolts. Even if you slightly / moderately overdo the preload the bearings will last considerably less than a gently <nearly tight> setup.

#Edit – if that is the case then the plastic thingy is for the bin but you can borrow one from another bike as once the cranks are done up the plastic thing is redundant.

If you’re lucky, you might be able to get away with just getting a new crank arm, as long as it’s not the splines on the axle that have worn down.

Thanks for the help all. I think it could at least be the most expensive of all the problems having cleaned up the axle splines.

I understand about the bearing preload- just like a headset yes where the NDS crank arm acts like a spacer? But there is no preload- even with the plastic bolt done right up- as in it will go in no further there is a gap between it and the NDS crank. Does that make sense?

there is a gap between it and the NDS crank. Does that make sense?

That’s a real problem. A different problem. Actually there was a question about this yesterday – ish. I’ll see if I can find it for you.

It just went wrong on a ride one day

Just thinking about that statment – Maybe the plastic “top hat” spacers have cracked / broken. The plastic bits that sit inside the bearing cups(twixt axle and bearing)?

I cant find the recent thread about this: grrrr!

These aren’t the threads you are looking for….

Thanks couldashouldawoulda, I found this yesterday

http://www.singletrackworld.com/forum/topic/crank-arm-problems-

which is very much like my issue. I think there could be a top hat issue. I think it is in two parts on the drive side. I’ve had it all for years though with intermitent spells of frequent riding- when stuff breaks I have to wait until I can fix/replace stuff. So maybe I should just get a new one.

These aren’t the threads you are looking for….

Go on then Onion – what’s your take?

Does the crank go on far enough for the little plastic clip that is between the pinch bolts fits in correctly? If so then I would say its the bb no need to buy a fancy one shimano will do. If not then it must be a problem with the preload bolt.

I would just replace the bb and if the preload cap is even slightly damage replace that too.

It’s a simple piece of engineering there can’t be many things wrong with it.