Trials bike problem, any users in here

hyperst · 31 May 2011 at 14:24

Hi, my son has a Onza trials bike, the bearings in the crank was making a bad noise and so took it to a local bike shop who said it needs a new bottom bracket which he ordered in and we took in the bike shop and had him replace it, thing is the next day the bottom bracket is loose and if holding each crank it can move up and down

, now I got my son to take it back to the shop who now says we need a new frame :eek:

, so is there any experts in here that can shed any light on this as I don't know where to start to diagnose what is actually wrong

Big Chris · 31 May 2011 at 16:15

Something's not right there... if they diagnosed a faulty BB and replaced it themselves (keep the receipt for this!) but are now saying it needs a few frame, presumably as the BB shell threads are damanged or stripped - they themselves have caused this as they fitted the BB.

I'd first ask for an explanation as to why they fitted a new BB to an already damaged frame, to which they won't have an answer since it seems very much like they damaged it themselves, so should therefore cough up for a replacement.

Supercow · 31 May 2011 at 16:17

As big chris said, ask them why he needs a new frame. I don't understand how it's actually possible FUBAR'ing the frame by installing the BB, so it might be a case of the BB shell already being warped and they mis-diagnosed to begin with.

hyperst · 31 May 2011 at 16:42

yeah I will go to the bike shop myself tomorrow and see what he says, and ask him why he replaced the bottom bracket and yet a day later it is all wobbling as when it went in originally it only made a rough sounding noise from the bearings.

here's a video of it so you can see what I mean, it's still proccesssing but should not take too long

Saytan · 31 May 2011 at 20:29

that's the axle moving in the BB, not the BB moving in the frame.

hyperst · 31 May 2011 at 20:32

Saytan said:
that's the axle moving in the BB, not the BB moving in the frame.

Now that is what I was thinking, the bearings have gone, but the bloke at the bike shop says it needs a new frame

Saytan · 31 May 2011 at 20:35

Go to a different bike shop - someone local will be able to recommend.

Supercow · 31 May 2011 at 20:38

Yea it does seem like the axle ... and now we have the directions to somewhere too!

hyperst · 31 May 2011 at 20:44

Not really possible to go else where with it, and only a small town where i live so will go back to him and tell him to show me what he did, I got a feeling he didn't change the BB at all and just greased the bearings up and pocketed £23, I did actually just order the BB, when he said it would be in stock I went back to the shop and he got shifty about selling it to me and said he would need to fit it as it required special tools so took his word for it and had to take the bike to him and leave it with him, do you think he's just after me splashing out on a frame so he can make some money?

Saytan · 31 May 2011 at 21:44

where do you live? i know a few guys in lincs who ride

hyperst · 31 May 2011 at 22:47

Saytan said:
where do you live? i know a few guys in lincs who ride

Alford mate, I will be in the shop tomorrow with it for sure as I am not happy what has been done, there was no mention of the frame needed replacing, I am going to get him to strip it and show me what is wrong as a new frame to replace what was originally rough sounding bearings does not sound right

hyperst · 2 Jul 2011 at 04:24

just reviving this thread as I think I might have found what is wrong, after some googling and looking at pictures of bottom brackets it seems the bike shop have installed a Raleigh bottom bracket, now I'm no expert but surely it should have been an onza bottom bracket

eXist · 2 Jul 2011 at 08:31

as far as im aware onza dont make bottom brackets, ideally they should have replaced the original faulty b/b with a sealed shimano unit and that would be the end of your troubles.

mistercrabb · 2 Jul 2011 at 08:47

Looks like that bottom bracket is the wrong size to me (needs spacing out), that crank sticks out way too far.
Or he tried to fit the old cranks/axle to a new BB that was too short for the frame anyway.

Take it back, get a refund (and the old bottom bracket!) and take it to a good bike shop if you can..
You definitely will not need a new frame unless the bottom bracket is actually moving.

hyperst · 2 Jul 2011 at 12:29

Here's the Raleigh one that the bike shop used

and here's the Onza one, I'm wondering if there is a slight difference in threads, I don't have the old one as the bike shop said they threw it away

The actual part that came loose on the Raleigh one is the thread side on the left of the picture which looks different to the thread on the left of the Onza, it has a raised part on the raleigh and on the Onza it doesn't, could that be the cause of it?

Andelusion · 2 Jul 2011 at 12:50

Why not email Onza and ask if the Raleigh one is compatible (give them the part number).

Are you also sure the crank isn't loose on the axle?

hyperst · 2 Jul 2011 at 12:57

Andelusion said:
Why not email Onza and ask if the Raleigh one is compatible (give them the part number).

Are you also sure the crank isn't loose on the axle?

I will try that, I'm not totally sure how to check the crank if it's loose on the axle?

Appelhanns · 2 Jul 2011 at 14:47

Unless they have mashed the threads to get it in, the Raleigh one will be compatible, whether or not it is fit to be used on a trials bike is another question!

To check the crank on the axle just wiggle it like in the video and see/feel if they move together or not. In the video it looks like it's mostly the axle as you can see the bearing inside moving as well.

hyperst · 2 Jul 2011 at 15:06

At the time of the video I knew nothing about how they work and it moves like that because I later found out on the other side the retainer? had worked loose and that's why it wobbled, the side that is loose is the side the bike shop says the frame threads have gone

, it's looking more like a new frame is needed, as the thread is quite loose and can wiggle about if not fully up to the frame

eXist · 3 Jul 2011 at 13:51

your original bottom bracket may or may not have been fitted incorrectly at the factory, over time the bearings wear out and need replaced.

The first thing the shop has done wrong, is fitting a much MUCH cheaper part than the original spec onza model.

The trouble you have tho, is proving the shop fitted the new raleigh bottom bracket on the wrong threads, therby stripping the threads on the frame.

As for compatibility, the raleigh model they fitted will do the exact same job as the onza one, as long as it was the correct bottom bracket shell size, and the correct bottom bracket axle size.

Your in a really tough spot tbh but you should argue with the shop that when they removed the onza b/b and tried to fit the raleigh , that they should noticed at that time if the threads were stripped thereby clearing themselves of any blame. personally myself, given that they managed to get the raleigh b/b fitted, i believe that its their mechanic who has fitted it on the wrng threads and that they should take part of the blame if not all of the blame.

Proving that it was them that stripped the threads is almost impossible tho so just argue and see how you get on....