Singletrack Mountain Bike Magazine

• Overview
• Bike Forum
• Chat Forum
• For Sale
• Wanted
• Forum Help
• Classified Rules

Bike Forum

1. trickydisco - Member

   Decided to get my BB sorted on the enduro (2009) as it was feeling very rough. My mechanic took the non drive crank arm off and then tapped the axle.. the drive side cup was still attached to the axle and most of the threads are ruined in the frame

   I am gutted. Said he'd never seen it before. He said the axle was turning on the plastic outer rather than the bearings.

   He put a new BB in with some loctite but he said he didn't know how long it would last

   How the fk could this happen? I haven't noticed any play when i've been riding.

   he said putting a saint BB in might help as it has longer threads.

   gutted it not the word

   Posted 1 year ago #
2. woody2000 - Member

   I don't know, but surely he's responsible for rectifying the problem?

   Posted 1 year ago #
3. sv - Member

   tapped the axle

   What with - a big FO hammer?!!

   Back to the shop and speak to the manager.

   Posted 1 year ago #
4. trickydisco - Member

   i was there when he did it! he literally tapped the axle. You wouldn't expect that kind of thing to strip threads. The drive side cup should have stayed in surely?

   Posted 1 year ago #
5. sam_underhill - Member

   My mechanic took the non drive crank arm off and then tapped the axle smacked it really hard with a mallet.

   FIFY

   EDIT: damn.... too slow

   Posted 1 year ago #
6. RealMan - Member

   Shop owes you new frame I'd say.

   Posted 1 year ago #
7. woody2000 - Member

   Was there a little bit of semtex on the end of the mallet?
   I can't believe it would be so loose and you didn't notice! Should be able to helicoil it os something I imagine?

   Posted 1 year ago #
8. seanoc - Member

   A race face bb has a fair few more threads than a shimano; I'd give that a go before relying on epoxy's and other similar cement type fixes.

   Posted 1 year ago #
9. Oscillate Wildly - Member

   why didnt he just take the other cup off first too before hammering it? was he just being lazy or do you genuinley not need to do so?

   Posted 1 year ago #
10. firestarter - Member

    I had stripped threads on one of my bikes and used a raceface one with a large thread and it oas sound once in

    Posted 1 year ago #
11. trickydisco - Member

    H'e put a race face in now with some loctite and it has held.

    Surely it would take some massive force to smashed threads out? I was there an honestly it was 1 tap

    Posted 1 year ago #
12. D0NK - Member

    Yeah shimano don't have very long threads (the road cups even less) with 2 spacers you ain't got much inserted into the BB shell.

    Posted 1 year ago #
13. trickydisco - Member

    why didnt he just take the other cup off first too before hammering it? was he just being lazy or do you genuinley not need to do so?

    Dunno.. i thought it's easier to get to once the drive side crank is off so you've got access to it. The bb's were seized and no longer moving. It was the plastic against the axle that was moving

    Posted 1 year ago #
14. trickydisco - Member

    why didnt he just take the other cup off first too before hammering it? was he just being lazy or do you genuinley not need to do so?

    Just looked at it now. You can't get to it to undo unless the crank is off AFAIK

    Posted 1 year ago #
15. woody2000 - Member

    You can if you have an open spanner. But the usual method is NDS crank off and tap out IME.

    Posted 1 year ago #
16. ir_bandito - Member

    tapping out the axle is normal
    sounds like the BB was overtightned when it was inserted and stripped the threads then.

    who put it in?

    Frame can potentially be fixed.
    Either get it reamed out and fit a helicoil type insert.
    Or, tap it deeper and fit a square taper BB for a narrow shell. Biggest problem with external setips is there's nio scope for chanign axle lengths.

    Posted 1 year ago #
17. trickydisco - Member

    I bought it from a shop as an ex demo bike.(that had been ridden 3/4 times) it's the mad bright yellow version.

    Will have a word with the shop i bought it from as i know the owner very well (would have taken it there but it's not very close)

    Posted 1 year ago #
18. foxyrider - Member

    Have the threads sheared coz the axle if fused/partly fused to the bearing? - If he ready did 'tap' it then I would say the BB threads were kneckered originally - I have seen and tapped loads of axles out and never had that? I would say metal fatigue?

    Posted 1 year ago #
19. trickydisco - Member

    the axle had fused with the bearing(s) and he had to prize it off.

    Posted 1 year ago #
20. I_Ache - Member

    I tap the axle (with a big rubber mallet) of my HT2 Deore cranks to get it out and have never had that happen. I cant see how hitting the axle with a sledgehammer would force out the opposite BB cup it is an interference fit and the worst that could happen (to the DS BB cup) is the plastic seal and bearings come out with the axle. Ive had the seal come out but not bearings and that was due to a very tight fit not a loose one.

    I would guess that it was the person fitting the BB that buggered up the threads due to over tightening and when they realised what they had done they just pushed the crank in and tightened it up to save them from a b0llocking. At a guess I would say the rough feeling from your BB is because the bearings seized and the cup was rotating in the frame, although this might be a bit extreme.

    Posted 1 year ago #
21. I_Ache - Member

    Oh and you may well get a replacement frame from Spech on warranty for that.

    Posted 1 year ago #
22. foxyrider - Member

    +1 I Ache - the axle should push the cartridge bears out?

    Posted 1 year ago #
23. DM52 - Member

    I had a similar experience on my bike however on closer inspection the threads on the bb cup had worn not the shell itself. If you still have the old cup it might be worth a look. You would like to think that the cups are made from a softer material to avoid permanent damage. Shimano XT bb and HT2 crankset.

    Posted 1 year ago #
24. Digger90 - Member

    The OP says the guy just tapped it, not smacked it hard with a whopping great sledgehammer.

    Given that, there's no way that tapping the axle lightly would drive the BB cup out of the frame stripping the threads in the process.

    Conclusion: the threads were already stripped by whichever numpty previously worked on the bike (you say it's an ex demo) and had been lightly reassembled.

    Your mechanic definitely does not owe you a new frame as some have suggested (unless you bought the bike from him/that shop).

    Solution?

    First, get the BB threads rechased, either by the shop or by your local machine shop/engineering shop/agricultural engineers.

    If that doesn't work, contact Specialized UK and see what they suggest. Unlikley they will warranty replace it given that it's the result of damage, but I have found them very helpful in the past.

    Posted 1 year ago #
25. trickydisco - Member

    Update: Spoken to the shop I bought it off and Spesh say they want the frame and BB to inspect

    Fingers crossed good result

    Posted 1 year ago #
26. ir_bandito - Member

    Good work. Good luck!
    Had another thought about this yesterday as I was putting in an annoyingly tricky BB. If it got cross-threaded when one side was inserted, but carried on screwing in with brute force, that could strip the threads...

    Posted 1 year ago #
27. ridethelakes - Member

    Same thing happened to me on my prophet. You can get it repaired properly, think its betd that do it, but its expensive. Other option as someone posted above is to get a downhill bb that gets more thread. I just sold the frame very cheap on the basis that it was broke.

    I can definitely see the benefit of press in BB's after that experience!

    Posted 1 year ago #
28. carlphillips - Member

    was riding to my mates house to start a ride on sunday morning, a nice knocking sound coming from chainring area,look down and my chain device is flapping in the breeze. no worries thinks I i'll just tighten the bb cups up, get off bike take crank arm out and cup just slides out with it!!, threads all stripped...(on my prophet bought from here too)
    phoned BETD this morning and they thread + glue in a threaded insert it costs ~£60 for one side and £90 for both, expensive but will ultimately save me forking out for a new frame, I'm going to give it a go.

    Posted 1 year ago #
29. trickydisco - Member

    seems this is pretty common after all!

    Posted 1 year ago #
30. buzz-lightyear - Member

    Heck I wallop my HTII axle with a rubber mallet to get it out - it's a tight fit into the BB cups/bearing. Not sure how else one is supposed to do it.

    Posted 1 year ago #
31. Klunk - Member

    I can definitely see the benefit of press in BB's after that experience!

    wish it was that simple, i've heard of several road treks that have become so sloppy with press fit bottom brackets the frames have had to go back to trek. And i don't think it's just trek either, from the park site:

    

    If the BB30 bearing comes out excessively easy, or is there is play in the bottom bracket from a loose bearing fit, apply a retaining compound inside the bottom bracket, such as Loctite® RC609 (Figure 5).

    Posted 1 year ago #

RSS feed for this topic

Topic Closed

This topic has been closed to new replies.