Hai need some helpz from the internets.

I got a MTB from Merlin Cycles about 2 years ago. Which was all very good.

Then about 1 year ago I took it into a Bike shop to have it serviced. Nothing majorly wrong with it but it needed TLC.

Anyway I get a call 10 minutes later with the Bike engineer saying theirs a major problem. Apparently on the frame where the bottom bracket screws in the frame wasn't 'finshed off' i.e when the tube part was cut in the facotry it wasn't filled down properly.

This meant the bottom bracket didn't go in straight but more importantly when the engineer took it out to have a look at it it then cross threaded the thread on the inside of the frame

The guy in the shop said it was a malnufacturers fault with the frame and that most frames are gaurenteed for 5 years.

The shop I got it off however says there wasnt a problem untill the guy removed it so it's not their fault.

I can post pics tonight if it helps, but has anyone ever come across this problem? Or any advice or pointers would be greatly appreciated.

— Sorry for the long post

Dirt Licker

How would you cross-thread is taking it out unless it had been cross threaded going in?

A frame two years old it is up to you to prove it is a manufacturing fault. Sounds to me more like the 2nd shop is making excuses for bad workmanship – I assume they are talking about facing the BB shell.

a professional should never cross thread anything.

You need to establish exactly what happened then pursue the shop that made the mistake.

If you've been using the frame for 2 years without issue, then it's unlikely the manufacturer will cover the alleged defect under warranty.

Can the BB shell be faced then re-tapped?

A crossed thread is better than no thread.

Shouldn't really be a major problem cant your lbs get the shell chased and faced for a few (<£15) quid?

Many frames, especially a budget one from a couple of years ago, dont come with the BB shell 'faced' this was never a problem until the increased popularity of external BB's.

It should have been a simple job for a competant LBS mechanic, and the worst that 'should' have happened was a pair of dead bearings in a external BB.

Also, if this happened a year ago, why are you only posting about it now?

Same reaction as grumm. Impossible to cross thread it taking it out unless it has been installed incorrectly in the first place. An unfaced bottom bracket could possibly make it more likely to cross thread the bb if it was a long way off square but I would say it is unlikely. In any case it should have been quite noticeable that the bb cup was not sitting square in the frame. What type of frame and BB are they?

Another possibility is that it was over tightened and possibly not been greased on assembly so the threads have bound. On being removed the thread has been torn out of the bb shell. That is possible but takes quite a lot of force to do. What is the frame (or more specifically bb shell) material?

Sounds to me like the 2nd shop have made an arse of either taking it out or putting it back in. Either way they should be able to put right the damage quickly but it sounds like they are a bit incompetent. I'd get a 2nd opinion if I was you. Well no I wouldn't I would just fix it myself. Sounds like our charlatans of an LBS.

Having worked in a bike shop for many years and never having seen a cross threaded BB, I would say this is sloppy workmanship on the part of your LBS. You would have known about the problem mush sooner if it had always been the case. You can buy a square taper BB for damaged frames if the threads are shot. They cost about £15 on ebay.

You would have known about the problem mush sooner if it had always been the case

if it had a cartridge BB, how ?

thanks for all the advice. FYI its a Merlin Malt 1 '07

I never had any problems at all, and it got a serious amount of ride time.

I'll post some pics this evening which i hope may shed some light on what has happened and we'll go from there.

Your "engineer" isn't an engineer, he's a bike butcher.

are they saying that it was already cross-threaded when they tried to remove, or they did it when trying to replace

this is fundamental to whether the fault is theirs, surely ?

who put in the original BB ?

The LBS has messed up your bike and is trying to make sure they don't have to buy you a new frame. The BB shell would almost have to have been made in two parts for it to be this bad. And if it were as drastic as that you'd have known about it by now.

If they can't chase the thread and face the shell themselves then they must be really incompetant.

I've only seen one knackered BB shell where I work now and that was a result of the BB being seized in the frame after 10 years and it bringing the threads out with it. BB was too worn for it to be rideable anyway so the frame was a write off.

This sort of thing doesn't happen within 2 years unless someone's made a serious cock up,a nd it sounds like the shop's bullshitting it's way out.

everyone's jumping on the cross thread and ignoring the 'unfiled end of the tube' problem. Why's that?

Because even if the end of the tube were unfiled it'd still mean the threads were OK when the frame was made.

If it's a simple case of it not being faced then that wouldn't effect the BB going in the threads OK, it just means the shell wouldn't bottom out properly on the frame. If it were so bad as to cross thread chances are it'd be a fair old wonk on the end of the tube that you'd notice- that and the BB wouldn't do up tight and would fall out.

I get you now. I read it as either the seat tube or the down tube unfinished inside the bb shell, forcing the bb off sideways as it was being screwed in or out. my bad.

so, OP bought bike 2 years ago, and had it serviced a year ago, and now at another shop it has a creamcrackered thread. Either the OP's current shop has crossed the thread or the previous shop fecked it when they put it in and it has just surfaced now… it's going to be difficult to prove either way. Nightmare.

The way i read the original post;

Bought bike 2 years ago

had it serviced 1 year ago

They called ten minutes ago to say the frame is not finished correctly???

then everyone on here assumes it is the current shop's problem, they killed the frame.

I think that te original post does not describe the fault well enough to come to this conclusion, and it is unfair to assume that it is the shop's fault.

Sometimes (from a shop's point of view) it is hard to explain the fault via a phone call to someone who does not really understand what you are trying to explain. The only way to explain is to show the person who owns the bike.

My advice would be to go to the shop, and ask for the mechanic to show you what is wrong with the bike, and explain in person. If you take biscuits with you it will help, trust me! He is only human, and is only trying to help you get your bike working properly again.