Bottom bracket shell stripped

Tonyandthewhale

Hi all,

I have an old steel frame road bike that I got second hand. It's got a shimano hollowtech II bottom bracket that was getting a bit wobbly. I thought the bearings were just worn out so I decided to remove it so that I could replace it with a new one (don't know how long its been on the road). loosened and removed the non-drive side fine but when I went over to the drive side I realised the wobbly wasn't from the bearings but rather the whole cup was loose. Turns out the threads had been completely stripped from the bottom bracket and the drive side bottom bracket cup was just sitting there for the last god knows how long.

So now I've got an empty bottom bracket shell that only has threads on one side. What are my options? Can I get a press-fit bottom bracket that will work with my tiagra crank? Can it be re-threaded? Is the frame now scrap? How do they get the figs in the fig rolls? Is there really a god?

Tonyandthewhale

Also, it's a standard (English?) bottom bracket and shell. Do I remember reading in a similar thread that it can be re-threaded to Italian threading? Or am I just dreaming that?

morana

Tonyandthewhale wrote: »

Also, it's a standard (English?) bottom bracket and shell. Do I remember reading in a similar thread that it can be re-threaded to Italian threading? Or am I just dreaming that?

came across this before where somebody in a similar position cut thru the shell with a hacksaw and clamped it tight and welded the seam and then rethreaded and it worked fine

ford2600

Tonyandthewhale wrote: »

Also, it's a standard (English?) bottom bracket and shell. Do I remember reading in a similar thread that it can be re-threaded to Italian threading? Or am I just dreaming that?

Not talking from experience, but if it's steel could you not thread internally on both sides?

What's internal diameter?

You need to be very tidy to get everything squared up.

Tonyandthewhale

morana wrote: »

came across this before where somebody in a similar position cut thru the shell with a hacksaw and clamped it tight and welded the seam and then rethreaded and it worked fine

Don't really want to cut my frame apart with a hacksaw if I can help it.

ford2600 wrote: »

Not talking from experience, but if it's steel could you not thread internally on both sides?

What's internal diameter?

You need to be very tidy to get everything squared up.

Ford 2600, what exactly do you mean by 'thread internally?'

ford2600

Tonyandthewhale wrote: »

Don't really want to cut my frame apart with a hacksaw if I can help it.



Ford 2600, what exactly do you mean by 'thread internally?'

Can you not cut a thread on inside of bb housing? Not sure if you could then get a bb to fit, might be an option depending on diameter.

I take it stripped threads are external if it's a hollowtech?

Tonyandthewhale

It is presumably possible to cut new threads on the inside of the bottom bracket but I don't know if this is economical or if there are some other drawbacks such as weakening of the shell or if it's actually possible to find a bottom bracket to fit the newly cut threads (since presumably the internal diameter would then be wider than the original).

ford2600

Tonyandthewhale wrote: »

It is presumably possible to cut new threads on the inside of the bottom bracket but I don't know if this is economical or if there are some other drawbacks such as weakening of the shell or if it's actually possible to find a bottom bracket to fit the newly cut threads (since presumably the internal diameter would then be wider than the original).

That or maybe a press fit that will do the trick?
Try one of the american forums, I'm sure your not the first guy to have this problem.
Seems a waste of a frame otherwise.

seamus

Holyboy fitted a threadless bottom bracket for me. It's not press fit, instead the cups screw onto the bottom bracket body itself, and so the bottom bracket holds itself in the frame, much like the cones on an axle.

http://store.velo-orange.com/index.php/grand-cru-threadless-bottom-brackets.html

I'm sure you can source one cheaper though.

Alek

Threadless BB:

http://store.velo-orange.com/index.php/grand-cru-threadless-bottom-brackets.html

or

http://www.sjscycles.co.uk/prestine-threadless-68mm-sealed-bearing-bottom-bracket-for-frames-with-damaged-threads-prod16505/?src=froogle

Tonyandthewhale

All those press fit options are for square taper cranksets only aren't they?

feck sake lads

to rethread it get an old steel squaretaper bottom bracket and carefully screw it into the shell, it will cut new threads if you do it right be carefull though.

Tonyandthewhale

feck sake lads wrote: »

to rethread it get an old steel squaretaper bottom bracket and carefully screw it into the shell, it will cut new threads if you do it right be carefull though.

Sounds alright for chasing smudged threads that have been cross threaded but mine are pretty much worn down so that the cup slides in an out, not sure this will be enough (plus I'm in Bulgaria and my frighteningly massive spare parts box where I keep things like old squaretaper bottom brackets is back in Ireland).

feck sake lads

oh your in trouble so, i don't think that shell can be re threaded.if i find a solution i'll get back to you.

Enduro

I think I recall reading recently that one of the big UK companies will insert a helicoil into the frame so that you can continue to use standard BBs. Might need to get it done myself soon, so will be investigating. Guessing it will be pretty expensive, especially since it might require shipping the frame to and fro.

feck sake lads

alkos wrote: »

Threadless BB:

http://store.velo-orange.com/index.php/grand-cru-threadless-bottom-brackets.html

or

http://www.sjscycles.co.uk/prestine-threadless-68mm-sealed-bearing-bottom-bracket-for-frames-with-damaged-threads-prod16505/?src=froogle

me thinks this is your way out.

Vino Veritas

If it is steel , get it repaired properly , Send it to a UK framebuilder , or in Ireland to www.bicycledesigncentre.com, a decent bikeshop should also be able to repair it

Keep_Her_Lit

Eastside Bikes in Edinburgh offer a thread repair service.

http://www.eastsidebikes.com/repairs

Bottom Bracket Thread Repair – £50 If the bottom bracket threads on your frame are damaged we can repair them without a respray. We can do this to British, Italian, Swiss and French threaded BBs. We do this by tapping the threads out to a larger diameter, then thread in a special insert which has British BB thread. We use high-strength epoxy to hold the insert in place and chase and face the new bottom bracket threads. This method results in a high-quality, long lasting repair and has resurrected many classics that otherwise were unusable

Including the cost of sending the frame to them, it probably isn't an economical option. But if you're really set on getting the bike back on the road it may be worth considering.

Alternatively, would you consider swithing to a square taper BB (as mentioned earlier) and chainset? There must be plenty of quality used chainsets knocking about.

seamus

There are hollowtech II press fit BBs, specifically for frames with no threads. MTB & Road HTII bottom brackets are interchangeable.

http://www.chainreactioncycles.com/Models.aspx?ModelID=61801

You need to get your measurements quite exact though, as the cups are polymer, so if the fit is too tight, the cups might crack or wrap.
What I'm thinking is that you get someone who is adept with a dremel to gently grind down the existing threads, and then press the new BB in place. If the frame is slightly too big for the cups, you could get someone to cut a shim which you fit into the frame and then insert the BB.

Tonyandthewhale

That press fit hollowtech bottom bracket looks like the most appealing option so far. I don't fancy switching to a square taper system if I can avoid it (that means buying a new bottom bracket and a new crankset plus it might be a hassle to find a suitable crankset in compact format) and paying to ship the bike from Bulgaria to the UK and back to Bulgaria as well as paying for the facing and re-threading and whatnot doesn't sound very economical.

It would seem that with the press fit BB71 I only have to buy a new bottom bracket. Thing is I've never come across press fit hollowtech bottom brackets before. Are they for frames like mine that have been damaged or are they designed for frames built with no threading in the bottom bracket? Basically how can I be sure it'll fit in my frame? And does anyone know what tools are necessary to fit it?

Tonyandthewhale

And if my bottom bracket shell is 68mm how is an 89.5/92mm bottom bracket fit in it? I've never even heard of 89.5/92mm bottom bracket shells! Maybe I should just buy a planet X...

clog

If there is enough metal left you could get the shell re-threaded from bsa 68mm to an Italian 70mm. You could prob get away with only doing the stripped side.

seamus

The press fit bottom bracket is for frames that have been designed with no threads in the frame.

A quick google suggests that in fact the push-fit HTII bottom brackets are significantly wider than standard bottom brackets. This makes the whole pedalling setup much stiffer, but what it means for you is that it appears that the press-fit HTII bottom brackets are 7mm thicker (i.e. the diameter of the cup) than a standard ISO BB, and therefore are no use for you.

So if your heart is set on HTII, you only option is to find a way to rethread the frame.

ddashk

i know this thread is a bit old but it comes up in google so someone might find it looking for a solution.
i have gotten around this problem with epoxy.
i bought an FSA bb because unlike the shimano ones they use a cup on both sides.
install it so it is centred and then put a lock ring on the damaged side to mark the depth.
remove everything and glue the damaged side in with epoxy making sure the threads are free from grease.
slide/thread it in till the lock ring is tight against the frame.
install the bb from the other side loosely to keep the cup in line as it sets.
wait till it sets then install the bb as normal.
this way you can still replace the bb from the good side. you will not be able to use a different size bb if you want a single chainring etc as you wont be to centre it.
i was sceptical about this but i did it three years ago on an old dawes and it is still good. it is a single speed and im not light so its plenty strong.
this something you can try before any major surgery.