Crank thread stripped

Page may contain affiliate links. Please see terms for details.

Holdsworth

Über Member
Location
Crewe, Cheshire
Yes the never ending saga of big repairs that cost enough to stop from buying a new bike continues!!!
angry.gif


This time the thread for the pedal on the drive-side crank has stripped itself, found this out when having a set of SPDs fitted by Williams's in Crewe. Had to limp home on one good pedal which was the flat one of the left side which he didn't bother to remove for obvious reasons.

I suppose I am going to have but A new chainset and BB to get up and running again (lots of money that I wish I wasn't spending
sad.gif
).

I suppose this is something that The LBS can do for me in a day, what sort of costs should I be looking at?
 

gbb

Legendary Member
Location
Peterborough
What speed and chainset / BB have you at the mo Holdsworth ?
 
OP
OP
Holdsworth

Holdsworth

Über Member
Location
Crewe, Cheshire
It is labelled as a "Shimano Biopace" "For narrow chain only" and has the number "52" engraved below it. The chainset is a double BTW.

It came on the bike which is around 20 years old now, I can't be sure if the chainset is original to the bike though.
 

byegad

Legendary Member
Location
NE England
OK. If the thread for the pedal is stripped, and you can find a local small engineering place, it can be Helicoiled. That is a bore out re thread and a sleeve fitted which allows you to fit a pedal. Not too expensive, but maybe a new chainset is not a lot more!
 

RecordAceFromNew

Swinging Member
Location
West London
If replacing the crankset is the preferred route Biospace is vintage Shimano so the BB is nearly certainly square tapered (you should be able to see 4 flat surfaces on the bb shaft adjacent to the crank arms). You can of course remove the crank and find out what the BB spindle length is (which will determine which crankset can be a straight replacement). Less reliably way is to find out the crankset's precise model (usually on the inside face of the crank arm) from which can be deduced which BB it has and from that which square tapered crankset can be a straight replacement, provided of course you have the tools and want to DIY.

You should also measure the bb shell width and chainline.

Otherwise the LBS can do everything for you.
 
OP
OP
Holdsworth

Holdsworth

Über Member
Location
Crewe, Cheshire
Depending whether or not I can get a straight replacement from the LBS, what sort of price would I be looking at for a full replacement? I can see that A helicoil would be around £30 or so according to Google shopping results.
 

Zoiders

New Member
Not worth the expense or faff to fit a helicoil on an aging ally chainset that could well break following the fitting of one. The Biopace chainset hung around in various forms with different model numbers/names and in slightly different colours and the actual arms and spiders are not special to biopace oval rings. A cycle jumble or a bike recyling project would turn up a replacement quite easily which even if not an exact cosmetic match would be usable, we usually have quite a few kicking around at the recyling project.

The BB is bog standard shimano square taper which will most likely be a 68mm BB shell and what ever size the LBS finds when it pulls the chainset - 113 being most likely although thats not set in stone. There are some identical looking spiders that took a tripple for MTB groupsets of the time, they sit further out from the taper face though so it's a difference that can be seen by eye.

A shimano UN54 or UN57 will drop straight in as a replacement, the 54 probably being what was fitted in the first place, about £20 in the LBS at the most.
 
OP
OP
Holdsworth

Holdsworth

Über Member
Location
Crewe, Cheshire
The bike has been looked over by another LBS but he can't get a matching crankset in for maybe up to 2 weeks so I will be off the bike for quite a while!!! He says that there is no need to go about replacing the BB either, no play in it and good to use.
 
OP
OP
Holdsworth

Holdsworth

Über Member
Location
Crewe, Cheshire
I have finally got the chainset replaced by the LBS, it has been a long wait to get one off of his suppliers due to the multiple bank holidays but it's on now and I'm happy.

It isn't Shimano though, SunRace R90, which I've heard aren't the best but as long as it works as it should then I'll be pleased. It looks rather nice now with SPD pedals fitted too and they fell great, despite a near clipless moment on the first run!
 
Top Bottom