BOTTOM BRACKET

daveapps

I AM TRYING TO FIX UP A FRIENDS CHEAP BIKE WHO HAS OVER TIGHTENED THE BOLT HOLDING THE CRANK ARM ONTO THE AXLE WHICH IS SQUARE TAPERED AND HAS STRIPPED THE THREAD.

I HAVE ATTEMPTED TO RE CUT THE THREADS WITH A TAP AND DIE AND HAVE HAD SOME SUCCESS APART FROM DAMAGING THE TAP.

I WAS GOING TO LOCKTIGHT THE BOLT INTO THE THREAD DO YOU THINK THIS IS A GOOD IDEA?

ALTERNATIVELY I COULD CHANGE THE BOTTOM BRACKET. CAN YOU CONFIRM THE THREADS ARE STANDARD?

WHAT MEASUREMENTS DO I NEED TO CONSIDER WHEN BUYING A REPLACEMENT?

THANKS FOR YOUR HELP
DAVE

maddog 2

CAPSLOCK

BBs are cheap to replace so I''d go down that route.

1. You need to know the shell width of your frame. Most likely this is 68mm (some Italian frames are 70, some mtbs are 72)

2. Then you need to know the axle width - you can measure this. 103, 107, 110, 113, 118, 122 are common sizes.

3. Then you need to know what type of threads the frame has. 99.9% will use standard threads but some frames run Italian threads.

4. Finally you need to know whether the taper is Campag (ISO) or Shimano (JIS). Yours will probably be Shimano.


Once you got all that info then head to

http://www.chainreactioncycles.com/

and get a sealed unit. UN53 is cheeap, UN73 is lighter and better.

daveapps

THANKS FOR THE ADVICE

DAVE

on the road

NO NEED TO SHOUT :shock:

Anonymous

on the road wrote:

NO NEED TO SHOUT :shock:

He's hurt his left hand trying to fix his mates bike and cant press the caps lock key in isolation.
Have a heart.

daveapps

I was worried that you old boys wouldnt be able to read without the oversized print. I am a spritly 42 year old so can see fine when sober!!

I have measured the bottom bracket and it is 68 x 127 it is a triple ring
there is a bottom bracket on wiggle:

http://www.wiggle.co.uk/ProductDetail.a ... %20Bracket

this seems to be the right one it says BS on it I assume this means british standard but do I need it to say BS triple?
Does IT mean Italian?

Anonymous

No, It wouldn't necessarily be stamped or labelled BS triple. It is the length of the spindle that is the important factor,not it's designated application.
You are right to assume IT denotes Italian thread.

daveapps

Thanks very much for your help. It is really good to be able to get advice when you need it.

All the best

Dave

maddog 2

If it's Italian threads then both sides will undo anti-clockwise

If it's British (standard) threads then the crank side (driveside) will be clockwise to undo.

The 127mm BB you reference on wiggle is Brtish threads (BS), not Italian.

If the shell is 68mm then it's a British, standard thread (BS), not Italian.

I'd also be tempted to run a narrower BB (IMO). 127 is pretty wide. I'll bet 122 will work perfectly well and bring your fee a bit closer together. More choice of BB too.