BB help needed

[durbanjacques]

I have an old Giant ATX870 (1998) with a square taper UN55 BB lying in the garage, which I plan on turning it into an SS over the next couple of weeks and wanted to know if anyone has tried replacing these types of BBs with a newer HollowTech II type BB, or if it is even possible to do?

[NotSoBigBen]

I am sure the 'ekspets' will be here any minute, they just having their coffee...... but if you change the BB to external you will also have to change the crank!

[durbanjacques]

The reason I want to change the BB is so that I can change the cranks nothing fancy just something lighter and that can handle a bit more torque.

[Vinnydabutcher]

Im almost sure it will but take out the BB an measure the BB shell width on the bike.

 

Take the BB to your LBS and compare the threads.

[NotSoBigBen]

yes an external BB will work

[divernick]

Remove cranks.

Remove BB.

Install new BB.

Install new cranks.

 

Done. Worked on an old Diamondback that I converted to SS. Easy Peasy.

[Christopher Brunsdon]

The reason I want to change the BB is so that I can change the cranks nothing fancy just something lighter and that can handle a bit more torque.

 

I upgraded from square taper to external this year - it was like buying a new bike. Got an SRAM crankset with bearings for R1K from my LBS.

 

Oh and you might just want to ask your LBS how much to do the job unless you want to buy two sets of BB tools. The square taper tool is about R120 from Sportsmans and a good external BB tool about R200 from a good LBS - check CWC

[Eldron]

The threads are identical - external BB will work.

 

I have the tools if you need 'em. Jhb based DurbanJacques?!

 

60 second job. For you - 1 packet of smarties.

[shaper]

Glad someone asked the question as have a trek 4000 (1999) thats been lying around collecting dust that am also thinking of converting to a SS. Crank is a SR Suntour and the chainrings are riveted! So need to change the whole crank.

 

Am assuming an external BB will work for the frame? Have an old Deore crank that want to use.

[Eldron]

Glad someone asked the question as have a trek 4000 (1999) thats been lying around collecting dust that am also thinking of converting to a SS. Crank is a SR Suntour and the chainrings are riveted! So need to change the whole crank.

 

Am assuming an external BB will work for the frame? Have an old Deore crank that want to use.

 

Yup.

 

Prior to BB30, BB90, BBpickyournumber there were only 2 BB thread standards - English (which is by far the most common and still is) and Italian (which some Eytie bikes use).