Bottom Brackets

[samson99]

Good morning all,

 

Hopefully someone can help me.

 

I currently have BSA BB on my bicycle, would a BB30 crank work?

Is there an adapter?

 

I do not understand all these different BB's

 

Thanks in advance.

 

S

[LOOK695]

+1 on this topic. All these different BB sizes are confusing

[GaryvdM]

This is an excellent guide to the different BB standards: http://www.slowtwitch.com/Tech/Bottom_Bracket_Standards_2573.html

To answer your questions, no. The BSA frame shell has too small a diameter to fit the BB30 bearings in it, and the BB30 crank axle has too big a diameter, and too small a width too fit in the BSA bearings.

 

Edit: just to add some info, due to the width of a BB30 crank, the bearings would need to sit on the inside of the frame. (Modern BSA BB's have the bearings outside the frame.) The outer diameter of the BB30 crank is 30mm (hence the 30 in BB30). The inner diameter of a BSA frame shell is 34mm. That would mean the bearing would need to be only 2mm thick, which is just not feasible.

[samson99]

Thanks Gary for the reply.

So if I want to replace the crank, I need to source a BSA specific crank or are adapters available for other BB's to fit?

 

Thanks in advance.

[GaryvdM]

BSA cranks and bearing sets are easy to source. All the group set manufacturers (Shamino, SRAM, FSA, Campagnolo) all make BSA cranks and bearing sets. (Shamino actually only make BSA.) Just ask your LBS.

 

If you bought the BB30 crank and bearing set, try return it for exchange.

[Pah Bear]

This is an excellent guide to the different BB standards: http://www.slowtwitch.com/Tech/Bottom_Bracket_Standards_2573.html

 

To answer your questions, no. The BSA frame shell has too small a diameter to fit the BB30 bearings in it, and the BB30 crank axle has too big a diameter, and too small a width too fit in the BSA bearings.

 

Edit: just to add some info, due to the width of a BB30 crank, the bearings would need to sit on the inside of the frame. The outer diameter of the BB30 crank is 30mm (hence the 30 in BB30). The inner diameter of a BSA frame shell is 34mm. That would mean the bearing would need to be only 2mm thick, which is just not feasible.

Thanx GaryvdM. Had to read the article twice and certain sections 3 times to get a clearer understanding. Excellent and very detailed article explaining this rather confusing subject. MUCH appreciation for bringing it to our attention.

[fanievb]

another guide

http://www.bikeradar.com/gear/article/complete-guide-to-bottom-brackets-36660

[Pah Bear]

another guide

 

http://www.bikeradar.com/gear/article/complete-guide-to-bottom-brackets-36660/ 

Fanievb. Site down seem to exist anymore.

[GaryvdM]

Fanievb. Site down seem to exist anymore.

 

Just a copy paste error

 

Try this: http://www.bikeradar.com/gear/article/complete-guide-to-bottom-brackets-36660/

[fanievb]

Fanievb. Site down seem to exist anymore.

 

 

Just a copy paste error

 

Try this: http://www.bikeradar.com/gear/article/complete-guide-to-bottom-brackets-36660/

 

yip there was an extra /