GXP Bottom bracket - 73mm shell. Will it fit?

[bernieUK]

Good evening all

I recently bought a Surly Karate Monkey complete bike. I am happy with it but the 32T/17T setup is a little too easy to pedal. I am thinking of buying an SRAM S300 1.1 Courier Singlespeed chainset. It comes with a GXP bottom bracket. My Surly frame has a 73mm bottom bracket shell. Would anyone know if the GXP BB is going to fit this ok?

To complete the setup I am going to have to buy a new chain. I am a little confused as to the size. Do I need 3/32 or 1/8?

I have tried the usual Google search for both but I cannot find anything definate.

If anyone could offer any advice it would be appreciated.

 

[RecordAceFromNew]

You will need a 3/32 normal road chain because sram's S300/S100 chainsets, including the single speed ones, are road chainsets. Their track chainsets are called Omnium.

The GXP bb will fit the 73mm English thread bb shell of your frame fine. This provides the spacer / chainline spec.

 

[bernieUK]

Many thanks!

 

[GrasB]

Stop right there! your bottom bracket will fit, the cranks WON'T! GXP requires the crank spindle to be the correct length for proper engagement with the cups.

 

[bernieUK]

Stop right there! your bottom bracket will fit, the cranks WON'T! GXP requires the crank spindle to be the correct length for proper engagement with the cups.

Thank you.

I have been checking the spec of the bike with the supplier. Apparently it already has a GXP bottom bracket. I thought it was something different. The current chainset is a TruVativ FireX 1.1 singlespeed. I was hoping to replace it with the Sram S300. As you said it will not fit I will certainly have to rethink now. My local Evans Cycles are selling the Truvativ Omnium singlespeed/track chainset for a very very good price! Perhaps that one instead of the S300?

I have to admit I am now more confused than ever!


Thanks again.

 

[GrasB]

Why not just buy new chainrings? Am I right in thinking you have a 32t chainring with a 17t sprocket at the back? You can but new chainrings for not much money. To work out the BDC of your current chainset use thos guide: http://www.sheldonbrown.com/gloss_bo-z.html#bcd My guess would be 104BDC in which case you have a wide selection of Specialities TA chainrings - Dotbike has most of them.

Just checked & from my understanding you can't use track/road GXP cranksets with a 73mm BB shell.

 

[RecordAceFromNew]

Stop right there! your bottom bracket will fit, the cranks WON'T! GXP requires the crank spindle to be the correct length for proper engagement with the cups.

Well caught GrasB! This is indeed the case and shown in the Truvativ chart linked above, which seems to indicate that for SS the GXP Stylo models are required.