gary408

I bought a used frame that came with SM-BB72-41 installed. It doesn't have any spindle though and my newbie guess is spindle come with crankset? Anyways, I want to put a track crankset on this and run the bike in SS. I would appreciate any inputs on which track crankset I should be buying.

fietsbob

Consider replacing the whole thing BB& all or replace a Road chainring with a Thicker 130 chainring..

Japan has NJS Track Bike standards requirements for KeiRin Racing matched bikes, so they dont drop designs as fast as Road parts do.

Dura Ace Track Crank & BB Is still Octalink Dura-Ace Track

gary408

I don't have a crankset yet. The frame as SM-BB72-41. If I understand right, you are saying I can remove the bottom bracket. Buy a bottom bracket and a track crankset which are compatible?

Slash5

That's a Shimano BB. Shimano doesn't make a track crankset to fit that BB. You will have to use a normal Hollowtech crank with a single chainring or change the BB. SRAM makes a GXP track crank, you'll need a pressfit GXP BB.

gary408

I'm thinking of "SRAM GXP 170mm 48T Black Omnium Track Crankset w/BB" combo.

https://www.amazon.com/SRAM-170mm-Bl...61ANMXYFHE0VY6

Would this bb fit my bike frame fuji roubaix 1.1?

alcjphil

The link shows a threaded bottom bracket while the one that is installed on your frame is press fit. Incompatible

Andrew R Stewart 

Generally the crank is the horse and the BB is the cart. Andy.

JohnDThompson 

Yes. Shimano doesn't offer a track crank for that Hollowtech bottom bracket, but assuming the shell is threaded, a standard square-taper bottom bracket should work.

alcjphil

The bottom bracket currently installed in the frame is a press fit type, so the frame isn't threaded

fietsbob

You have seen Gary's frame? , he says the bearings are screwed in externals..

alcjphil

Don't need to. Looked up that particular bottom bracket. It is press fit.
https://bike.shimano.com/content/sac-...-bb72-41b.html

fietsbob

Then the only option is buy a road crank and replace the chainring , I guess..

job is not in front of me, just playing 20 questions, online.. the Sram offer its own press fit BB? IDK.

gary408

How about this one?
https://www.amazon.com/SRAM-GXP-BB86...53NV3MCS5CGYFE

Can "SRAM GXP BB86 Bottom Bracket" replace sm-bb72-41 installed in my frame? If so, which of the SRAM GXP (or any) track crankset be used with "SRAM GXP BB86 Bottom Bracket"?

Appreciate all your inputs.

Slash5

You can get a GXP pressfit BB to use that SRAM crank. It should work fine.
Sram/Truvativ GXP BB86 Bottom Bracket > Components > Drivetrain > Press Fit | Jenson USA

dsaul

That frame has vertical dropouts. How do you plan to get the correct chain length in order to run it as a single speed? Hope for the perfect gear combination or use a tensioner pulley?

alcjphil

I had the same thought as well, just another barrier that the Op hadn't considered. The frame is simply not a good choice for the intended use

gary408

Yes. I may have to use a chain tensioner pulley.

gary408

I would agree with you. But I have seen videos on youtube for converting geared bikes having vertical dropouts to SS. It may not be efficient but doable and I'm interested in learning something out of this conversion project. I have a carbon frame bike that came with alloy wheels. I replaced the wheels with carbon wheels. The stock alloy wheels are of no use now and I want to convert it as SS.

gary408

Thanks for the pointer.

gary408

Thanks for the pointer.

TimothyH

A little bit out of my league here and I'm open to correction but this is my understanding...

BB72 is not a sizing standard. BB72 and BB92 are Shimano product numbers and refer to product levels such as Dura Ace or Ultegra. BB92 is a higher quality and more expensive version of a BB72 but they are the exact same size and install identically.

The size specification is BB86. A BB86 bottom bracket shell on the frame is 86.5mm wide and 41mm diameter while the crank spindle is 24mm. Any BB86 bottom bracket from any manufacturer will fit the OP's frame. The problem is finding a single speed crankset for BB86.OP may want to ask if there is a BB86 single speed crankset in the Single Speed forum.


-Tim-

gary408

Thanks for the info.

Being a newbie, it's getting a bit complex for me to understand compatibility of drive trains. My goal is simple. Ride faster (20-25 mph) on flat road using SS. I have 11-speed wheelset that I can convert it to a SS using SS conversion kit and put in on the aluminum frame with vertical drop outs. I may want to change the setup back to a geared bike in the future. So, I decided to put shimano fc-5800 52/36T crankset to fit BB86 SM-BB72-41 BB. I hope, either SS chain (1/2", 1/8") or 10/11 speed chain works.

TimothyH

Looking over this thread again and it appears that @Slash5 is correct.

GPX BB86 Bottom Bracket linked above looks like it will work with the S-300 crankset.

I didn't think anyone made a 1x road crankset for BB86. My hat is off to you sir.


-Tim-