snowsubi

I've searched all over the forums and have tried to solve this issue to no avail. Advice is solicited.

Relevant parts I'm working with -

Specialized Transition Frame (Inherited with english threading BB shell)
SRAM/Truvativ GXP Team BB
SRAM RED Crankset with 53/39 chainrings

After installing the BB (cleaned/greased/proper torque), I tried to install the crankset w/ chainring. Drive side goes through fine and began to tighten NDS. However, when the NSD is properly torqued, the crankset cannot spin freely, as the inner chainring rubs/clips the chainstay. The chainring has almost no space between the chainstay and if used would likely destroy the carbon chainstay. I removed the crank, reinstalled the BB, double checked everything and am beside myself.

Is there something obvious that I am missing? Are the parts that I am using not compatible with the bike?

My initial thought would be to add spacers to the BB, but my thread searches say that should not be done on a road bike and that it may throw off things.

Any help is appreciated. Thanks.

ultraman6970

I got a similar problem like 3 or 4 years ago with the same BB cups but with a set of low end truvativ cranks. Never figure it out exactly the problem. Even the guy at the store put it in another bike to show and cleared it just fine.

A thing I did not try back then was to put a BB shim in the driver side. LBS always have those moving around, maybe 1 or 2 mm will do just fine.

Ask in your lbs for BB spacers or BB cup spacers, always are inside of the MTB shimano or sram cranksets so they might have a few moving around, all of them do.

Hope this helps

snowsubi

Thanks. I was leaning towards the spacer, but most everything I've read says that GXP for road bike should use no spacers.

ultraman6970

Dont ask me man, some stuff is just plain weird and with so many manufacturers and standards is kind'a logic that at some point stuff wont work with all the bikes in the market. For the record since what you have in there is a TT machine why not use that with a single chainring?? unless you live in the middle of the alps and in that case a TT bike is kind'a useless anyways.

snowsubi

Understood. Using the bike for triathlon and many of the events round here tend to need an inner ring, or at least that is what I tell myself

ultraman6970

Hehehe a 50T or 48T chainring takes care of the problem

ksisler

Is the spindle available in different lenths? Many are and it is not unusual to tune an installation by installing the correct length spindle. In your case, I suspect a spindle intended for a triple crank would easily shift your crank over and away from the chain stay.

FMB42

Welcome to the "BB/crankset/chainring size/chainstay clearance" game. Lot's of fun huh? The good news is that a 1-1.5mm spacer should solve your clearance problem (like others have mentioned). Pretty cheap fix imo. Btw, I spent a fair amount of time researching which BB/crankset/chainring size would clear my particular "frame up" SS build. I finally decided to skip the "it might, or might not, clear" game by running a 46T(!) chainring. Figured this would allow me to get the darn thing rolling for sure (looks like a 48 or even a 50T should clear, now that I've got it together).

snowsubi

Thanks for the insights.

The spindle length is standard for the RED cranks and a triple is not made.

The "advanced" frame by Specialized sure has thrown me a curveball here and my only guess at this stage is to go down the spacer path. My only hesitance was whether this was something that would harm the frame/BB/crank. I suppose the spacer will cause less damage then, say rubbing a crank against carbon, so it seems logical. I tested out a cassette spacer I had lying around and sure enough it did the trick. I'll get some "proper" BB spacers and move onto the next issue which will surely arise shortly.

Thanks for all the help!

fietsbob

Steel Frame ? I have no issues with getting out the Ball pein Hammer,
and using 2nd hammer to strike it, making a strategically placed dent in the chainstay tube
where the potential point of contact is.
OK a metal frame in general.. not CF ..

but standard parts and a normal frame, made to take standard parts ,
the builder should have considered that , initially.

snowsubi

Yeah, no hammering on this one.

I spent a lot of time picking out parts for this and thought everything would workout. Perhaps it is just a different geometry than I was used to being a TT frame?

The prior owner used Shimano cranks w/ Hollowtech II BB, but did not recall whether any spacers were used or needed. Based on that, I couldn't understand why the GXP w/ SRAM cranks would cause a problem. Sounds like the spacers is the simplest solution and/or explanation at this point. Thanks.

neurocop

This is off topic, but a similar problem can occur with old-style non-sealed BB's. The solution with these is to get a longer spindle so the inner crank wheel clears the frame. On newer sealed BB's the shims are the only practical option.