BB30 to BB24



Tech72

Member
Nov 29, 2003
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I recently bought a new frameset with the BB30 standard bottom bracket. I have a Sram Red crankset and GXP ceramic BB to intall, but here's my dilema. The Red crankset and GXP BB is the "standard" 24mm version. I don't want to spend more $$$$ for a BB30 crankset and BB30 bearing set when I already have perfectly good parts, To use my current cranket and BB, I will need an adapter. So my question is: Should I install the threaded sleave into the BB30 bottom bracket to fit standard English thread BB's or do I install BB30 bearings and use outboard BB24 adapters. Or perhaps there is yet another BB30 to BB24 conversion method. This is my first frameset with BB30 so any advice or suggestion is welcome.
 
Your use of the nomenclature "BB24" is a bit confusing since there is no such standard. I assume you are talking about the usual SRAM crankset which just happens to have a 24mm diameter axle.

So my question is: Should I install the threaded sleave into the BB30 bottom bracket to fit standard English thread BB's or do I install BB30 bearings and use outboard BB24 adapters.
I'm presuming here that your question is really "should I sleeve the frame so I can use the threaded GXP bearing cups or should I sleeve the axle to accommodate BB30 bearings?". I'm pretty sure you can't sleeve axles so the only option would be to use sleeves in the frame with threads for your BB cups.

That aside, adapting a BB30 frame to a GXP BB is still a second rate solution compared to using the BB and cranks designed for the frame in the first place. If your cranks are new, why not just flog them to someone else and get the purpose made gear?
 
"Your use of the nomenclature "BB24" is a bit confusing since there is no such standard. I assume you are talking about the usual SRAM crankset which just happens to have a 24mm diameter axle."

[SIZE= 12px]Yes, correct. It is the 24mm diameter axle. In this case, the SRAM Red crankset.[/SIZE]


"I'm presuming here that your question is really "should I sleeve the frame so I can use the threaded GXP bearing cups or should I sleeve the axle to accommodate BB30 bearings?". I'm pretty sure you can't sleeve axles so the only option would be to use sleeves in the frame with threads for your BB cups."

My terminology may have been confusing. But yes, I was referring to the sleeve that fits into the frame to accommodate threaded BB cups.


"That aside, adapting a BB30 frame to a GXP BB is still a second rate solution compared to using the BB and cranks designed for the frame in the first place. If your cranks are new, why not just flog them to someone else and get the purpose made gear? """

This is an angle that I've also been considering. I was hoping to be economical by using components that I already have, but with further thought I'm leaning towards just getting a SRAM Red BB30 crank and BB30 bearing set instead of going "second rate". I'll just put the standard Red crankset and BB on my town runabout.

Thanks
 
Now that I've decided to go with a true BB30 crankset, instead of using adapters. I've been searching online (yes, even ebay...) and have found a SRAM Red BB30 and a FSA K-Force Light BB30 crankset. Both come with standard, non-ceramic BB30 bearings and are similar in price and specs. The few grams difference in weight and "stiffness" are non issue to me. I'm a performance/fitness rider so the last milliseconds of advantage is not important. But which company uses better quality BB bearings? Which will last longer and is "better" quality overall?
 
Bearings are bearings, you will probably find that neither SRAM nor FSA (nor Shimano nor Campagnolo) make their own sealed bearings but simply buy them off the shelf from big bearing makers like SKF or Timken. It makes sense for them to do this because they aren't really bearing experts and because all the necessary parts are already available in a huge plethora of sizes and types to match the application.

In the end I'd be more inclined to go with the model which matches the rest of the components on the bike.
 
Agree the bearings should be essentially the same quality. Actually, FSA may make their own bearings. At least for my FSA Megatech BB circa 2003, the bearings have "THI" stamped on them, which I believe is the name of their source/parent company in Taiwan. If you plan to keep the bike a long time, the future availability and price of replacement bearings might be a factor to consider (mine are no longer in production or available).