Custom carbon frame - which bottom bracket?

[jever98]

My custom carbon frame is being built over the winter and I can't make up my mind which BB shell I should choose.

Currently, the plan is to go with a PF30 and to install Specialized S-Works cranks with a power meter. The S-Works need to be modded slightly to fit on a PF30.
Weight: Crank + P2M (no rings): ~511g
Bottom bracket (wheels MFG): 114g (or SRAM at around 89g)
Total: around 600g to 625g

An alternative would be to go for a BSA shell:
Frame weight increase: ~50g
Quarq dZero carbon with: 559g (from site)
GXP BB: ~100g
Total: ~710g

Seems like I'm looking at about 100g weight penalty if I go for BSA. My concern is that the PF30 does have more creaking tendencies, even when built well (which I trust will be the case)

Does anybody have brilliant ideas how I can improve on the two options above?

...Maybe with a T47 shell, using a CK BB to fit the Specialized cranks?

Thanks

[Marin]

BSA. Unless this is a total weight weenie project I'd focus on hasslefreeness

That said, I'm running BSA but I'm modding Shimano BBs for GXP for 30g savings...

[Marin]

So, who's building your frame and what's it gonna be like?

[jever98]

Hi Marin,

Rich Craddock from Filament. And it will be awesome, tremendous ;-P.

My aim is to be sub 7kg in a completely rideable clincher setup, which is not easy with my size and weight (2m / 88kg). So every gram counts

It's the disc carbon frame I posted a drawing of elsewhere: viewtopic.php?f=10&t=146699

[physeter]

Another vote for BSA

Two custom bikes, both with BSA

[havana]

That would be a total no brainer for me. BSA.

Press-shit is the ultimate example of a solution for a non-existing problem.

[Marin]

Thanks, I remember now! Sub 7 with disc is hard, but BSA still makes sense IMO.

[jever98]

Thanks, I remember now! Sub 7 with disc is hard, but BSA still makes sense IMO.

Yes, my bank account won't like me I fear...

Current thinking is:
- Schmolke TLO bars and post, Extralite stem
- Schmolke TLO disc clincher or Bike Ahead Bituro road (both around the 1200g)
- Probably ETAP HRD - I like Shimano, but the clean-ness of SRAM is attractive

[Broady]

BSA or maybe T47.

[JackRussellRacing]

.

[Lieblingsleguan]

A creaking PF30 can be remedied with a threaded Wheels Mfg PF30 bottom bracket if necessary. There is no such solution for BB30, but I wouldn't worry about PF30.

Agree with the others that BSA is perfectly fine but if you want to hunt for grams, go PF30.

[kkibbler]

My heart says BSA but it does rule out the odd crankset choice.

PF30 with a thread-together BB for the best compatibility.

[hambini]

BB386 would be my choice - and I make bottom brackets!

Almost all bottom brackets are press fit because the final interface between the bearing and the cup or frame is an interference fit. The reason why most people pick BSA is because it forces bike manufacturers to be accurate with their machining, also any inaccuracy is external of the bike frame, so you don't have a compound tolerance stack up.

Press fit allows bike manufacturers to have half caked tolerances. If they got the tolerances correct, then press fit would not be a problem. Cannondale, Boardman and Cervelo all take the mick with their tolerances. Look and Time are at the other end of the spectrum.

Have a watch of this

https://youtu.be/zryhuHkbb-o

[jever98]

Thanks Hambini, I saw your vids .

Richard makes a one-piece shell, which should keep tolerances in check. The attraction of PF30, for me, is that you can have the shorter axle cranks like S-Works and Hollowgram.

Would you consider making a PF30 / BB30 version of your BB?

Best

[hambini]

Thanks Hambini, I saw your vids .

Richard makes a one-piece shell, which should keep tolerances in check. The attraction of PF30, for me, is that you can have the shorter axle cranks like S-Works and Hollowgram.

Would you consider making a PF30 / BB30 version of your BB?

Best

Hi,

For BB30, I can't make a bb30 bottom bracket. I've seen some people that make them one piece but they have frigged the bearings and will compromise life.

For PF30 to fit a BB30 crankset, that is doable but there is a general trend now towards BB30 (90mm) cranks. so they aren't 68mm anymore. So I can make them as a special but I don't keep them as a stock item.

Hope that helps

Hambini