BB formats clarification - SRAM RED BB30 PF on a BMC TM01

Florian

Hi there.
I get very confused with BB compatibilities, a science I know NOTHING about, so here's my situation:

I have a BMC TM01 which is claimed to have a BB30, but not "pressfit".

There is currently an FSA BB-ALM3 inside, which seems to be an adaptor for 24mm:
https://www.bike-components.de/en/FSA/I ... xo-p28161/
I will not use it and will have to remove it.

I bought a SRAM RED crank w/ Quarq power-meter:
https://www.amazon.com/gp/product/B007W ... UTF8&psc=1
Version 177.5mm BB30.
When I measure the diameter of the crank, it is 29.5mm. On the arm it says "BB30, PF+30, AL 7050".

I need to know what type of BB30 I have to buy, so I can then go to the bike shop, they remove the old one and put the new one.
I would like to buy a ceramic from Wheels Manufacturing on Amazon that are at decent prices, but I can't figure out which one, everything seems to be 24mm inside.

Please help me understand this whole BB30 thing!
Thanks a lot.

sungod

bb30 is easy

just get a set of bb30 bearings, if they are 24mm they are not bb30, bb30 is 30mm id 42mm od

these are fine... https://www.amazon.co.uk/Sram-BB30-Bear ... B00283NJ50

more here... https://www.amazon.co.uk/s/ref=nb_sb_no ... 0+bearings

ceramic bearings will make little to no difference in a bb, cheap ceramic bearings may be worse than good steel ones

StillGoing

Your BB shell width is for BB30. Your SRAM crankset axle diameter is BB30. You need a BB30 bottom bracket and not a PF30 bottom bracket. Plenty of manufacturers will list BB30 bottom brackets. Contact the retailer of the bottom bracket make you want and ask them to verify it fits your frame.

http://wheelsmfg.com/bb30-vs-pf30

Florian

Thanks for the replies.
@sungod: do you mean that in fact I don't need any "big thing" between this crank and the frame, just some bearings and I put that crank in there?
How is it held in place then?
So that's the same thing but ceramic version right? https://www.amazon.com/Truvativ-Ceramic ... 002K9EOTC/

Florian

PS: Ah, I found a video:
https://www.youtube.com/watch?v=BUjHgt4hxHk
So is this all there is? 2 bearings and no "body" ?
So that means this FSA adapter will just have to be forced out by pushing from the inside right?

figbat

The BB30 is just two bearings and a shaft - rather like a steering headset or an automotive wheel hub. The bearings are held in by being an interference fit, then the axle (with chainring and one crank) goes through it and the crank arm gets tightened onto the end. There's typically a circlip set inside the BB to locate the bearings at the right place as you drive them in, with spacers to make sure it all sits right.

I really must get mine done.

sungod

yes, the bb shell of the frame will have a 42mm diameter recess each side

at the rear of the recess it'll have either an integral lip against which the bearing sits, or an annular cut that you fit a big circlip into (supplied with the bearing kit)

the bearings are then pressed in to rest against the lip/circlip

then the outer shields (supplied with the bearing kit) are placed over each side, you insert the crank through and tighten per the instructions (some use a wavy washer and/or shims or adjuster, some just use shims, some maybe nothing)

there're pics here, might help make it clearer...

http://www.parktool.com/blog/repair-hel ... rvice-bb30


make sure the bb shell is really clean before installing, then grease it/bearings (with marine/waterproof grease) before fitting the bearings


yes, those trutativ ones are the same thing in ceramic (trutative is another sram brand)

and yes, the fsa adaptor needs to be removed

Florian

Ok so no rocket science there Thanks a lot!
I'll probably just buy the tool and do it myself then. I just need to be very careful when pushing to keep everything perfectly parallel...

sungod

you may be able to insert them without a press tool, it really depends on the tolerances - i can just about install mine ok using both thumbs to push the bearing in

Florian

Ok I see.
Well, I'll get that tool anyway: https://www.amazon.com/Park-Tool-Bearin ... B00426ENBU
plus a long threaded bolt, but I wonder if that tool will work to push the adapter out.

figbat

I was planning to try and ghetto mine out and in using drifts. I was going to use the old bearing race to drive the new ones in, probably after putting the bearings in the freezer and maybe getting a hairdryer or heat gun on the frame. I also plan to lif out the bearing seals to make sure they are well-greased, before refitting the seals. This method has worked well enough on motorcycle wheels.

When I get around to it, that is...

sungod

Florian wrote:

Ok I see.
Well, I'll get that tool anyway: https://www.amazon.com/Park-Tool-Bearin ... B00426ENBU
plus a long threaded bolt, but I wonder if that tool will work to push the adapter out.

that park tool does both removal and installation

Florian

I know but it's not really designed to remove an adapter ... I don't know what's the inner shape of that FSA 24mm thing, probably not ideal but I will probably work with a bit of care

StillGoing

I wouldn't buy a tool. Ask your local bike shop if they'll lend you their's or at worst, hire it to you.

sungod

Florian wrote:

I know but it's not really designed to remove an adapter ... I don't know what's the inner shape of that FSA 24mm thing, probably not ideal but I will probably work with a bit of care

ah, i misunderstood, i meant it installs/removes bb30 bearings

no idea about the fsa thing, as above i'd try lbs if it needs specific tools to remove it