BB30

[Polisman]

I'm frustrated trying to fit an Sram Red chainset into a BB30/PF30 press fit bracket. It comes with various plastic and a metal wavy washers, but no matter how I arrange them when I pre load the Allen bolt on the left crank arm, it's either too loose, or there's significant friction going on down there.. I'm determined to crack this, rather than go cap in hand to my lbs, who, as far as I know don't have much experience of press fit either

[Valbrona]

You don't say whether you got a BB30 bottom bracket or a PF30 one, but either way I believe the assembly arrangement is the same. Expect to use spacers if you have the wavy washer in order to get the right compression.

Note that SRAM BB30 bearings have a metal bearing shield, other BB30 bottom brackets, like FSA, have metal shields with rubber coatings. I would stick to SRAM bearing shields.

[alexnharvey]

Can we assume that you have previously been able to achieve smooth running with another BB and crankset and if so what type? What is the frame?

[Jamesh]

I found this helpful.

https://www.google.com/url?sa=t&source= ... Eqz8LnEDjL

If one washer is causing too much friction then removing one might help.

Cheers James

[Gattonero]

I'm frustrated trying to fit an Sram Red chainset into a BB30/PF30 press fit bracket. It comes with various plastic and a metal wavy washers, but no matter how I arrange them when I pre load the Allen bolt on the left crank arm, it's either too loose, or there's significant friction going on down there.. I'm determined to crack this, rather than go cap in hand to my lbs, who, as far as I know don't have much experience of press fit either

Like already said: you must say what chainset is, they all fit slightly different but usually is better to do a "dry-fit" first with ony the seal above the bearings and no spacers. Tighten the Lh crank (if it's the type that has to go to a dead end) and see how much play you have.
Some BBs/cranks will need a "wave-washer" (mostly) between the Lh bearing and the crank but sometimes this goes between the Rh bearing and crank (mostly, for the Sram cranks). Some others don't use a spring-washer and will have a preload adjuster built inot the Lh crank, other cranks have none.

Just start with no spacers and zero preload, then add spacers or preload asnecessary. Under no circumstances you are to leave the Lh crank bolt loose "because there's too much friction", I've seen many cranks ruined by doing this.

[Polisman]

It's an Sram Red 22 chainset. The frame is your standard Chinese press fit 30. I'm from the generation where if a bottom bracket was well fitted and greased, and did not spin for at least 20 seconds it was 'too tight'. With the pre load adjusted, no play, the cranks go round okay, but they do not spin. How much friction is to be expected on a press fit, pre load set up? They don't feel bad, but certainly quite 'sticky'.

[Gattonero]

It's an Sram Red 22 chainset. The frame is your standard Chinese press fit 30. I'm from the generation where if a bottom bracket was well fitted and greased, and did not spin for at least 20 seconds it was 'too tight'. With the pre load adjusted, no play, the cranks go round okay, but they do not spin. How much friction is to be expected on a press fit, pre load set up? They don't feel bad, but certainly quite 'sticky'.

You have to fit wityh preload/washer in a way that the play has just disappeared. The bearings are much larger so there is apparent more friction when spun by hand. Bearin mind (pun intended) those cranks will have a lot less deformation in use, so the "friciton" you may feel when hand-spun is basically irrelevant (unless you're racing on the track or at national levels).
As long as the cranks spin even with no dead-spots, with standard bearing it's fine to get them to fully spin 2-3 times.

Alternatively you can try by fitting two bearings that have been fully degreased and lubricated with oil only, and oil around the seals/covers too. That makes a substantial difference, but it's only for riding in bone-dry conditions

[Polisman]

It's an Sram Red 22 chainset. The frame is your standard Chinese press fit 30. I'm from the generation where if a bottom bracket was well fitted and greased, and did not spin for at least 20 seconds it was 'too tight'. With the pre load adjusted, no play, the cranks go round okay, but they do not spin. How much friction is to be expected on a press fit, pre load set up? They don't feel bad, but certainly quite 'sticky'.

You have to fit wityh preload/washer in a way that the play has just disappeared. The bearings are much larger so there is apparent more friction when spun by hand. Bearin mind (pun intended) those cranks will have a lot less deformation in use, so the "friciton" you may feel when hand-spun is basically irrelevant (unless you're racing on the track or at national levels).
As long as the cranks spin even with no dead-spots, with standard bearing it's fine to get them to fully spin 2-3 times.

Alternatively you can try by fitting two bearings that have been fully degreased and lubricated with oil only, and oil around the seals/covers too. That makes a substantial difference, but it's only for riding in bone-dry conditions

Thanks for the advice. The problem I'm noticing is that they don't really spin at all. In fact they have to be turned by hand. It's not a tremendous amount of friction, but if I ease back on the preload they are far too loose. I can't help but think I'm doing something very wrong. So far using a wavy washer and a plastic 1.5mm spacer on the RH side. The spacer though, seems a bigger ID than the spindle of the crank.

[Gattonero]

It's an Sram Red 22 chainset. The frame is your standard Chinese press fit 30. I'm from the generation where if a bottom bracket was well fitted and greased, and did not spin for at least 20 seconds it was 'too tight'. With the pre load adjusted, no play, the cranks go round okay, but they do not spin. How much friction is to be expected on a press fit, pre load set up? They don't feel bad, but certainly quite 'sticky'.

You have to fit wityh preload/washer in a way that the play has just disappeared. The bearings are much larger so there is apparent more friction when spun by hand. Bearin mind (pun intended) those cranks will have a lot less deformation in use, so the "friciton" you may feel when hand-spun is basically irrelevant (unless you're racing on the track or at national levels).
As long as the cranks spin even with no dead-spots, with standard bearing it's fine to get them to fully spin 2-3 times.

Alternatively you can try by fitting two bearings that have been fully degreased and lubricated with oil only, and oil around the seals/covers too. That makes a substantial difference, but it's only for riding in bone-dry conditions

Thanks for the advice. The problem I'm noticing is that they don't really spin at all. In fact they have to be turned by hand. It's not a tremendous amount of friction, but if I ease back on the preload they are far too loose. I can't help but think I'm doing something very wrong. So far using a wavy washer and a plastic 1.5mm spacer on the RH side. The spacer though, seems a bigger ID than the spindle of the crank.

Sounds to me that you have the type of cranks without the preload-ring (those have the locking bolt on the Rh side) but rather the ones without the adjuster (the fixing bolt is on the Lh side) and those will need the wave-washer on the Rh side (between the bearing cover and the crank).
You ought to have the wave-washer not slack nor fully compressed. If not add or remove spacers as necessary. It's all about the first installation, then it's easy once you know how many spacers are required.

[Jamesh]

Could it be that your bearing have been over packed with grease and with a little riding they will free off??

Cheers James

[Gattonero]

As a rule of thuimb, Sram GXP has the Lh crank (most of their cranks have the fixing bolt on the Lh side) that locks onto the crank axle on a dead-end.
This means that the distance between the Lh crank and the Lh bearing is fixed and cannot be altered. In the case of a BB30 if you put too many spacers (or a thick bearing cover) between the Lh crank and th bearing you cause the bearing to jam.

On the other side, the Rh crank is "floating" with the Rh bearing and that is the reason why on a BB30/Press-Fit BB you will have a wave-washer to prevent the bearing form been dislodged (this is not necessary on that threaded BB, because the threads hold the BB firmly in place).

So agin, make sure the space on the Lh side is spot-on

[alexnharvey]

https://youtu.be/dkAxXNYzBGg

A bit more on SRAM gxp problems here and a general opinion on their manufacturing being very poor. Contains foul language.

So far we've glossed over the fact that you might not be doing anything wrong in the installation. You could have problems that are inherent to the frame's BB shell alignment or the crankset alignment and concentricity.

That was also why I want to know what cranks you were using before.

[Gattonero]

...You could have problems that are inherent to the frame's BB shell alignment or the crankset alignment and concentricity...

Since the frame shells are usually a machined piece of aluminium, and cranks are machine-made with CNC finish, this is goes well after the wrong number/type of spacers used in the assembly.

[alexnharvey]

Not all shells are aluminium. As you know, moulded shells are increasingly common.
Not all cranksets are equally well machined.

[Gattonero]

Not all shells are aluminium. As you know, moulded shells are increasingly common.
Not all cranksets are equally well machined.

One-piece carbon shells for BB30 are (thankfully) very rare, more common for "press-fit" nylon cups (whether using 24 or 30mm ID bearings).
And the discrepancy in machining a crankset ought ot be the bad apple, and a far cry from incorrect installation. The former, will give the odd "tight-spot", the latter will give constant friction or play all around.