Are Pressfit BBs still considered evil?

[bobb]

Never had a bike that has a pressfit BB. I know many people who have don't have many good things to say about them.

I'm looking at a potential new MTB and the Canyon Grand Canyon 9 looks just the sort of thing I'm after.

However, from the specs:

Bottom bracket

Shimano Pressfit BB-MT500
Bottom bracket standard: PF 89,5/92

Thoughts? Is that enough to drop that bike from my list of potentials? Or is it nothing to worry about?

Ta.

[Hot Flatus]

To give you an idea, I fitted a have a bike with a BB86 (shimano pf Road standard) and it was faultless for 7 years of all weather riding.  In fact, the only reason I had to replace it was that a di2 cable frayed and I had to take bb out to get to it. Pressed in a new one but for all I know the old one may have gone on forever.

The one you are looking at is pretty similar in design, as in PF, with cups. The really troublesome ones tend to be the ones where the actual bearing is pressed straight into the frame

[D.A.L.E.]

It's not the BB that's the problem.

[Keef66]

Sample size of 1, but I've had a Scott carbon road bike for a decade now on the factory fitted Shimano BB86.  Still utterly smooth and silent.  It is my drier weather bike though

I get the impression that problems tend to occur with pressfit if BB shells are inaccurately sized / shaped .  Pot luck I guess...

[sojournermike]

As noted - if the shells are incorrectly sized or not parallel and concentric then you may have some problems / usually creaks. If a frame is within tolerances all will be fine, so I wouldn’t exclude a bike because it has pressfit. For carbon, I’d actually prefer pressfit than binding in a threaded piece.

You can fit them with loctite silicone retaining compound if needs be and that may prevent creaking. They can still be knocked out easily enough if you don’t buy the wrong one!

[bobb]

OK, thanks. All reassuring 

[Hot Flatus]

It's not the BB that's the problem.

This is true, but PF BBs (with plastic sleeve)  go some way to mitigating issues with concentricity and roundness of the holes in the frame. With BB30 type you are just stuck with it.

[rr]

The Rose has a Shimano press fit BB and I've had no problems, despite running it under water a few times. As others have said the issues people have had are usually due to poor manufacturing of the BB shell, particularly in carbon fibre, rather than the bearings - see Hambini and Mapdec on you tube.

[FifeingEejit]

It's not the BB that's the problem.

This is true, but PF BBs (with plastic sleeve)  go some way to mitigating issues with concentricity and roundness of the holes in the frame. With BB30 type you are just stuck with it.

This

My Synapse with BB30a isn't too bad really but the PF on the Focus was great until the bearings failed,
I've got 3 dead frames in the garage due to stuck threaded BBs

[finch]

Bb30 should just be converted to HT2/GXP with a sleeve cause it’s just better , unless you’ve got a fancy shmancy SISL crankset then the benefits outweigh needing to get non BB30 cranks

PF with cups is absolutely fine

[D.A.L.E.]

Bb30 should just be converted to HT2/GXP with a sleeve cause it’s just better , unless you’ve got a fancy shmancy SISL crankset then the benefits outweigh needing to get non BB30 cranks

PF with cups is absolutely fine

Pray tell how GXP is better.

[finch]

It’s a question of how well the frame is made I guess , loads of BB30 bottom brackets creak in frames where they don’t seat “perfectly” there’s squillions of anecdotal evidence of this. That’s probably why PF took over because the bearings are contained within the BB - much like a threaded HT2/GXP/Mega Exo system. My own experience of BB30/a is that it required a lot of attention to keep it nice and quiet whereas pressing in a sleeve and using a Mega Exo has been basically maintenance free , much like others experience of PF or threaded systems

As you mentioned upthread it’s not really the BB that’s the issue but they get the blame because an adapter can cheaply solve the issues. It’s more that frame manufacturers fault but it doesn’t change the fact that you don’t get those issues with PF or threaded

Cannondale created BB30 & BB30a and they’ve just binned it off for threaded

[bobb]

Ok, a lot of people are mentioning the BB itself not being the problem. I know that. Maybe I should have been more explicit in my title! I just thought it obvious that I was referring to the various pressfit interfaces with the frame...

Thanks everyone for the information though 

[vorsprung]

agree with Flatus that BB86 105 grade bottom brackets are pretty ok
mine had a little bit of unsmoothness in after 2 or 3 years so I replaced it
replacing it is horrendous.  I used a headset remover and a sledgehammer to get the old one out and istr a BB86 headset press (they are cheaply available) to fit the new one