MajorMantra

Against my better judgment, I've just bought a PF30 CX frame. I haven't made my final decisions but I may end up running a Shimano crank. I've been investigating the various options and if I do go down this route, I want to be able to use Hollowtech II bearings rather than running a conversion type BB such as this Praxis:

https://praxiscycles.com/pages/conversion

Truvativ (SRAM) offer this set of conversion cups:



Some shops selling it mention that a permanent or semi-permanent installation can be carried out with a retaining compound. Has anyone taken this approach? Curiously, the installation instructions on the SRAM site make no mention of this, and would have you install the BB cups in the adapter before pressing the adapter into the frame, which I've read some people have had some problems with. Obviously, being a breakable plastic cup, it would be better not to have to remove the adapter every time the BB is replaced.

Thoughts?

well biked

We've had great luck in our shop with Wheels Mfg adapters in PF30 bb's when running Shimano cranks. They're simple, allow you to use the PF30 bearings as is, and they're fairly inexpensive. I've personally got about 8000 miles on this setup on one of my own bikes, no problems at all. Running PF30 bearings w/ Ultegra 6700 cranks w/ the appropriate Wheels Mfg adapters.

linus

Wheels Mfg adapters work okay, but Rotor 4624 BB worked better for us.

Maybe you can experiment with this?

https://www.emabearing.com/product-de...&tId=12&sId=19

MajorMantra

My logic in wanting an adapter would be to let me use HTII BBs as they're cheap, and I have at least 2 in my spares box already. I'm a little surprised to hear the Wheels Mfg recommended actually as I've read some very negative comments about them in the course my research. More data points are always useful though!

Interesting. I've just discovered a UK shop selling these quite cheaply. It's just moved to the top of my list! Thanks.

reptilezs

the one you linked to is not permanent at all. if anything they like to walk out of the press fit after some use. loctite 609 retaining compound is recommended

MajorMantra

But with Loctite, is it not feasible to treat it as semi-permanent? I.e, can you get away with repeatedly installing and removing threaded cups into the adapter without having to remove or replace the adapter? I would assume it's possible with care, but I haven't tried it.

Crankycrank

To me the Praxis looks like the best option since it screws together and eliminates some of the sqeaking and loosening problems of some PF's. It's not much more expensive than the Shimano BB + Adapter and if you have some mechanical skills the bearings can be pressed out for replacement at a fraction of the cost of a new BB. My guess is that the original bearings will last a long time so won't need replacing often.

well biked

[QUOTE=Crankycrank;16364627]To me the Praxis looks like the best option since it screws together and eliminates some of the sqeaking and loosening problems of some PF's. [QUOTE]

Our shop has sold a lot of bikes with BB30, PressFit30, BB86, etc. The BB30's are the only ones that have been problematic with noisiness, etc. We've never had a noisy or problematic bike w/ PF30 bearings installed. The interface with the frame is completely different with PF30 compared to BB30, and that's where the noisiness problems usually originate with BB30. PressFit 30, in our experience, is a good, dependable bearing system.

MajorMantra

Are the bearings definitely a standard size though and not something hard to track down? (E.g. like Trek's ones.)

I do think the Praxis looks good, but if I could achieve the same practical results using a cheaper semi-permanent adapter I'd rather do that.

Crankycrank

I don't know for certain what size bearings are used in the Praxis but all bearings have size/type numbers stamped on them and can be bought from bearing supply shops. Be aware that they are pressed in and need a special technique to remove and replace if you don't want to spend $50+ on a bearing removal/install tool.

MajorMantra

Don't worry, I'm a mechanic.

I know bearings are theoretically available for everything but IME practice can be another matter. (cf. Trek V2 BB90 bearings, Shimano's 6mm thick HTIIs, headset ACBs etc.)

reddog3

Major Mantra- Why fret, or go away from the PF30 setup? Seems backward to me to have a frame that offers the advantages of PF30 and convert back to an old, heavier BB/spindle type. Plus Shimano cranks are ugly- JMO.

PF30/BB30 cranksets are much lighter due to the alloy spindles, and narrower. You heard the horror stories about noise and reduced bearing life but it doesn't need to be that way with either PF30 or BB30.

BB30 and PF30 use the same bearing but the frame interface is different.

On BB30 shells the bearings press directly into the shell, seating against a snap ring or circlip. This is a problem with the BB30 system. If the shell ID is not sized properly (usually too small/tight) it will reduce internal clearances within the bearing, and cause premature wear and noise. The other spec problem with BB30 shells is the bearing seats. If not exact in depth it will side-load the bearings and cause premature failure. This is harder to deal with than bore size, after the fact, but can still be worked out. Unfortunately none of the bike specific BB reaming tools are precise enough, and machining a BB shell (in the frame) isn't the handiest, but doable.

The other problem with BB30, and PF30 to a degree, is crank/spindle installation. All instructions call for seating the bearings into the frame, and then pressing the crankset into the bearings. Since this is a press fit, and you are pressing the spindle into the non-supported inner race, the bearing is sideloaded- won't run smooth and will wear prematurely. I press the drive side bearing into the frame and pull the crank into the bearing supporting the inner race. I then press the NDS bearing in/onto the shell and spindle simultaneously supporting both the inner and outer race. This eliminates install procedures of becoming a problem.

Ironically Cannondale "set" the BB30 standard, and they seem to be the worst for holding tolerances and experience a lot of bearing troubles.

PF30, though they share the same bearing as BB30, have fewer problems because of the frame interface. The shell ID is larger and they employ (usually) a composite adapter to house the bearing. The composite is more forgiving of tolerance issues, and doesn't load the bearings so much if the shell is out of spec. And the bearing depth is set within the adapter (unlike the BB30 clips) and is more easily controlled because machining can take place off the bike after the frame is manufactured. Careful install procedures still apply.

You might think, why bother with all the precision required, when the "old system" worked fine with less hassle? It really depends on how important saving a couple hundred grams, or more, is to you.

MajorMantra

Fretting (and complaining) is kinda my thing: https://thesetbackpost.com/

I could just go native PF30, but unlike many I actually like Shimano cranks, and I find they outshift pretty much everything else. Plus, on this side of the Atlantic, Shimano stuff is easy to find heavily discounted, more so than SRAM/FSA etc. at least when it comes to spares like BBs.

I have been offered a PF30 compatible FSA Gossamer cheaply but I'm not sure it's nice enough for me!

Decisions, decisions.

well biked

I completely agree, Shimano cranks rock. I personally just think you're overthinking this in trying to find an adapter that will allow you to thread in Shimano bearing cups. The PF30 bearings are, in our experience at least, very reliable and trouble free. Again, I've got extensive experience with them on one of my own bikes, along with the Wheels Mfg adapters. PF30 bearings are what your frame is designed for. Plug those Wheels Mfg adapters in there and the PF30 bearings are perfectly compatabile with 24mm spindles. It's a simple solution to what you're trying to do, and you get to use PF30 bearings. I think if you're totally determined to use Shimano bearing cups, you should have chosen a frame with a threaded shell that's designed for them.

MajorMantra

You may well be right. I've read many, many criticisms of the Wheels adapters though - the impression I've gleaned of them has been overwhelmingly negative aside from your recommendation!

I wouldn't have chosen this frame, but in other respects (weight, price, looks) it's what I want so I decided I could live with PF30 in some form.

MajorMantra

After all my agonies my frame arrived today and it's BSA threaded! They changed it without notification. I should be annoyed (I'll have to return the adapter I bought) but I'm pretty darned happy about it.

surreal

Another happy ending.