Following from the thread about Specialized carbon frame and SRAM PF30 BB, this is my 4 month old FSR Carbon stumpy having a brand new SRAM PF30 BB fitted. So we are talking newish frame and new BB…WTF, I thought I was going to need a Press fit press, this is surely going to trash my frame in no time with this tolerance

You tube video link of my new SRAM BB going into my new carbon FSR frame

I have contacted the warranty dept of Specialized but I understand they are likely fob me off saying glue it in…to me thats a bit a cop out.

Press-fit bottom brackets are a very bad idea for this reason – I’d never build or sell a bike with a press-fit BB.

I have had creaking issues with mine. The instructions from Specialized (avialble on the website) is to glue the plastic cups in. I idn’t like that idea because at some point the plastic cup will need replacing so I’m now using one of the Praxis Works BB’s no creaking it’s great.

EDIT

Beeing able to fit the cups that easily is normal.

Using a bearing retaining compound to “glue” in bearings is nothing new and is very common in other industries. That’ll be Specializeds get out clause. Me personally i would have said def use it anyway. Loctite make it and its about £6-8 a pop.

Can you elaborate on what product loctite make to do the job, I spoke to specialized about what to use and they said 3M DP420. And it seems that stuff is like rocking horse poop

Wow, like chucking a chipolata round the Albert Hall.

Is there any play when you assemble everything?

I’ve used a Wheels Manufacturing PF30 (it has aluminium cups), so might provide a more snug fit. I beleive Hope are designing a PF30 to come out soon that is threaded, which may help hold it together, but I guess none of these address the fact that it seemed to slip in too easily. Interested to see how this goes, I have a PF30, not a massive fan but kinda stuck with it.

bencooper – Member
Press-fit bottom brackets are a very bad idea for this reason – I’d never build or sell a bike with a press-fit BB.

^ This ^

Is there any play when you assemble everything?

Not really any noticeable play, but when I fitted it I put a tiny marker on the frame which lined up with the BB to see if it turned in the frame, and yes it did ! Cant feel any wear currently due to the fact it turned, as it only was a quick test ride to see if it rotated plus the cups in theory are softer than the shell (Delrin or nylon I think)

As suspected fobbed off a bit by Specialized customer service guys. I wrote a rather robust Email, suggesting that glueing in cups is a bit of a cop out and a bodge, but got the response that its not considered a bodge and is normal procedure for a lot of manufacturers, and an inference in the nicest possible way that, that is their solution, and they feel that in providing this advice they have fulfilled their obligation. Hard to know how to approach it next.

If press fit becomes the only standard available on new bikes then i’ll have to only buy second hand frames. Always seemed like a poor idea to me.

I have ordered a Wheels Mfg one, with the Angular contact bearings. Just hope that isnt like a c**k in a sock too ! Then I dont really know what I will do after that. Has anyone found the wheels one a snugger fit ?

I tried the Wheels MFG one, it creaked like a b1tch! fat worse than the standard Specialized unit, the instructions also say to bond it in. I dumped it after a week and fitted the Praxis one.

Press-fit bottom brackets are a very bad idea for this reason – I’d never build or sell a bike with a press-fit BB.

LOL! Headsets must give you nightmares then.

If it isn’t the SRAM BB tolerance Specialized will warranty it.

Got a link to the Praxis unit ?

I’ve had no problems with the Wheels one, no creaking or anything (it’s been in about 5 months with occassional weekend rides so still time yet). It certainly was a very snug fit in my whyte and I needed a headset press to push it in place. I would have guessed that the aluminium cups are more precisely engineered than the SRAM plastic cups so hopefully could be a better fit for you. I also don’t like the idea of glueing things in place on a bike, just seems like it’d make it harder to service/maintain/replace, however glue does seem to be a very common answer/solution.

Hi

Here you go

Praxis

The Wheels MFG one was just a push fit in my frame, no different to the SRAM cups. I tried it dry, with grease, with carbon paste. Drove me mad for a week in the Pyrenees!

Thanks for the link,
sadly its not going to be any good, as I have 30mm spindle SRAM cranks

Bummer!

LOL! Headsets must give you nightmares then.

Headsets are under completely different loads than bottom brackets – BBs have very large cyclic offset loading. Pretty much the worst conditions for bearings you could think of.

Threaded bottom brackets have worked for over 100 years, the reverse threading cleverly makes the BB tighten itself with every rotation. Press-fit BBs only have an interference fit and some Loctite to hold them in.

Headsets are under very different loads – for one thing the loads are mostly along the axis of the bearing not tangental to it, and they’re not cyclical to the same extent.

tl;dr: Press-fit headsets have worked for decades. Press-fit BBs are failing after 10 minutes.

The load on the bearing is the same regardless of threaded/press fit. At least with a BB the load is more or less balanced across both bearings. With a headset you have ONE bearing taking a 4g load at around a 40 degrees angle from the main load (BB).

Watch some BMX vids of guys with 70psi tires with zero compliance frames dropping 10ft to concrete. The press fit BB’s have been coping just fine with That abuse for years.

The problem with press fit BB’s is not the concept, it’s the execution. Most of the BB’s on the market have crap tolerance and bearings/sealing. If Shimano made one there would be zero issues like the King model. That said I can make the Sram’s last a season in BC with two or three bearing regreases.

Shimano do make press in bb just not for pf30
And they don’t seem to last to well either but then I never found there ht2 ones all that good