Press Fit 30, GXP bottom bracket advice needed

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

Post Reply
User avatar
Mr.Gib
Posts: 5577
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Bike: Parlee Altum, Red 22.

I moved the Red GXP crankset over from another bike and have tried to make it work with a Praxis PF 30 to GXP conversion BB but creaking cannot be eliminated. (Mr.Gib definitely got it wrong - should have reviewed the thread on Praxis conversion BB issues. Forum member highdraw made it pretty clear it wouldn't work.)

I am considering two options:
1. Keep the Red GXP crankset and buy a Kogel F30/GXP bottom bracket.
2. Buy a new BB30 Sram Red crankset and standard Sram PF30/BB30 bottom bracket.

Is the Kogel a real solution or just another band-aid? Option two is of course many hundreds of dollars more expensive but if that's what it take then so be it.
Last edited by Mr.Gib on Fri Apr 29, 2016 10:12 pm, edited 1 time in total.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

eric
Posts: 2196
Joined: Tue Nov 11, 2003 9:47 pm
Location: Santa Cruz, California, USA
Contact:

by eric

The Kogel looks like the two bearing carriers are held in by the crank. This means that you will have to use spacers or wavy washer or both to set the bearing preload. The normal way GXP works is that the NDS bearing provides lateral location and the crank floats in the DS bearing.

The Praxis converter keeps that method, as does the KCNC one.

I had a KCNC and now have a Praxis in my BB30 FM066SL. Both have worked without creaking; the Praxis has less drag. However PF30 might be different. Possibly a dumb question but are you sure its not the PF30 inserts creaking in the frame, instead of the GXP inserts creaking in the PF30 inserts?

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



stormur
Posts: 1173
Joined: Tue Aug 12, 2014 3:50 pm
Location: FIN

by stormur

Buy C-Bear. It REALLY works. Ceramic bearings are a bonus.
Go to Heaven for the climate, Hell for the company.
Mark Twain


I can be wrong, and have plenty of examples for that ;)

User avatar
Mr.Gib
Posts: 5577
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

eric wrote:The Kogel looks like the two bearing carriers are held in by the crank. This means that you will have to use spacers or wavy washer or both to set the bearing preload. The normal way GXP works is that the NDS bearing provides lateral location and the crank floats in the DS bearing.

The Praxis converter keeps that method, as does the KCNC one.

I had a KCNC and now have a Praxis in my BB30 FM066SL. Both have worked without creaking; the Praxis has less drag. However PF30 might be different. Possibly a dumb question but are you sure its not the PF30 inserts creaking in the frame, instead of the GXP inserts creaking in the PF30 inserts?


Not sure I follow all you have written but GXP uses a wavy washer.

The problem with the Praxis conversion BB for Press Fit 30 is that it is really just a BB30 unit with a plastic sleeve over top to take up the larger inside diameter of the Press Fit 30 bottom bracket shell. You can't use Loctite to quiet it. If you do, you may or may not be able to remove the sleeve. I don't want to go down that road.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

User avatar
Mr.Gib
Posts: 5577
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

stormur wrote:Buy C-Bear. It REALLY works. Ceramic bearings are a bonus.


Yes, C-Bear was another thought. I mentioned Kogel because they are in North America as am I, but C-Bear has a longer track record. I found a thread on the web that suggests that Kogel, that used to distribute C-Bear, basically copied C-Bear's designs and started their own BB production business. There is bad blood there.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

User avatar
bikerjulio
Posts: 1900
Joined: Fri Dec 11, 2009 10:38 pm
Location: Welland, Ontario

by bikerjulio

Eric described the GXP system correctly.

It was designed back in the day when all BBs were threaded.

Normally, no spacers or washers are used or needed, in fact they could lead to damage of the bearings.

The spindle is clamped to the NDS bearing and therefore relies on a strongly located BB, which is a failing of pressed-in systems.

Therefore the screwed-together BB's, like Praxis are preferred over any of the pressed-in solutions.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

User avatar
Mr.Gib
Posts: 5577
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

bikerjulio wrote:Eric described the GXP system correctly.

It was designed back in the day when all BBs were threaded.

Normally, no spacers or washers are used or needed, in fact they could lead to damage of the bearings.

The spindle is clamped to the NDS bearing and therefore relies on a strongly located BB, which is a failing of pressed-in systems.

Therefore the screwed-together BB's, like Praxis are preferred over any of the pressed-in solutions.


Understood, but that doesn't solve the problem with Praxis for PF30 and GXP. The necessary plastic sleeve means no chance of a silent BB. And like you say, GXP is anchored on the non-drive side bearing thus requiring a solid fitment. Sounds like this is knock against any press in bb, Kogel and C-Bear included.

Is there any argument against switching to a BB30 crank for a PF 30 frame?

FWIW I have had and continue to have flawless performance with Sram GXP cranks on three other press fit bikes - two Treks and one Giant all with the standard press in BB's, and all using wave washers as per Sram's instructions.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

eric
Posts: 2196
Joined: Tue Nov 11, 2003 9:47 pm
Location: Santa Cruz, California, USA
Contact:

by eric

I had to go to axial load bearings for my PF30 MTB (Specialized Epic). With standard BB30 bearings the BB creaked and had more drag than I prefer.

With GXP using threaded cups you don't need the wavy washer. That's what's on my bikes so it was what I was thinking of. With press in bearings you would use it, because the NDS bearing that is doing the lateral locating is not as tight a press fit in a frame as it is in a threaded BB cup. You don't want it moving in the frame.

User avatar
spookyload
Posts: 1048
Joined: Wed Feb 23, 2005 6:47 am
Location: Albuquerque, NM

by spookyload

I have Kogel BBs in two bikes. A ti crosser and a carbon hardtail. I am using a Shimano PF30 on the ti and a GXP PF30 on the carbon bike. Not a creak since installation. The cups go very far into the frame and are a very precisely machined part. Ceramic bearings. A very good choice for converting the PF30 to GXP.

User avatar
Mr.Gib
Posts: 5577
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Thanks for that data point spookyload. (Although I always wonder about your nickname a bit. Don't think I really want to know what exactly is a "spooky load". :P )

A question for you: did you install with Loctite or just grease?
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

User avatar
Frankie - B
Admin - In the industry
Posts: 6573
Joined: Mon Jun 02, 2003 8:17 am
Location: Drenthe, Holland

by Frankie - B

May I suggest Wheels mfg screw in bb converter? because they drew into place they are much tighter fixed in place then anything press fit.
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'
If you want to see 'meh' content of me and my bike you can follow my life in pictures here!

bikerector
Posts: 44
Joined: Thu Nov 12, 2015 4:04 pm

by bikerector

I will add another option, VCRC's direct adapter BB's. I've been using them for years to use my GXP stages PM on numerous bikes without issue. One of their older designs has traveled between 3 difference carbon frames over the years. I haven't used their newer screw together design but it seems like it would be a lot nicer to deal with when it comes time to service the bearing and knocking out PF bearings can be a pain. Usually I'll just leave them in, remove the seals and service right on the bike but I never feel like it's as thorough as a full soak and repack work. The BB's still work so it must be somewhat effective.

I will also note, I have one bike using a press-in threader cups adapter from sram and then the threaded gxp BB into the adapter and that has worked well also. Bearings are easier to service fully in the design.

User avatar
bikerjulio
Posts: 1900
Joined: Fri Dec 11, 2009 10:38 pm
Location: Welland, Ontario

by bikerjulio

eric wrote:With GXP using threaded cups you don't need the wavy washer. That's what's on my bikes so it was what I was thinking of. With press in bearings you would use it, because the NDS bearing that is doing the lateral locating is not as tight a press fit in a frame as it is in a threaded BB cup. You don't want it moving in the frame.


This is where I'm going to have to disagree. It should not be the job of the crankset to hold press-in cups in place. If the cups can move, then it's a problem.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

rbrtwyn
Posts: 252
Joined: Thu Dec 09, 2004 1:57 pm

by rbrtwyn

I'll 2nd the VCRC BB. I've used them off and on for over 10 years. They were one of the first companies to offer ceramic, also they are in the USA. Great small company to work with. If I'm not mistaken, they are a husband and wife outfit. My team was sponsored by them a while back and at that time at least, they were just a 2 person operation doing a great job.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Post Reply