# Sram GXP BB garbage?



## MoPho (Jan 17, 2011)

Built up a new bike with brand new Rival cranks/bb and after about 200 miles the bb developed a tick that I could feel through the crank (felt like the cranks were loose). Installed a brand new spare GXP BB that I had which seemed to solve the problem, but now at about 800 miles it too is getting crunchy with a similar tick. 

I searched here and didn't really find any complaints, so is this unusual or are they known for being junk? Any other options, I am not too keen on spending $200 for a fancy ceramic BB?


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## bikerjulio (Jan 19, 2010)

I have a TruVativ GXP crankset on one bike (same as you have). It's an excellent outboard bearing system that does not preload the bearings.

Yours sounds like an installation problem - BB shell not true, using spacers you should not be, are a couple that come to mind. Look at the instructions and check the installation.


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## reptilezs (Aug 21, 2007)

frame chased and faced with piloted taps?


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## MoPho (Jan 17, 2011)

I have a TruVativ on my other bike, it's actually slightly different in design (Italian thread) than this but have had no problems with it thus far

Can't see how it is an installation problem, there are no spacers, it just screws on to the frame per the instructions 

Frame is a 2010 BMC Pro Machine bought new


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## bikerjulio (Jan 19, 2010)

Those BMC's have really thick white paint. If yours has it around the BB area where the cups sit, I'd suggest removing it. Measure the BB width.

does the crank turn freely after installation, with no binding or strange noises?

I see a spacer/washer on the LH side. Mine does not have this. What do the instructions say?


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## MoPho (Jan 17, 2011)

bikerjulio said:


> Those BMC's have really thick white paint. If yours has it around the BB area where the cups sit, I'd suggest removing it. Measure the BB width.
> 
> does the crank turn freely after installation, with no binding or strange noises?
> 
> I see a spacer/washer on the LH side. Mine does not have this. What do the instructions say?



Those are the instructions, illustration only

Crank turns freely

ring on left is a cover not a spacer

Didn't see any white paint or anything (bike is red) but will check again when I take it apart

I can only feel it when under load riding, can't replicate on the stand.
Thought it might have been the chain/drivetrain but I can feel it in the same place on every pedal stroke and it went away last time when I changed the BB
Tried different pedals to rule that out

Perhaps I should replace this one with another GXP and see if it fixes it again to be sure it's the BB

thanks


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## pmt (Aug 4, 2009)

Yes, they can wear out fast for no good reason. I have one that wore out quickly on a freshly face/chased steel frame, but the identical replacement has been great for a long time.


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## MoPho (Jan 17, 2011)

Hopefully third time's a charm, just ordered another one....

thx


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## Aindreas (Sep 1, 2010)

The installation could be the issue.

The cranks need to be tightened to the proper torque settings. Apparently this can be tricky, since 2 guys helped me with mine -- one a shop owner and the other an experienced wrench. The first 2 times it was attempted, they thought it had been tightened correctly but the cranks were still loose. The 3rd guy, the owner of the shop I wrench at, fixed the problem (ever-so-slightly loose cranks) in a pinch. When the cranks are tightened into the BB, the splines on the ends of the axle actually dig into one another, creating new splines and properly affixing the sections of the axle inside the BB.

HTH in some way.

In other words, have a really good mechanic do it for you if it's needed. And, no, adding another wave washer/spacer isn't necessary.

/ If you need another GXP threaded BB (The kind that comes with the crankset) for whatever reason, I have a spare I can send you. PM if you want it.


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## MoPho (Jan 17, 2011)

Thanks for the offer, I have another one on order already :thumbsup:

I did tighten it up with a torque wrench to the specs, but in hindsight this one was a bit harder to tighten up than the cranks on my other bike. I will check the splines, perhaps there is something wrong there.

thanks


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## royta (May 24, 2008)

My bike came equipped with Sram Rival. My first time out, I heard a squeek from the bottom bracket, which was caused by a loose non-drive side crank arm bolt. I torqued it to spec and now have over 1500 miles on my GXP BB, with zero problems. I'm prepping my bike for a long race on Saturday, so I pulled the crank arms off today and each BB bearing feels silky smooth. Strange that you are having problems. You have both outer seals, right? The ones that go over the actual bearings themselves?

ETA - There is a tech manual on the Sram website that goes over the installation in a little bit more detail.


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## FTR (Sep 20, 2006)

Every GXP BB I have ever had in my Moots has developed a tick over time.
Next BB will be a Chris King.


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## Wookiebiker (Sep 5, 2005)

My first one lasted about 200 miles. I replaced it with ceramic bearings which worked beautifully for a long time. Then I sold that bike.

My next GPX BB has worked well for several thousand miles. What I found out searching the interwebs is that you need to tighten the cranks down, more than spec, and you should be fine.


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## Aindreas (Sep 1, 2010)

Wookiebiker said:


> What I found out searching the interwebs is that you need to tighten the cranks down, more than spec, and you should be fine.


I suspected as much, that it could be beyond spec.

Any idea how much more? (I'm guessing it's the usual bike-mechanic "Until it is tight enough-- and not any more than that" )


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## Wookiebiker (Sep 5, 2005)

Aindreas said:


> I suspected as much, that it could be beyond spec.
> 
> Any idea how much more? (I'm guessing it's the usual bike-mechanic "Until it is tight enough-- and not any more than that" )


No idea how much more...but mine is pretty darn tight. Since I did this...No problems at all


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## MoPho (Jan 17, 2011)

Interesting, you don't have to worry about over-tightening it?

Unfortunately I am away on a business trip for a week with no bike (bummed) I will install the new one when I get back and try cranking







down on it beyond the torque specs and see if that works. 

Glad they're only $29


Thanks


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## Aindreas (Sep 1, 2010)

Wookiebiker said:


> mine is pretty darn tight. Since I did this...No problems at all


Same here. We got it really tight, then I went out and did up-hill standing sprints and then a bunch of bunny hops in the parking lot to test it. (I didn't _really_ have to do the bunny hops, but it was lots of fun.)

A coupla hundred miles later and it's still 100% tight, with no crank wobble as there was before.

Once you get the BB and cranks dialed in, MoPho, you should be really happy. SRAM Rival is teh sh!t. :thumbsup:

/You don't need to load the crankset down with grease. The instructions say something like add extra grease in a few places if proper torque isn't enough to get the crankset tight. Too much grease will just ooze out.


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## MoPho (Jan 17, 2011)

Thanks, I've actually logged nearly 2k miles with Rival already, I had put it on my old DeRosa (with an Italian thread TruVative BB) earlier in the season prior to getting the BMC. Like it a lot, great bang for your buck that is for sure. :thumbsup:


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## bigreen505 (Jun 10, 2007)

If you do a search you'll see a lot of people with the Red/Ceramic BB complaining about crappy bearings and switching to the Rival BB. I have a few hundred on mine with no issues, though there is a lot of drag. However, a truly parallel BB shell is critical with these. I have a steel bike that no amount of facing would fix. Shimano works fine on it.

Bearing pre-load doesn't work like the Shimano system. Basically, pre-laod is set by the length of the spindle and the width of the BB shell. It's not exactly adjustable. The splines on the spindle prevent too much pre-load, so just crank it down.


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## PlatyPius (Feb 1, 2009)

Tighten your cranks at 200 miles. SRAM cranks tend to come loose once after installation.

Tighten the BB.

Face the BB shell.

Those are the only things I can think of. SRAM bottom brackets aren't any worse than any other external BB.


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## royta (May 24, 2008)

The grease thing is just so the crank arm spindle slides into the bearing races easily. I'll grease the spindle, and start it into the bearing races until the spindle sticks out the non-drive side. Then I'll put on the non-drive crank arm and slowly tighten it onto the spindle. I can feel it bottom out, at which point I know I am fully seated. Then I torque it to spec.

I'm guessing that Sram suggests more grease if there is still play because they are thinking a lack of grease is keeping the spindle from bottoming out. It's not like the grease will take up the play or anything.


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## mpower13 (Jun 10, 2011)

What is actually GXP?


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## royta (May 24, 2008)

Giga-X-Pipe


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## bikerjulio (Jan 19, 2010)

bigreen505 said:


> Bearing pre-load doesn't work like the Shimano system. Basically, pre-laod is set by the length of the spindle and the width of the BB shell. It's not exactly adjustable. The splines on the spindle prevent too much pre-load, so just crank it down.


This is not correct. The GXP system locates the axle by means of a small shoulder that engages the inner face of the LH bearing. The LH crank engages on the outer face of the bearing. Thus the crank is clamped to the LH bearing and does not require preload. The axle therefore "floats" in the DS bearing, allowing for minor differences in BB shell width.


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## Pieter (Oct 17, 2005)

bikerjulio said:


> This is not correct. The GXP system locates the axle by means of a small shoulder that engages the inner face of the LH bearing. The LH crank engages on the outer face of the bearing. Thus the crank is clamped to the LH bearing and does not require preload. The axle therefore "floats" in the DS bearing, allowing for minor differences in BB shell width.



Yes, that is how I understand it. But I am puzzled by a 1mm washer on my GXP equipped bike, between the DS bearing cup and the BB. Is there any reason this was seen as necessary?


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## royta (May 24, 2008)

Pieter said:


> Yes, that is how I understand it. But I am puzzled by a 1mm washer on my GXP equipped bike, between the DS bearing cup and the BB. Is there any reason this was seen as necessary?


You have a washer between the bottom bracket shell and the drive side cup? I'm guessing it is there to dial in the chain line or to get the crank arms perfectly centered on the frame.

ETA - I'm not sure what I was thinking. After bikerjulio's comment below, I realized the shim could possibly make sense on the non-drive side IF the bottom bracket shell were narrow enough to not bottom out the drive side crank arm into the drive side bearing.


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## bikerjulio (Jan 19, 2010)

Pieter said:


> Yes, that is how I understand it. But I am puzzled by a 1mm washer on my GXP equipped bike, between the DS bearing cup and the BB. Is there any reason this was seen as necessary?


I'd be puzzled too. Like any external bearing system, the GXP system counts on the BB width being within spec - ie not over, because as you can imagine, an over-wide BB would ruin bearings as soon as the crank was tightened up. Since the crank is located by the LH bearing, spacing out the RH bearing would seem to have no purpose at best, and be destructive at worst.


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## royta (May 24, 2008)

bikerjulio said:


> I'd be puzzled too. Like any external bearing system, the GXP system counts on the BB width being within spec - ie not over, because as you can imagine, an over-wide BB would ruin bearings as soon as the crank was tightened up. Since the crank is located by the LH bearing, spacing out the RH bearing would seem to have no purpose at best, and be destructive at worst.


Yep, you're right. Not sure what I was thinking.


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## Pieter (Oct 17, 2005)

royta said:


> You have a washer between the bottom bracket shell and the drive side cup? I'm guessing it is there to dial in the chain line or to get the crank arms perfectly centered on the frame.
> 
> ETA - I'm not sure what I was thinking. After bikerjulio's comment below, I realized the shim could possibly make sense on the non-drive side IF the bottom bracket shell were narrow enough to not bottom out the drive side crank arm into the drive side bearing.




Yes but heck fine tune a chain line by 1mm??? And the chain line is determined by the position of the NDS bearing anyway, as you said.

Thanks for the clarification anyway !


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## Pieter (Oct 17, 2005)

bikerjulio said:


> I'd be puzzled too. Like any external bearing system, the GXP system counts on the BB width being within spec - ie not over, because as you can imagine, an over-wide BB would ruin bearings as soon as the crank was tightened up. Since the crank is located by the LH bearing, spacing out the RH bearing would seem to have no purpose at best, and be destructive at worst.


Thanks yes, you are correct - in this case shimming the BB wider can only cause problems and not rectify any. Maybe someone thought some bearing axial preload was in order... the bearings are still perfectly smooth after 13500km, so...


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## PlatyPius (Feb 1, 2009)

Pieter said:


> Thanks yes, you are correct - in this case shimming the BB wider can only cause problems and not rectify any. Maybe someone thought some bearing axial preload was in order... the bearings are still perfectly smooth after 13500km, so...


Maybe your BB shell is 67.2mm instead of 68mm?

I've had a few bikes that needed just a bit of clearance between a chainring and the chainstay too, and I've added spacers for that.


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## Optimus (Jun 18, 2010)

Shimano definitely has a better system!!! The Mrs. is running the GXP bb/crank, and it has developed play, no matter how I clean, grease, tighten it, that small amount of play is still there. I ordered a new bb, just to see if it'll solve the issue. Maybe I'll try the spacer approach, but seriously considering going to Shimano on her bike as well. I've had NO issues w/ the hollowtech II system at all!!


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## LongIslandTom (Apr 20, 2011)

I own a Motobecane LeChamp Ti Heat from Bikesdirect, all Rival stuff on the bike.

Like the OP my SRAM BB developed a very pronounced tick on every turn of the crank after just 100 miles of riding.

LBS helped me isolate the problem by trying different pedals, seat post clamp, headset adjustment, drivetrain adjustment, etc. After all that, there was no doubt it was the BB. As a last resort they removed the seals to pack new grease into the left-side bearing on the BB as per the SRAM instruction sheet. That got rid of the tick. And, the LBS guy told me there was very little grease in the BB when they took off the seals.

I suspect it was a quality control problem at SRAM, me having the rotten luck of getting a BB with insufficient grease inside the bearing cartridge.

Two months after that a new problem developed-- a grinding noise from the drive side bearing. LBS looked at the bearing and found that grit had gotten through the seals. They asked me if I want to repack the drive-side bearing with grease like they did with the left side earlier.

I decided I've had enough with the SRAM GXP BB. At that point I already spent $100 on LBS visits to deal with the SRAM BB. I told them to throw the SRAM BB in the trash.

Ordered a Chris King BB with the grease injector tool so I won't have to pay the LBS to tear apart the BB to lube it. Put the CK BB on my bike and have no problems so far, after 500 miles.

My advice in short: the minute your SRAM GXP BB starts to crap, get rid of it and get a Chris King BB.


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## Pieter (Oct 17, 2005)

I removed the GXP left crankarm yesterday, to check, clean and reinstall with fresh copper grease.

The NDS bearing felt a liitle 'dry' - not quite rough. I removed the seal, cleaned and repacked with grease.

Are these special bearings? They feel much tighter than normal deep-groove ball bearings.
Let's say they fail : can they be replaced with off-the-shelf standard cartridges, or will these allow too much play? Maybe some preload is required after all?

I have seen bike mechanics fit standard SKF bearings in Shimano cups. I am not sure if GXP-sized inserts are available. The seal in the bearing cartridge says 'Truvativ' - it looks suspiciously like a very proprietary size.


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## bikerjulio (Jan 19, 2010)

The good news is that yes, they are std bearings - BUT with a small difference I didn't notice the first time. The difference is that the LH bearing has a pressed in sleeve to fit the reduced diameter of the crank at the end, and fit against the shoulder. I was able to punch out the sleeve using a couple of socket wrenches and reuse it.


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## maxxevv (Jan 18, 2009)

bikerjulio said:


> The good news is that yes, they are std bearings - BUT with a small difference I didn't notice the first time. The difference is that the LH bearing has a pressed in sleeve to fit the reduced diameter of the crank at the end, and fit against the shoulder. I was able to punch out the sleeve using a couple of socket wrenches and reuse it.


Ohh ... that's a sleeve ?? Didn't notice, thought it was a custom bearing ! 
Thanks for sharing. :thumbsup:


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## Pieter (Oct 17, 2005)

bikerjulio said:


> The good news is that yes, they are std bearings - BUT with a small difference I didn't notice the first time. The difference is that the LH bearing has a pressed in sleeve to fit the reduced diameter of the crank at the end, and fit against the shoulder. I was able to punch out the sleeve using a couple of socket wrenches and reuse it.


I noticed that NDS sleeve - excellent advice about the wrench sockets thanks. One could even use a large bench vise to do the pressing, with the sockets.


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## kbiker3111 (Nov 7, 2006)

Pieter said:


> I removed the GXP left crankarm yesterday, to check, clean and reinstall with fresh copper grease.
> 
> The NDS bearing felt a liitle 'dry' - not quite rough. I removed the seal, cleaned and repacked with grease.
> 
> ...


Its a preloaded design, so you're better off getting the BB than trying to replace the bearings.


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