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Truvativ GXP DUB Bottom Bracket


Richie612
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9 minutes ago, Adam@TartyBikes said:

They don't all have to engage though...

The DUB BBs aren't serviceable. What's happening to make you want to tinker with it?

Just trying to find the source of a creak. I thought I would take the BB out and clean the threads and re-grease. The cranks are tight still as there isn't any wobble and torqued to 50nm.

When I mentioned servicing I meant taking out, cleaning the bottom bracket housing and re-greasing not stripping the bb down :P

Rich 

 

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8 hours ago, Richie612 said:

Just trying to find the source of a creak. I thought I would take the BB out and clean the threads and re-grease. The cranks are tight still as there isn't any wobble and torqued to 50nm.

When I mentioned servicing I meant taking out, cleaning the bottom bracket housing and re-greasing not stripping the bb down :P

Rich 

 

Mine also has a slight creak, greasing didn't didn't help. Definitely worth trying though. Worth having a good look around the cranks for tiny cracks as well. 

Edited by Rip
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2 hours ago, Rip said:

Mine also has a slight creak, greasing didn't didn't help. Definitely worth trying though. Worth having a good look around the cranks for tiny cracks as well. 

Thanks for that, I'm sure there's no cracks at the moment though as the bike is pretty new and hasn't been given a lot of abuse.

Rich 

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8 minutes ago, Richie612 said:

Thanks for that, I'm sure there's no cracks at the moment though as the bike is pretty new and hasn't been given a lot of abuse.

Rich 

Hopefully a bit of grease and the right torque spec will sort it then. 

Edited by Rip
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Not sure what bike you have but this info is from someone at Inspired but is probably useful anyway:

The only thing I'd note is that typically, if it's time to replace a BB you'll usually get more of a 'popping' kind of sound rather than a creak. A creak would generally just imply very small movement between some parts, whereas when the BBs go it's usually due to the bearings failing. As they break apart, they get forced past the other bearings in the cartridge giving that 'popping' or banging sound. 
 
It may be worth taking everything in your crankset apart, giving it all a thorough clean and check for cracks or any other damage/wear, then reassemble it all with plenty of grease. That includes things like your pedals in the cranks too! It's usually tricky to pin-point causes of creaks in that area because it's all under a high amount of load and will generally all have a similar sound if anything is a touch loose.
 
And:
 
I forgot to mention, but the crank bolt on the Truvativ cranksets needs a bit more torque than most - I believe they recommend 54Nm, so much higher than conventional ISIS or square taper cranks. If it's a bit under, it may have that tiny bit of play that could lead to creaking.
 
mark@inspiredbicycles.com
Edited by Rip
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When bikes are new things inevitably tend to bed in and slightly loosen off, so things like pedals, headsets, cranks and BBs can sometimes need a nip up. Due to the leverage BBs and cranks have got going through them, the smallest loss of tension (and therefore the smallest bit of movement) gets exacerbated and you'll generally hear about it fairly quickly. You shouldn't need to full remove and re-grease it, I'd just whip the cranks off and nip the BB up. That should generally get you sorted. If it remains then you can strip/re-grease/re-build, but it'll have been greased from new so it'll most likely just have bedded in and worked loose a touch.

As above, the tools for these BBs don't necessarily engage on every spline. There's still plenty of tool contact, so as long as you make sure that there's still pressure holding the tool onto the BB interface when you're giving it some beans you won't have problems. The extra splines are just a neat way of reducing weight while also increasing functionality. It's similar to the Echo SL freewheels which used to have 8 slots for a freewheel remover, but only needed to use a 4-prong tool (and then ended up just having long slots rather than the traditional small, prong-sized slots).

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12 hours ago, Mark W said:

When bikes are new things inevitably tend to bed in and slightly loosen off, so things like pedals, headsets, cranks and BBs can sometimes need a nip up. Due to the leverage BBs and cranks have got going through them, the smallest loss of tension (and therefore the smallest bit of movement) gets exacerbated and you'll generally hear about it fairly quickly. You shouldn't need to full remove and re-grease it, I'd just whip the cranks off and nip the BB up. That should generally get you sorted. If it remains then you can strip/re-grease/re-build, but it'll have been greased from new so it'll most likely just have bedded in and worked loose a touch.

As above, the tools for these BBs don't necessarily engage on every spline. There's still plenty of tool contact, so as long as you make sure that there's still pressure holding the tool onto the BB interface when you're giving it some beans you won't have problems. The extra splines are just a neat way of reducing weight while also increasing functionality. It's similar to the Echo SL freewheels which used to have 8 slots for a freewheel remover, but only needed to use a 4-prong tool (and then ended up just having long slots rather than the traditional small, prong-sized slots).

Thanks for the information Mark, much appreciated.

Next rainy day I'll whip the cranks off and give the bb a nip up if it needs it. I'm used to full suspension bikes you see and they don't get quite as much abuse as a fully rigid so I see how things can come a little loose easier.

Just a quick question, the non drive side has a preload adjuster, what's the deal with that?

Do I undo that to remove the non drive crank and re tighten to a specific torque?

Sram cranks are new to me.

Rich 

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A big part of it isn't so much the rigid setup of the bikes, but just that you're not doing constant full pedal rotations. The way that pedal and BB threads are orientated is to counter precession, something that only really 'works' if you're doing full pedal strokes. Because trials is a lot of jabbing forward/backward motions it makes it more likely things will loosen off.

For the DUB preload adjuster, that's kind of independent to the rest of the BB in a way. The SRAM manual does a pretty decent job of explaining how to use it - skip down to P20 and you'll see the start of the preload adjustment bit. Those locking collars are fairly 'soft', so just go easy on them. It's something you really only need to nip up rather than cranking down on - the 54N/m on the crank bolt is the thing that's really keeping it all in place!

https://www.sram.com/globalassets/document-hierarchy/user-manuals/sram-mtb/drivetrain/dub-mtb-and-road-cranksets-and-bottom-brackets-user-manual.pdf

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