GXP BB Questions

[snowbeast]

Howzit,

 

Off the bat I am not a very technical person nor a racer, I just ride to see whats on the other side of the hill.

 

I bought a 2008 Mongoose Meteore Team off a hubber last year sometime and over Christmas we stripped my GT i-drive (original was bought in 2004!) in the hope of building up my Mongoose. Once the bike was stripped bare we realised the BB's where not compatible.

 

My question is, if I order a GXP BB, are they all the same? Will my old cranks fit?

 

This is a link to a french guys build to on the same frame to give some sort of indication.

http://veloptimal.com/forum/viewtopic.php?p=248353

 

Cheers!

[BLACKvoodoo]

Don't worry nobody on here is very technical or a racer....

[snowbeast]

Thanks man, some forums get overly technical.

[Li Mu Bai]

A GXP BB is specific to some models of SRAM/Truvativ cranks. It has 2 different sized bearings one on each end, which only fit with a matching GXP crank. Hence you cannot use Shimano or other BBs with GXP cranks.

[Butterbean]

What he said. Shimano spindles are 24mm and have same size bearings.

 

If it's a proper Sram GXP, it will be two different size bearings and Sram won't be compatible with shimano bb and the other way around.

 

Unfortunately a lot of people will refer to a non bb30 bottom bracket as GXP, when it could be GXP or shimano, or a whole host of other more rarely used ones. Check and make double sure.

[CdT85]

One thing you can be sure of is that both the GT and Mongoose has english thread bottom brackets.

Below is a gxp, as the guys said, GXP cranks is 24mm drive side and I think 22mm Non drive side, hence the two different size bearings

 

The Shimano Hollowtec (below) is 24mm drive and non drive side

 

You can the same bb tool to remove and install both. I currently have a cheap BBB Bottom bracket tool that I use on both my gxp and shimano bb's on my bikes. Bought it cheap cheap at my local bike shop

 

edit:

 

So in closing, if your crank is a GXP crank, it will fit any GXP BB. The only different GXP BB's you get is Eglish or Italian threaded cups. but as stated earlier, the Mongoose and GT has english thread.

 

Good luck with the build bud

[snowbeast]

Thanks a lot for the replies. I've just gone and raided my Dad's spare box and found a BB exactly the same as Otero's first pic.

I eventually called my boet who works for PYGA and he explained the difference. My GT has an ISIS BB (can I say that without having my phone tracked?).

 

So now all I'm looking for is a cheap crankset just to get it going, then the fun starts.

 

I have a Fox RL32 for the front and the rest of the components are coming from my old Idrive.

I'll start a thread when I start building.

[CdT85]

Thanks a lot for the replies. I've just gone and raided my Dad's spare box and found a BB exactly the same as Otero's first pic. I eventually called my boet who works for PYGA and he explained the difference. My GT has an ISIS BB (can I say that without having my phone tracked?). So now all I'm looking for is a cheap crankset just to get it going, then the fun starts. I have a Fox RL32 for the front and the rest of the components are coming from my old Idrive. I'll start a thread when I start building.

 

From personal experience, get rid of the ISIS BB. They never last long. They tend to seize  up, and I have bent a few, and snapped one ripping my calf to pieces.

 

The GXP BB's are awesome, they are just way more expensive than the Shimano BB's. So if the GXP BB from your dad's spare box is still in good nic, then look for a good secondhand gxp crankset.

 

Else If you have some money saved, rather look for a cheap secondhand Shimano Hollowtech crankset ( I picked up a Deore crank for R600 off the classifieds not to long ago) And a new shimano BB is not to expensive either (cheaper than a new ISIS BB and will outlast it a 100 times over).

 

The Shimano spares are cheaper than SRAM and more readily available in the classifieds in general. You might be able to get a crank and BB for less than the price of a GXP crank if you find a good deal.

 

Good luck with the build bud

[David Marshall]

When the time comes to replace a BB or chain rings on an older bike it is worth doing a bit of homework.  If the BB type had a short life in the market - like the ISIS, Octolink 1 (and soon 11) and things like the 19mm Mega EXO you may as well look at a new crank.  The Shimano ones - which come with a BB - cost a similar amount or even less than the chain rings + BB for your old crank.