Wanted: gxp bottom bracket

looking for a gxp bb for an english shell. nothing fancy (ceramic or team) just the simplest version to try the system out with some cranks i got.

I've got a spare Mega-exo bb if I can get it off my old BMC frame... I think the spindle is 30mm right?

i have no idea :S

never had integrated cranks before - recently bought a pair of truvativ rouleurs to try them out.

this is what i managed to find:

"As you can see to the left, there are a few bearing variations of Mega Exo; Light, Regular, and Quad. Each works with specific cranks." (from bikeman.com)

i think i read that gxp is not compatible with other systems.. if there is an expert here, please share the knowledge!

What cranks do you have?
It's a nice system, albeit with what's generally considered a shite manufacturing tolerence in some aspects

truvativ rouleur

:)

i've heard that dirt likes to and does get in easily, if that's what you mean.. i actually can't decide between the DA7700 octalink and the truvativ gxp system.. (for the mali project in cp)

:)

i've heard that dirt likes to and does get in easily, if that's what you mean.. i actually can't decide between the DA7700 octalink and the truvativ gxp system.. (for the mali project in cp)

Yup, it'll be a straight up GXP bb. 24mm spindle drive side and the kicker; a 22mm on non drive side.
Longevity aside, I've used the GXP system on my work bike for quite some time and I'd have to agree with your concerns. I personally found the combo nice and stiff (Omniums and S300 crank sets), but despite efforts to keep both shell and seals clean, it was futile.
The seals don't really do much to keep dirt out, but I give the bearings credit in keeping smooth.

My main two concerns were the non drive side bearings were the smaller 22mm and to fit tightly over the axle, a sleeving/shim system is incorporated to give a snug fit. I noticed over time that because the shim was made of aluminium, constant force applied tended to flatten it into the Bearing cover on the BB itself, which in turn made for crank arm play because of the mm or two space, which if ignored as I stupidly did, let a surprising amount of dirt it, resulting in a bitch of seized BB which made for a lot of hair pulling.

It's a light, and easy system, and I'm still using it as I write this...sort of....but it does have a few flaws.
I haven't tried any of the more expensive alternatives like the Hope or Chris King BB's, but the standard one I used stayed smooth till the bitter end. Some recommend the more expensive alternatives, but for how cheap and (shocking to say) durable-ish the standard BB is. I'd say go with it.

The last octalink system I used was aeons ago, so cannot comment on their effectiveness as a system, but If I remember right, I was terrified of even looking at it.

P.s I can show you what 2 years of daily use looks like, and I know if I put them on now they'll carry on working for another.

thanks for that, really useful.

why terrified of the octalinks? is it the short splined bb? i currently have a set of DA7710s on my track bike (short splined) and they are still working perfectly. no play, no dirt getting in. well, it is a track bike but it's the only bike i have at the moment so it gets street use and is in fact a brakeless setup so the cranks have to handle all the skidding and stuff.

and yes, i'd like to see what happens to a gxp system with proper use, if possible :) (more interested in this shim-thing with the 22mm part - the bearing on this side is a non-standard one, right?)

My old polo bike's crank kept coming loose, can't remember which side, but it was a bit unnerving... Needed a replacement something or other... I was totally out of my depth TBH...
#oldfart #squaretaper4lyf

#oldfart #squaretaper4lyf

:D

i can imagine it being frustrating, might just end up selling them. but first i'd like to know how it feels to ride integrated as the most up to date system i have is octalink.

will be using square taper on the weekend bike, but that's a campag record 102mm - can almost be considered cheating as it is so short that feels stiffer than other square tapers

i have found a bb in the meantime but still interested in the answers!

thanks for that, really useful.

why terrified of the octalinks? is it the short splined bb? i currently have a set of DA7710s on my track bike (short splined) and they are still working perfectly. no play, no dirt getting in. well, it is a track bike but it's the only bike i have at the moment so it gets street use and is in fact a brakeless setup so the cranks have to handle all the skidding and stuff.

and yes, i'd like to see what happens to a gxp system with proper use, if possible :) (more interested in this shim-thing with the 22mm part - the bearing on this side is a non-standard one, right?)

Morning!

Ah, I was a moronic teenager at the time and my hands were too pretty to mess with all that filth. At least...that's what girls told me..
Anyway, GXP. I go by the "If it ain't broke...." motto. I'm the same as you, track bike, daily city mileage and quite a high gearing with all the skids (chainring bolts are threaded and I can't be arsed to change them) so I put quite a lot of torque on them.
Here are mine after around 2 years of use.

You can see that despite all the external sealing, dirt still gets in and mixes with the grease. I will be honest and say the secondary bearing seals hold up pretty well, and while a bit stiff, the bearings still turn freely using a finger.
If you look at both cups from the top, you'll notice the different bearing sizes. The 22mm/24mm divide is because as you said, its non standard. The shim thing is on my replacement BB. The one in the picture, from what I can see, the extra shim is within the inside walls of the outer casing.
Here's another pic of the bearings themselves. Seals weren't difficult to remove at all.

You can see that dirt does get into the bearings.
I'm afraid I don't have the right tools to measure everything, otherwise I'd give you more specific details, but I will tell you that it's not a difficult BB to maintain, and I'm actually gonna give tearing it down, cleaning and re-assembling it a shot to see how it would run again.

Here, I found a source that explains things way better then I can: GXP In Detail

although i cannot see your photos, i get the picture - that site sums it up really well. i know a guy who knows his way around a lathe so i might ask him to throw something together to see how it performs. thanks for all the info!