play in cranks/bottom bracket

frankspencer1979

Got some lateral play going on through the cranks, just a couple of mm's. It is becoming more noticeable whilst riding, andI feel it's making the whole ride feel a lot harsher.

Does this automatically mean the bb will need replacing or is it potentially possible that something could be tightened/re-packed with grease? It's gonna be an LBS job, and I don't want them doing unnecessary expensive work!

supersonic

What is the crank and BB?

frankspencer1979

It's all the standard gear that came with the bike. The cranks are Truvativ, I'm not sure of the exact make/model of BB, but it's an external cup design and GXP* (which I know has something to do with SRAM, but don't fully understand!) Bike is a Vitus.

*Edited spelling so I don't look like too much of a numpty!

The Rookie

If it's GXP the bearings have probably had it, Truvativ is part of the SRAM empire, like rockshox and avid are (go to the websites), the GXP are nowhere near as reliable as other external bearing's and fail all to often, they are meant to be getting better though!

frankspencer1979

So if I'm told by the LBS that I need a new BB then I shouldn't be too surprised!?

Is this a part worth spending extra on, say a Hope one for £60ish, or would that prove only as reliable as a cheaper one anyway? Don't want to spend £80-£90 for ceramic bearings or any of that nonsense, but don't mind spending a little bit more for decent kit.

supersonic

Make sure the main crank bolt is torqued correcrly first.

nicklouse

Or the bearings just need some grease in them.

MontyDog

Had the exact same problem with a GXP and Truvative Stylo crank. The plastic sleeve on the drive side kept slipping out which left some play. I ended cutting 10mm of road innertube and slipping in on the drive side of the crank over the hollow shaft. When you tighten it back up, it forces the sleeve in to place and stops it slipping back out.
Or, as the other have said, the bearings are worn. Easy to replace.

delcol

when i change my cranks to noir carbon on my hardtail i decided not to use the crapy gxp bb i just converted my trusty hope one that i had on the bike.. it's really easy to do takes seconds.. and with the hope bb when the bearing fail they are replaceable...

it's a job you could do your self with basic tools..

frankspencer1979

Hmmm.... got a few things to be going at there.

supersonic wrote:

Make sure the main crank bolt is torqued correcrly first.

Could do that myself, just need the right tool. I should probably invest in a few more bits than just an Allen key set.

delcol wrote:

when i change my cranks to noir carbon on my hardtail i decided not to use the crapy gxp bb i just converted my trusty hope one that i had on the bike.. it's really easy to do takes seconds.. and with the hope bb when the bearing fail they are replaceable...

it's a job you could do your self with basic tools..

This I don't really understand. Get the basic idea, but I don't even know the difference between GXP and non-GXP :? Can anyone recommend a site that'll explain the basics to me!?

cycleclinic

I would recomend chainging your chainset to a shimano or race face and fitting a shimano slx/XT BB, those work well and may save you money ion the long run. How much is a deore chainset ~£70 and they come with a BB although it a deore one but decent enough. How much is a GXP BB, I don't know I would not touch them with a barge pole.

sloppycowpat

about £ 26 quid and they are a ball ache but when they work they work well it is just a bit hit or miss

i bought a gxp crank second hand and tbh i wish i hadn't and just got a shimano/ race face/ fsa they just work better but oh well it works...






just about :twisted:

delcol

first off this should help show the difference and explain how (easy) to convert a hope bb..

i would dissagree with the 2 posts above.. raceface bb have to be as bad as the gxp i had 2 fail on me after weeks of use.. my hope bb is still going strong some 18 months after it was purchased. it has now been converted to a gxp style one... this will show you how easy it is to change the bearings in a hope bb...

mrmonkfinger

The Hope BB is far superior to the Truvativ one, IME. The GXP lasted me six months before bearings died, Hope is still going strong after near on two years.

Just factor in the £10 converterwidget required to make the Hope BB work with SRAM/Truvatic GXP cranks.

delcol

hope bb will cost around £60 (merlin sale) and the gxp converter is around £8

chris king also make converters for their bb's so they can be used with gxp cranks....

Anonymous

thecycleclinic wrote:

How much is a GXP BB, I don't know I would not touch them with a barge pole.

£20, thereabouts, and they're fine so long as they're the modern design with improved seals and dust cap, and the cranks are fitted *properly*.

Mistakes are in not torquing cranks up sufficiently (they do need a high torque), not making sure the crank non-drive side is seated flush (this is where the loading is), fitting the dust cap backwards!, trying to fill the gap on the drive side axle (yes there should be a gap) and thus causing side load on the bearings, not greasing up the relevant parts properly and sufficiently before assembly.

That and attempting to fit them using SRAM instructions alone. The kit is fine but the instructions are terrible!

Jet washing them these BB is also seriously bad.

Had three GXPs now, never a problem with them other than confusion with fitting initially.

frankspencer1979

delcol wrote:

first off this should help show the difference and explain how (easy) to convert a hope bb..

i would dissagree with the 2 posts above.. raceface bb have to be as bad as the gxp i had 2 fail on me after weeks of use.. my hope bb is still going strong some 18 months after it was purchased. it has now been converted to a gxp style one... this will show you how easy it is to change the bearings in a hope bb...

Thanks for these video links, things seem so simple when explained by a friendly northerner! It seems to me the idea of GXP is to remove the risk of applying too much pressure to the bearings.

First thing I need to do then is track down an 8mm Allen key and check me cranks are tightened enough. Will have to get the LBS to check the bearings as I'm not set up or kitted out for that type of thing yet! Then if needs be it sounds like it's worth investing in a Hope BB. Might be pricey, but if it's quality it's worth it.