Discussion in 'Bicycle Mechanics and Repairs' started by yellow v2, 20 Aug 2007.
How much (if any) movement, is acceptable in the cranks before replacement of bb?
There really shouldn't be any play in a chainset/bottom bracket assembly, regardless of which type you're using(ie square taper, octalink, outboard etc). If there is then you're likely to possibly damage the bottom bracket frame shell threads from the movement, and you'll also be losing power when pedalling to boot.
If it's a cartridge type bottom bracket and there's actually play in the bearings becuase they're worn (as opposed to the BB not being screwed tightly into to frame shell) then it's probably time to change it.
As your description is a bit vauge it's difficult to advise further without seeing it.
Either way if you can't sort it take it to a REPUTABLE bike shop and they wil be able to advise further.
It is cartridge type and that is exactly my understanding also, I will be changing it then.
How long have you had it Yellow as I once had a Shimano BB cartridge for till the frame snapped: 1993 - 2006
It's about 18 months old, but I have just acquired it and noticed when cleaning a small amount play in the bb. just thought I would get some opinions before I jumped in and replaced it!
That does sound a bit soon (unless you do phenomenal mileages!) . My tourer is 7 years old with a Shimano 105 bracket used daily for a lot of that time as well as some hilly tours. It seems fine so far..
hmm - 3 months and a 1000 miles saw off my ISIS bottom bracket! - a coast to coast ride which was rather wet proper finished it off - ready for the bin. I have then 'upgraded' to the shimano hollowtechII setup with tiagra triple chainset - which is a bit weird as it doesn't actually have any bearings - well not metal balls anyway, just a plain bearing made from some sort of plastic - very strange
Interesting mine is an ISIS bb too, I am also considering fitting Hollowtech II bearings with Tiagra compact chainset. The mileage on mine was about 3000 which is more relevant than the age.
Looks like I will be haveing to replace a FSA MegaExo after 3000miles !
The shortest life span of an ISIS bottom bracket on a mountainbike in our household was 2 hours before play was detectable! Those things were the worse piece of crap to be palmed off on the cycling public since . . . . who knows.
The ball bearings in them are tiny (peddle size) and badly sealed. Unfortunately Mrs TB has an expensive chainset on her racing mtb and replacing the BB always seemed to be worth while rather than changing everything. Luckily the last replacement BB was an SKS one that has lasted for over a year. But then it should at the price.
In the mean time my old Shimano square taper BB goes on year after year, summer and winter on my mtb. And I've never noticed any 'lack of stiffness'.
Tim has beat me to it (above) but yes the ISIS isn't the best design of BB ever - I believe it was a downhill std and made to be light weight rather than resilient - would that sound right? - also the Bearings are tiny and just don't last. Mine did, as I said, a very wet c2c route and that was it - grease washed away, useless!
The hollowtechII - well I am very impressed - they feel very strong they weight next to nothing and are very easy to install / service - I got my tiagra triple for £39 in Ribble - I had originally wanted the 105 but it was going to be over £80 for the chainset - I decided it probably wasn't that much better. At £39 for the chainset and £14 for the BB cups - you can't beat the hollowtech in my opinion.
do you really mean the MegaExo - the one that looks like the HollowtechII stuff - i.e. this one:
you won't need to replace that for a while I wouldn't have thought - not heard of them failing that much! all the race teams in the TdF had them in place of the shimano DA bearing - which is some endorsement.
I believe that FSA make one of only two decent ISIS bb's too - which is this one:
the platinum which apparently has excellent seals and lasts well
the other being this:
where, as you can see, they have cunningly moved the bearings outside of the BB shell itself so they can be of a decent size. It looks more like a hollowtechII with an axle than a true ISIS.
BB's seem to be quite variable in terms of mileage/lifetime, I've had Shimano UN70's destroyed in a year with MTB riding, but recently Campag Veloce type BB's seem to go on forever - I think its down to sealing & riding conditions.
gkerr4 The first link is a FSA Ceramic Bearing I dont have that one on the bike I have the FSA Gossamer Mega Exo Bottom Bracket using the FSA Gossamer Compact MegaExo Double Chainset about £115 difference between the two bottom brackets.
If I was going to replace I dont think I would pay a extra £100+ for the ceramic bearings, at the moment I have a lot of creeking but not a lot of play in the bearings I took the bb and chainset apart for the 3rd time and cleaned it today so I will see how it gos but its looking like a new bb will be needed.
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