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I've got a Giant Rapid 1 with Shimano Tiagra Double chainset, 34/50 with external Bottom Bracket. I noticed the other day a lot of movement in the crank - yet again! Tightening up doesn't solve anything. I've only had it 14 months and am looking a third new Bottom Bracket, the second has lasted less than 6 months! I ride approx 100 miles per week, is this an expected norm? I didn't replace the BB on my last bike in 3 years.
Has anyone else experienced this with a similar set up? is it because it's a double rather than triple chainset (heavier loadings?), is there a better (more hard wearing) BB i could replace it with? Is it possible to replace just the bearings?
Is it being fitted correctly? The most common cause of wear is too much pre-load.
Being a double or triple is irrelevant.
Oh - and are you making sure that there is no high-pressure water from the likes of a jet-wash near it?
Yep.The most common cause of wear is too much pre-load.
Also, did you find any water or moisture in the frame when you replaced the first one? An old road bike of mine used to collect water via the seatpost if I was ever cuaght in the rain without guards. If you use the bike in the wet, or wash it regularly, it might be worth pulling the seatpost out and inverting the bike to drain water. (I've prolonged BB's on susceptible bikes by years doing this - after learning the hard way!)
@druidH I fitted the last one myself, i don' have a torque wrench but just tighten to what seems sensible, not over doing it. Not jet washing.
@bowglie I don't remember any water in there, but you've just reminded me that both times they've gone, a few weeks before there's been a brown liquid discharge from between the BB and pedal arm, which ends up all over the left pedal arm. I thought it looked like rusty water, but as it's all alu i couldn't work it out or where it had come from.
My original thought was a seal inside the BB had failed, maybe water getting in and rust is from the bearings? I do ride in all weathers and wash it a lot, but surely it can't be that easy for water to get in?
Try a hope, at least they will probably warranty it if it fails too soon
I don't know whether the HTII BB came as standard on the bike or not but if it didn't, did you get the BB faced 'n' chased prior to fitting? Un-parallel faces could prematurely wear the bearings.
Water can collect in the frame quite easily from the seat post so its worth taking Bowglie's advice and turning the bike upsidown after a wet ride and see if any water comes out.
Also, your not spraying anythign like WD40/GT85 on the bearings are you? This will wash away the grease and cause premature wear.
yes, brown ooze is from bearings rusting. get stainless bearing bb (hope is not only option but a good one). and/or keep greasing.
with the weather next few weeks probably won't matter what you have 😀
Consider Castrol CL grease - it is a marine grease and I found it more resistant to breaking down that the lithium greases.
When you tighten the side to side fitting it only needs to be tight enough to remove end float - DO NOT PRELOAD THE BEARINGS as this will cause them to fail. Ball bearings are not great at taking constant end on loads unless designed for it
change to a Phil Wood square taper...
Your answer suggests to me that you don't understand what "pre-loading the bearings" actually means. That worries me.simbob - Member
@druidH I fitted the last one myself, i don' have a torque wrench but just tighten to what seems sensible, not over doing it. Not jet washing.
change to any decent square taper...
FTFY
that'll be water ingress then. Could try drilling a small hole in the lowest part of the BB shell to drain any water getting in.there's been a brown liquid discharge from between the BB and pedal arm, which ends up all over the left pedal arm