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MTB bottom bracket question: re-use? replace? cause?

S

starbuck

pfm Member
I am in the process of stripping out my (self built with Kinesis frame) hardtail and was going to swap some of the bits onto my full suspension Marin, as they are of a better quality and have much less use. Removing the Shimano BB ES71 bottom bracket from the Kinesis, I find this (picture taken immediately upon removal with nothing cleaned yet):



A rust coloured ring around about half of one end and a corresponding ring on the matching cup.

The bottom bracket in question has only covered about 100 miles of mostly road riding and lightweight XC, it has just sat in the bike frame for about 4 years because I retired the bike not long after fitting it.

My question is, is the rusty coloured ring something I should be concerned about and therefore get a new bottom bracket, or is it something to just clean off and then I should be okay to re-use? If I should replace, what is a good quality but not too expensive replacement for it (68mm x 113mm and Shimano Octalink by the way)? Can anyone suggest how/where the moisture got in to cause the rusty discolouration in the first place? I ask about whether I can just re-use it because I have already part way disassembled my Marin in preparation to fit these parts (lightly used bottom bracket, XT cranks/triple chain rings and XTR rear mech, plus new chain and cassette), and don't want to put the Marin back together again twice, if you see what I mean.

Thanks for any advice.
 
The moisture flicked up off your back wheel and crept on down your seat post, under the seat collar and into the seat tube.

If it feels anything less than smoothly resistive, bin it. And always remember to flip your bike up side down with the seat post out after a rainy ride.
 
Well there's your problem - it's gone rusty hasn't it. You may be able to clean it up but you'll have to treat it with something to stop it going rusty again (e.g. Kurust).
 
Clean off the rust, smear it with grease, put it back in if the moving parts are OK. It's a sealed bearing so the important bits are unaffected by this.
 
The rust is nowhere near the bearings. BB sealed bearings are meant to be stiff from new as they are very tight packed [preloaded is the jargon]. As longs as it turned ok before removal it's fine.
 
First, congratulations on extracting the mofo.

It could be contact corrosion between the ring and the body of the cartridge. Plastic rings are often used now, possibly because of this.

I guess you could re-use it, but grease all the surfaces like your life depends on it.
 
Ah I have just been building up a saracen n zyme I got really cheap. Another Bike :).. I have several of these bottom brackets ready to go.

I have them in all axle sizes from 107mm to 122.5

I have never seen rust creep too much into the body but its perfectly possible for water ingress or condensation rust to build up during storage

I think they are good units and youre ok as long as the bearing turns smoothly with no roughness clicks or pit. Polish the rust off, smear with grease and you are good to go.

Ive just binned a bottom range TS30 which has probably been in there for for 10 years. It was just slightly rough with a tiny catch point
 
The thing is that it's only a BB, as they are so easy to remove (unless seized!) you can sling old ones back in without fear that they will foul anything else. If they creak and click, then nothing else is going sick as a result other than your ears. With mine I can put up with a certain amount of noise but after a while it just gets too embarrassing so they get replaced.
 
Thanks for all the replies and advice, much appreciated, particularly as it seems to be saying I don't need to spend any more money - rotation is smooth and without any stickiness or notching (as you'd hope for a less than 100 mile old component). Point taken re. water ingress via the seat post, could well be that combined with longish term storage in a slightly condensation prone Keter plastic shed. Will break out the Autosol and lithium grease, and then install in my Marin - looking forward to it as the presently fitted Giga X Drive is a bit creaky/clunky.

Thanks again!
 
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