Yet Another Cycling Forum
General Category => The Knowledge => Topic started by: Hummers on 12 February, 2011, 05:15:11 pm
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Oh dear.
The things you find out when you clean your bike. :(
I had some wobblyness in my drive-side crank on the last 200 that I first thought was a loose crank and then, when I found the crank to be tight, assumed might be a knackered BB sealed unit.
Stripping everything down reveals that the it is the drive side BB shell that is at fault. When the drive-side of the bearing is screwed in to within 2mm of it's fullest extent, it just turns loose in the BB shell whereas when it was fitted (two years ago) I could tighten it up onto where it butts up against the shell. This leaves the bearing loose in the frame and causes the wobbly drive-side crank.
I tried a brand new BB bearing in there and the same thing happens.
My theory is that the shell itself has been distorted or rusted (although it wasn't too bad to disassemble) and is now too big for the bearing.
I am thinking one way to remedy this would be to bulk it out somehow with a washer or old BB lock ring between the shell and bearing flange which will move the chainset out about 2mm (not a major problem but not ideal) but wondered if anyone had come across this before and had any other suggestions?
H
P.S.This problem has occurred on the same side as the 'Crack of Doom' that turned out to be a crack in the paintwork rather than the frame and with everything stripped down, still seems to be the case.
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Ouch. Can't a frame builder /engineer add some metal and retap it for you?
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If it's just thread damage then you might get away with retapping it. I have the tool here if you can be arsed to drive over, although Ural, Mal and I appear to be going for a jaunt a week tuesday if that's any incentive. It probably is just stretched thread due to previous overtightening. It's sometimes fixable, sometimes not. The fix given non-repairable is a non-threaded wedgy bottom bracket - have search around SJS who normally carry them.
<edit>
Like this:
Sealed bearing bottom bracket THREADLESS for frame (http://www.sjscycles.co.uk/yst-sealed-bearing-bottom-bracket-threadless-bb-993-prod4521/)
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On closer examination, it seems the threads aren't stripped, just really loose and my idea of packing out is not going to work.
It wasn't over-tightened. I reckon it may have come loose and then 'waggled' for a bit which has caused the problem.
The SJS threadless solution and braze/retap may be the only options.
Bugger. :-[
H
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Have tried a 'Liquid Steel' Epoxy bodge for now which appears to be holding body and soul together for now. Will see how it manages with the first proper hill before getting too excited.
H
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Check out YST threadless brackets on eBay. Fitted one to my friends 'shagged-thread' frame and it works well. :thumbsup:
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Cheers Steve. This will be the next thing to try.
H
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mrcharly has had similar problems with his Mercian IIRC. Not sure what his solution was but the Velo Orange Grand Cru threadless BB might be worth looking at too: Velo Orange Threadless BB (http://www.freshtripe.co.uk/Freshtripe/Blog/4ED41DF2-B266-4A09-9021-CE9B30C46408.html)
It seems to have a better fixing method than the YST.
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Agreed, the VO is a much better BB all-round than the YST.
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We got through two YST BBs on the back of the tandem, the first lasted fifty miles, the second about a thousand. We then had the threads re-cut.
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Agreed, the VO is a much better BB all-round than the YST.
"110mm Out of Stock".
Hmmmmm 113mm would do the trick and makes little odds as I am sure the chainset I have on there now requires > 110mm anyway but have (just) got away with it.
Will bear it in mind if the bodge up fails me.
H
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Mrcharly here :)
I bought a Prestige BB similar to the one sold by SJS. It didn't work in my case, because the BB shell was distorted too much. I filled round the shell with metal epoxy and sanded it back so that the Prestige only just fitted.
That seems to have worked.
If I were doing it all over again, I'd buy the grand cru - it works very differently to the prestige, having an expanding wedge system. I spent literally hours fitting the Prestige and there is no chance of refitting something.
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I could be mistaken, but I'm sure I remember a f[r]ame restorer telling me that he would cut a channel into the BB shell and then compress it to make a tighter fit. I dunno, I might have imagined it...
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Requires brazing and painting.
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...a fame restorer...
Like Max Clifford? ;D
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...a fame restorer...
Like Max Clifford? ;D
Ahem, stuck key on my keyboard... ;)
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Requires brazing and painting.
.... and a re-thread.
The non-drive side is OK, it is just the drive side.
Test run will be on Wednesday with the Epoxy bodge.
H
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I have a longstaff tandem rear BB which has been fettled with Araldite for years.
sound of George rotating in his grave
Tips - clean and de-grease well, You can dismantle after wards with a good BB tool and a long spanner.
I decided not to use the chemical metal because IMO it would never come apart again.
I will be fine!
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It will be fine
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Epoxies degrade with heat, be careful about damaging paintwork though.
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Epoxy solution lasted all of 30 miles and up until the first time I got out of the saddle.
Will investigate the threadless crank options.
H
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When you try a threadless bb, fit it without final tightening and see if there is any play, any at all, between the shell and the BB. IME, if there is, you need to shim it out with something so that the BB shell is a friction fit. I achieved this with metal epoxy, with less distortion you could probably get away with coke-can shimming.
Reading details of the grand cru, it only seems to expand out to 34mm, so wouldn't have helped me.
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The coke can shim... Genuis!
:thumbsup:
Thanks for the tip, that makes a lot of sense.
The (not too local) LBS had a Prestine threadless BB and I bought this for the 200 on the weekend as the Grand Cru is on order.
H
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Hmmmm.
Prestine threadless BB fail 100k into a 200k perm - came undone despite threadlock and extra beefyness in tightening up.
I had to lash something up using cable ties to get me home.
Reassembled it with more threadlock (no shims this time ???) and it seemed to withstand 40 miles at the weekend. My Velo Orange BB has turned up too (looks shiny) so will be fitting that before the next proper outing. Watch this space.
H
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Have you tried plumbers PTFE tape ? Dodgy bodge though it may work ?
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Have you tried plumbers PTFE tape ? Dodgy bodge though it may work ?
Tried that originally but the thread was too far gone.
Will see what happens with the Velo Orange and threadlock on the weekend.
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Damn. How much play is there when you slide the prestige bb in?
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Damn. How much play is there when you slide the prestige bb in?
Loads. Tried the shim/tin can idea on both sides and packed it out OK but it came loose.
Oddly, I redid it without the shims (different threadlock too) and it seemed to hold fast despite being given a bit of a Hummers out of the saddle beasting on Satueday.
H
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I think that you can't have any play or it will work loose.
Mine is still fine in the mercian after a good few hundred miles. No Hummer beasting, but it was through the worst of the winter weather so include hammering over some rough roads.
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Try some epoxy resin, like Araldite.
When I was in Ireland I discovered that the thread had sripped in my BB. There was still somethread there, but my BB kept working it's way out.
I limped to a town and bought some epoxy resin and glued it in place, ate in a cafe to bide some time to allow it to set a bit, then rode back to the hostel, carefully.
It did at least another 1000 miles, no trouble. The frame has since been scrapped (It was in a bad way) but it would have probably held up for plenty more miles.
Either way, you might as well get another frame and save yourself time, money and hassle. Having a bike you can rely on saves money on train fares home when an unreliable bike breaks. Plus, you's still need to buy another reliable bike on top of having to pay to get home.
Have a nice new bike, save yourself some money and have a nicer ride instead of flogging a dead horse. :thumbsup:
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Try some epoxy resin, like Araldite.
When I was in Ireland I discovered that the thread had sripped in my BB. There was still somethread there, but my BB kept working it's way out.
I limped to a town and bought some epoxy resin and glued it in place, ate in a cafe to bide some time to allow it to set a bit, then rode back to the hostel, carefully.
It did at least another 1000 miles, no trouble. The frame has since been scrapped (It was in a bad way) but it would have probably held up for plenty more miles.
Either way, you might as well get another frame and save yourself time, money and hassle. Having a bike you can rely on saves money on train fares home when an unreliable bike breaks. Plus, you's still need to buy another reliable bike on top of having to pay to get home.
Have a nice new bike, save yourself some money and have a nicer ride instead of flogging a dead horse. :thumbsup:
All of the above is true but I can't bring myself to pension it off. I still have the Velo Orange BB to try out so it is not so much a dead horse as a bit of an old knacker.
H