Mountain Biking - Deore Rear Der Adj. - L->L, H->H - Is this right? (ld 24" Rockhopper)
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01-05-12, 12:45 AM
I got this little Rockhopper (24" wheels) at a sale for $10 in the fall. Only needed a LOT of cleaning, a new barrel adjuster, and the front brake was dismantled in a weird way for some odd reason.
I noticed while adjusting the rear der, that when I go to big-big:
the jockey is swung way forward,
the chain drags on the stay.
Is this normal? I mean, I don't think one would really need these particular combinations, but... Then again, I usually only have my hands on road bikes so maybe I'm just ignorant and out of the loop.
01-05-12, 12:54 AM
That is normal. Chain's a little slack in the small/small but I wouldn't remove a link in this case or bad things will happen if a rider accidentally chooses the big/big.
Nice old Rockhopper. Love the DX RD. Does it have DX thumbshifters also?
01-05-12, 01:18 AM
Yup, normal when in big/big just don't ride it that way.
Hella extreme crosschaining.
01-05-12, 01:36 AM
It sure does (have DX thumbs)
The best part is, the seatpost is as long as The Titanic, so even I (at 6'1") can have plenty of fun on it.
This is still set before min. insertion.
I didn't even know they made a 24" model. Well, at least I've never ever seen one.
Chain length seems correct (but maybe you can remove 2 links and still have a long enough chain for big-big), but your rear derailleur does not have the proper capacity for your gear combination (front chainrings/rear sprockets). If you want to rectify the problem, you should put a rear derailleur with a longer arm (SGS type in case of Shimano mountain RD).
01-05-12, 11:21 AM
A long cage rear derailleur (SGS) would definitely fix this.
Look: Biopace crank and u-brake rear. Late 80's vintage? Lester?
01-05-12, 03:09 PM
You know, I think there's an XT (or maybe an lx) rear in the basement... but if it's the one I'm thinking of, the arm is split and the cogs are nowhere around that I know of.
So if the rear der isn't capable... it can still be original?
Yeah, that rear brake is interesting. I like it. I'm not knowledgeable enough to know if I SHOULD like it, however.
01-05-12, 04:22 PM
I love U-Brakes. It's the location that make that one kinda suck a little for cleaning and adjusting, kinda suck a LOT on mud rides.
Late 80s sounds about right to me kenhill3, I reckon 89 or so.
I'd assume the rear derailer is original. They might have opted for mid-cage thinking 24" wheels, so you don't want a long cage dangling closer to the rocks on the trail???
I'd still run that derailer if it was mine, just stay out of the 28x14 (or whatever low gear is). If you want to problem-proof it for a youngin' to ride I'd swap out for a derailer that pulled more chain,though.
Small-small is a combination that you should never use during riding. If you want to keep the rear derailleur, I would check how slack is the chain in the normally used combinations. With the smallest chainring, you normally use only the first 3 rear sprockets (the biggest 3). If on small front chainring and third largest rear sprocket the chain is still slack, then I would replace the rear derailleur with a longer arm one.
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