Mountain Biking - old school!!!
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i just picked up an old school 7sp shimano XT rear derailer, and some old school XT crankarms on specialized rings.
im worried if the derailer might not work with my 8sp Xray gripshifters and 8sp xt cassette? does anyone know for sure?
also how are the cranks? are they decent? i mean they are XT but they are probably 10 years old or something. rings are a bit worn and the arms arent "hollowtech" design. its the 5arm square taper style.
haha wow, taking it back to the old school... just worried about my rear derailer and shifters they might be problematic:(
07-18-02, 08:43 AM
the stuff is probably good - i have an '89 Specialized Stumpjumper with thousands of miles (was heavily used when i bought it in '92, my primary MTB for 5 years, and now my commuter) - and i've never even replaced the cassette or rings or anything (bottom bracket, chain, sure) - i think it's much more durable than any of the new LX or XT stuff which i replace almost annually on my new MTBs --- although it is heavier and only 7sp
shifters: i don't know much about mismatching components, but i think you might have problems:
1) the gear spacing might be different
2) you have an extra gear in the shifter so you have to watch out for "shifting off the cassette"
A 7sp derailluer will work with an 8 speed cassette. Just a matter of adjusting the limiting screws. Don't worry about an "extra gear", you have a 8 sp shifter mated w/ an 8 sp cassette and that's what really matters.
What you may need to watch out for is the chainrings. If you wait to long to replace a chain, it stretches quite a bit and the chainrings and cogs wear to match. Sometimes when you replace any one or two of these (chain, chainrings, or cogs) without replacing all of them, you get chain skip.
alright well i got tricked and the derailer i bought is really junk. its beat and bent, although i hammered it back into original alignment. :mad:
but anyone one thing i never figured out was how to install a rear derailer? i mean i can bolt it onto my frame or dropout but i had a lot of trouble tinkerin with it to get it to shift correctly. bottom line, it doesnt shift correctly. it skips gears in the rear.
is there a special way to install the derailer? which gears do i put it into? limit screws start all the way in or all the way out? how do i know how tight the cable should be? etc
right now with a 8sp shifter and 7sp derailer on 8sp cassette, i only get 3 clicks on the grip shifter, and it goes from 8 to 4 to 2 and the next click it will go off the cassette into my spokes
im gonna get a new derailer, a 8sp xt, but i'll also need to try and find a drop out because my frame is the simple kind. it came with a shimano altus with built in dropout on the derailer itself
07-19-02, 06:20 PM
There's nothing wrong with getting an XT, but for the sake of economy, also consider the DeoreLX. If it's adjusted well, it'll still work well.
To adjust the rear derailleur, first get the add-on derailleur hanger you'll need, and attach it like your old derailleur's built-in one did (if this is your first time working with these, take careful note of how the old one was).
Now you should have the derailleur hanger bolted into the axle slot, and the rear wheel on the bike. Before going further, note the little "tail" with the adjuster screw, hanging right off the derailleur's upper pivot bolt. Watch this screw carefully as you begin to thread the derailleur into the hanger, the derailleur must be swung back far enough that this screw misses the derailleur hanger entirely, or you'll be a hurtin' unit! :eek:
Once the derailleur is safely onto the plate, use a 3mm allen key to remove the lower pulley from the derailleur, so you can route your chain through it. While you've got the cage open, note that the inner cage plate has a metal "finger" that keeps the chain in, not only behind the bottom pulley, but also right below the top pulley. Make sure the chain runs on the proper side of this finger.
Now you should have the chain properly routed. Before hooking up the shift cable at all, grab your #2 Phillips screwdriver and use the H limit screw to limit the stroke so the chain happily rides on the small cog without clatter, but doesn't want to fall off to the outside. Usually, if you sight from the rear of the bike, it will appear that the derailleur's upper pulley is just a bit further out than the teeth of the small cog, perhaps 1mm or so. This step ensures that even if your cable slipped, the derailleur still will not go past the small cog.
Now pedal and shove the derailleur inboard by hand to the big cog, and stop. Use the L limit screw to limit this end of the stroke.
Now shift your shifter to the high gear (8, in your case) so that the cable is as relaxed as possible. Run the adjuster barrels into the derailleur and the shifter as far as they go, then back them out maybe 2 turns so you have a little leeway later. Run the cable through the derailleur's adjuster barrel and fasten it down on the correct side of the cable-anchor bolt (for an XT or an LX, that would be the inboard side). Snug down the cable-anchor bolt moderately tight while pulling firmly on the cable to draw it taut.
Next, click the shifter one click, from 8 to 7. What you want is for this to produce exactly one shift. Chances are, it will clatter-clatter-clatter and maybe shift. If necessary, dial the adjuster barrel on the rear derailleur counter-clockwise a turn or two, until the derailleur runs quietly in the second cog while the shifter is on 7.
Keep shifting inboard to the second-to-last cog, dial the derailleur's adjuster barrel counterclockwise until you hear a faint noise of the chain rubbing on the side of the big cog, and then turn the adjuster barrel back clockwise about 1/2 turn or until the noise stops. Test the shifting in this position, both upshifting and downshifting. If the upshifts are hesitant, crank the adjuster barrel clockwise 1/2 turn and try again, until it's right.
Finally, put the bike in the lowest gear: inboard chainring, inboard rear cog. Pedal backwards. Does the system go bump-bump-bump as the teeth of the large cog reach through the chain and touch the teeth of the upper pulley? If so, screw in the B-tension screw most of the way and test again. If it still won't behave, you may need to shorten the chain, but don't shorten it so much that it cannot wrap around the largest-size cog and chainring at the same time.
All of those steps are founded on the premise that the derailleur hanger is in alignment when the wheel is bolted down. If you get the derailleur onto the mount and it looks like it's not parallel to the rest of the frame, then you may want to take the derailleur off again and use an adjustable wrench to carefully realign the mount.
You said your system was skipping, and a second cause of that would be a worn chain on a brand-new cassette. Did you put a new chain on when you got the new cassette? If not, might want to pick one up.
hey thanks for the info. that was very extensive and i will follow the guidelines this time with a new derailer. most of it i was already doing. what is the b tension screw? so the idea is to have the adjuster barrel all the way in as opposed to all the way out? how should the H and L limit screws be when i first put on the derailer? all the way in or all the way out? and how tightly should i pull the cable once its through the barrel and just about to be clamped? is hand-pulled tight enough or should i take some pliers and pull it REALLY hard? what if said and done, the shifter still causes the chain to jump cogs?
if it helps, all my parts are used. the chain and cables are from my bike a 96 giant, the grips are xray grip shifters the better ones, the cassette i think is used but it looks to be in great working condition and apprearance. the derialer is the altus that came with the bike. i had a newer chain but it caused all kinds of problems so i switched back to my older chain. the newer chain did not work well with the chain tool and the tool actually broke, and i ended up taking off a few links on that chain because one of the cylinder things came off the link sockey. my used chain is dirty but not too worn and no sign of rust. my next derailer will be a used xt in fact i am about to pick it up right now from the guy selling.
07-19-02, 08:26 PM
Oops, I forgot to edit my post all the way so it would be apparent what the B-tension screw is. If you look at the rear of an XT or LX derailleur, there are the two limit screws, and above them there is that third screw that I was saying to be careful of. That's the B-tension screw, and its job is to boost the strength of the spring inside the upper pivot if necessary to prevent the bumpity-bump problem.
Go with the H and L screws as they come right out of the box at first, that is generally a good place to start. Then go through the procedure described, to fine-tune them.
Putting the cable adjusters most of the way in is a good plan, since cables stretch and you may need the range of adjustment later to take out the slack.
When pulling the cable taut, you can just pull firmly by hand, or grab it with pliers and apply more force. It'll all come out in the wash when you do the next steps to dial in the indexing.
With a chain and cassette from different bikes, it could be that you'll have chain skip if they're at different stages of wear. Just like you wouldn't re-use your old pistons after having a car's engine block bored, you can't expect worn parts to necessarily mesh well with parts at a different stage of wear (newer or older). There's a sweet spot, hopefully your parts are within it. :)
alright thanks man. i just picked up my xt derailler and it's a newer model but not the newest one. older one was a m735 this one is a m739 still old school i think. i am going to duke it out now, i hope i get it right this time!
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