Bicycle Mechanics - Rear Derailleur Shifting Problem
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Hi folks! Appreciate any time you can take to help me with this.
I upgraded my trike shifting from a 7-speed, 11-28 cassette, Mega-Range derailleur and MRX Gripshift to a 8-speed, 11-32 cassette, ESP 7.0 derailleur and ESP 7.0 Gripshift. I have some experience with the swapping of components so I am not a total newbie (subject to revision).
The problem is with the set up of the rear derailleur. I went through the standard procedure for setting up a new derailleur with the new cassette (install cassette, cut chain to length, install derailleur, install shifter, run cable, set high and low stops, run chain through derailleur, adjust indexing, check B-adjustment).
Consistently, after setting the indexing per several sources, the alignment is off on the 2nd largest sprocket leading to undesirable clattering. But the shift from the smallest to the 2nd smallest sprocket works well. If the clattering of the 2nd largest sprocket is adjusted out then the shifting is generally fouled up and the chain will not shift from the 1st to the 2nd smallest sprocket.
To some extent, this existed with the 7-speed arrangement as well tho occasionally I would hit that magic point occasionally where it worked perfectly.
Suggestions of what to look for or a modification to the adjustment of the indexing?
08-04-02, 12:17 PM
It sounds like you know what you're doing, so I doubt these suggestions will be new ideas, but how about
check the alignment of the derailleur hanger
make sure the lockring holding the cassette to the hub is tight
make sure the pulley bolts are tight
if the pulleys are position-specific, make sure they're in the right positions (but my impression was that, unlike Shimano, neither pulley has built-in float on ESP... care to edify me whether that's correct?)
Beyond those ideas, a couple more possibilities:
the shifter's detent for that particular cog might be positioned incorrectly
if the clatter is being generated because the derailleur pulley is not under the 2nd-to-largest cog, perhaps the spacer between that cog and the 3rd-to-largest is abnormally thin
if the clatter is being generated because the side plates of the chain are hitting the largest cog despite the derailleur being directly under the 2nd-to-largest cog, then perhaps the spacer between the largest and 2nd cogs is abnormally thin
You could check the cog spacing with some kind of impromptu feeler gauge to confirm/deny those scenarios. Good luck! :)
See if tightening up the hi limit screw a bit has aany effect.
I agre with mechBgon check the der. hanger alignment.
08-05-02, 07:50 AM
I was thinking along Mechbgon's idea about the chain rubbing the side of the large cog. In other words, it may not be a derailleur problem at all, but a chainline thing. When you have a 32 or 34T large cog it is sticking out quite a bit beyond the snd cog. It doesn't take much chain offset from the 2nd cog for the chain to touch the big cog just a bit. Does the rubbing only occur when on the smallest chainring? Generally crank compatibility is not that big a deal; I use a 6sp double crank that works fine with DA 9sp shifters and ders. But then I am not using an extreme cog. I am not suggesting you run out and change cranks. If it turns out that it is this and the rubbing only occurs on one gear combination, and one seldom used at that, it might be something you can just ignore.
You might try a 9sp chain. It will work fine on 8sp because the inside width of multi-speed chains is a standard 3/32". Only the outside width is narrower which will give you a little more space.
08-05-02, 08:46 AM
A couple of other ideas:
You mentioned it's a trike. Is it possible that the hub sits canted to one side in the frame? Not knowing exactly how it's built, I'm just speculating. If the cogs themselves were angled with respect to the frame, that could provoke rubbing.
It's not too common, but I have seen hubs with loose freehub bodies, allowing the whole cassette and freehub body to rock. This needs to be corrected ASAP to prevent abnormal bearing wear and stress on the freehub body. If it's a Shimano hub, this is done by removing the axle set and the driveside ball bearings, inserting a 10mm allen key into the freehub-body fixing bolt, and tightening it firmly.
The bike is a trike so it has a long chainline. Side-binding and extreme chain angles should not be an issue. The trike is a homebuilt so front-rear alignment may be an issue.
I am not aware of methods to check the derailleur alignment without the appropriate bike-specific tools. Any help there? I try to use my LBS as a last resort. I purchase tools on an as-needed basis, the real purpose of projects such as this, right?
I will dig into the setting of the H-limit adjustment tonight. Generally the limit stop settings consist of visually lining up the pulley with the inner and outer sprockets but I can see where it would have a definite effect on that first shift from 8th (smallest cog) to 7th. There may be a cumulative misalignment if the derailleur is not set just perfect for that first shift.
The clattering in the larger sprockets is the chain rubbing on the larger sprocket(s) next to the sprocket on which the chain is riding.
I appreciate everyone's posts and have not ruled out any of the suggestions. I will keep you posted of the final result with the hope that when someone else has these problems, they will have some options.
Tool option: When changing cassettes I was not able to purchase a chain whip on short notice. I was able to purchase the cassette retention nut tool tho. Rather than wait a week for the chain whip, I used a 1/2" air wrench to remove the nut. Clamping the wheel in a bench vise, I grabbed the cassette with a leather glove and gingerly applied the air wrench to the cassette retention nut. Rattled it right off!
08-05-02, 10:39 AM
The commercially-available derailleur-hanger alignment tools are intended to reference to a true wheel, as you may know already. If your drivetrain isn't mounted in the vincinity of a wheel, you can do a pretty good job by eye. You want the derailleur's mounting bolt to be perpendicular to the plane of the frame, so shift to a gear that puts the cage in a fairly upright position, then sight from the rear and see if it seems to be in-plane with the frame. If not, you can remove the derailleur and gently align the mount with an adjustable wrench. Good luck! :)
This is an item I am concerned with since it doesn't appear vertical to my eye. But I do not trust my eyes and have been trying how to check the vertical-ness of the dropout with accuracy. There may not be an easy way short of fabricating something.
08-05-02, 11:11 AM
I think the most relevant reference point would be the cogs themselves. Try this: remove the chain from the derailleur so it doesn't interfere with your viewing, then shift the derailleur to the 2nd-to-lowest gear and try sighting down on it from above and behind, so you can look through the gaps between cogs and see the derailleur's cage. That should give a reasonable idea of how the cogs and derailleur are lined up with eachother.
It's going to be a busy evening!
I tried the H-stop adjustment, an advanced setting routine from Park Tools. It was a no go.
Last resort of obvious fixes was the derailleur alignment. As reported above I suspected the alignment was off but did not trust my eyes. After a little work with a level and applying some suggestions from mechBgon, the misalignment was confirmed. A quick and delicate bend with a crescent wrench and the problem appears solved. The system now shifts like I would expect of a SRAM level 7.0 system would be expected. Fortunately, the dropout was fabricated with steel and was easy to bend.
Good glad to hear that is al that it was and you fixed it.
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