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Rear Derailleur is hiting spokes in highest gear. Seems loose?

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Rear Derailleur is hiting spokes in highest gear. Seems loose?

Old 06-05-14, 07:04 PM
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BradMitch
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Rear Derailleur is hitting spokes in highest gear. Seems loose?

Ever since I bought my bike which came with a Sunrace RDR86 Short Cage Rear Derailleur I have had issues in the highest gear. The gear works but the end of the derailleur hits the spokes so I wouldn't really use that gear. It is not the limiter as the chain sits in a proper spot.

The derailleur cage plate could be bent but doesn't seem to have any obvious bend to it. I noticed that is has a somewhat loose give to it around where the plate meets the pivots but I don't know how common that is and don't notice a screw to help tighten it up.

I tried a Mavic tire and the spokes didn't hit but I think it's due to the long hub and Mavic spacer.

I also tried another tire I have that has a tighter drive side and the spokes didn't hit, however I don't want t have to tighten my drive side extra tight because of the risky of spokes breaking.

Any advice? Fixes? Buy a new derailleur?

Last edited by BradMitch; 06-05-14 at 07:46 PM.
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Old 06-05-14, 07:12 PM
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First a bit of nomenclature.

Gears on bikes are numbered low to high the same way they are on cars. So low is the easiest gear, and high the fastest. Therefore, it's safe to assume you mean the RD is hitting spokes in Low gear, or on the largest (innermost) sprocket.

Since it's only one spoke, spin the rear wheel and observe whether a single crossed pair in sticking farther out than the rest. Depending on degree, that might call for spoke work to tighten the outer crossing spoke and slacken it's inside partner.

OTOH- bikes are build with reasonable clearance between the Rd and wheel in Low. So unless the single crossed pair was way out of line, odd are that your rear hanger is bent inward and you need to have the RD too far in when in low. This is an easy rough check.

Shift to a gear where the RD cage is roughly vertical (no precision, just sort of vertical)
Place a broomstick (or any straight edge) vertical against the rear wheel, and compare visually to see if the RD cage is close to parallel, or leaning in at the bottom.

This can be fixed (roughly) at home, or you can let a shop do a more accurate job. If there's a local bike co-op, that may be your best bet for an inexpensive but professional job.
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Old 06-05-14, 08:35 PM
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And "tire" refers just to the rubber part. Sounds like you swapped "wheels" (hub + spokes + rim) .

As FBinNY pointed out, it might be just 1 spoke a bit loose. You may also be able to improve it a bit by limiting the rear derailleur a tiny bit, such as 1/2 turn clockwise of the "L" limit screw. This will stop the derailleur from moving quite as close to the spokes, but might still be enough to get low gear. I had just the same issue on one of my bikes recently, now the "ting, ting" is gone as well as the chance of the derailleur getting tangled in the spokes.
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Old 06-05-14, 08:47 PM
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It's not just hitting one or two spokes it hits many more (I have 32 spokes). As for the limiters... this might sound bizarre but the limit screws don't seem to do ANYTHING. I don't know if Sunrace is something most people stay away from? Anyway I adjust things with the barrel adjuster and even the highest and lowest gears are on without any clicking/chain skipping.
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Old 06-05-14, 08:58 PM
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Originally Posted by BradMitch View Post
It's not just hitting one or two spokes it hits many more (I have 32 spokes). As for the limiters... this might sound bizarre but the limit screws don't seem to do ANYTHING. I don't know if Sunrace is something most people stay away from? Anyway I adjust things with the barrel adjuster and even the highest and lowest gears are on without any clicking/chain skipping.
Stop fooling with the limits until you understand how they work.

As the name implies these screws set the inner and outer travel limits (end points) for the RD. They don't move it, that's the job of the cable and return spring.

If you don't get this, picture parallel parking a car between two others. Those two cars re like the limit screws in that they determine how much room you have to move back and forth. If either of those move, you'll have more or less room to move, but they don't move your car, only you can.

OK so the wheel doesn't seem to be the issue, so go back and use the broomstick as I described to see if the RD is vertical. That's most likely the problem.

However DO NOT RIDE THE BICYCLE UNTIL YOU CORRECT AND CONFIRM THAT THE INNER (LOW) LIMIT IS PROPERLY ADJUSTED. Failure to do this may allow the RD to shift into the spokes, costing you the RD, wheel, and possibly the frame too.

Have a friend hold up the bike with the rear wheel off the ground. Pedal and shift to low by pushing the lower body in as far as it goes (to the limit), and confirm that you can shift to low, but no farther, and than the RD Dors not touch the spokes.
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Old 06-05-14, 09:36 PM
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Originally Posted by FBinNY View Post
Stop fooling with the limits until you understand how they work.

As the name implies these screws set the inner and outer travel limits (end points) for the RD. They don't move it, that's the job of the cable and return spring.

If you don't get this, picture parallel parking a car between two others. Those two cars re like the limit screws in that they determine how much room you have to move back and forth. If either of those move, you'll have more or less room to move, but they don't move your car, only you can.
I understand this concept, but I have stood behind a bike mechanic with the gearing cable loosened. As he adjusted the high limiter and you can see the derailleur move in and out to properly set it... or so was the case at that moment.

Anyways, I just did the broomstick method and the cage plate is not fully parallel. There isn't a specific point where the cage curves it steadily moves in from pivots to outermost point. I can push the tip of the cage and get it to go almost parallel (this is the loose/give that I am talking about and I don't know if it's common)
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Old 06-06-14, 08:47 AM
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Testing the limit screws on the workstand is not the same as a test ride. It is possible that turning the "L" (Low) limit screw in (clockwise) a little bit, to restrict movement, will prevent spoke contact, while still allowing 1st gear. That's part of the finetuning process when setting up gears.

A bent cage or hanger is a separate issue.
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Old 06-06-14, 10:25 AM
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Originally Posted by BradMitch View Post
.......Anyways, I just did the broomstick method and the cage plate is not fully parallel. ....
You have a bent hanger or bent RD. No adjustment of the RD is going to solve this. First get the hanger measured and adjusted if required. If the RD is bent; replace the RD.

All RD have some flexibility built in, they will not operate without some flexibility.
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Old 06-06-14, 11:45 AM
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Your derailleur should not be hitting spokes. If it is, or even comes close, there's a strong possibility that the derailleur hanger is bent and/or your limit screw is improperly adjusted.

As for your question about Sunrace quality... I don't know if it's relevant because the problem is likely an alignment or adjustment issue. With that said, though, my experience with them is generally positive, at least for the price point.
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Old 06-06-14, 05:13 PM
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I went to my local bike shop and tried to talk with the owner working there. He was the only one there and I was trying to understand if the hanger was bent or the cage and he told me he won't tell me or help me unless I commit to a payment. I told him I want to understand which part is the issue before I commit but, I decided to pay him 10 bucks. He got the derailleur hanger straightening tool and straightened it somewhat. It isn't fully straight because he said it keeps bending back into place and he is scared to use more force. Anyways, my spokes don't get hit now. Probably should have going to the bike co-op like FB mentioned but I don't have a car and it's further.

Note: I installed a new hanger before going to the bike shop but noticed no change. I suppose the frame where the hanger attaches was bent?
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Old 06-06-14, 05:31 PM
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Originally Posted by BradMitch View Post
...... It isn't fully straight because he said it keeps bending back into place and he is scared to use more force. Anyways, my spokes don't get hit now. Probably should have going to the bike co-op like FB mentioned but I don't have a car and it's further.

Note: I installed a new hanger before going to the bike shop but noticed no change. I suppose the frame where the hanger attaches was bent?
It's normal, or if not normal, common for hangers not to mount correctly aligned. The system is IMO a poor one and many hangers don't mount predictably (varies by design, of which there are many dozens). -

BTW- if you have a chance go back to the shop and let a regular mechanic finish the job. You're entitled to have the hanger sit perfectly parallel. All metals have "springback" when bent, so you always have to overbend and let it spring back to where you want to end up. Hnagers are also prone to flexing away form the bolt as they're bent which increases the apparent springback.

Now, reset the limits and cable adjustment based on the RDs current position. Note, that if you go back, and they bend it more, you'll need to reset the limits anew.
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