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Shimano RSX front deraileur

The front deraileur on my Stealth seems to be junk. It wont shift to the biggest ring. It will try, but it just wont go out far enough. And it seems to be going out as far as it can. The limiting screw is all the way out.

I have played with the derailuer position, but it hasn't improved it.

I looked up the Shimano RSX, and in 1997 it was the lowest group of the road groups.

Any suggestions as to a replacement?

Unless the thing was damaged in a crash, or has rusted away completely, it should be possible to get it to work properly. Shimano RSX parts are definitely not junk, even if they were at the lower end of the group ranking.

I can't diagnose the problem, much less tell you how to fix it. Take the bike to a mechanic you trust. Only get another front derailleur as a last resort.

Safe riding,
Joel Dickman

I don't think it was damaged in a crash, but I think it is worn out. The cage seems like it has been bent at least slightly. The back/bottom of the cage gets really close to the teeth of the big ring, while the front/top part is still a ways away.

While I am not a professional bike mechanic, I have been working on my own bikes for years.

If I pull the cable as much as possible, it trys to shift onto the big ring. Then if I physically push the cage just a little further (to it's max) I can get it to shift. It seems like the cable just doesn't have any more leverage to pull it out.

One thing I need to check is whether the cranks are pressed on enough. I think the previous owner said something about having the bearings replaced. If the chainring side crank isn't pressed on enough, the big ring would be farther out, and the derailuer would need to push the chain out farther...

I found an eBay auction for a Shimano Deore DX M650 Front Derailleur. (I did a buy it now) I think this might work. If it doesn't, I can always remount the RSX.

I found a post on about the earlier RSX stuff being designed for a 46 tooth chainring. But the later RSX FD A417 being designed for a 52 tooth chainring. I have seen pics of the FD-A417, and it looks way different than what is my bike. I think I might have the FD-A410? So maybe a newer RSX might make a difference.

1) The Deore DX is a mountain bike derailleur, if memory serves. You might be better off with a road bike front derailleur, as the cage is shaped to handle a larger big ring. But if you already have the Deore, it doesn't hurt to try it out. Maybe it will be fine.

2) Yeah, the crank arm might not be fully pressed on the bb spindle. Or maybe the bb spindle is just too long! Or maybe... this gets tricky. Sometimes people replace parts with slightly different ones that do not work well together. I have done this myself. Often.

3) If the RSX cage seems bent, maybe you can bend it back the way it should be. Bike builders often do this with frames, but instead of calling it "bending", they like to call it "cold working".

Sounds better.

Good luck,
Joel Dickman

Yeah, the Deore is a mountain bike derailleur, but I wasn't finding a lot of choices for a triple chainring, 7 speed front derailleurs with a 28.6mm clamp. The Deore is higher in the food chain than the RSX. I like how the Deore comes out and up, compared to the out and down of the RSX. It seems like this will be easer to adjust. I can always keep my eye out for a NOS RSX.

The RSX in general seems...loose...or weakened... When it trying to push the chain on the big ring, the cage was shaking all over the place. It just seems like it has taken a lot of abuse.

The rear derailleur works fine so far.

I haven't a chance to check the cranks yet. It's possible that someone replaced the spindle with a slightly longer one. I could always replace it with a sealed bearing BB with a 1 or two mm shorter spindle.

I wonder if I could get specs from Lightning.


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