Bicycle Tutor

I just got a new rear derailer last summer and it was fine for a while then it started shifting on its own so i have to hold the shifter to keep it form shifting on its own what can i do to fix that?
Thank you,
Donn

Hi Donn,
It sounds like a shifter problem... what kind of shifter is it? Maybe the springs/pawls inside the shifter are worn or broken.

It is a 7 speed dyna grip shifter... is there a adjustment I can do or should I get a new one?

It sounds like your shifter might be broken. Watch this: http://bicycletutor.com/grip-shift-cable/
Once you're inside the shifter, see if the plastic looks broken or worn. Let me know what you find.

Ok thanks I will reply soon hopefully.

Ok, I got the grip off and from what I can see there is or were 2 rows in the grip and a lot of the plastic is worn off of the outside of the grip and the inside does not look any better... so do you know any thing to do or do I just get a new one?

Yeah, if it looks bad on the inside it's probably time for a new one. They are known to wear out more often than other types of shifters. Before you buy a new one, clean the insides as best you can and put it back together. If it's still not working it's likely had it's day. Watch this video to see it done.

What about the plastic around the outside that the cable wraps around? If that is worn does it make a difference?

If any of the plastic is worn it'll probably make a difference. Did it work when you got it back together?

No, so I am probably going to get a new 7 speed shifter off of ebay.