Downers Grove Bicycle Club

[chota300]

I have a 1990'ish Raleigh on/off road bike with a Shimano 100GS 7 gear rear sprocket. The shifter has set positions, plus a lever to switch to manual positioning.
I have always had intermittent problems with the rear gear staying in the selected gear. I have had it professionally adjusted several times by different people, & I tried some adjustments myself. It usually works well for a few hours to a few days, then becomes inconsistent again. Even without adjustments, it may work well one day, bad the next, then good again. I have recently started using the manual positioning & it works better, but sometimes still slips gears no matter how carefully I change.
I am wondering if this derailleur is just a flakey model, or if there is some other likely problem. I thought I might just need a new chain, but this behavior has occurred since the bike was new.
I can live with it as is because we plan to move soon & I may buy a brand new bike after we move. But if there is an inexpensive solution I would like to try it. I ride every day I can & this is just annoying when it happens.

Thanks very much,
John

[ABFJIM]

It's real hard to say without seeing the bike. I'm assuming you have the older top mounted shifters, since you can adjust it from index to friction shifting. Alot of times the screw that holds everything together is too loose, this makes the lever move out of it's place. Also if the shifter has ever been apart or repaired sometimes not all of the washers and spacers are reinstalled correctly, again allowing the lever to slip. It very well could just be an adjusting issue as well. Limit screws adjustments ,cable tension or derailleur allignment could all be need to be addressed.


So, the best thing to do is bring it into a professional bicycle retailer and have them check it out for you.


Jim