Shifting Problem

[vandeec5]

My girlfriend mountain bike is having problem shifting. When I try to shift the gears from 8-6, it's very smooth, but if i try to shift from 6 to any lower number, its very hard to press to the point where my thumb would hurt. I have to press it with lots of force just to get it to change.

How can I fix this problem? I would like to learn how to fix it myself rather than take it to the shop.

[tkblazer]

how old is the bike and when was it last serviced? i would check the cables and housing as there may be frayed housing or just dirt in it. new cables and housing is a cheap fix.

[Rob]

Yep, sounds like dirty cables. You may be able to fix it without replacing. Shift the rear der. into the lowest gear(easiest). Then, without rotating the cranks, shift all the way into the hardest gear on the shifter(but don't pedal). This will leave the der. in the easiest gear but will make the cable very loose. Then pull the housing out of the rear der and the frames cable guides.

You can then slide the housing back and forth. Clean off any dirt and put some tri flow or other non wax type chain lube onto the cable and slide the housing back and forth.

Do the same with the housing near the shifter.

If the bike uses full length cable housings, you may just need to replace it instead.

[vandeec5]

Thanks all, I will try once I get a chance.

BTW it's a Trek 3900 which was service about 6th months ago. I believe its a 2004 model? not sure.

[onegymrat]

Originally Posted by vandeec5

BTW it's a Trek 3900 which was service about 6th months ago. I believe its a 2004 model? not sure.

You probably have open housing, which means the cable is exposed on the way to the rear derailleur. The more often your ride, especially in extreme dusty or wet conditions, the more it will get dirty and obstruct smooth shifting. Keep in mind that unlike an automobile, your bike's shifting and braking may still go out of whack right after a tune. It's just the nature of the abuse a bike takes. You may need to wipe, clean and lube, as Rob had pointed out, on a regular basis. Once you get the hang of it, it's a piece of cake. I often have to adjust my mechanical brakes' pads, almost after every ride. The shifting has been great since I now have full housing. Good luck!

[vandeec5]

Thanks, it's fixed now. LOTS of cleaning had to be done