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Poor Shifting - How do I fix it?

885 views 9 replies 5 participants last post by  perttime 
#1 ·
My bike is not shifting correctly in the front or the rear dérailleur.
Front:
When trying to shift from the middle to the top or bottom the chain doesn't move when the dérailleurs move. Instead you have to push on the rapid fire buttons really hard and hold them for several rotations on the cranks until the chain catches. Also the chain will fall off the largest gear down into the middle gear some times when I hit a good sized bump.

Rear:
there is slow shifting on some of the speeds, always the same ones, and it skips the 2nd largest gear when going up but not down

What could be the problem here?:madman: :madman:

Thanks,
Garrett
 
#2 ·
Adjustments

I suggest you get Zinn and the Art of Mountain Bike Maintenance. It's all pretty self-explanitory if you watch what is going on. Check to see the derailleurs are aligned properly, the set screws in the right places, then adjust the cable tension to get the gears spot on.

Also check the Park Tool website and Sheldonbrown.com
 
#4 ·
All excellent references given above, but I'm going to say take it in to the LBS and have them fix it. If you are not experienced with troubleshooting drivetrain adjustments, you can get in over your head pretty quickly. It's certainly not rocket science, but it's rarely black-and-white simple.

Bring some snacks/coffee/beer or whatever for the shop crew, and ask the LBS wrench if they will let you look over their shoulder as they are troubleshooting & adjusting (consider making an appointment, if possible). This kind of experience will be huge when you use the previously mentioned resources to DITY the next time (hopefully then it won't be with compounded issues, as it sounds to be now - letting several drivetrain issues pile up makes them exponentially harder to properly identify and fix).

Cheers, Chris
 
#5 ·
I agree with Chris and pimp....

your derailleurs/cables have come out of adjustment. Both the symptoms of the front and rear shifting that you describe are indicative of slopped out cables (cable stretch if you will). This type of thing is one of the reasons that most bike shops offer a free tune up at some predetermined time after the purchase, usually 30 days.

If you understand how the derailleur systems work, are mechanically inclined, know the terminology (high limit and low limit screws, barrel adjuster etc.). Then you should be able to figure out what to do using any of the above listed references. Go get em and tinker away. But, if you don't, or don't feel confident that you can do it. Take it to the shop as Chris says and have them adjust for you and see if they'll let you watch. As was said, it ain't rocket science, but it is really easy to get in over your head and just make things worse!

My guess is that you don't know what you are doing, no offense. But from your description of how the cable tension on the front D should be when in the smallest cog it kind of shows. The cable should not be slack! At least not very. There should be some tension on it when in the small ring. If there is slack it creates a "slow shift" to the middle ring and makes it so you have to push the thumb lever farther to actuate the shift. So my suggestion would be that you take it to a shop and have them work it over. Like Chris said take along some doughnuts or something and see if they'll let you watch and explain what they are doing. It's not rocket science but it does take a bit of experience and a certain amount of finess to do proper adjustments. After seeing it done once or twice and with a little help from Zinn you should be able to do it too. :thumbsup:

Good Dirt
 
#6 ·
Ok, thanks.

I do not know much about bike repair but I am machanically inclined. I will check out the online sources and see just what each adjustment screw is supposed to adjust and if I can't get it fixed fairly quickly then I'll go to the bike shop and watch. Thanks for the reply.
G:thumbsup:
 
#7 ·
It is not rocket science ... pretty simple mechanisms.

One more idea: the rear symptoms could be caused by a bent deraileur or, more likely, deraileur hanger. Or even a loose bolt that is connecting those parts. The deraileur needs to be vertical.
 
#8 ·
Got it...

I looked on ParkTool.com and it was extremely easy to follow. I got all of my controls - front D, rear D, front break, rear break, and both brake levers - all tuned up. Now everything feels buttery smooth. It is even smoother now than when it was brand new out of the box. One of the biggest things wrong was cable tension was loose on everything. I guess the cables stretched out over time. Also the high/low screws on the front D were off a little and it was mounted too high above the chainrings from the factory.
 
#9 ·
gdpolk said:
I looked on ParkTool.com and it was extremely easy to follow. I got all of my controls - front D, rear D, front break, rear break, and both brake levers - all tuned up. Now everything feels buttery smooth. It is even smoother now than when it was brand new out of the box. One of the biggest things wrong was cable tension was loose on everything. I guess the cables stretched out over time. Also the high/low screws on the front D were off a little and it was mounted too high above the chainrings from the factory.
:thumbsup: Excellent!

Keep that Park Tool page bookmarked - it's a lifesaver.

Cheers, Chris
 
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