I just bought a new bike. I know a lot about riding, but not a lot about the bikes themselves. On two difference occasions, the chain has slipped between the slowest cog and the spokes of the real wheel. This causes the chain to jam, and of course jam the wheel rotation as well. Very difficult to get the chain out – requires help of the bike shop. Simply rotating that little screw in the derailleur to the proper place doesn’t seem sufficient. Any thoughts?
Thanks, David
David in NY,
No time better to learn than right now!
Since you have very limited mechanical knowledge of your bike, you should take your bike to your shop immediately and have this adjustment made. Failure to properly adjust/tune-up your shifting or adjusting it improperly could result in a catastrophic failure. In this instance, a little knowledge really can be dangerous.
Minor adjustments of this sort are not uncommon with a new bike as it is broken in. They are usually covered at no cost for some short period after purchase of your bike. Most shops want the bike to perform properly and for you to have a positive purchase and riding experience.
When you bring your bike in, ask to talk to the mechanic and explain your lack of or limited knowledge about adjustments of this sort. Ask if he can show you how to determine what adjustment needs to be made and how to go about making it properly. He should share with you the consequences of not making the adjustment or making it improperly. Then you will have to decide for yourself if you are willing to take on these sorts of adjustments and the management of these risks or if you feel more comfortable letting a qualified bike mechanic perform these adjustments.
Good luck.
Thanks for your thoughts…
Are you sure it’s not the L-limit adjustment?
Follow the instructions here:
http://www.parktool.com/repair_help/FAQrindx.shtml
FWIW try to go through the whole adjustment procedure from H and L limit to B-Screw
You need to learn how to adjust your rear derailleur. Its not hard but it is frustrating because you’ve got to potentially mess with 3-4 screws.
My bet is that its still the barrel adjuster screw.
Before you start turning the “limit screws” (see the link to that piece in this thread) before you start turning those screws, put your bike on a trainer, get it stable. Put the bike in the most difficult gear in your system. Largest chainring in the front, smallest sprocket in the back. This makes Its easier to turn the barrell adjuster screw that way.
Just turn that sucker, that plastic barrel adjuster screw, all the way clockwise until you can’t any further, and from that point, start going through the gears on your shifter. It probably won’t go through all of them at first. Then, just turn that barrel adjuster screw counter clockwise, 1/4 a turn until the chain goes through the sprockets.
If the chain starts coming off onto the spokes, up at the top, and still does that. Find the L Screw back there. See Link in this thread. Its the bottom screw. Turn it to the right 1/4 a turn until it restricts the range.
Yup…its the L screw. Its the only limiter to the rear der that would allow the chain to drop into the spokes. After you’ve made adjustments like this a few times it becomes rather easy. If you’re like me you’ll mess it all up a few times before you get it right! **: ) **
The barrel adjuster cannot be tightened to the point that the rear der goes beyond the stop point of the L screw. This screw limits the rear der point at the top of the cog set.