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| *Vultures Knob>>>Mountain Bike |
Do you know anything about mountain bike maint.? |
i recently bought a schwinn mountain bike, and i ride it pretty hard on trails and everything. recently, when i would start pedaling hard up hills, my gears would change by themselves or my chain would slip off. does anyone know how i can fix this or what is causing it to happen. any help is appreciated If the gears are shifting by themselves, and the chain is slipping, it is because the transmission that controls the chain below the main sprocket on the back wheel is letting them. One thing I would check is the cable running from the shifter to the transmission. If the screw/bolt holding the cable has come loose, the spring on the transmission will pull the chain to the most relaxed position it can, i.e. a different gear or off the sprockets altogether. Another thing to look for, is that the rear axle, when mounted to the frame, can be further back or closer to the pedals. If you truly ride it hard, it make have moved forward closer to the pedals, causeing the chain to loosen. I doubt this is the case, as the transmission is supposed to keep the chain in tension. It is still worth checking, though. like any bike make sure the mechanisms are clean and free of dirt. use stuff that cleans off the old grease and dirt from the gear changers and clean the chain and re-oil all of them..this way you know nothing in the chain or gear changers are causing the gears to change..then check to see if the gear changers are in the proper alignment with the front to back...and if not adjust them with the little screws on them, and or if they are bent. carefully bend them back into place and check to see how they work ....if you need to do a little more bending do it a little at a time.. then make sure the gear change levers are semi tight..so they are not slipping when you are riding causing the gears to change.. also check to see if your front and rear sprockets are not warped..if this is the reason ..you may need ne ones.. other than that I do not see any other reason for this to happen unless your sprockets and chain are worn out...and letting them slip.. but start by turning the bike upside down and do some cleaning then do the checking if after all this and it does not work..bring it to a shop.. good luck hmmmmm u may need to mess with the cable tension for your front derailer. there are also two screws on the front der. and to tighten or loosen one of them should help keep it from throwing your chain off but id have to go bust out my book to be able to tell you which one does which. if you wanna get into mt bike maint. check out Zinn and the art of Mt. Biking, awesome book. Oooh. Another thing to check is to make sure that the crank arms are tight...especially the drive side where the gears are. If the chain comes off the back and it is a full suspension bike it could be play in the rear suspension. Should this be a Wal Mart or Target model I'll bet it is more due to a loose assembly than cable adjustment. If you don't have any experience with maintenance, I would take your bike to a local bike shop and ask them for help. A good bike shop will explain what they are doing and show you tips to keep your bike in good running order. cable tension needs adjusting and your hi low stop screws probably need adjusting also. if the bike is new , your shop should offer you a free adjustment after 90 days as cables usually stretch quit a bit if not prestretched by a good mechanic |
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