im using an acera r.d. and when i shift between the 6th-7th gear, sometimes the chain just jumps to the 8th sprocket bypassing the 7th sprocket.
214390
There should be a barrel adjuster on your rear derailleur near the cable anchor bolt. You can either increase or decrease the cable tension as necessary by turning it incrementally. \n\nIf your chain seems to want to shift past the cog that you're shifting to, then your cable tension is too high. If it's not quite making it to the cog, then your cable tension is too low.
394817
Sorry, you need a chain tool unless the chain is made be Sram. It isn't Sram unless it was already replaced.
582409
As far as reving high, you need carburator adjustment. This may solve the choke problem as well. For the bike kicking into gear by itself, if it is new they will do that until broken in properly but if it is older you need to check the clutch plates as they may be worn and need to be replaced.
163826
A lot depends on what kind of shimmy it is, there could be a few causes. First thing that comes to mind is something wrong with the tire. Check tire pressure of both front and back tires. They should be equal. Also have the balance checked. It's new enough to still be under warranty. If it's bothersome return to where you bought it and have them check it out. Better to be safe than sorry on a bike. Good luck!
281780
If the chain skips the teeth on the gears, then go back to the shop where you had the work done.  Tell them to fire the orangutan working in the back, fix the chain length, and give you a water bottle or something for your troubles.  Make sure that the teeth on the gears have not been worn down because of their incompetence.  They should have done a test ride before returning it to you.\n\nIf the chain skips from one gear to the other when you pedal hard, then check the alignment of the derailleurs.  You may need to adjust the cable tension on that derailleur.
549631
get smaller gearing and itll make it harder to pedal a little bit but youll get more speed so yeah or u could just get lighter parts so easier to pedal just make sure everythings tight or ulll get screwed over so yea if u need to know anything else bout bike email me crashnbad@yahoo.com
626021
In addition to the above answers, look at how the cable is routed - any sharp bends, or the cable not being seated properly in the levers will give you a hard time. If you raised the bars it will raise the cable housing with it, and it will now be too short and causing the brakes to drag or be inneffective.\n\nWhat type of pads did you replace the old ones with? If department store-type, you can't expect much from these. Get some decent pads from the bike shop and give it another go if this isi the case.\n\nThe brakes themselves may be adjusted too tight or corroded at the pivot point(s). They should easily move back to thier resting position if you squeeze them by hand.\n\nAlso, if you have linear-pull (or "v") brakes and a lever designed for sidepulls or cantilevers you can adjust all day and not get any better. Soemtimes, on department store bikes, these are mis-matched right from the factory and you'll need to get the correct levers for the brakes.
500698
It could be your choice of drivers. Try switching them and see if this helps. You can also go to a local short track. There are some really nice ones in Minnesota.
402821
Look at flexions at the point of supprt:\n1 is the support solid so its flexure can be ignored\n2 is the steel rod held by a grub screw. If it extends any distance to lock the rod then some rotation will occur due to it bending\n3 if held in a chuck check slippage.\n\nIn motor cars torque transmission is usually accomplished using splined shafts, but for small oscillations the backlish in these will be large.
630316
Bicycles these days have things like index shifting, this develpment has made cycling much eazer for the beginer. Back in the old days, "the 70's", I had to learn to shift by feel. This led to a lot of looking down and back, while working the shifter levers," once rode head on into a parked car doing that, even the people who owned the car were laughing". So you have the advantage of this wonderful index shifting. When approaching a hill down shift as you feel your legs begin to bog down, with index shifting you can down shift 1 gear at a time untill you reach the top of the hill. As you become stronger you'll down shift less. What you want to do is keep a steady cadence," RPM of the cranks", and use the different gear ratios to fit the terrain.
652541
bearings/hubs going bad...   or a freewheel problem.  Get thee to your local bike shop and have it inspected!\n\nYou might also have a few loose spokes which should also be checked out (wheel needs to be trued).
522679
If I was to do an upgrade I'd start with Hub-sets and wheels first, that will give you your biggest gain. From there I'd change out my bottom bracket and go with a Shimano BB6500 and replace the Bontrager crank-set with an Ultegra. Then think about the derailleurs, chains and so on,\nIf you bought the bike this year I really don't know why you want the upgrade so soon.
505023
Yeah 'cos there's nothing you can't fix with WD40 and a hammer eh!\n\nIf you look on the top of the derailleur you will two screws one marked H or high, the other L or Low. Shift into the big ring on the front then adjust the H screw to allow the derailleur to move further out. This should fix it.
167901
the crank trigger is going bad...
418385
Changing out your six speed cassette for an eight speed is doubtful without changing the hub-set. you may get away with adding one gear but two is doubtful, another thing too look at is the spacing of your chain-stays they too may not accept an eight speed hub-set without being stretched to the point of breaking. \n\nRemember every time you add a gear and a spacer for that gear you add approx. 1/8" in width to you cassette. Your six speed cassette should measure approx. 1-1/4" from inside to out an eight speed is approx 1-1/2" grab a tape measure and check.\n\nYour question states will I be able to transplant a 8 speed cassette straight onto the 6 speed freewheel?  That's also a no no as a freewheel is threaded onto the hub-set and a cassette uses a lock ring to secure it in place, again you would have to replace the hub-set to use a freewheel, they won't interchange.
531110
Regular derailleurs have the cable slack in the high (smallest gear) rear position. Rapid rise are opposite- the derailleur is at rest on the largest rear cog.\n\nSTI stands for Shimano Total Integration. I think all Shimano components are STI, provided you use the recommended component groups..you can't use LX shifters with XTR, for example.
630773
The left hand lever will contol the gear shifter on the chainring (at the front) and the right one will control the shifter on the sprockets (at the back).  \n\nPulling either lever back will move the chain to a larger chainring or sprocket.  At the back a larger sprocket means a lower gear (pedalling is easier but you have to pedal faster) and at the front a larger chainring will mean a higher gear.  An "older" bike will probably have 2 chainrings on the front and 5,6 or 7 sprockets on the back.  This means that you will be making most of your gearshifts using the right hand lever, forwards for higher gears and backwards for lower.  Think of your left hand lever as a "low range" or "high range" selector, you pull it back for higher gears when you are going fast and push it forwards for lower gears when you are going slower, climbing hills.\n\nIt is a common problem to lose the chain when you move from the small chainring to the large.  This means that your shifter is moving a bit too far, pushing the chain off.  To stop this from happening you need to set the limit stops on your shifter mechanism.  Your front shifter will have 2 small screws attached to it, if you move the left hand gear lever you will see that these screws limit the movement of the shifter cage.  Find which screw stops the movement of the shifter when you pull the lever back and tighten this one by about a half turn.  If you are losing the chain off the small ring then you need to make a similar adjustment to the other screw.  If you then find that you can't shift the chain between the rings hen you have over adjusted and you need to loosen the appropriate screw a little.\n\nIf you are having problems withthe chain at the back the rear mechanism has a similar arrangenet of 2 limit stop screws and the same principle applies.