Question about Trek 3900

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For shifting gears up on the front gear derailer, i cant move up the chain, and therefore can't move up to the 3rd gear, but i can go down fin the the second and first gear.

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Http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur

http://www.parktool.com/blog/repair-help/categories/derailleur-systems

and don't try to use large chainrings with large cogs or small with small (cross-chaining is unnecessary and potentially damaging).

Posted on May 22, 2011

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Do I have to buy new bikes to get higher range of gears?


Actually no! you can visit your bike shop and ask them for higher range. What they do is change the front wheel ring in order to give you higher range.

Jan 17, 2013 | Cycling

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Comfort 050 technology attachment catches the rear wheel spokes and causes the chain to come off the spokes.


Matthew, The item giving you trouble is the rear derailler. It works by moving the chain in (closer to the spokes) and out (further away from the spokes) so that the chain can climb onto the next larger or smaller gear. Yours is apparently going too far in when you try to shift to the largest gear. There are a pair of adjusting screws that limit how far in and out the derailler will go. Use this link to find some great repair help. Just click on the derailer on the bike in the picture. Good luck.
http://www.parktool.com/blog/repair-help

Aug 27, 2012 | Cycling

1 Answer

I need to n know how to adjust the front derailer so it will shift from the middle gear to the high gear. It seems to tpuch the chain but won't move over enough to engage the chain


Assuming the front mech hasn't been moved around or up or down the frame tube, you need to adjust one or both of the following:

1. The "barrel adjuster" on the shifter to increase cable tension
2. The "H" limit screw on the mech to allow the cage to move further out at maximum cable tension.

For detailed instructions google "Park Tool Front Derailleur Adjustments" and click the first hit.

Jun 09, 2011 | Cycling

1 Answer

Cannot get rear derailer to work properly 24 inch girls evolution


Don't start messing with the derailleur yet! Make sure your shifting trouble isn't due to something else, such as a warped, dirty, or stretched chain, gummed-up pulleys, crud in the cable housing, trapped cable, or a bent derailleur hanger
Clean the chain and the rear derailleur pulleys. Pull the chain away from each pulley, and turn the pulley to make sure it can move freely. A pulley that offers resistance to turning must be replaced.
Now check the cable to be sure it slides freely. Mud and grit within the cable housing, or on a cable-guide, can keep the derailleur from moving a "full gear" during downshifts. If the cable doesn't slide freely in the housing, you may be able to clean or lube it to restore smooth shifting.
Let the high-gear limit screw. In your highest gear on the shifter, and with the chain on the smallest cog, position the derailleur so the upper pulley exactly matches the teeth of the small cog. Run the chain a bit with the front derailleur in the large ring, adjusting the limit screw until the pulley and the cog seem to match perfectly.

Setting the high-gear (small cog) limiting screw.



Once you're sure the derailleur matches the cog, move it just a whisker (1/8 to 1/4 turn) towards the other cogs. (You may need to readjust a bit if you get chain-skip.)

Closeup of setting the limiting screw.



Now adjust the low-gear limit screw. Shift into the lowest gear (largest cog). If it won't go, loosen the limit screw. With the chain on the largest cog (and the front derailleur in the small chainring), adjust the derailleur so the upper pulley exactly matches the teeth of the large cog.Once it's perfect, turn the limit screw so it moves the derailleur a tiny amount towards the other cogs (1/8 to 1/4 turn usually works).

Setting the low-gear (largest cog) limiting screw.



Now shift to the highest gear (smallest cog). Push the shift lever to downshift one gear (go from the smallest cog to the next-smallest). If it doesn't shift, tighten the cable with the barrel adjuster, 1/2 turn counter-clockwise. Backshift and try again. Continue tightening until it shifts. If it overshifts, going from the smallest cog to the third-smallest, loosen the cable by turning 1/2 turn clockwise. Backshift and repeat until it shifts exactly from the small to the next-smallest cog.

Fine adjustment of tension in the derailleur cable.





Now go to the second-smallest ring. Tighten or loosen the cable slightly, until the outer side plates of the chain are just clearing the third-smallest cog. Shift up and down, fine-tuning until you're satisfied.

Checking the position of the chain on the cogs.





Mar 04, 2011 | Pacific International Pacific Evolution 24...

1 Answer

I had to take off the rear weel of my falcon apache mountain bike to get it in my car o travel from my grandparens home to mine but i cant get the back weel gear arm back on. how do i do this??


By the "gear arm" I assume you mean that part of the rear derailer that the chain zig-zags through. This arm moves in two ways. It moves in and out (toward the wheel and away) as you move the shift lever - which is how it changes gears, by moving the chain onto different sprockets (gears). It also moves forward and back (toward the front and back of the bike) under spring pressure. This forward and back motion is necessary to take up the slack in the chain when you are using the smaller sprockets (the smaller the sprocket, the "higher" the gear). When the wheel has been removed, this arm moves forward (under spring pressure) as far as it can to take up all of the slack in the chain. All you have to do is grasp this lever and pull it toward the back of the bike, allowing the lever and the chain to pass behind the sprockets (gears) as you pull the wheel back into it's position. You can safely pull this arm forward and back at any time without doing any damage. One more tip-- I find it a little easier if you first put the shift lever in a "middle" gear position. Then when you pull the wheel into place, you should aim to put the chain on a middle sprocket. You don't have to hit the exact correct sprocket as you can simply lift the rear wheel and turn the pedals forward (after installing the wheel) and the chain will move to the correct sprocket corresponding to the setting on the shift lever.
Good luck! Please vote if you found this helpful. Al K

Oct 14, 2010 | Falcon Cycling

1 Answer

My shimno sora front derailler shifts perfectly to the small and large chain set cogs, but on the middle, the chain rubs along the cage.


Set the rear derailleur to the lowest gear (big cog) and the front to the lowest gear (small chain ring). Disconnect the derailleur cable. Screw in the adjuster for the cable tension all the way (this adjuster is on the shifter of a mountain bike or the down tube of a road bike). Pedal to make sure the chain is not rubbing on the derailleur cage. If it is, adjust the "L" setting on the derailleur until the chain moves by without touching the cage. Now pull taut and reattch the cable and shift the front to the big ring while pedaling. If it does not shift up well or completely, hold the shifter past its normal shift and adjust the "H" screw so that the derailleur allows the shift. Shift into the highest cassette gear and keep pedaling. The chain should not be touching the front derailleur's cage when you pedal. Adjust with the barrel adjuster until the chain moves freely without touching the derailleur cage.

i hope this helps
-matthew

Oct 30, 2009 | Cycling

3 Answers

Wont change gears 12or3


There should be one or two limiting screws for the front derailleur that you can use to adjust how far out/in the derailleur moves to shift the chain over. You can ask a friend to lift the back end of the bike off the ground while you do the adjusting of these screws and then try shifting the gear while moving the peddles with your other hand.

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1 Answer

I had bought a Titan Glacier unisex 21 speed middle gear will not


Here is link that might help:http://www.parktool.com/repair/byregion.asp?catid=53. Also sight from back to front along the chain. The cage of the front derailleur should be parallel to the chain along its length in all three positions. Hope this helps.

Aug 16, 2009 | Cycling

1 Answer

Gears slipping on bike


The center bolt of the thumb shifter is a friction bolt, some have wings, some have a "D" ring, and some will just have a slot to put a screw driver into, tighten this screw a little at a time until it is comfortable to use but will hold back the derailleur.

Hope this is of some help.
Ed

Apr 24, 2009 | Cycling

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