Bicycle Mechanics - Shifting Problem

Hey everyone,

It's recently come to my attention that my front gearbox (err, excuse me for the car lingo) has had trouble upshifting, especially from 2nd to 3rd gear. Occasionally it happens going from 1st to 2nd, but it almost ALWAYS happens when going from 2nd to 3rd. When I look down to see what's wrong, it looks as though part of the chain catches on, but can fully make it on because of the front gear cover (which is a Shimano SIS). However, I have noticed that if I make the first revolution when changing gears slower, it does work better; however, that takes away a lot of momentum.

Does anyone have any idea how to fix this problem? I've been thinking about taking the gearhead off, but I don't know if that's the problem/if it's the right thing to do or if that's even what I should do in a situation like this. It's also an odd situation seeing as the bike is almost brand new.

What do you guys think is my problem and have any of you had a similar difficulty?

Shane

P.S. Oh, and if anyone was wondering, this is on the 4100.

Try oiling the chain and the derailleur. Still not really sure what you're talking about. :p

Here's what's happening: when I shift from 2nd to 3rd, it generally makes a noise similar to when the chain falls off of a bike (this is when i see it partially make it on to the 3rd gear but then fall off to the 2nd) and takes a few revolutions (sometimes up to 5 or 6) before switching in to third gear. I was thinking about oiling the chain, but I wasn't sure if that really would help at all or just be a wast of oil, but I guess that is what chain oil is made for!

Shane

The thing over the chainrings that adjusts the gear is called a front derailleur. Use the barrel adjuster on the shifter pod to align the derilleur over the front chainrings. You can take it back to the shop you bought it at and they will probably do this for you for free since it's a new bike, as well as adjust the rest of the cables and rear derailleur.

I have a similar problem with my FD ... it won't shift from 3rd to 2nd under load, so I'm still trying to work on that. Fortunately for you, there's an LBS you can go to for solving your problem.

Ah ... the wisdom of buying used ... from eBay ...

Just take it back and ask them for a tune up. Usually, bikes need a tune up after their break-in periods, which sounds like you just got it.

If it will not quite shift up to the next ring, turn the barrel adjuster, that is the knob right where the cable comes out of the shifter, like you were trying to unscrew it, 1/4 turn. Test the bike, if you still have hesitation then give it another 1/4 turn. If this does not take care of the problem then it is probably a height or angle problem and will need bike mechanic attention for sure.
And of course, if you have free service, let them do it

I was having trouble with this for awhile too. I was told by a couple LBS that when upshifting to the larger gear in the front, you really can't have much of a load on the pedals. You want to be pedaling lightly for the shift. You can try taking it back, but it may not be improved much. When I change to a larger front gear, I'll stop pedaling when I press the shifter, then pedal real lightly to get the chain moved over.

I got a trek 4100. and i sorted the problem by ditching the piss poor sis job and went deore.

it worked for me.

Well Chi, shifting a front der under load is where it does not perform as well as would be desired. There is too much tension on the chain, and the derailer does not pull/ push the chain with much force.
You have to address this by shifing earlier, or by reducing your torque to shift.
If you are going up hill, which I think may be the problem here? That takes a bit of planning, and some serious effort.
You have to Peddle really hard, pick up a bit of speed, and then quickly shift, and spin to let the chain drop.
On a steep hill, this is difficult! Eventually I hope to not keep doing this, and maybe plan ahead a bit more myself!

Scoob