Bicycle Mechanics - Is this Normal - Shifting Problem

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ptmurphy
08-25-03, 09:06 AM
I have a tripple up front that has sometimes trouble shifting from the smalling chainring to the largest. When I push the lever, it tries to go up, but sort of struggles and the chain will then drop down around the bottom bracket.
I took it to the LBS and they said they couldn't find any problems and recommended just holding the shifter over until the chain catches. This doesn't seem right, as I don't have to do this on my mountain bike.
The FD is either Tiagra or 105, can't remember.
Is there any adjustment for something like this? All the adjustments I have tried seem to just help outer and inner travel.
Thanks,
Phillip
spazegun2213
08-25-03, 09:19 AM
i have had this problem a little with my tiagra FD. Try going from small to med to large. i have noticed that sometimes mine has trouble jumping from small to large.
just a thought
-Ross
live311
08-25-03, 09:19 AM
I used to do that when I first got my road bike with a triple. First off, you cannot switch from the small ring straight to the large ring. You have to go to the middle ring first. Second, if you have Shimano STI shifters, you should have noticed that the lever clicks twice when you shift from the small to the middle ring. This is meant as a trim adjustment to keep the chain from rubbing the front derailleur in certain gear combinations. The secret to successful upshifts from the small ring is to push the lever all the way to the left until it stops. If you stop on the first click you will get chain suck. Then if you want to go higher you must first wait until the chain catches completely on the middle ring. Then you can shift to the large ring. It takes a little practice but once you get the hang of it shifting will be flawless.
ptmurphy
08-25-03, 12:35 PM
Sorry, typo on my part...
I meant going from the smallest to the middle chainring.
Thanks,
Phillip
mightypudge
08-28-03, 07:23 AM
I had a bike with the same setup and had the same problem. I came to learn this is pretty normal, and once I got used to shifting the front I was fine.
miamijim
08-28-03, 07:35 AM
whenever you shift, regardless of the gear, back of on yuor pedal pressure. Full pressure on your drivetrain puts tremendous strssses on the components. Get your cadence up, back for a split second when your shift and your shifts will be much smoother.
U should try adjusting your front derailer a little. I had the same problem on my bike. It wouldn't go from smallest to middle, kinda get stuck inbetween and make a really ugly grinding noise, would have to shift up again and it would pop onto the largest ring, then I would have to shift down to the middle ring.
I dunno what your deraileur looks like but my Shimano Altus (yeah, yeah I know its a piece of crap) has a few screws which u can tighthen/loosen to set the shift position(s). So you just set the shifter for the middle ring, adjust the screws till the deraileur sits above the ring and the same for the rest. My dad played around with them until it shifted properly.
It works most of the time now, it only stuffs up when i pedal too hard (usually when i am heading up a hill, then its all stuffed cos no momentum.)
Anyway thats my 2c worth and I could have no idea what I am talking about. :rolleyes:
Hot Pepper
09-04-03, 06:46 AM
Those screws on the front(and rear) derailleur are for adjusting the limits. That is, to prevent the chain from coming completely off the small or large ring. They will not help sluggush shifting.
1) How old is your chain? A worn chain will have a lot of lateral slop, and will not shift cleanly
2) Is there any slack in the derailleur cable? If so, try first to take up the slack with the barrel adjuster on the downtube, if that's not enough, you might have to loosen the cable binder on the derailleur, and pull the cable taught. I suggest screwing the barrell adjuster all the way in first, and then out again by 2 turns so you retain some adjustability.
3) Is it possible your chainrings are worn? Chainrings nowadays have pick-up pins embedded in them to help the chain move up.
4) And this is very possible from your description:
it tries to go up, but sort of struggles and the chain will then drop down around the bottom bracket.
the shifter itself may be at fault. It sounds like it is not catching in the position you want it, and returning to the small ring position, where it then falls off the ring and comes to rest on the bottom bracket shell. The screws on the front derailleur are for making this adjustment, to keep the chain from falling off.
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