cant firgure out wuts going on...

Quoted post said:

Originally posted by kardon2
when i stand up on my bike and really start to pull forward, sometimes the pedal falls a big like it were shifting gears, and i dont even have my hands on the shifters and its still in the same gear... only sometimes... anyone know whats going on?

Hi, when did you brought your bike to service ?

I believe your gear cogs and chain need to be replaced, they are simply worn.

If that is not the case check you Chain rings specially the middle one (32 T ?).

How big are you? I'm 90 KG.(almost 200 lbs.) and the 32T chainring does not work for me, i have to replace it with a 36T. But even then i have to be really carefull, wenn i am ridding up the stairs......Sorryly the new front deraileurs do not take any bigger middle chainring.

Good luck

Mehrdad

Yeah, sounds like a rear derailleur thing. Have your bike serviced. That should fix it.

ive had it for 4 days... im only like 140 or sumthin

Quoted post said:

Originally posted by kardon2
when i stand up on my bike and really start to pull forward, sometimes the pedal falls a big like it were shifting gears, and i dont even have my hands on the shifters and its still in the same gear... only sometimes... anyone know whats going on?

It sounds like the chain is slipping over the cogs or chainrings. Since the bike is new this is probably due to a too-long chain on the bike, or a "B" screw adjustment issue on the rear derailleur. One of the rear derailleur's jobs is to take up the slack in the chain when you are riding with the chain on a smallish chainring and smallish cog. If the chain is too long or the "B"screw is not in far enough (pushing the derailleur body back) the chain will be a little loose and may be able to jump on either a cog or chainring, especially if you sre standing on it hard and going over rough terrain.

You can find some info on this at the park tools web site. Since the bike is new, I'd take it back to the shop and have them check it out. You might also consider riding in a little lower gear. If you have to stand up to really pound it hard, you may be in too high a gear (again depending on the terrain).

TD

i found the best way to avoid it is to use the gears more efectivly and get in the right gear before i go up something.

If it's a new bike, this is probably the result of initial cable stretch messing up the tuning of the rear derailleur (the front will also be messed up but it usually takes a bit longer, as it's not used as often.)

What needs adjustment is the cable tension. Fortunately this stretching is just an initial thing with new cables; once they have finished stretching (after a couple of weeks) they should hold their tension fine for a while.