Lately, when I change from large chain ring to small one the chain simply
drops off (every 3rd-4th change).
Once it even did so when going from small to large chain ring.

As Peter (Qui si parla Campagnolo) mentioned, the Chain Watcher will
eliminate the possibility of the chain coming off. Another option is that
it's possible your chain is worn out. You don't have enough mileage per se
for that to be an issue, unless your chain is worn due to being dirty &
neglected; that can wear out a chain faster than the miles would indicate.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"Yuri Budilov" wrote in message
...
Hello everyone

I have a 2004 Trek 1000 road bike, with about 1700 km on the close, which
has Shimano Sora group set - double chain ring. Generally I am happy with
the bike given its low price anyhow....

Lately, when I change from large chain ring to small one the chain simply
drops off (every 3rd-4th change).
Once it even did so when going from small to large chain ring.

I wonder if anyone can shed some light on this? My LBS checked it and in
test could not fault it. The only advice they could offer me was to change
a
few rear cogs up/down so that the chain is more or less "straight" when I
am
about to change from small to large chain ring or vice versa. I have been
trying this and it certainly does help somewhat but I can not help
thinking
this is all rather odd.

Is this as good as it gets with Sora? Is there anything else that can be
done/adjusted? The LBS did adjust the chain and pronounced it good.

Will a 105 or Ultegra group set suffer from the same gear-change problem?

thank you