Shimano Sora Drivetrain Problems.

downhill paul

Hi all
for a while I have been having a few problems with my drive train.
the chain sometimes rubs against the inside of the front derailleur when the chain is on the small front chain ring and the large cog on the rear cassette. as I move down the rear cassette I can click the front derailleur in to a middle position between the small and large chain ring so the chain doesn't rub on the front derailleur. but on the 7th 8th and 9th cog on the rear cassette, I can hear the chain rubbing on the inside of the front derailleur. the same thing happens when I am on the large front chain ring and on the 7th 8th and 9th cog on the rear cassette.
I have also noticed that clicking the shifter to move on to the large front chain ring usually takes an extra push on the lever after the click to actually get the chain to move without catching on anything.
is it simply a case of adjusting the limit screws or do I need to take my bike to have the gears realigned?

imposter2.0

downhill paul wrote:

is it simply a case of adjusting the limit screws or do I need to take my bike to have the gears realigned?

That's effectively the same thing. A few seconds with a screwdriver should sort it out.

downhill paul

But if I adjust the front derailleur so that in certain gears the chain doesn't rub against the inside plate, won't that mean that in other gears the chain will rub against the outside plate?

downhill paul

I also seem to have a problem with the gear cables rattling against the underside of the down tube.
the gear cables cross under the down tube, after a quick search on google I have found that this is done so that the cables have a smoother arc around the head tube. all this is fine and I have had no shifting issues so far.
but is there anything I can do to stop the bare cables rattling against the underside of the down tube?
they only rattle on rough roads but it's still annoying.

sungod

downhill paul wrote:

But if I adjust the front derailleur so that in certain gears the chain doesn't rub against the inside plate, won't that mean that in other gears the chain will rub against the outside plate?

there are high and low limit screws, and there's the cable tension

the low limit screw needs setting to stop the cage move inwards too far when the cable isn't tensioned

the cable tension needs setting so that it holds the cage in the correct position to clear the chain by c. 0.5mm when on big front/small rear

the high limit screw needs setting so that when shifting to the big ring, the cage does not move so far that the chain falls off the outside of the ring

if limit screws are correctly set but cable tension is too high, it'll be ok on the big ring, but cause chain rub on the cage in the small ring

imposter2.0

downhill paul wrote:

I also seem to have a problem with the gear cables rattling against the underside of the down tube.
the gear cables cross under the down tube, after a quick search on google I have found that this is done so that the cables have a smoother arc around the head tube. all this is fine and I have had no shifting issues so far.
but is there anything I can do to stop the bare cables rattling against the underside of the down tube?
they only rattle on rough roads but it's still annoying.

just uncross the cables - problem solved.

keef66

Imposter wrote:

downhill paul wrote:

I also seem to have a problem with the gear cables rattling against the underside of the down tube.
the gear cables cross under the down tube, after a quick search on google I have found that this is done so that the cables have a smoother arc around the head tube. all this is fine and I have had no shifting issues so far.
but is there anything I can do to stop the bare cables rattling against the underside of the down tube?
they only rattle on rough roads but it's still annoying.

just uncross the cables - problem solved.

People were complaining about the crossed cables hitting the downtube on recent CR1 builds. So I didn't cross them when I built mine up and so far it's silent.

imposter2.0

I tried crossed cables once - made no difference to performance, but it did make a kind of 'ker-ching' sound like an old cash register whenever I shifted. Got bored of it after a while though..

downhill paul

If the shifter cables don't cross under the down tube then the outer cables rub against the sides of the head tube.
I know this because me and my girlfriend have the same bike, my bike was assembled at the shop it was bought from, her bike was assembled (I'm guessing) by the supplier before they were delivered to me. my cables cross under the down tube and hers don't. as a result, my gear cables rattle under the down tube and hers don't. but then her outer cables rub on the sides of the head tube and mine don't.

keef66

downhill paul wrote:

If the shifter cables don't cross under the down tube then the outer cables rub against the sides of the head tube.
I know this because me and my girlfriend have the same bike, my bike was assembled at the shop it was bought from, her bike was assembled (I'm guessing) by the supplier before they were delivered to me. my cables cross under the down tube and hers don't. as a result, my gear cables rattle under the down tube and hers don't. but then her outer cables rub on the sides of the head tube and mine don't.

I'd rather stick a couple of patches of helicopter tape on the head tube than have cables constantly pinging against the downtube.

downhill paul

But now that the cables are routed to cross under the down tube, how do I stop them rattling?
in the not too distant future I will be upgrading all the cables (inner and outer) anyway. so I will be asking whoever does it for me if crossing the cables under the down tube or in front of the head tube is better. if it turns out that crossing the cables under the down tube is the better method then so be it.
I don't know enough about bikes to start fiddling with things.

wakou

Gets some 'doughnuts' to stop the rattling...

imposter2.0

downhill paul wrote:

But now that the cables are routed to cross under the down tube, how do I stop them rattling?

You un-cross them, as explained earlier. Donuts will not work, they will just wobble their way down the cables and end up underneath the BB. Cable rub on the headtube might wear some paint off, but it is not going to kill the bike. Or use protective tape, as mentioned above.

downhill paul

Thanks guys.
I might just wait till next month when I have all the cables replaced. if crossing the shifter cables under the down tube really is the best way, then I will look in to ways to stop the cables rattling and taking paint off the frame.