Problem with gearing changing from big cog to smaller cog uphill

[ttcycle]

twice this has happened, on one of my bikes when shifting from the larger cog to the smaller one up a hill it's momentarily stuck and the chain jolts and the gear doesn't shift up. I've been near thrown off the bike twice now when clipped in going up a hill. It's campag centaur.

I don't have funds to get it down to the LBS, assuming it's an indexing issue is it just adjusting through the usual derailleur screws or is there something else going on. Haven't ridden the good bike for a long while but it never seemed to have this problem before.

Any ideas of how to resolve it at home?

 

[Steve H]

I find the key to changing gear when going up hills is to ensure two things:

- make sure you still have a reasonable cadence. If you are turning the pedals too slowly, it is hard for the gearing to shift.

- try to ease off the power when you are changing. If you are changing gear at the same time as trying to pedal really hard, the mechanisms will crunch and grind.

It's normally the combination of the above two that cause problems with gears on hills. If you are already doing both of these and still having a problem, then suggest they might not be set up right. If you are unsure how to adjust then pop into your local bike shop and get them to take a look.

 

[byegad]

If the bike was OK before the lay off and isn't now the first thing is lubrication. If there's a dry cable, chain or joint in the dérailleur it will cause problems.
SteveH said it about changing early with little power on as you change.

 

[Glover Fan]

From the sounds of it you are changing gear way too late.

Top tip for climbing hills, be in the right gear before you hit the climb this means you can keep a steady rhythm and lower the risk of generating excessive wear on your chain and chainrings.

 

[ttcycle]

Just to clarify it isn't about when to change gears and being in too large a gear that is throwing me off the bike, good cadence and not overly heavy pushing on the pedals.

It's a set up issue as far as I can tell, the chain/cog just jolts/jams and doesn't switch from the large into the small, lubrication is not an issue - I've by this point used up the range of gearing in the larger cog and would like to transition into the smaller cog but the chain jerks and doesn't transfer over.

Just wanting to confirm it is indexing at the front and not potentially something else.

 

[Zoiders]

Just to clarify it isn't about when to change gears and being in too large a gear that is throwing me off the bike, good cadence and not overly heavy pushing on the pedals.

It's a set up issue as far as I can tell, the chain/cog just jolts/jams and doesn't switch from the large into the small, lubrication is not an issue - I've by this point used up the range of gearing in the larger cog and would like to transition into the smaller cog but the chain jerks and doesn't transfer over.

Just wanting to confirm it is indexing at the front and not potentially something else.

That answers the question.

The combination of largest chain ring at the front and the largest sprocket at the rear is not a good one, especialy if the chain is a few links shorter than is ideal. Other than that you could be essentialy locking the drive train up because the front mech cage is almost touching the chain already using that combination, you can help this by giving the indexing and cable tension a tweak though so the cage stops in a slightly higher position, that way when it kicks back down again using the spring pressure it's at least getting a bit of a run at it before it wipes the chain down off the top ring. Also check if you have the front mech banded onto the frame at the right height above the chain set as that can cause the problems you describe as well.

Try shifting down to the smaller chain ring before you hit the very largest sprocket if you can, things will work better and your chain life will improve as well, just because a bike is described as having for example - 18 gears, that does not mean you actually have 18 usable ratio's to use.

 

[ttcycle]

Cheers Zoiders - that makes sense I'll check those issues out.