Friction shifting problem, chain falling between chainrings

[litcrazy]

Thanks for all the input.

I dug deep and found that the shimano norm is pretty much 7mm big ring to middle and 8mm middle to inner. The sugino xd with willow chainrings was 8 but I decided to put some .8mm spacers inside the middle to cut that to 7.2 (give or take at least .5mm as I measured from the centerline of the downtube).

The chain had just registered as worn out via the Pedro’s tool so I replaced that as well. I confirmed that it was a 9 speed chain, so that wasn’t the issue.

By the changing both aspects at once, I made it impossible to know which did the trick assuming this works. I switched from a squirted chain to a waxed chained, so I wanted to deep clean the chainrings. At that point both changes seemed to go hand in hand.
.
The shifting still seems okay with that narrower spacing, though that 46-30 combo can be rough.

Hopefully it all works since we’re hoping for 3-4K feet of climbing tomorrow.

[truth]

Originally Posted by litcrazy

Thanks for all the input.

I dug deep and found that the shimano norm is pretty much 7mm big ring to middle and 8mm middle to inner. The sugino xd with willow chainrings was 8 but I decided to put some .8mm spacers inside the middle to cut that to 7.2 (give or take at least .5mm as I measured from the centerline of the downtube).

The chain had just registered as worn out via the Pedro’s tool so I replaced that as well. I confirmed that it was a 9 speed chain, so that wasn’t the issue.

By the changing both aspects at once, I made it impossible to know which did the trick assuming this works. I switched from a squirted chain to a waxed chained, so I wanted to deep clean the chainrings. At that point both changes seemed to go hand in hand.
.
The shifting still seems okay with that narrower spacing, though that 46-30 combo can be rough.

Hopefully it all works since we’re hoping for 3-4K feet of climbing tomorrow.

How does adding a spacer decrease the distance?

[dddd]

Originally Posted by truth

How does adding a spacer decrease the distance?

That middle ring is on the left side of the tab, so adding a spacer pushes it toward the little ring, resulting in tighter chainring spacing.

[lorenbike]

Bumping this thread --

I have a triple on an early 90s commuter with friction shifters. Currently setup with DT shifters but had the same issue with bar end shifters too. Suntour front derailleur with touringish gearing (50-39-28).

The derailleur shifts fine between the mid and outer rings but is slow to shift to the inner ring, and won't shift under any sort of pedaling on more than a flat road. Even in the stand, I can't get it to shift without a delayed lag with the shifter all the way forward. I've experimented with cable tension, derailleur alignment/height, and the limit crews. Currently, to get it to shift I have to run the limit screw so there's a 5mm gap or so on the inner edge so there's enough leverage for the derailleur to swing over, but this risks dropping the chain. Chainring teeth appear to be in good condition without much wear.

Any suggestions? Thanks!

[MikeD]

Originally Posted by lorenbike

Bumping this thread --

I have a triple on an early 90s commuter with friction shifters. Currently setup with DT shifters but had the same issue with bar end shifters too. Suntour front derailleur with touringish gearing (50-39-28).

The derailleur shifts fine between the mid and outer rings but is slow to shift to the inner ring, and won't shift under any sort of pedaling on more than a flat road. Even in the stand, I can't get it to shift without a delayed lag with the shifter all the way forward. I've experimented with cable tension, derailleur alignment/height, and the limit crews. Currently, to get it to shift I have to run the limit screw so there's a 5mm gap or so on the inner edge so there's enough leverage for the derailleur to swing over, but this risks dropping the chain. Chainring teeth appear to be in good condition without much wear.

Any suggestions? Thanks!

Can you fit a 3rd Eye Chain Watcher, N-Gear Jump Stop, K Edge or equivalent to prevent chain drop? Then you can adjust the inner limit screw for a positive shift without risk of dropping the chain. Is the front derailleur adjusted to within 1-3mm of the big ring and the outer cage parallel to it?

[litcrazy]

Did you or someone else install a shorter bottom bracket?
I’ve found that if I install too short of a bottom bracket to reduce the Q factor that this sometimes creates the shifting problem you describe. Maybe check the chainline and see if it’s particularly short.

[lorenbike]

Originally Posted by litcrazy

Did you or someone else install a shorter bottom bracket?
I’ve found that if I install too short of a bottom bracket to reduce the Q factor that this sometimes creates the shifting problem you describe. Maybe check the chainline and see if it’s particularly short.

Hmm, never heard of that but I will check. I was under the impression that it's the original bb but not sure!

Originally Posted by MikeD

Can you fit a 3rd Eye Chain Watcher, N-Gear Jump Stop, K Edge or equivalent to prevent chain drop? Then you can adjust the inner limit screw for a positive shift without risk of dropping the chain. Is the front derailleur adjusted to within 1-3mm of the big ring and the outer cage parallel to it?

Yep, 1-3mm of the big ring and I realigned everything. Haven't heard of the chain watcher before, seems like it could be worth trying for $10.

[fourflys]

wait, why would you need to bend teeth on chainring that did NOT come with bent teeth and is being used in the intended way? Isn't that trying to find a fix for another problem instead of fixing the initial issue? I'm not trying to be argumentative here, just can't understand modifying a part that should be installed as intended.. if it's not working as intended, that tells me something has changed (like a worn out ring or chain).. is the bent teeth to account for the worn chainring until you can buy a new one?

[rccardr]

You don’t mention exact equipment, that would help here.
If this has been going on a long time and you’re just now trying to get it ‘right’, try the following:
1) don’t shift into the granny ring unless in one of the three largest cogs
2) double check chain length- it may be too long
3) try alternative front derailleurs- Deore style FD’s tend to have a shaped cage end to avoid what you describe

Sometimes, you just gotta juggle bits around until it all works right. If nothing else, a dog tooth chain catcher will get you halfway there.