Chain drop problem

Quoted message said:

I have a new-old bike that has a Sachs 3x7 rear wheel. I am running a single 52t chainring on the
inside position of a Shimano 105 crank (130 bcd) to get the gears I need. I have a problem with
occasionally dropping the chain off the outside and more rarely off the inside of the chainring
while shifting the rear derailleur. The chainline looks good and centered on the cassette. I've
looked around online at chainguards and can't find any that are made for a 52t chainring. To
complicate matters the bike has an odd sized seat tube, measuring
33. mm, so the dog fang/chain watcher/jumpstop solution for inside drops may not work. Does anyone
have a suggestion about how to cure this at moderate cost?

A standard chainwatcher will adapt to any diameter up to 34.9mm, but what you really need is a front
derailleur that's been adjusted to a fixed position over your chainring. Given the odd size of your
seat tube, *that* could be a problem. However, you should be able to shim a 34.9mm derailleur to
fit, especially since the derailleur isn't going to be seeing a lot of force on it.

--Mike-- Chain Reaction Bicycles chainreactionbicycles.comchainreactionbicycles.comOpen ↗

"Mike Jacoubowsky" <[email hidden]> wrote in message
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Quoted message said:

A standard chainwatcher will adapt to any diameter up to 34.9mm,

but what

Quoted message said:

you really need is a front derailleur that's been adjusted to a

fixed

Quoted message said:

position over your chainring. Given the odd size of your seat

tube, *that*

Quoted message said:

could be a problem. However, you should be able to shim a 34.9mm

derailleur

Quoted message said:

to fit, especially since the derailleur isn't going to be seeing a

lot of

Quoted message said:

force on it.

Thanks. That sounds like it will work.