Chain drop prevention hacks?

defever

Hello fellow road cyclists,

A hopefully straight forward question asking for cheap & simple DIY hacks / product suggestion on how to prevent chain drops.

Some details:

• It's for 80s retro bike.
• Originally set up as double chaining (43/53T) and 5 speed freewheel (14-22ish).
• Currently having to run single chainring (53T) due to the seized front derailleur (regrettably, removed and binned...).
• As expected, there's chain line deviation causing chain drop over a bump.
• Sometimes doesn't drop, sometimes drops 2-3 times on 14.5mile commute.
• Always drops on the outside (i.e. onto the crank and pedals), never into the inside (i.e. never on to the BB square taper)
• Not a problem putting the chain back on (with a help from roadside twig), but it's getting tedious now.
• I can't put the 53T on the inside of the spider (too big and hits the frame)
• I don't want to replace the chain ring with 43T (on the inside of the spider) as I spin out too early at speed

Solutions I have considered:

• Find NOS 80s front derailluer (Sachs-Huret) to re-fit: So far, I haven't found NOS in decent price so far (lots of cheap "used" and tired looking ones, which I'm not interesed).
• Thinner chain (9 speed): Installed, much less drop episodes of chain drop over same distance, but still once or twice over 50miles or so.

Is there a cheap "chain keeper / catcher" product or DIY ideas like this?:
Paul Component Engineering USA: Chain Keeper ($66.00)


What would you do in this scenario?

Many thanks as always and happy cycling!

flasher

Surely if it's dropping off the outside it can't be a chain line problem, sounds like you need to adjust the high limit screw, I'd try that before trying a DIY hack.

timothyw

The modern solution is to use a narrow-wide chainring - unfortunately you aren't likely to find one in a 130bcd to fit your old chainset.

Really though, any old front derailleur that you can fit (even a seized one) that will direct the chain onto the chainring should solve the issue - just adjust the limit screws as required, probably don't even need to attach a cable to it - perhaps squeeze the cage in a bit with some pliers to direct the chain.

Miles cheaper than that Paul components option.

defever

Thanks both for your comments

Flasher wrote:

Surely if it's dropping off the outside it can't be a chain line problem, sounds like you need to adjust the high limit screw, I'd try that before trying a DIY hack.

Actually, you're right. I forgot to mention that I adjusted the rear derailleur as well, but to no effect. When I'm on 14T on the freewheel, the jockeys sit ever so slightly towards the 15T (the next gear up the freewheel) than 14T without hesitating between those two gears. But the chain drops on bumps so I'm suspecting that the top chain line (where the chain meets the chainring when pedalling) gets dropped as to the bottom chain line. I'm assuming this as I never had the chance to see how exactly the chain drops.

TimothyW wrote:

Really though, any old front derailleur that you can fit (even a seized one) that will direct the chain onto the chainring should solve the issue - just adjust the limit screws as required, probably don't even need to attach a cable to it - perhaps squeeze the cage in a bit with some pliers to direct the chain.

Indeed, I thought of just getting any front derailleur just to act as a chain guide. But my greed tells me, if I'm doing that, then might as well get a decent NOS item, re-cable the front mech, and put back 43T to make use of the double chainring.

Upon reflection, the chain drop isn't affecting me that much that I'm happy to wait for a reasonably priced NOS item to appear than just getting a tired looking derailleur to use as a chain guide. I just wondered (being a cheapskate, which is pretty obvious from owning a 80s bike to commute than investing on a more modern, lighter, efficient bike!) if there was a cheap quick DIY hack. Possibly I'm dreaming!

Thanks again both, and happy cycling!

arlowood

Just a thought

Have you considered running your chain a link or two shorter. Might increase the chain tension enough to minimise the bounce that appears to be causing the chain to unship.