Onyxaxe

I've got a french bike with the odd sized downtube of 28mm. I'm picking out parts for it and was wondering if I can just 1x it. How important are chain catchers?. Ideally I don't want to have to shim and mount anything to the downtube, and I want to modernize it. I have other 7 speeds, single and 2x.

dsbrantjr

How much do you mind digging a greasy chain from between the chainwheel and frame?

superdex

maybe, maybe not. If you run a purposeful 1x chainring like from SRAM (https://www.sram.com/sram/road/produ...sync-chainring), it'll have alternating teeth that should help. A track chainring won't have ramps either. You still might get some chain jump, depending on your riding and rear derailleur setup. I ran a Deore LX 8spd rear with a Sugino track chainring, I'd get drops here and there on upshifts because the upshift would cause a ripple-wave up the chain, just enough to pop it off the chainring. When I threw that setup onto a CX course, it was almost unusable without a chain watcher (something like this: ORIGIN8 Torqlite Ul Chain Guide > Components > Drivetrain > Chain Guides & Tensioners | Jenson USA )

hth,

FastJake

Depends what you're doing with it. Smooth road riding and a non-ramped non-pinned chainring and you should be fine.

Going to race cyclocross? Get a chain keeper.

wphamilton

No chain-catcher on mine, but I have a DIY chain guide similar to what superdex linked to, that works adequately. It doesn't have to be anything robust and sturdy - the chain just needs a touch to interrupt the wave or bounce in the chain that throws it off. You could probably even put two washers, with nuts holding them, on a long thin bolt and screw that into a clamp on the downtube and I bet it would work.

Andy_K 

You can definitely get away without a chain catcher if all of the following are true:

-Your chainring isn't ramped.
-Your chainline is reasonably good.
-You don't ride a lot on bumpy surface.
-You don't ride through thick mud.

A lot of people are going without chain catchers on gravel bikes these days. Narrow-wide chainrings and clutch-type rear derailleurs seem to be the key to making that work. I suspect they still drop a chain once in a while, but it apparently rare enough that most people don't mind. If that works on gravel, then really you could probably get by on smooth pavement with nearly any setup at all.

Regarding a question you didn't ask, you really could probably use a front derailleur with a 28.6 clamp on your bike. I just built up a '72 Motobecane that had a 28mm seat tube and I used a braze-on adapter (because I need that for the FD I was using) with a 28.6 clamp. I had the bike powder coated, so it wouldn't surprise me if my seat tube actually is closer to 28.6 now, but the point is that 0.6mm really isn't very much at all, and it's just 0.3mm of gap all around. I think most derailleur clamps will handle that.

Onyxaxe

Interesting. I rattle canned it and that might be as thick as your paint. Wouldn't hurt to try, thanks.

dsbrantjr

"One accurate measurement is worth 1000 expert opinions." ADM Grace Murray Hopper

Onyxaxe

Thank you everyone for your input. I wish I could say my local roads are smooth but they definitely aren't. I dare say they're gravely lol. Since the roughest patches I ride are also where the drivers pass the closest and fastest I think I'll either use a front derailleur or a chain catcher. It's prob a bad habit or result of mashing but I tend to lose ALL balance with no chain tension. I've already had one pretty bad wreck because of a dropped chain lol.

gsa103

You can always run a disconnected FD as a chain keeper. Just position it using the low limit screw and it'll stay there forever.

CliffordK

There are a couple of different "drop stop" chainrings available. Wolf Tooth is one vendor/manufacturer.

I think a few other brands make 1x narrow/wide chainrings too.

Another option would be to mount bashguards on both sides of the chainring.

Sci-Fi

This. It's the most economical solution. Some Shimano Nexus/Alfine cranks come with dual chain guards and work just fine.

Moe Zhoost

Interesting. I have about 200 miles on a 650B conversion that I set up as a 1x11. I never realized that I may have needed a chain catcher. The first 2 items on this list are satisfied, and I don't ride through thick mud, but I routinely ride on bumpy surfaces. I have not yet had a problem - should I anticipate one?

Andy_K 

Very possibly not. Note that I said that if you met all four of those conditions you "definitely" don't need a chain catcher. With three of the four you're in OK shape. Thick mud is probably the worst of the four for throwing chains. With rough surfaces it depends on how you ride. If you are bouncing the bike enough that you hear the chain slapping the frame there's a good chance the chain will come off once in a while.