Machin

After about 2 years of only using my inner chain ring (road bike, double), I decided I'd clean up the looks by taking off the parts I don't use... first to come off was the FD... rode like that for a few weeks with no problems.

Decided I might as well take off the outer chainring (got some shorter chainring bolts to all this) to give it a real clean look... 3 miles into my Sunday ride and the chain had fallen off twice whilst upshifting on the RD! both times it fell outwards... clearly the outer chainring had been keeping the chain on before... I'm surmising that it fell off due to the shock of changing gears causing a slight jolt. I guess it fell outwards both times due to the ramps on the chainring teeth being designed that way (to ease shifting onto the outer ring) (or maybe just luck?!).

Is this normal (its probably not that normal to use a single chainring, but the sort of riding I do doesn't require more than 9 gears). Do I need to fit some sort of chain guard in place of the outer chainring? At the moment I've put the big ring back on and it works just fine again.

fietsbob

Things you can do.

1) chain minder+ chainguard (this is what I do with my Bike Friday with a Rohloff hub..

2) Lose the ramped and pinned derailleur chainring in favor of an old style tooth .. one
no shifting aides , because the aides go against the single ring plan..


3) chainline readjust .. 1 ring needs to be in the center of the rear cluster,
just leaving the chainring on the outside of the double makes it worse at the low end in back ..

Moving it to the center is better.. middle of a triple is centered.


Cyclocross racing long ago adopted a double guard disc for single ring use over rough turf.

you might just put the FD back on and center it with the lo stroke screw screwed in , over your 1 chainring.
wont even have to hook up the cable.. again.

Wheels Of Steel

fietsbob's recommendation to install a non-ramped non-pinned chainring is a good one. If you want to continue to run a single ring in front this would be the first change I'd make, then address chainline. You could employ one of these Race Face chainrings:

https://raceface.com/components/rings...g-narrow-wide/

or

1. Combine a chain watcher on the inside with a chain guard on the outside
2. Use a chain keeper from the likes of Paul, Problem Solvers, K-Edge or other

wphamilton

Putting a bashguard where the big ring was would probably work, maybe the easiest solution.

In my limited experience of replacing the rings with a single, installing a slightly longer bottom bracket improves the chain line and helps somewhat on the chain falling outside. It will also silence the chain a bit it you've noticed some noise in the higher gears.

Simple attractive and inexpensive solution: I made a chain-guide out of a p-clamp, aluminum pc slot cover and small bolt, which works perfectly and is less obstrusive than the commercially available ones. Just wrap the aluminum strip around the bolt, tighten it down between the p-clamp bolt-holes, bend and trim over the chain. When the chain derails there's no force in it - it just bounces or slides off, and it just takes the slightest touch to guide it back. The flimsy looking aluminum guide is probably overkill in fact so I think you could creatively substitute for the aluminum strip.

FBinNY 

If the ring you have has shift gates (the cut down teeth, usually at opposite ends) they increase the chances of the chain coming off.

When the chain is coming from an angle, each tooth holds the chain in line enough that the point of the next tooth can glide between the inner plates. When the chain passes over the the shift gate it isn't supported (sideways) as well and moves over slightly, so that the next tooth can snag on the inner plate rather than sliding in. This may not cause chain falloff every time, but increases the risk.

When you shift it sends a wave down the chain, much the same as when you flick a rope trying to get it clear of some obstacle. The wave combined with the effect of the shift gate is enough to dump the chain.

When riding SS, it's best to use a non-gated chainring which does a better job retaining the chain.

Otherwise, you can sometimes solve the problem with a file. If the chain consistently falls to the outside, you want to move the point of the first tooth after the gate outward a bit so it's more likely to slide between the plates. You do this by carefully filing the inside (toward the frame) of the tooth at a long angle. Do this by degrees testing and file no more than necessary to solve the problem.

Your other choice is to use a guide ring which is what they do in cyclocross, or one of the FD like chain keepers. I like guide rings because they keep chains on even on very bumpy roads. You can buy one and mount it in the outer position, or you can take the outer ring you no longer plan to use and cut or file all the teeth off, then shape a nice bevel onto the blank rim.

Machin

Cheers guys, some good ideas there... I'll see what I can do!

Thanks!

JohnDThompson 

Even simpler and less expensive fix: put the front derailleur back on. If you don't want to run a cable to a shift lever, just adjust the limit bolts to hold the cage where it needs to be to keep the chain on the ring.

GeoKrpan

Either put the front derailleur back on or get one of these, looks better.

https://www.paulcomp.com/chainkeeper.html

sreten

Hi,

Another option is putting a closer ratio low high gear cassette on the back.
I run a 52/42 with a 7 speed 14-28 rear, both front rings are equally useful.

rgds, sreten.

onespeedbiker

Since the OP has a double, the chainline sits centered on the edge of the spider arms. The OP is using the inner chain ring position and is experiencing the chain dropping off the outside when up-shifting, which I assume means the smaller cogs. I would recommend the OP switch to chainring to the outside position, which would mitigate the chain being pulled off the chainring when the chainline becomes more extreme with the outside smaller cogs. I do agree with all however that either a FD, Paul chain keeper (Origin 8 makes a similar contraption for 1/2 the price), or bash ring (grind the teeth off a large chainring) is a more secure solution.

fietsbob

Double chainring the center.. is the Spider itself , the big ring to the right of it,

The small one to the left of It..

Six jours

Honestly, as a huge fan of simplicity of function and cleanliness of line, I love the look of a single ring on a derailleur bike. But as the OP (and about a zillion cyclocross racers over the decades) found, it just doesn't work. You either need a chain guide, a chain guard, or a "zeroed out" front derailleur. Which then brings back the clutter and extra stuff you were hoping to get rid of in the first place.

I tried all of them, and eventually decided a pair of chainguards ("bash guards") was the best compromise. They even make them in carbon now, if that's your thing. Ultimately, though, I stopped trying to swim upstream and just went back to a front derailleur. C'est la vie...

onespeedbiker

I thought that's what I said; "The chainline sits centered on the edge of the spider arms."

fietsbob

semantics poll , let's vote..

surreal

+1.

rms13

I don't have a 1x bike but this is why I don't. I considered converting my Cross Check to a 1x9 for a minute but then I researched it and found that if I really wanted it to work I would have to add a good chain keeper which not only adds but clutter but adds another $100 or more by the time I get all the parts I need. So I've decided to stick with my 2x9 for now and probably convert it to single speed down the road if I want to de clutter and simplify

FBinNY 

There's no reason that you can't enjoy a 1x? system's clean lines and simple operation without needing any extra stuff. Bike companies have been selling 1x? bikes for 50 years and continue to do so. These wok fine and rarely drop chains when used on paved roads. Off road and CX is a different story because of all the bouncing around, but for on road use you need only a good chainring made for single speed use (without shift gates), and good chainline. A chain with highly good bellmouth on the inner plates also helps because it picks up sprockets better when coming from an angle, but most chains are fine in this respect.

Grand Bois

I can't understand how the ramps and pins on the inside face of a single chainring would tend to throw the chain chain off. The chain will never touch them. The shortened teeth I can understand, but not the ramps and pins. Somebody please explain it to me.

wphamilton

True, for a quick-fix and they can be had new for dirt cheap. But there is something inelegant about it when just about anything you can secure to the frame and bend over the chain will work. Better and cheaper than spending $60+ on a chain keeper though.

There was an earlier thread here where Gerry Hull had set up a 1x11, and had evidently tortured himself a bit with this, and with making the chain quieter, but with a good result in the final analysis. I'd been riding a 1x8 with far fewer problems, perhaps one chain drop per couple of thousand miles. No doubt the smaller, lighter 11-speed chain has unique difficulties. But it takes almost nothing to keep the chain on - you're basically only disrupting a wave in the chain and it just takes a touch in the right place with no force to speak of.

FBinNY 

Hi-

The ramps and pins have nothing to do with causing the chain to fall. As you correctly point out they're on the inside face of the ring where the chain never goes.

HOWEVER, ramped or pinned chainrings usually also have shift gates, which as you're aware are the issue.

I think we see people referring to the ramped tings being problematic, when they mean gated rings, though it's often the same.

surreal

50 years ago, it was 1x5 on 120mm rear ends with awesome chainline. The game has changed,obviously, and nowadays most 1x_ completes will at least have a "bash" ring, which is less about bashing and more about preventing dropped chains, afaict.

Very good point about using a "ss" style ring, though; those long, uniform teeth go a long way towards keeping chain retention. But I fail to see how a 1x_ is cleaner or more simple than a 2x_.

I think ppl gravitate towards 1x_'s because it seems like a smart, easy way to find middle ground between a SS and a f/r derailer system. They were super popular about, what, 8 years ago? I blame Salsa for hyping it more than most of the other companies, but surely there are other ppl to blame. But, I feel like it isn't simple or wise to spend money on a new ring and/or bashring or shorter chainring bolts plus maybe a dogfang or chainkeeper, and then have some orphaned rings, front shifter, and FD stuck in the parts bin. All of this complication to achieve false "simplicity", with the bonus consequences of reduced range and less reliability.


PS- What do most brifter ppl do? Do they buy a left-side brake lever, or do they just leave the impotent shifter where it is, trying to keep its life worthwhile as a brake lever only? (I think doubletap brifters allow removal of the shift paddle, but what about the rest of em?)

Six jours

I eventually solved the "problem" with a Rohloff hub. Now I get 1x__ looks without the dropped chains.

Of course, my wallet is now a couple of thousand bucks lighter, my bike a couple of pounds heavier, and I live with that little grinding sound that may threaten my sanity some day...

TommyBing

Bashguard on the outer ring, same size as the inner ring.

Put a chain watch on the inside. I use the stupidly overpriced K-Edge. It's virtually impossible for me to drop a chain in this set-up. It also is completely quite in every gear no matter how crazy the chain angle. It's a 1 x 11, and 42 x 12 is a steep angle. A Campy 11 chain lasted me around 7000km with that set-up. Now I've got a KMC on it.

Yan 

I recommend a bash guard in place of the big ring. They protect the chainring from damage, they keep the chain from falling off, and they keep grease off your pants. What's not to like?

Leebo

One more thought, shorten the chain to the correct length if you are not using the large chainring.