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Easy workaround to keep chain on a single front ring?

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Easy workaround to keep chain on a single front ring?

Old 10-16-13, 02:21 PM
  #1  
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Easy workaround to keep chain on a single front ring?

I don't need more than one front chainring for my CX bike. Or, for my roadbike for that matter.

But if I try to just go minimalist up there -- and skip the front derailler -- once a ride I'll throw my chain.

The crazy thing is that I never notice the derailler making any "chain catching" sounds, like when it's saving a chain that would've otherwise fallen off.

And I can't find a pattern to the derailing.

So does it really have to happen? And do you really need some kind of guard to prevent it?

Let's see, singlespeeds don't have them.

And the front der only prevents derailing at the top. So something must be happening as a tight chain goes onto the ring after pulling past the top of the rear cog. But what? Is it a slight change in tension that allows slack which in time with some kind of sideways motion or bump throws the chain off?

I've tried one of those "shark tooth" things and I suppose that stops inboard derails. The chain would still sometimes fall off to the outside and cause bad trouble (like in a sprint).

Lately I just slapped a front der back on during summer use with a 53t front ring and racing rear cogset on a roadbike.

I'm now in CX season and I use the same bike for CX. So I now have a 40t ring up front and would like just to be shed of the excess front der. Maybe that shark-tooth would do the trick. Who knows, maybe small rings drop their chain some other way and might tend to more reliably keep a chain. I dunno. I guess I do hear about 'crossers using chainguards for single rings.

I just like to save all possible weight and would love to ditch that hunk o' metal there that's only keeping my chain on and doing nothing else.
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Old 10-16-13, 02:38 PM
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Keeping the FD on makes the most sense. But if your chainring has shaped teeth for shifting speed then you may get some benefit from using a single-speed chainring with full size teeth.
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Old 10-16-13, 03:13 PM
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Originally Posted by JeffOYB View Post
So does it really have to happen? And do you really need some kind of guard to prevent it?

Let's see, singlespeeds don't have them.
Single speeds

1. Don't have rings with truncated teeth in "downshift zones" which encourage derailment.

2. Have a straight chain line which wouldn't cause bad interactions.

And the front der only prevents derailing at the top. So something must be happening as a tight chain goes onto the ring after pulling past the top of the rear cog. But what? Is it a slight change in tension that allows slack which in time with some kind of sideways motion or bump throws the chain off?
I've had problems with un-commanded shifts to the next smaller ring when using one of the two biggest cogs with a worn (perhaps with a slightly bent tooth) chain ring in two situations

1. Worn big ring. I fixed that problem with a new crankset.

2. Worn middle ring on a triple with the same chain-line as a single-ring crank. I replaced the ring.

Presumably the same thing could happen to the outside, and obviously a 3/32" single speed ring without down-shift zones would be a better solution for a one ring bike.

I've also gotten the upper and lower derailleur pivots dirty enough that it didn't follow the chain promptly. My problems stopped at chain slap although I suppose more could have happened.

Last edited by Drew Eckhardt; 10-16-13 at 03:22 PM.
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Old 10-16-13, 03:14 PM
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No personal experience, but I would look into the single speed chainrings. I was looking at the SRAM X11 stuff and they had a pretty gnarly chainring tooth profile to keep the chain on that single front chainring in all gears.

Putting the derailer on would ruin the set-up IMO. You'll still have to trim it to keep it from rubbing, and once you are at that point you may as well put the other chainring back on and run a double.
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Old 10-16-13, 03:45 PM
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https://www.paulcomp.com/chainkeepers.html
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Old 10-16-13, 04:01 PM
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Yes, sadly, you need a real chain keeper to hold it on for cyclcross. Only for road biking can you maybe get away without one.

And it needs to be as close as possible to the chain (vertically.) Or else the chain can slip through.

Originally Posted by JeffOYB View Post
The crazy thing is that I never notice the derailler making any "chain catching" sounds, like when it's saving a chain that would've otherwise fallen off.

So does it really have to happen? And do you really need some kind of guard to prevent it?

Let's see, singlespeeds don't have them.

And the front der only prevents derailing at the top. So something must be happening as a tight chain goes onto the ring after pulling past the top of the rear cog. But what? Is it a slight change in tension that allows slack which in time with some kind of sideways motion or bump throws the chain off?
You don't notice it because when it's (potentially) being thrown off you're going over a bumpy section and not looking at your chain...

Yes, it happens. You only need to ride without a chianguard to find that out.

Single speeds don't have them because they don't have rear derailers (which hold the chain sort-of on track using a spring.) With a single-speed there is nowhere for the chain to go. It CAN'T fall off.

You only need to prevent derailing at the top because when the chain derails from the bottom you just pedal a bit and it will be right back on. When it derails from the top you're screwed. I have a Paul chain keeper on my cross bike and my chain will sometimes derail from the bottom. No big deal. Just don't try pedaling backwards when that happens or you can have a serious jam, and ruin your chain keeper.
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Old 10-16-13, 06:28 PM
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You don't have to have a chain keeper OR a real single-ring if your chainline is perfect. I mean *perfect*. Line it up with a straightedge and use whatever spacers or respacing you have to do to get it within .1mm.

After that, get a dedicated single-ring on the front.
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Old 10-16-13, 06:36 PM
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https://www.cyclocrossworld.com/thorn...hainring-guard

+ one of the several chain catchers to keep it from coming off to the inside..
that wrap around the seat tube and reach to the chain, ...

Im less weight conscious, Surly single speed rings in stainless are fine..

you might prefer Ergal alloys.

a set : https://www.cyclocrossworld.com/thorn...-chainring-kit
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Old 10-16-13, 06:38 PM
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Ben Berden's front ring set up. use the inner ring for the toothed gear and a blank ring like above for the outer and get the K edge keeper that has a "roof" on it so it won't bounce up


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Old 10-16-13, 07:01 PM
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Originally Posted by ShartRate View Post
No personal experience, but I would look into the single speed chainrings. I was looking at the SRAM X11 stuff and they had a pretty gnarly chainring tooth profile to keep the chain on that single front chainring in all gears.

Putting the derailer on would ruin the set-up IMO. You'll still have to trim it to keep it from rubbing, and once you are at that point you may as well put the other chainring back on and run a double.
Pretty much this, although keeping your FD on makes the most monetary sense.

As an alternative to SRAM, check out Wolf Tooth Components. They have a decent new selection of rings that can be run 1x10 with no chain guide, and I've only heard very good things.

Last edited by solipsist716; 10-16-13 at 07:05 PM.
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Old 10-16-13, 07:44 PM
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These are designed specifically for that purpose. They work better with a clutch type rear derailleur, but they work well without them. https://www.wolftoothcycling.com/
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Old 10-16-13, 08:40 PM
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Originally Posted by pmt View Post
You don't have to have a chain keeper OR a real single-ring if your chainline is perfect. I mean *perfect*. Line it up with a straightedge and use whatever spacers or respacing you have to do to get it within .1mm.

After that, get a dedicated single-ring on the front.
The OP is talking about a 1x8, 1x9, 1x10 or whatever setup, not a single-speed setup.

But you're right, no chain keeper is needed on a single-speed/fixed gear. If it is, something is wrong.
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Old 10-16-13, 09:24 PM
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We need to sticky one of these threads. Every week, it seems, someone comes up with the bright idea of "simplifying" their geared ride by making it a 1x__, and then everyone shows them the doo-dads that are shaped like FDs and the bashrings that are like toothless chainrings, and the deeper-toothed rampless/pinless rings that help too, and then the OP says "really? wow. gosh. I didn't realize that i'd have to spend extra money and buy extra parts in order to 'simplify'." In the end, the only parts you're eliminated are the left shifter and its cable-- and about half of your gear range.

Yeah, well, that doesn't seem so simple now, does it?

Maybe it's just me and my inability to think abstractly or tolerate goofy half-measures, but it seems to me that one oughta decide: am I a derailers person, or a SS person? (If you truly can't decide, consider becoming an IGH person...) I love SS, I love it to death, but I have some geared bikes, too. And once you've delved into that whole mess, you might as well get derailers on both ends of the drivetrain.

-rob

PS-it's the rear that musses everything up, anyway, with the goofy 7/8/9/10/11/infinity arms race and the difficulties in cross-compatibility. The front has been pretty much double or triple for ages now, with a few 4-ring oddballs popping up from time to time....
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Old 10-16-13, 09:44 PM
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Originally Posted by surreal View Post
Maybe it's just me and my inability to think abstractly or tolerate goofy half-measures, but it seems to me that one oughta decide: am I a derailers person, or a SS person? (If you truly can't decide, consider becoming an IGH person...) I love SS, I love it to death, but I have some geared bikes, too. And once you've delved into that whole mess, you might as well get derailers on both ends of the drivetrain.
I agree with the above except for cyclocross. For me, the single ring up front is simpler, I don't need the extra gears (I actually prefer a wide range cassette for that application) and I never have to worry about dropping the chain. With a double I dropped the chain a couple times before I got rid of it.
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Old 10-17-13, 02:46 AM
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I used to ride a 1x5 system, that was how the bike came. The chainring teeth were unramped and there was no keeper or guard.
I think modern chains may have more lateral movement than chains of old, has anyone tested for this?

1x8 or 1x9 systems can provide enough gear range for rolling terrain without steep hills. The chainset is much lighter and cleaner with fewer dirt traps. There is nothing wrong with the concept as long as you can get it to work reliable with modern components.
Fit unramped rings, a chainkeeper device or some plastic chainring guards.
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Old 10-17-13, 05:36 AM
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If you want to be really minimalist about it, I'd try this experiment:



No wait, if it turns out this is enough to prevent the chain being thrown (probably in conjunction with a SS ring), then you can disassemble the RD's pivots and drill new holes for the springs, to set a higher chain tension. Harder than usual to reassemble.

BB derailer pulleys, as always, are a good idea too (plastic not ally).
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Old 10-17-13, 07:00 AM
  #17  
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Hmmm. My son just built himself a 1X10 hard tail mountain bike. He split a tire on a night ride last night so you know he's really mountain biking it. I wonder how he keeps his chain on the front ring. I'll let you know when he answers me back.

There's his answer: He uses an MRP chain keeper.

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Old 10-17-13, 09:26 AM
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Originally Posted by MichaelW View Post
I used to ride a 1x5 system, that was how the bike came. The chainring teeth were unramped and there was no keeper or guard.
I think modern chains may have more lateral movement than chains of old, has anyone tested for this?

1x8 or 1x9 systems can provide enough gear range for rolling terrain without steep hills. The chainset is much lighter and cleaner with fewer dirt traps. There is nothing wrong with the concept as long as you can get it to work reliable with modern components.
Fit unramped rings, a chainkeeper device or some plastic chainring guards.
Once you fit a chainkeeper and/or bashguards, most of your weight savings is gone.

1x5 or 6 is more reliable b/c chainline doesn't vary so widely. You're more likely to drop the chain at the upper- or lower-extremes of a 8, 9, or 10speed cassette.

There's no doubt in my mind that a 1x__ will provide enough range. The thing is, many ppl question the need for a double crank and a front derailer, b/c they feel they don't need the extra range. I feel like they need those items to keep their chain on the rings; the added range is just the icing on the cake.

If you like "clean lines" and "simplicity", get a SS or a FG. IGHs are nice, too. If you like derailers, I see no reason to forgego the front one, as you'll need to clutter and ballast the bike with other crap to keep the chain on anyway.
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Old 10-17-13, 09:31 AM
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One: Align your front chainring with the center of the cassette.
Two: Trim your chain to the minimal amount that will work.
Three: Check your RD's chain tension get it as high as you can without a friction issue.
Four: You'll probably need a chain guide of some sort anyhow, good luck.

A 1x front is a great thing, but once you go past 7 speed it's very likely to have too much of an angle to travel on the outer low/high gears and will probably still pop off unless you have a guide/guard of sort.
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Old 10-17-13, 09:38 AM
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carbon fiber chain guards are out there.. FSA for one https://www.bikeman.com/CR4021.html

Less bashable than what logjumping MTB's use .. .

the one in the 9th post, has most of the aluminum cut away.. so weighs less than the chainring it replaces..


save weight get 12oz beers instead, of 16s.. ?

Last edited by fietsbob; 10-17-13 at 10:56 AM.
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Old 10-17-13, 09:49 AM
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Originally Posted by fietsbob View Post
carbon fiber chain guards are out there.. Less bashable than what logjumping MTB's use .. .

the one in the 9th post, has most of the aluminum cut away.. so weighs less than the chainring it replaces..


save weight get 12oz beers instead, of 16s.. ?
Save more weight and get cans instead of bottles?
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Old 10-17-13, 10:33 AM
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It helps to keep pedalling over bumps -- the chain is slack when you're coasting over bumps, and that's when it can get dislodged.
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Old 10-17-13, 09:53 PM
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I'm with surreal. 1-x-something seems like it's more trouble than it's worth.
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