Single chainring

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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evenfasterson
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by evenfasterson

Hey guys, Im not much of a CX rider, infact ive never riden CX, but I was wondering how you stop the chain coming off over bumps etc. with a single chainring.

Im considering putting a single ring on my XC bike as I never seem to use the other 2 rings. (Ive actually removed the little ring altogether)

Thanks in advance.

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Stolichnaya
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by Stolichnaya

From your comment I understand that you have a triple crankset right now. The easiest and most weight efficient way to keep the chain on when running a single chainring on a triple crank is to:

-Purchase a chainring guard that fits your largest ring's bolt pattern (BCD) -Install a Third Eye or Deda Dog Fang chain watcher on your seat tube (if your seat tube is round and allows one to be installed.)

With that set up you have the chain in place from both sides.

Not sure where you are, but if you are in the States, take a look at cyclocrossworld.com
The attached link has both chainring guards for the outside and chain watchers for the inside. Your LBS should be able to order, or may even have in stock, one or both items.

http://cyclocrossworld.stores.yahoo.net/chainrings.html

You will probably also want to switch your left shifter to a non-integrated brake lever only version. It will be lighter, although the shape may be different, especially if you run Shimano currently.

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evenfasterson
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by evenfasterson

Thanks Stolichnaya.

Its for a MTB so I dont have integrated levers and unfortunately it doesnt have a seat tube so I think I may have to lock out the front mech or machine a new one. Im starting to think its going to be easier to just use a triple but with a small road cassette. eg. 22-23 is not far off 32-30 which is what I currently run and it will probably save more weight than buying a double specific chainset.

Unless a DA or Ultegra chainset would be strong enough for XC? :?

Hmmmmmmmm.....not sure.

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simon
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by simon

strong enough is not the problem, but could you live with a 38 inner ring? or 34 with compact? i think the most used double configuration is 29-442 or 44 on mtb's? you would also have to check the axle length, because road frames are 68 mm wide and mtb's 73(at least back when i had to buy a new bb every 2 months).
i ride a road cassette at the moment, but i don't think it's a very good solution(i just didn't want to use the xtr cassette that came new with my bike and put a 12-25 on instead). in cx i like riding with single chaingring more than 39-46, and with 12-25 on the mtb i'm always shifting on the front, wich slows me down every time i do it, under full load the chain won't come from 32 to 22 and so on...i would go for double setup in a second if i could, but that's impossible with the 2006 xtr cranks.
back to your question, i would try it with borrowing rockrings and put them on left and right from your chainring. you could also put on 2 bigger chainrings, maybe file the teeth down. after that, you can still make your own guides out of plexiglass or carbon. spooky guides are just available in 130 and 135 mm(shimano road and campa). i would not spoil to much for this for just trying it out.

OJ
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by OJ

I had chainguard/dog fang set-up on my cross bike. It seemed to be working well untill today when I did my first cross race of the season. Chain jumped off on a steep "step" and I just pushed it after pushing the chain past dog fang and bending a tooth or two on my chainring. Since I have just couple of mm's of clearance between the chainring and chainstay those bent teeth naturally grinded a nasty scratch on the chainstay. Naturally the chain didn't stay on very well after this. So go for double chainguard set-up as it should be better.

I hope that my frame will last this falls races as I can't afford to buy a new frame at this time.

And then a question. Should I put the chainring on outer or inner place? Or is this just frame specific? It sure looks better if the outer chain guard is on outer chain rings place.
http://demarere.blogspot.com/" onclick="window.open(this.href);return false;

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the Repeater
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by the Repeater

I don't think it matters too much whether you have the inner or outer position. I think chainline might be a little better with outer, but I use the inner with a chainguard and a "fang."


With one ring, absolutely make sure you use the shortest chain you can.
Serious delirium.

JBV
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by JBV

The key with a "standard" single ring setup is to run the chain so that when you're in your smallest cog, the derailleur pulleys are roughly vertical. Longer than that and you're looking to drop a chain.

By "standard", I mean anywhere from a 39-42 ring, and a 12/26 or 27 cassette. I don't really know how well this works if you use long cage derailleurs, or really small rings. I've seen some guys run a 34 single with a 11x23 cassette, but only at little local races...I have no idea how well they work.

Double guard is the best, but if you must run a single guard and a "watcher", the N-Gear Jump Stop is unquestionably the best product of it's kind. I run that setup now only because my frame/crank combo don't have room for double guards. No chain drops in the last 2+ years of racing.

OJ
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by OJ

I made some measurements and I think that I can't fit double chainguard on my bike. I used derailleur as a chainguide before and I had no problems with that. Everything in my drivetrain is the same now than before with derailleur but I might be able to shorten my chain by one link. I run 42x12-26.
http://demarere.blogspot.com/" onclick="window.open(this.href);return false;

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