If I'm planning to run a 1x drivetrain, do I need something to keep the chain on?

[H1449-6]

Looking to set up a bike as a 1x7 or maybe 8 depending on what I have in my parts box.

Do I need something to keep the chain on the chainwheel? I suspect not but if so what's the best practice here?

Thanks.

[gdw]

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

http://cyclocrossworld.stores.yahoo.net/sinchainkitw1.html

I ran a 1x8 on a mtb with just a guard and never had problems but some people like the security of also using a chain wtcher/deflector. Chaingaurds are easy to make from an old outer ring if you want to save money.

[William]

http://www.webcyclery.com/image.php?productid=16455


See them on a lot of cross bikes.



William

[Louis]

I suspect not

I tend to agree with this. Imagine a double crank that you never shift in front - same thing there, no need for any extra "keepers" in that case. Plus, imo those guards are pretty ugly. I can see using one on a cross or MTB, but on a road bike, no way.

Good Luck
Louis

[Lifelover]

Great question. I've wondered that myself.

I've always heard that you do but don't understand why.

I know people who use a front derailer as the guide but don't have it hooked to the brifter. As far as they can tell, they is never any rubbing on the FD which seems to mean that it is not needed.

[93LegendTG]

I have an old 1 x 7 that I use as a commuter and can tell you that you will need something. If you hit a nice pot hole or shift at the same time you go over a bump, you'll suddenly find your chain has bounced off the big ring with no way to fix it, but to get off and put it back on. It doesn't happen often, but when it does its a PITA. I put on a cheap front derailleur, locked it in place with the limiting screws, spread the fork of the derailleur a bit and the problem was solved. In the good ol' days, TT bikes that used a single chainring were often run this way.

[markie]

Yep, you need something unless you are just going to be cruising. Even then your chain may fall off when you least want it to.

There is this: http://www.gvtc.com/~ngear/whatis.html

But you also need something to prevent falling off on the outside...

Why not just single-speed?