Why do you need a chain guide or roller?

[Virginian]

Understand that I am old school, based on when I went to school, not how I think. With the current suspension geometry I can understand the need for the swingarm guard up front, but why do you need the stuff in the rear? The old bikes only had something to keep your pants out of the chain. What am I missing? Thanks in advance.

[novotny99]

I'm no pro but my friend had a broken guide and it would jump around and damage both the sprocket and chain. So as far a I know it lines the chain up with the sprocket so everything functions correctly no matter how lose or tense your chain is ( due to suspension ) fairly inexpensive to keep from wearing out parts excessively. Hope that helps.

[Nirvana]

My chain jumps around like crazy,wether its tight or loose..I think its probably normal but it will obviously speed up maintenance intervals..I will be installing rollers in the front and in the rear chain guide..Hopefully it will help.?

[JoeBlow Kokomo]

Whan suspension compresses and the distance from the pivot swingarm to axle gets shorter that chain IS going to move sideways. I'm running a too wide 160 rear tire on my 650L motard and it has nice little chunks out of the outside edge of the tread where the chain has chewed it up. A 150 usually clears it.

But the chain DOES move side to side when suspension is compressed, or too loose.

Previous owner cut off all the guides for looks and to clear the tire. I'll be installing rollers as well.