Topic: CB550, lookin to go up a few teeth with the rear sprocket...

[rusty_tank]

I've never heard that going one tooth smaller would put excessive strain on the chain. Anyone else had this actually happen to them? The difference in circumference is not that drastic. I'm just not buying the theory. The chain can go a lot tighter radius than the size of the sprocket.

Yea, I'm with you. I can't see one tooth being an issue. Like I said though, it's my understanding that the concern can be a reality when dealing with a bike with much more hp and going down 3 teeth on the front sprocket. But not with these little guys

[MCRider]

I've never heard that going one tooth smaller would put excessive strain on the chain. Anyone else had this actually happen to them? The difference in circumference is not that drastic. I'm just not buying the theory. The chain can go a lot tighter radius than the size of the sprocket.

Yes its true, well I don't know if its "excessive", though no personal experience. But a tighter arc will cause everything to wear just a little bit more (pins and bushings). Generally, 2 down from the stock is the most. I've known drag race guys who took CB750s from an 18 to a 15. And even went up on the rear to boot.  But all they ever did was drag race so what the humph. Same for a bike that doesn't get ridden much. Who cares?

Still better to go up on the rear, larger arc, less wear.

Usually on a street bike, you can't go up more than 2 without fouling the chain guard. And 3 or more on the rear may require a longer chain.

A compromise is down one on the front and up 2 on the rear. Modest wear increase, probably same chain length, and probably fit the chain guard OK. Should satisfy the urge for more get up.

[Retro Rocket]

I've never heard that going one tooth smaller would put excessive strain on the chain. Anyone else had this actually happen to them? The difference in circumference is not that drastic. I'm just not buying the theory. The chain can go a lot tighter radius than the size of the sprocket.

Yes its true, though no personal experience. But a tighter arc will cause everything to wear just a little bit more (pins and bushings). Generally, 2 down from the stock is the most. I've known drag race guys who took CB750s from an 18 to a 15. And even went up on the rear to boot.  But all they ever did was drag race so what the humph. Same for a bike that doesn't get ridden much. Who cares?

Still better to go up on the rear, larger arc, less wear.

Usually on a street bike, you can't go up more than 2 without fouling the chain guard. And 3 or more on the rear may require a longer chain.

A compromise is down one on the front and up 2 on the rear.

Yep, I agree, smaller circumference equals more stress on the chain, the reason that it doesn't really matter on a drag bike is because of the small amount of "road" covered, you aren't doing thousands of miles. 

[Powderman]

I would think it would be more of a concern on a drag bike because, although it is short runs, every shift is hard and every mile put on it is at it's extreme,  with the most extreme sprocket ratios provided. A chain just going around in circles on a street bike sees very little stress compared IMHO.

[Retro Rocket]

I would think it would be more of a concern on a drag bike because, although it is short runs, every shift is hard and every mile put on it is at it's extreme,  with the most extreme sprocket ratios provided. A chain just going around in circles on a street bike sees very little stress compared IMHO.

I'm just going on what I was told years ago when I worked in a bike shop that had its own road race team, it was the advice I gave to many over the years. Its the continuous use on the road that wears a chain out, drag racing is more about stretch, the decreased radius the chain goes through with a smaller front sprocket is magnified by extended use the same way metal fatigues if repeatedly bent, thats the way it was put to me anyway, and it makes some sense...