Rear sprocket reccomendation

Jlovvorn · Post by **Jlovvorn** » Wed Jul 04, 2012 8:58 am

I have two rear wheels, one with a 31T and one with a 37T.

I have read a lot of forum posts on gear ratios, and concluded I am not smart enough to interpret the data.

Any reccomendations on which to run on my stock Cb77?

31? 37? Neither?

I ride mostly around town, never on the highway, never over 60, and only above 50 for less than an hour at a time. In short, I am not cruising this bike at high speeds.

Given the choice, I would like more acceleration off the line in exchange for a lower top speed.

I think this means I should mount the 37, or maybe something larger.

Thanks for any thoughts anyone is willing to share.

mike in idaho · Post by **mike in idaho** » Wed Jul 04, 2012 9:22 am

37 teeth is standard gearing on the CL77, it's just about perfect for use with the CL's 19 inch rear wheel. The larger rear sprocket will raise your top gear rpm about 20 percent, over the smaller one. Around town performance will be a lot better. If it feels too buzzy going down the highway you could go up one tooth on the front sprocket to split the difference.

Jlovvorn · Post by **Jlovvorn** » Wed Jul 04, 2012 10:19 am

Thanks for the quick help, as always, Mike.

I mounted the 37, mostly because it was already attached to the better of the two wheels.

But now my chain is too short, so I guess its time to replace it.

It also seems like the chain might slap on the muffler mount, but maybe thats just because its not pulled tight yet.

Anyone know if a CB550 chain will fit this bike? I got one of those in the garage.

I am laid up with a torn toe ligament for a month (no crash involved), so no walking or riding, and I am going to be in the garage a lot.

Vince Lupo · Post by **Vince Lupo** » Thu Jul 05, 2012 5:56 pm

I think 30/15 was the stock setup for the CB77 -- 37 would be quite a change on the back!

Personally I'd go with the 31. 530 non o-ring chain should fit -- I like the Tsubaki's.

Jlovvorn · Post by **Jlovvorn** » Sat Jul 07, 2012 9:49 am

Thanks Vince!

I think I will try out the 37, since its already mounted.

As soon as I am able to ride again, I will report on how it affects things.

Vince Lupo · Post by **Vince Lupo** » Sat Jul 07, 2012 12:06 pm

I'm thinking that you'd be topping out 4th gear pretty quickly with that 37 rear sprocket. From my recollection, with the stock configuration in 4th gear, you're pretty well at 1000rpm per 10mph. So at 6000rpm you're doing about 60mph. And (I could be wrong), I think that with each tooth change on the rear, you affect the rpms by about 500. So going from a 30 to a 29, at 60mph in 4th you'd be turning about 5500rpm. Going from a 30 to a 37, that calculates to about a 3500rpm difference, which seems like a heck of a lot! And being that you live basically in the region where I live (DC/Balt/NOVA), there's a likelihood that you'll have to use either the Beltway, Route 50, Route 15, I-270, I-66 or even the Leesburg Pike at some point (particularly if you want to explore some of those great Virginia or Maryland backroads outside the metro areas), so I'd think you'd want more in reserve at the top than what that 37 rear sprocket can offer. As you say though, once you ride the bike with the 37 you'll know for sure.

Here again, my math could be totally way off, so if someone could enlighten all of us, that would be great.

mike in idaho · Post by **mike in idaho** » Sat Jul 07, 2012 12:21 pm

17 teeth on the front with a 37 tooth rear would be approximately equal to a 15/33 tooth combo, about a 5% increase in rpms/miles per hour over stock.