Author Topic: number of teeth on a sprocket (Read 8771 times)

Jicima · « **on:** July 29, 2005, 09:13:49 PM »

Hello fellow Banditos y Banditas,

I am new to the forum and the Bandit. I bought a used 02 B12S about 3 weeks ago and have logged about 4k miles on it. I am now in need of a new set of sprockets and chain. I have read a lot on the forum and it seems the D.I.D. chain is the way to go.

About the sprockets though. There are three major companies it seems and the prices vary so widely it his hard to know what to get. To compound this problem, the number of teeth is greatly variable. I understand that some will give more torque and others lower rpm's, but, what is the magical formula. More teeth rear and front or less on one more on the other?

If any of you extremely knowledgable Banditos can give any advice on the topic of sprocket company selection and number of teeth, this nuevo bandito would greatly appreciate it.

Gracias Amigos/as

ray nielsen · « **Reply #1 on:** July 30, 2005, 09:18:42 AM »

I've had very good service from Sunstar or Sprocket Specialists brand of sprockets. Sunstar is available through Dennis Kirk <www.denniskirk.com> whle Sprocket Specialists is reachable at <www.sprocketspecialists.com>.

As for chains, the DID X-Ring chains last a long time -- I get about 40K miles per set of sprockets and chain in a touring mode. I use a Scott Oiler which keeps the chain "wet" with oil and probably it helps a bit too.

DID makes two X-ring chains, 530 VM and 530 ZVM, the latter being much more expensive and supposedly lasting longer. I've only used the VM series.

Both chain and sprockets should be replaced together in my opinion.

Red01 · « **Reply #2 on:** July 30, 2005, 07:26:29 PM »

Stock gearing is 15 teeth up front and 45 in the back, for a 3:1 ratio (three turns of the transmission output shaft for every one of the rear wheel). A lower ratio (which is higher, numerically) will give you snappier acceleration, higher engine RPM at a given gear & road speed and a theoretical lower top speed, while a higher ratio (numerically lower) does just the opposite.

The second generation B6 & B12 get their speedo reading from the front sprocket, so any gearing changes from stock will have an effect on the speedo. (The 1G bikes drive the speedo off the front wheel, so are not effected by gearing changes.)

To lower the ratio, go down in front and/or up in the back and vice-versa for a higher ratio. General rule of thumb is one tooth up front is roughly equal to three teeth in the back.

A one tooth change up front usually does not require a change in chain length, so some folks will buy a stock and a second (or third) front sprocket so they can change gearing to suit them.

To do the math to figure other ratios divide the rear sprocket by the front, (ie; 45/15, 45/16, 42/15, etc.).

Jicima · « **Reply #3 on:** July 31, 2005, 10:26:46 PM »

Thanks for the info guys. I think I am going to stay with the standard arrangement for the time being (15/45).

Sven · « **Reply #4 on:** August 01, 2005, 08:01:43 PM »

This is interesting, since I am starting to have some chain noise/problems. My question for this thread would be WHICH direction will I want to go when I do the eventual replacement?

I'm a stock kinda guy, haven't even replaced the exhaust on my '03 B12s (el bandido de cerceta). I don't feel like I need snappier acceleration, not looking to lower or raise the top speed, About half my riding is commuting/errands, and elbandido's acceleration is great for beating everything else onto the freeway, etc.

Does this mean I should just go with a stock ratio? Or is there benefit I'm not seeing in to a lower or higher ratio?

Red01 · « **Reply #5 on:** August 02, 2005, 12:07:55 AM »

If you're happy with the current speed & acceleration stick with the stock combo. Some will change the gearing to get the harmonic vibe that kicks in ~70 mph to move to a different speed if they spend a lot of their riding time at ~70... just remember if you change the gearing, the speedo & odo will be different than now.

Sven · « **Reply #6 on:** August 02, 2005, 07:03:10 PM »

As you suggest, I will probably stick with the stock setup. I'm happy with the bike, and not crazy about the idea of the speedo becoming unreliable. Thanks for the guidance!

Steve · « **Reply #7 on:** August 03, 2005, 04:18:13 AM »

Just for clarification, the speedo does not become unreliable. It is just a bit more optomistic if you change to lower gearing.

Initially I thought I would get something like the yellow box to calibrate the speedo but the change is of little impact. I easily adapted to the speedo thing, a few runs by a radar trailer and you have it down pretty good, or use a GPS if you wish.

I run 15/47 on my b12 and love it! The bike feels lighter and runs through the gears very nicely. The only impact on the top end is that I seem to get there a bit quicker. Vibes at cruising speeds are better too, at least judging from the mirrors.

Nothing wrong with the stock gearing, I tried 15/46 - too subtle of a change for me - 15/47 is just right. The vortex rear sprocket looks cool too (especially with the gold ZVM)!

Steve

Sven · « **Reply #8 on:** August 03, 2005, 07:56:42 AM »

I'll have to give it a bit more thought...hoping to not have to make any decisions too soon! Thanks for sharing your transision experiences.

BANDIT#999 · « **Reply #9 on:** August 11, 2005, 11:37:22 PM »

Hey Sven, take into consideration that if you do decide to go up one tooth on the front be prepared to do a little shaving. By this I mean, on my 04 B12 I had to use a die grinder (Dremel will work) and shave a little extra clearance for the chain. Easy to do but not an exact science to it. Where the bolt goes through at the top (if i remember correctly) just scoop away a bit of the aluminum and test fit. Even if it goes on the first time, rotate the chain on the gear to check for clearance until nothing drags. Otherwise go with the smaller rear.

ray nielsen · « **Reply #10 on:** August 12, 2005, 10:13:38 AM »

I've gone up one tooth (to 16) on the countershaft to drop the highway RPM and to correct some of the speedometer error.

The countershaft sprocket nut provides the speed sensor with impulses as it rotates. With a larger sprocket the impulses are less per unit of time with the result that the speedometer reads a bit lower, about 6%.

This reduces the speedometer error but the odometer is now off by about the same amount, reading low. I've looked inside the instrument cluster for any calibration adjustments, but I can't find anything adjustable. Still I like a more accurate speedometer, I can correct for odometer error when checking mileage.

On my 2003 Bandit 1200 I've also replaced the rear tire with a 170/60-17 Metzeler ME 880 that has a taller profile -- about 1% taller. That further reduces the speedometer error -- now my speedo is dead on at 60 and 72 MPH, taking just 60 and 50 seconds per mile marker, on the freeway, respectively. The odometer is about 6.5% low.

Hope that helps.

Sven · « **Reply #11 on:** August 12, 2005, 06:11:00 PM »

Um, what are we shaving off? You're talking larger sprocket, so presumably you meam some extra room around/above the sprocket?

Red01 · « **Reply #12 on:** August 12, 2005, 07:41:13 PM »

Sven...

Quote from: "BANDIT#305"

Where the bolt goes through at the top (if i remember correctly) just scoop away a bit of the aluminum and test fit.

He's referring to the sprocket cover/fasteners. Once you put a 16T sprocket on, you'll see where it needs a little clearancing.

BANDIT#999 · « **Reply #13 on:** August 12, 2005, 08:19:03 PM »

Ok Sven, this may be a bit on the big side, but here goes. In the bottom right of the picture look for the #25. That's the one you have to remove material from on the inside when you take off the cover. Hope that helps.
Oh yeh, click for bigger picture.