Chicagoland Sportbike Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
102 Posts
Discussion Starter · #1 ·
I know this has probably been asked about many of times. I was looking at replacing the chain and sprockets, and I was reading how some people went up in the rear and or down in the front. What are the diffrences in going up in the rear to going down in the front? Where are the best places to get the parts? I was also reading that instead of a gold chain someone had bought a red chain, does anyone know where I can get on of these chains? Thank you.
:confused Nick:confused
 

·
Registered
Joined
·
5,002 Posts
It depends on the current ratio of front to rear but a rough rule of thumb is one tooth up in front equals 2-3 teeth down in rear and similar in reverse.

To the the actual change you have to look at the actual starting and ending ratios.

Of course this all assumes you have enough torque to turn a bigger front/rear ratio.
 

·
habitual line stepper
Joined
·
3,235 Posts
It's common to go down a tooth in the front or up in the back. Commonly you'll find that your motorcycle feels more torquy and in some cases you might even achieve a higher top speed.

Going down in the front will cause more wear and higher loads on your front gear and chain--they might not last as long. Going up in the rear you'll need a longer chain--not a big deal if you're replacing the chain anyway.

All these changes will cause your speedo to be off, except on some bikes where the speed is determined from a sensor on the front wheel--SV 650 for example. You usually compensate for this by installing a yellow box or similar device that allows you to adjust the impulses, selectively take a few away, to make the speedo read correctly. Some people just go get a bicycle speedo and have a clock, speedo, and top speed indicator. :)

Something else to consider is to go with a lightweight chain. Most racers do a 520 conversion and use titan tough aluminum rear sprocket. This reduces reciprocating mass and will benefit performance as well. Now if you have a busa, I wouldn't suggest it.

Matt Drucker (http://www.mdracingstp.com/) can get you a good deal on the parts and steer you in the right direction. I'm not sure what a gold or red chain is but you might consider upgrading to a red powerband.
 

·
Who's faster Lupi
Joined
·
4,957 Posts
Jack, I have never heard of anyone going faster with (-) in the front or (+) in the rear. Your engine will have to spin more to go the same distance. But going (+) in the front or (-) in the rear will do the opposite less RPM's for more distance = higher top end speed but less mechanical advantage so more work on the engine.

Now^^^ could be a bunch of BS but thats what I think.

But the easiest way to think about it is to look at your bicycle. the larger the gear in the front the more work you need to exert but the faster you will go.
 

·
Banned
Joined
·
3,495 Posts
Champ91 said:
Jack, I have never heard of anyone going faster with (-) in the front or (+) in the rear. Your engine will have to spin more to go the same distance. But going (+) in the front or (-) in the rear will do the opposite less RPM's for more distance = higher top end speed but less mechanical advantage so more work on the engine.

Now^^^ could be a bunch of BS but thats what I think.

But the easiest way to think about it is to look at your bicycle. the larger the gear in the front the more work you need to exert but the faster you will go.
It mostly depends on where you are in your powerband at top speed. If you've past your peak HP then lower the gearign will onyl slow you down or eventually cause you to hit the rev limiter before you reach the drag limit. But if you're drag limited before you peak HP, then lowering the gear ign will help you go faster. This is common with big twins that are geared assuming your goign to make performance mods which will increase the power ouput. Soemtimes it's also for noise restrictions.

I the higher gears, it's not so much the leverage or mechanical advantage that you're concerned wiht, it's mostly about keepign the bike in the powerband at a given range of speeds.
 

·
habitual line stepper
Joined
·
3,235 Posts
Champ91 said:
Jack, I have never heard of anyone going faster with (-) in the front or (+) in the rear. ....
Yeah, I know it's not conventional wisdom, but Cherry hits on it. It has to do with drag. I've been the FAQ editor for the CBR mail list for a few years and hung around there. I'm not much a top speed guy, but several have shown that changing the gearing on a stock F4 for example, 2 up in the rear, or 1 down in the front, actually gave them a higher top speed.

I don't have an F4 so I don't know, and the XX has seen 166 packed like a mule but I can't say I've hit its top. But the moral of the story is that you can change the gearing an be a better all around bike except the pain in the ass of recalibrating the speedo.
 

·
Banned
Joined
·
3,495 Posts
Here's what you can do. Try going up 2 in the rear. IF you don;t like it, you can always shorten the chain and go back to stock gearing. Or buy 2 front sprockets. You can usually go up or down 1 tooth in the front wihtout changing the length of the chain. I tried going down 1 in the front once and didn't like it. I think I'll try going up 1 in the rear next time. It think it will be the best comromise.
 

·
habitual line stepper
Joined
·
3,235 Posts
At MAM I switched to 520, went down one in the front and up two in the rear on the RC! Yeah Boy! :) I like it, but haven't tried it at Blackhawk yet. At MAM there was a short straight I would bounce of the limiter before braking and it wasn't long enough to shift and get a drive, so it wasn't optimal for every corner there.
 
1 - 8 of 8 Posts
Top