Gearing ???

[surfinspacegirl]

OK, I'm looking at doing a 520 conversion on the SV, but need some advice on gearing...Hoopty? Anyone else?

[Anonymous]

Try dropping one in the front ... makes a nice improvement. Or go up 3 in the back, it's about the same. Don't go more than one down @ front though as it puts more stress on the chain to bend tighter.

[surfinspacegirl]

Try dropping one in the front ... makes a nice improvement. Or go up 3 in the back, it's about the same. Don't go more than one down @ front though as it puts more stress on the chain to bend tighter.

Thanks, Ralph, but remeber you'e talking to a gearing newbie here.



Going -1 at the front will do what? The front sprocket will turn faster, thus pulling the rear wheel faster..... better acceleration????

Going +3 in the back will do what? Front sprocket turns the same speed as before, rear wheel has a larger sprocket so turns further with each revolution....more power????

Help

[yakuza]

It's going to vary by track, but I bet Jurgen would have some good baselines for you. I'd bet one down in the front would be a good starting point, although I'm not very familiar with the SV. I went down 1 in front and up 2 in the rear on my bike, and it's still geared too tall for PPIR and SCR, I'll probably get a 50 tooth for the rear.

[yakuza]

It's a ratio between the front and rear sprockets, dropping teeth on the front will have the same impact on the ratio as adding teeth in the rear. And yes, you are on the right track with your thoughts on the effects of changing the teeth.

There's a handy Excel spreadsheet gearing calculator floating around the 'Net, I've got a copy here:
http://www.3dstickfight.com/F4i/
although it's setup for an F4i. You'd need to change your gearing ratio's and tire sizes, etc, but then you can see the effect on your drivetrain from adding and removing teeth.

Give a holler if you need help setting it up.

[Nick_Ninja]

Torque is the all-important factor. A bike will accelerate at a rate that matches its torque curve (ignoring rolling / air resistance). The torque peak is the point at which the bike has maximum acceleration, either side of this peak it is less. For a given torque at the rear wheel, the acceleration of the bike is the same, irrespective of the engine speed. Horsepower increases with the engine speed until well after the torque peak, and only peaks when the decreasing torque compensates for the increasing rpm. The acceleration at the torque peak is greater than that at the power peak.

Gearing down reduces the speed at the rear wheel with a corresponding increase in torque. This does not affect the power of the engine apart from frictional losses.

About gearing...

The stock gearing of your bike is likely to have been determined by choosing a compromise ratio based on what worked best for test riders in "average" conditions. As soon as the bike is taken out of average conditions - by engine tune, terrain, track design or rider style the stock gearing might no longer be the optimum solution - a different setup might get you round the track faster.

Maximum speed occurs when the driving force is exactly counterbalanced by the air and rolling resistances. At this point the acceleration has fallen to zero.

Setting up the gearing of any vehicle is a trade-off between acceleration and top speed.

Gearing a bike up to produce higher top speed with less acceleration is done using a larger countershaft (gearbox) sprocket or a smaller rear sprocket.

Gearing a bike down giving it more acceleration with lower top speed is done using a smaller countershaft (gearbox) sprocket or a larger rear sprocket.



I got this info off this site:
http://www.renthal.com/website/Resources/guide.htm

[Anonymous]

Also the -1/+3 thing comes from the sprocket size (in terms of number of teeth). The front will have roughly 1/3 the teeth of the rear. So dropping one tooth in front increases the ratio. Going up 3 in the back is roughly the same change since it's a 3:1 ratio, you're making the difference larger.

By changing gears you make the bike go through the RPM's faster or slower. It doesn't give you more power per se, but you will accelerate faster. It also means you hit redline sooner and loose top end when you spread out that ratio, but on a track like SCR you're more concerned with being able to shift into the power band and have more corner speed, since you won't see your top end there anyway. This is why racers will change gears for the track, on tracks with huge straights they will usually go with taller gearing (closer ratio) to a point, to give more top end so they don't get stuck by the rev limiter and get passed.

If you're going to attack this track thing seriously you will want a range of sprockets anyway to adjust for the track. For street you can probably just lose one up front and be happy.

[Nick_Ninja]

Here is a cool little program that will calculate most any ratio and bore/stroke formulas :


http://john.rushworth.com/Motorcycle...eed/index.html

[Ytry2]

my gearing per track on my 01 GSXR600 stock is 16/45
Second Creek 14/49
CDR 14/48
PPIR 15/49
Pueblo 15/47
La Junta ? been told it is about the same as Pueblo only faster * yea thanks that helps
Sandia 14/49


*lol* for drag racing on my GSXR 1K -2 / +3 makes for HUGE wheelies if not launched right

[Anonymous]

Hanna, you've already gotten a lot of good advice so far, but in case the science is still not clear (sorry, I didn't take time to read the linked articles), I did some research a couple of years ago when I changed the gearing on my ZX-11. Here's a brief summary (I think I'm having deja-vu, because I feel like I've posted something like this already ):

When going with shorter gearing (dropping teeth in the front or adding teeth in the rear), the engine is spinning faster (higher RPM), for any given speed. This translates into:
- more torque & HP at the same speed over stock gearing
- quicker accelleration
- lower top speed in each gear
- decreased gas mileage

Maybe this will help - this is a dyno chart showing a stock ZX-11 vs. the same bike with Jet kit, ignition advancer, K&N & new gearing. The gearing is in no way responsible for the increase in horsepower, but it does make the power available at a lower speed, which makes for quicker accelleration:

[Anonymous]

- more torque & HP at the same speed over stock gearing

Or translated slightly, by causing the engine to rev up faster you will be in the HP peak sooner at a given speed; the HP will remain the same it will just be more where you want it for how fast you're going.

If you have any notion of street riding with big gearing changes also consider a yellow box to correct your speedo; it probably picks up off the final drive of your transmission, and when you change gearing, that rotates at different speeds than before. The yellow box will move your speedo back into reality.

[surfinspacegirl]

Ouch my head's spinning...satellites I can do, but this....

Just kidding. Thanks for all this great advice!

Time to really have a think about what I'm trying to achieve and find the right solution....

[JohnS]

just going down 1 tooth in the front doesn't do much on an SVS. I went with the 520 conv. and after alot of thinking decided to just go with 1 tooth down in front an 3 up in the rear. The naked SV is already one tooth up from the SVS in the rear so thats basically why i went 3.

so far I'm happy with the pull. Gas mileage is a bit worse but who cares. I haven't had a chance to take the bike down to pueblo yet with this set up so i'm not sure what the top end is like.

either way a new 520 by itself is a nice change!

[Hoopty]

You don't want to go smaller than a 14 tooth front sprocket Hanna, I believe we have a 15 tooth stock. I still have a stock front sprocket but I did go up one on the rear (45 tooth now, just like a stock naked SV). For racing I would definately be changing the sprockets (gearing down by either going smaller on the front and or larger on the rear), but on the street you have to worry about gas mileage and a higher cruising RPM on the highway etc.

I'd suggest the 520 kit down 1 in the front and maybe up one or two in the rear, that should give her a nice kick in the pants!