Question about track gearing

[daverdfw]

I have a 2009 250. About to go hit up a fun little. 1.3 mile track. top speed never gets above 80ish on my 250. I am currently running the stock 520 chain and a 15/45 stock gearing setup. I looked around at some forums my local racers use and found guys doing some stuff like 13/47 setups. Could I do that with a stock 106 link chain, or would just dropping to a 14/45 show some nice gains with this sorter track? Thanks!

this is the track for reference https://www.youtube.com/watch?v=yokvPy1A6Ck&t=939s

https://www.motorsportranch.com/1-3-mile-road-course/

[jrshooter]

i look at a few things for gearing. and i dont worry about first gear on the track. one time per session or race the bike ever sees 1st gear.
on one track i cant hit reach the top speed of the bike in 6th gear.
so igear down for pull out of the corners, wich also gives me the added bonus of a higher top speed on the straight. but things are very track specific.
any way can you ask buddies what there running, that woud get you in the ballpark. oh , in my gearing choices i look at corners , so im not on the limiter
thru the important turn. trial and error.

[daverdfw]

Originally Posted by jrshooter

i look at a few things for gearing. and i dont worry about first gear on the track. one time per session or race the bike ever sees 1st gear.
on one track i cant hit reach the top speed of the bike in 6th gear.
so igear down for pull out of the corners, wich also gives me the added bonus of a higher top speed on the straight. but things are very track specific.
any way can you ask buddies what there running, that woud get you in the ballpark. oh , in my gearing choices i look at corners , so im not on the limiter
thru the important turn. trial and error.

from what I read they said to go -1 in the front. or if you wanna shift a lot more -1 and +2

so i might try 13/45 as a starting point and can always go 13/47 later. I don't want to be shifting mid-corner for sure.

[tgold]

I'ts not so much the total length of the track that matters, but more the number of turns combined with the length/number of the straights that matters more.

Gearing is almost always a compromise but a good rule of thumb for a starting point is to gear your bike to hit redline in sixth gear right at the end of the longest straight. So you start from there and see how it works. Sometimes you may find that it works great and other times you may find that it causes a gear change in an inconvenient location (say in the middle of a big corner). Another would be bumping into the rev limiter just before you want to shut off for corner entry.

Once you settle on the gearing, don't assume that your gearing choice should be set in stone. If you are improving and getting faster at a given track you will often find that you will be moving the points where you hit redline earlier and earlier until it becomes a hindrance to going faster.

[csmith12]

Timm is pretty much spot on.

[tgold]

Thanks Chris,

A few more thoughts (some of this depends on your goals):

The Ninjette is much more demanding on getting the gearing right because you don't have much power to work with. (Unlike an SV650 where most people run stock gearing and it works very well.) To help you play around with gearing combinations that yield the top speed you are looking for check out this site: http://www.gearingcommander.com/

Another possibility: Looking at the track map they say that there are six turns, but there are lots of "ess" sections, so I'm guessing that you're going to be really busy turning most of the time. One option is to keep your gearing the same (or even a bit taller) and treat your bike as a five speed. This allows less shifting so you can devote your concentration to other things and the result can be that your overall laptimes can be better.

You can also use this technique for individual turns in a scenario like this: Say you have the gearing the way you want it for top speed on the longest straight amd it works well in most places on the track, but you have a particular corner where you are really busy on corner entry. For example this can happen on a short straight where we don't have much time to prepare for corner entry because we are still "recovering" from exiting one corner and bam! we're entering the next one. So, say, two downshifts might be ideal for better drive out of the next turn, but since we're also cramming in the thinking about getting our turn-in right, braking (not much of that on the Ninjette!), etc, we have trouble doing it all at once. The option would be to do only one downshift and sacrifice a bit of drive but concentrate more on getting the corner entry right to carry more corner speed and effectively go faster.

[cbinker]

Dont forget to configure tire circumference into your equation.
My current gearing is 14/45 with a 120 rear tire, that is a change from 14/44-120; shifting didn't change much, but I was not losing as much ground on the smaller guys upon acceleration from corners. I am going to test 13/45-120 this fall.