Gearing for specific mx track: what would you do?

[rablack21]

Ok. So here is the story. I was at my local mx track recently. The track is relatively short with alot of 180 degree turns in it. Right now, I get a really good jump off the line and alot of acceleration. I mainly use 3rd and 4th gear around the track. There are a couple places where I might could use 2nd, but maybe not needed. Here is the dilemma. There is one place where I could use a little more speed/longer pull in 3rd gear. I come out of a turn, hit a step up, then a double. Right now, I can clear it all as intended, but am generally pegged out in 3rd. A little longer gear pull would be helpful. Another part of the equation, there are 2 small straight sections on the track where I max out 4th gear, one a little longer than the other. 5th gear is not practical as I could not stay in it long enough to be worth while. So right now, I am basically having to over rev or max out and then let off for a couple seconds and get back on gas in 4th gear. I am running 14-37 gearing. So here are my options: 1. gear up to 15-39/40 gearing, 2. run as is and don't worry about it, 3. gear down and try to use 5th gear more. So here's the question for you racers: what would you do? The reasoning for option one is this: I don't think 1 or 2 teeth difference in the back would be enough to amount to enough change, but not 100% sure.

(One other bit of information that I think is important to note: I am running a 310 pv with race dome and cr250 ignition, so engine revs out very fast.)

All opinions are welcome, but please have a reasoning for your opinion. (examples and experiences also welcome)

[atvmxr]

rev that sucka out!!  


based on my experience racing MX for ~15 years

[rablack21]

rev that sucka out!!  


based on my experience racing MX for ~15 years

LOL. love your choice of words. So just to be clear, you would just keep the same gearing and just keep it maxed at those locations?

Thanks for the input by the way.

[atvmxr]

yes, leave the gearing as is.  on that jump in 3rd, leave it in gear and rev it out.  on those long straights, if you have time to give it gas, let off, and gas again - you have time to shift to 5th, even if its only for a couple seconds

[jamieg45]

I run a 14/39 gearing and I have ran short and long course tracks, I would bump up the rear 2 teeth and see what you personally think. I have tried a 37 rear and didn't really like it and the 39 worked the best for me.

[rablack21]

yes, leave the gearing as is.  on that jump in 3rd, leave it in gear and rev it out.  on those long straights, if you have time to give it gas, let off, and gas again - you have time to shift to 5th, even if its only for a couple seconds

You make a good argument for option 2. Anybody agrees.....disagrees?

[rablack21]

I run a 14/39 gearing and I have ran short and long course tracks, I would bump up the rear 2 teeth and see what you personally think. I have tried a 37 rear and didn't really like it and the 39 worked the best for me.

The thing I am worried about with gearing down is this. I could probably get into 5th gear easier in the straight aways by doing so, but I am concerned about: 1. having enough speed to still clear the double after the step, I don't think 4th would be practical. There is a right turn right after the double I have to make,then a table top.  2. having to shift excessively due to short track and engine revving out fast.  

But I am open to your idea. Also, this might help you guys actually look at the track. Here is a video I took of our race series at the track recently.
[video=youtube;Ra9qZEE2RhM]https://www.youtube.com/watch?v=Ra9qZEE2RhM[/video]

[Drewski]

Grabbing fifth gear instead of staying in fourth and letting off the throttle and getting back into it is what you should do. Letting off the throttle isn't in the playbook! Also, as mentioned earlier, why not jump up two teeth on the rear and see how it feels? Cant hurt to try.

[rablack21]

Grabbing fifth gear instead of staying in fourth and letting off the throttle and getting back into it is what you should do. Letting off the throttle isn't in the playbook! Also, as mentioned earlier, why not jump up two teeth on the rear and see how it feels? Cant hurt to try.

Also duly noted: I may give this a shot since I have a 39 tooth rear already. The only issue will be whether I can still clear that double in the front after the step up you see in the video. With my current gearing, I could switch to 5th gear, but only for probably 3 seconds or so maybe.

[jamieg45]

I don't see you having a problem with the double man, I run the 14/39 at all the tracks I went to. And they were all pretty similar to the one in the video bud. You will just have to get the feel with the different gearing in practice, and test things out in practice. Be the last one out for practice or the first and just try it, I even ran that gearing for flat track and I was fast on the oval with it too.

[Drewski]

Throw the 39 at it and practice. I wish I had a better view of this stepup. It kinda looks like a small dragonsback. Im wondering why everyone is bouncing over it. Ever try just clearing the whole mess and landing on the downside? what gear are you coming over the 'stepup' in with your current gearing? You may have to come into the corner before the stepup a little faster, carry more speed and get over that stepup smoother and quicker after you gear it to the 39. Either way it looks like a lot wasted effort and lap time beating and bouncing over the stepup . In other words, if your'e worried about clearing the double after the stepup, I would start looking at getting into the corner faster, carrying more speed out of it, getting over the step up cleaner, smoother and faster. The double don't look like a problem, its the obstacle just before it.

[rablack21]

Throw the 39 at it and practice. I wish I had a better view of this stepup. It kinda looks like a small dragonsback. Im wondering why everyone is bouncing over it. Ever try just clearing the whole mess and landing on the downside? what gear are you coming over the 'stepup' in with your current gearing? You may have to come into the corner before the stepup a little faster, carry more speed and get over that stepup smoother and quicker after you gear it to the 39. Either way it looks like a lot wasted effort and lap time beating and bouncing over the stepup . In other words, if your'e worried about clearing the double after the stepup, I would start looking at getting into the corner faster, carrying more speed out of it, getting over the step up cleaner, smoother and faster. The double don't look like a problem, its the obstacle just before it.

Actually it really is more like what I would call a dragonsback also. It steps up then steps down. I already come into the corner with alot of speed and also hit the dragonsback fast, but it's too long to technically clear the whole thing. Even the pros can't clear the whole thing, just land on the step down part. Right now with my current gearing, I it the corner in 3rd and run it all the way through the double. It's not really a matter of not getting up to speed fast enough, it's more about my top out speed in 3rd. I hit max rpms coming over the dragonsback and that gear is maxed before I evened get to the double. With that said, I at that point, have enough speed to get over the double, I just wished the gear didn't have to be wound so tight. I am a little concerned that I would lose a little bit of top speed in 3rd if I went to a higher tooth to try to stay in 5th on the straight aways.

[JoePA]

I run into the same issue Ryan. I run a 14/37 almost %90 of the time. Early in the season when I'm not in shape I switch to a 14/38 as it helps on the bottom end ever so slightly for the tight track I ride on as well as my lack of stamina to hang on at higher speeds.

 I'm curious if it's more of a traction issue and the reason i say that is this. At the one race a guy showed up with a Roll 265R set up for MX...nothing crazy but just a clean bike. Anyway we were talking after his race and I said you are jumping stuff and clearing things I have now chance in hell of doing. we talked set up and gearing came into the conversation and long story short....we ran same gearing with similar engine mods but he was putting his power to the ground much more efficiently than I was. Have you tried messing with your air pressure? Maybe scoot that A$$ back just a bit more on the straight away?? Just throwing some ideas out there.

As mentioned don't be afraid to mess wiht the gearing but that 39 rear gear you may be shifting like a MOFO on the holeshot but then again it may help with the traction? Keep us posted.

[jamieg45]

With the 39 rear I start in second gear and usually beat most of the people off the line.

[rablack21]

With the 39 rear I start in second gear and usually beat most of the people off the line.

I also start in 2nd and already beat most guys off the line. My last 3 races, I have lead 3 holeshots and been not further back then 3rd out of 7 out of the gate. Some of that may just be dumb beginner luck.LOL.