General > Riding Tips & Tricks
Power vs. Speed
Hillclimb#42:
I have often been tempted with this concept, and try not to blurt out my ideals (opinion) on anyone else's thread, but am interested in your opinions, especially the ones based on facts about this. In hillclimbing, and I assume drag racing, along with many other forms of racing, the rear tire is spinning the whole race. No spin, or not enough wheel spin, will hook-up and wheelie which results in the on/off throttle, or crash, and you ultimately lose against anyone who didn't crash. UNDERPOWERED or OVERGEARED
Flip side of this is too much wheel spin and your bike never accelerates, and the back end won't stay behind you.
UNDERGEARED and NO TRACTION
Many factors are involved such as soil density, moisture content, and soil composition. The tire tread pattern, condition and air pressure, Gearing Choice, Power Supply, Suspension and Riding Technique are all factors really.
Power is basically Potential Speed in my opinion. Getting it to the ground is another art, also IMO, as with this whole thread, I guess. Far from an expert here. Presently, I have a basic set-up and will alter tire pressure 3-5 lb.s either direction, or switch 2 teeth either way on the rear sprocket, shorten or lengthen rear axle adjustment.
A little less air pressure and it will hook-up a little better, more pressure, it will spin a touch easier.
Longer suspension will help keep the front wheel down and help give a little wheel spin, shorter then would help give some traction to the ground ( I never try to shorten up a stock length bike)
2 teeth less on the rear and the bike is noticeably hooking up better, 2 more teeth and you will come out of any load sensitive bog and/or wheelie. (1 tooth bigger on the front is close to changing to three less on the back sprocket and vice versa, and is even more noticeable change than two teeth on the rear)
Suspension adjustments are aimed at keeping the rear tire putting power to the ground. Bumpy terrain needs a faster suspension and a big jump might need to be stiffer and slow to rebound. Suspension is an adjustment that I really need advice on. I usually leave it alone because of my ignorance of input and response with the adjustments to conditions, especially how it relates to the short hills that I race. The write-up by Paul, the former Administrator, about Race Sag and Static Sag really helped get the spring right and that made me alot faster. Thanks for that Paul.
don46:
Kyle,
On my 4t I gear so that I'm almost or in some cases may hit the rev limiter, of course you have to know your power curve with the mods you have, some bikes fall flat on their face once you hit a certain rpm, in other words understand where peak hp/torque are generated and gear for it. On the 2t again the mods you have may dictate where you want to run, as an example my 500 on gas will pull 15 counter and anywhere from a 47 to 51 depending on the hill, and if I ever get the 250 ignition tamed a bit maybe taller. on a stock length bike try to run as far back in the slots as you can, and if your still having issues with the front end coming up, pull the fork tubes up in the triple clamps 10-15mm, that will help keep the front end down. I also like to run a wide rim, you can go all the way to 3.5" that will flatten out the footprint giving you more traction, doesn't corner well but hauls in a straight line.
Hillclimbing is about momentum,once you lose it your ride is essentially over.
good luck
kaw rider:
Kyle
You what about 15% wheelspin and 25% overgeared.
Hillclimb#42:
Very good suggestions, Don. I have seen the forks raised in the clamps a few times. Does that help a stretched bike also? I have seen the fat rims, (think I saw a 4" on a CR500)and the 18's with monster tread like the Terraflex on it. That's kinda THE hillclimb upgrade. I may get a fat rim eventually, just not ready, yet. When you say "depending on your mods" you still refer to me knowing where the bike pulls the best, right? Generally, tall enough to keep a load on the motor the entire climb, right?
Do you have a source for figuring spring rates with the bike extended? Will race sag and static sag settings be measured to stock axle location? I have heard of revalves, spacers, heavier oil. Is there any reason the stock shock wouldn't work with a stiffer spring for 6-8" stretchers?
Kaw Rider, not sure what that means, other than you are almost twice as concerned about being geared tall enough over having some wheel spin.
Thanks for your input guys. Working on some set-up plans, and need to be ready for adjustments.
don46:
Many climbs dictate what the Max length you can run, so if you have issues keeping the front end down you need to figure out how to accomplish this, the easiest is pulling the forks up in the triples. I run 3.5" rims, not sure I could fit a 4" in the swingarm, a 2.5 will help more than you can imagine if traction is an issue. I've been doing this long enough that I have a pretty good idea on what spring I need to run and have a fairly good selection to choose from. Revalves can be a great thing, the key is to find a suspension tuner that understand hillclimbing, typically you will run a stiffer spring and a little more compression and alot of rebound. You could go stiffer oil but I wouldn't go to stiff like 7.5 wt or maybe and thats a big maybe 10wt, there are some guys around here that are running 20 wt, but then you can see the results speak for themselves. I still set my race and static sag at the same position as if the bike were stock and look for the same numbers roughly 100mm race and 25-30mm static.
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