Friday, February 27, 2009
Suspension Setup
Suspension Setup
As you know, there's a lot more customization that goes on with a dirt bike than a pocket rocket. Why? The riding conditions are different and if you want to be competitive, your bike has to fit you like a glove. One of the first things to tweak is the suspension. Right out of the box your bike's compression clickers and the rebound setting might be set anywhere.
The best place to start is to set these two settings in whatever the manufacturer recommends as “standard”. This is a good starting point. If no setting is recommended, just choose a middle setting. This is what an average might employ.
The rear spring may or may not be right for you. Did you buy your bike second hand? In that case, it might not be standard for you model; the former owner might have customized it. Take it for a test ride. Does it feel right for you? If so, you're on the right track. Otherwise, before you start tuning the suspension to your liking you might want to consider installing the standard spring.
You'll want to set your rear shock's static sag. Follow these steps to configure the preload.
1.Locate the locking ring and loosen it.
2.Adjust the main ring to adjust the shock's preload.
3.With the bike elevated so that the back wheel is not in contact with the ground, take a measurement from your axle nut to a reference point on the bike somewhere above it.
4.Now set the bike back on the ground.
5.Measure the distance between the axle nut and the reference point.
6.Subtract one measurement from the other.
7.Adjust the ring until the difference is about 25mm of sag.
Now it's time to set what's called the laden sag or racing sag.
1.Stand the bike it an upright position and write down the vertical height.
2.Put on all your race battle gear and assume your best attack position on the bike.
3.Have a friend take the measurement now on the fully loaded bike.
4.Do the math again as before. Now adjust the preload again to get it between 90mm and 110mm.
Going through these set-up routines might seem to be a hassle but they are worth the effort. No factory setting is going to satisfy every motocross racer. If you've been in the game for any time at all, you know that the devil is in the details. Who can afford to throw away even the tiniest of advantages?
Moto x
MX Training Journal
As you know, there's a lot more customization that goes on with a dirt bike than a pocket rocket. Why? The riding conditions are different and if you want to be competitive, your bike has to fit you like a glove. One of the first things to tweak is the suspension. Right out of the box your bike's compression clickers and the rebound setting might be set anywhere.
The best place to start is to set these two settings in whatever the manufacturer recommends as “standard”. This is a good starting point. If no setting is recommended, just choose a middle setting. This is what an average might employ.
The rear spring may or may not be right for you. Did you buy your bike second hand? In that case, it might not be standard for you model; the former owner might have customized it. Take it for a test ride. Does it feel right for you? If so, you're on the right track. Otherwise, before you start tuning the suspension to your liking you might want to consider installing the standard spring.
You'll want to set your rear shock's static sag. Follow these steps to configure the preload.
1.Locate the locking ring and loosen it.
2.Adjust the main ring to adjust the shock's preload.
3.With the bike elevated so that the back wheel is not in contact with the ground, take a measurement from your axle nut to a reference point on the bike somewhere above it.
4.Now set the bike back on the ground.
5.Measure the distance between the axle nut and the reference point.
6.Subtract one measurement from the other.
7.Adjust the ring until the difference is about 25mm of sag.
Now it's time to set what's called the laden sag or racing sag.
1.Stand the bike it an upright position and write down the vertical height.
2.Put on all your race battle gear and assume your best attack position on the bike.
3.Have a friend take the measurement now on the fully loaded bike.
4.Do the math again as before. Now adjust the preload again to get it between 90mm and 110mm.
Going through these set-up routines might seem to be a hassle but they are worth the effort. No factory setting is going to satisfy every motocross racer. If you've been in the game for any time at all, you know that the devil is in the details. Who can afford to throw away even the tiniest of advantages?
Moto x
MX Training Journal
Sunday, February 15, 2009
Motorcycling Gearing.
Motorcykling Gearing
When the factory engineers develop a new bike, one of the most important things they have to do is optimize the gearing. They use their own test moto track with their own test riders. They use average riders and the track is an average, generic track so what do they end up with?
Average gearing. But when you think about it, it's all about mass marketing. That's a good thing though. If they manufactured a myriad of choices, delivery time would slump and manufacturing costs would be passed along to us. A large number of riders will be content with this set-up, but more aggressive racers want a custom gearing configuration. Let's look at some factors to consider.
To Gear Down or to Gear Up; That is the Question
This is really a personal preference but part of it depends on the tracks you ride on. Does it have a lot of long straight legs where you can get up a head of steam? Lots of tight coffee-cup turns at the base of steep jumps?
Gearing up: this is achieved by by either using a smaller rear sprocket or a larger countershaft. The net effect is to add more speed while lowering the final drive ratio.
Gearing down: achieved by using a larger rear sprocket or a smaller front sprocket. Net effect? It raises the final drive ratio, while lowering speed. Great for climbing.
But What is the Final Drive Ratio?
Alright, it's time to apply that schoolhouse math. To arrive at the final drive ratio, divide the number of teeth you've got on your rear sprocket by the number you have on your countershaft.
But what does the number tell you? It's the number of times your countershaft will turn during one complete rear wheel rotation. A smaller number tells you that you'll experience higher RPMs for a certain speed and a higher number is the opposite. Now it all makes sense, right?
Riding at Altitude?
If you're planning to ride at a high altitude, not only should you get there a day or so early to acclimate and avoid light-headedness, but your ride needs modification too. Higher altitudes mean less engine power, so gear down to compensate.
Clutch Implications
An interesting side effect is that the lower your gearing, the less you'll have to use your clutch. Why? Because your engine will be more responsive and run freer.
What About the Power band at Higher Gearing?
Basically, it's the opposite of what we just discussed – you'll put a bit more wear on your clutch; but on the other hand, your engine will be easier to control.
And Lower Gearing Power band?
In a low gearing configuration you'll find yourself shifting much more often to stay in the sweet spot. It's just the opposite of taller gearing.
Be Your Own Pit Crew
Be ready to fine-tune your gearing configuration on the fly without having to change the chain. Put together a starter pack to haul along with you to the track. Include a spare rear sprocket that's two teeth larger than the current one and a countershaft that's one tooth less. The tooth ratio of rear sprocket to countershaft is ½:3.
NOTE: As a rule of thumb, one tooth change at a time in gearing is the max.
Wear and Tear: Your Sprocket Should Match Your Chain
If your existing chain is worn and you use it with a new sprocket, you'll be throwing your sprocket money away because the sloppy chain links will wreak havoc with the new teeth.
Of Rear Sprockets and Countershafts
The smaller your countershaft is, the faster your chain is going to wear. It's a friction thing. Say you decide to ride with countershaft that's one tooth smaller. Your best bet is to use your standard counter coupled with a new chain with an extra link and a rear sprocket that's three to four teeth larger. But avoid the temptation to lengthen the chain with an extra master link; that's asking for trouble!
motox
MX Training Journal
When the factory engineers develop a new bike, one of the most important things they have to do is optimize the gearing. They use their own test moto track with their own test riders. They use average riders and the track is an average, generic track so what do they end up with?
Average gearing. But when you think about it, it's all about mass marketing. That's a good thing though. If they manufactured a myriad of choices, delivery time would slump and manufacturing costs would be passed along to us. A large number of riders will be content with this set-up, but more aggressive racers want a custom gearing configuration. Let's look at some factors to consider.
To Gear Down or to Gear Up; That is the Question
This is really a personal preference but part of it depends on the tracks you ride on. Does it have a lot of long straight legs where you can get up a head of steam? Lots of tight coffee-cup turns at the base of steep jumps?
Gearing up: this is achieved by by either using a smaller rear sprocket or a larger countershaft. The net effect is to add more speed while lowering the final drive ratio.
Gearing down: achieved by using a larger rear sprocket or a smaller front sprocket. Net effect? It raises the final drive ratio, while lowering speed. Great for climbing.
But What is the Final Drive Ratio?
Alright, it's time to apply that schoolhouse math. To arrive at the final drive ratio, divide the number of teeth you've got on your rear sprocket by the number you have on your countershaft.
But what does the number tell you? It's the number of times your countershaft will turn during one complete rear wheel rotation. A smaller number tells you that you'll experience higher RPMs for a certain speed and a higher number is the opposite. Now it all makes sense, right?
Riding at Altitude?
If you're planning to ride at a high altitude, not only should you get there a day or so early to acclimate and avoid light-headedness, but your ride needs modification too. Higher altitudes mean less engine power, so gear down to compensate.
Clutch Implications
An interesting side effect is that the lower your gearing, the less you'll have to use your clutch. Why? Because your engine will be more responsive and run freer.
What About the Power band at Higher Gearing?
Basically, it's the opposite of what we just discussed – you'll put a bit more wear on your clutch; but on the other hand, your engine will be easier to control.
And Lower Gearing Power band?
In a low gearing configuration you'll find yourself shifting much more often to stay in the sweet spot. It's just the opposite of taller gearing.
Be Your Own Pit Crew
Be ready to fine-tune your gearing configuration on the fly without having to change the chain. Put together a starter pack to haul along with you to the track. Include a spare rear sprocket that's two teeth larger than the current one and a countershaft that's one tooth less. The tooth ratio of rear sprocket to countershaft is ½:3.
NOTE: As a rule of thumb, one tooth change at a time in gearing is the max.
Wear and Tear: Your Sprocket Should Match Your Chain
If your existing chain is worn and you use it with a new sprocket, you'll be throwing your sprocket money away because the sloppy chain links will wreak havoc with the new teeth.
Of Rear Sprockets and Countershafts
The smaller your countershaft is, the faster your chain is going to wear. It's a friction thing. Say you decide to ride with countershaft that's one tooth smaller. Your best bet is to use your standard counter coupled with a new chain with an extra link and a rear sprocket that's three to four teeth larger. But avoid the temptation to lengthen the chain with an extra master link; that's asking for trouble!
motox
MX Training Journal
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