I've been struggling with this for as long as I've been riding. I can't get comfortable at speed because the faster I go, the more out of control the bike gets. Going down high speed straits on a rough track the bike starts bouncing around and gets major head shake, which makes it hard to hang on, which then leads to arm pump forcing me to slow down. I'm currently on a 2011 KTM 250 SX. I'm 5'8", 150lbs. The suspension is stock. The forks were set up by the shop recently when I had the seals and wipers replaced and I was told I would need to swap out the shock spring (which I can't afford right now). I had this same problem with my last bike too, a CRF250, even after getting it set up (re-sprung, re-valved, etc. which made the bike 100x better, but I still had problems keeping control at high speeds). I set the sag on the shock I've played with the clickers without any noticeable improvement. Any advice would be greatly appreciated! Thanks
Unstable at high speeds
Started by
vinnied180
, May 01 2012 04:07 PM
13 replies to this topic
Posted 01 May 2012 - 04:32 PM
I think you have three possible options here that all MIGHT help.
1) Steering Stabilizer, I dont know much about HOW they work, but I've heard that they work good.
2) Soften suspension, I know a guy who says he sped up his forks so that it will be easier for him to hang on to at speed. (idk if it worked or not)
3) Workout, If you are stronger the bike SHOULD tend to be more in tune to you because you are controlling it more.
Other than that, the more you do it, the less "out of control" it will feel, Its like exposure therapy.
1) Steering Stabilizer, I dont know much about HOW they work, but I've heard that they work good.
2) Soften suspension, I know a guy who says he sped up his forks so that it will be easier for him to hang on to at speed. (idk if it worked or not)
3) Workout, If you are stronger the bike SHOULD tend to be more in tune to you because you are controlling it more.
Other than that, the more you do it, the less "out of control" it will feel, Its like exposure therapy.
Posted 01 May 2012 - 05:46 PM
The CRF is notorious for head shake, its a combination of the rake and trail which causes it. Not much you can do with the stock triples to resolve all of it all.
The KTM has a much different rake/trail, so my guess is, you're simply looking at a compound issue.
The 2011 is still a PDS bike and the stock PDS system, does not work, period. So the first thing you need to do is send that shock out to someone who knows how to build it properly and replace that stock piston. I'm working with Moto Pro right now, but MX Tech and Smart Performance are for sure options if you don't care for Moto Pro for some reason. You need the perfect spring and the perfect sag to make the PDS system work. I would also venture to say the stock forks will need work as well, but for sure that shock is the key first.
The second part of the issue is for sure rider related, rather then setup related. The faster you go, the more you've gotta be pinching the bike and keeping the front end light, especially through sand/loam conditions where you don't have any traction to begin with. You shouldn't be giving the bars too much input, if you do give them a lot of input because your hanging on for dear life, then that can easily cause things to get out of hand quickly. The key is to practice riding the bike with your arms/hands loose and using your legs to control the machine rather then your arms.
Stabilizers are a last resort, they are great at covering up issues the bike has. But its much better to resolve those issues, rather then buy a stabilizer and never get the bike working properly.
The KTM has a much different rake/trail, so my guess is, you're simply looking at a compound issue.
The 2011 is still a PDS bike and the stock PDS system, does not work, period. So the first thing you need to do is send that shock out to someone who knows how to build it properly and replace that stock piston. I'm working with Moto Pro right now, but MX Tech and Smart Performance are for sure options if you don't care for Moto Pro for some reason. You need the perfect spring and the perfect sag to make the PDS system work. I would also venture to say the stock forks will need work as well, but for sure that shock is the key first.
The second part of the issue is for sure rider related, rather then setup related. The faster you go, the more you've gotta be pinching the bike and keeping the front end light, especially through sand/loam conditions where you don't have any traction to begin with. You shouldn't be giving the bars too much input, if you do give them a lot of input because your hanging on for dear life, then that can easily cause things to get out of hand quickly. The key is to practice riding the bike with your arms/hands loose and using your legs to control the machine rather then your arms.
Stabilizers are a last resort, they are great at covering up issues the bike has. But its much better to resolve those issues, rather then buy a stabilizer and never get the bike working properly.
Posted 01 May 2012 - 06:23 PM
Working out is definately not and issue. I also race XC mountain bikes, I'm currently training for a triathlon, and I can bench nearly double my body weight. A steering stabilizer isn't an option due to the cost.
I don't have the CRF anymore so that's not an issue. But with booth bikes I just can't keep the wheels tracking on the ground.
How do I check wheel balance?
I don't have the CRF anymore so that's not an issue. But with booth bikes I just can't keep the wheels tracking on the ground.
How do I check wheel balance?
Posted 02 May 2012 - 08:50 AM
If you increase the rear sag you will effectively increase the trail and that should help with the head shake.
In general head shake is caused by the front forks "packing" because the rebound is too slow and/or the "trail" was designed for quick turning, which equals high speed instability. Find a section that gives you head shake and then turn the rebound clickers counter clockwise, 2 clicks each time/run, and see if the stability gets better. You will need the proper fork springs in order to achieve the proper rebound rate. If you run out of rebound adjustment, your springs are too light. Slowing the compression rate will also help, but it will also stiffen the front end. The risk with speeding up the rebound is at some point the front end will "push" in the turns or climb out of rutted turns. If this happens, you need to loosen the bolts on the triple clamp and raise the front end (push the forks down). Go back and slow the rebound until she turns properly. Raising the front end will increase the "trail" and stability (similar to increasing sag which lowers the rear-end). This will of course slow the turning, but that's exactly what KTM did on many of their newer bikes, including my 2011 KTM 250 SX.
1. Your overall suspension needs to be close.
2. Get proper fork springs
3. Speed up the fork rebound
4. Raise the front end in the triple clamps
5. Steering stabilizers help, but get the suspension as good as possible first
In general head shake is caused by the front forks "packing" because the rebound is too slow and/or the "trail" was designed for quick turning, which equals high speed instability. Find a section that gives you head shake and then turn the rebound clickers counter clockwise, 2 clicks each time/run, and see if the stability gets better. You will need the proper fork springs in order to achieve the proper rebound rate. If you run out of rebound adjustment, your springs are too light. Slowing the compression rate will also help, but it will also stiffen the front end. The risk with speeding up the rebound is at some point the front end will "push" in the turns or climb out of rutted turns. If this happens, you need to loosen the bolts on the triple clamp and raise the front end (push the forks down). Go back and slow the rebound until she turns properly. Raising the front end will increase the "trail" and stability (similar to increasing sag which lowers the rear-end). This will of course slow the turning, but that's exactly what KTM did on many of their newer bikes, including my 2011 KTM 250 SX.
1. Your overall suspension needs to be close.
2. Get proper fork springs
3. Speed up the fork rebound
4. Raise the front end in the triple clamps
5. Steering stabilizers help, but get the suspension as good as possible first
Posted 02 May 2012 - 09:04 AM
CurtisA, on 02 May 2012 - 08:50 AM, said:
If you increase the rear sag you will effectively increase the trail and that should help with the head shake.
In general head shake is caused by the front forks "packing" because the rebound is too slow and/or the "trail" was designed for quick turning, which equals high speed instability. Find a section that gives you head shake and then turn the rebound clickers counter clockwise, 2 clicpks each time/run, and see if the stability gets better. You will need the proper fork springs in order to achieve the proper rebound rate. If you run out of rebound adjustment, your springs are too light. Slowing the compression rate will also help, but it will also stiffen the front end. The risk with speeding up the rebound is at some point the front end will "push" in the turns or climb out of rutted turns. If this happens, you need to loosen the bolts on the triple clamp and raise the front end (push the forks down). Go back and slow the rebound until she turns properly. Raising the front end will increase the "trail" and stability (similar to increasing sag which lowers the rear-end). This will of course slow the turning, but that's exactly what KTM did on many of their newer bikes, including my 2011 KTM 250 SX.
1. Your overall suspension needs to be close.
2. Get proper fork springs
3. Speed up the fork rebound
4. Raise the front end in the triple clamps
5. Steering stabilizers help, but get the suspension as good as possible first
In general head shake is caused by the front forks "packing" because the rebound is too slow and/or the "trail" was designed for quick turning, which equals high speed instability. Find a section that gives you head shake and then turn the rebound clickers counter clockwise, 2 clicpks each time/run, and see if the stability gets better. You will need the proper fork springs in order to achieve the proper rebound rate. If you run out of rebound adjustment, your springs are too light. Slowing the compression rate will also help, but it will also stiffen the front end. The risk with speeding up the rebound is at some point the front end will "push" in the turns or climb out of rutted turns. If this happens, you need to loosen the bolts on the triple clamp and raise the front end (push the forks down). Go back and slow the rebound until she turns properly. Raising the front end will increase the "trail" and stability (similar to increasing sag which lowers the rear-end). This will of course slow the turning, but that's exactly what KTM did on many of their newer bikes, including my 2011 KTM 250 SX.
1. Your overall suspension needs to be close.
2. Get proper fork springs
3. Speed up the fork rebound
4. Raise the front end in the triple clamps
5. Steering stabilizers help, but get the suspension as good as possible first
That's spot on! do these things.
Posted 02 May 2012 - 11:27 AM
on crf 250 the headshake is caused by fork deep in stroke , too soft fork , as stock on 2010 - little better 2011 and 2012 , make headshake , the fork work in the hard part of travel ,midstroke
Posted 02 May 2012 - 12:12 PM
gotta check your wheels on a trueing stand its a pain but do u notice any vibrations in the handle bar?
Posted 02 May 2012 - 06:20 PM
Lowering the forks in the triple clamps and increasing the sag are the correct response. Weight training isn't! Natural frequency is something to avoid, not out muscle.
We had a tough time getting my son's 2005 CR125 tuned such that head shake wasn't problematic and the suspension and cornering still worked. On the other hand on my 2005 CR250 you couldn't head shake if you wanted to which is interesting because the frames are very similar but the suspension isn't.
We had a tough time getting my son's 2005 CR125 tuned such that head shake wasn't problematic and the suspension and cornering still worked. On the other hand on my 2005 CR250 you couldn't head shake if you wanted to which is interesting because the frames are very similar but the suspension isn't.
Posted 03 May 2012 - 08:54 AM
Yeah, I don't care how big your arm msucles are, you can't stop head shake with muscles, but staying in shape really helps you ride faster and longer.
Posted 03 May 2012 - 09:11 PM
Headshake "on the gas" & headshake "off the gas" are caused by 2 different problems. If you are having the headshake while on the gas and trying to get up to speed then its usually caused by 1 or more of the following.....fork comp clickers/spring/valving to stiff, fork reb to quick, forks to low in the clamps, R'S fork bound up or shock sag to low, shock comp. clickers/spring to soft. If this is the case just try raising the forks up in the clamps a cpl. mm's & see if it starts helping.
If the headshake is while braking or coming down from speed then just the opposite as above....
doc
If the headshake is while braking or coming down from speed then just the opposite as above....
doc
