JS7 bike setup


19 replies to this topic
  • mattmoto441

Posted January 26, 2011 - 01:36 PM

#1

anyone notice how choppered out Js7 has his bike setup this year? its completely different then his setup from last year,

it is also wayy off track from what the OEM sells the bike as.

a stock 10-11 yz450f clamp offset is only 22mm and if you look at JS7s bike his forks are wayy out there. i have seen 24mm clamps on a 10 yz450 and it didnt look to have the forks out that mutch futher then stock. James bike has to have something 26mm + ?

also look at out much Race sag/lower suspension link they have the rear suspension, i dont know if its because james it a short guy to have it that low or are they trying to get a different angle out of the chassis to get it to turn better.


but it you look at the other yamaha teams they arnt going to the extreems that js7 is on the rake and chassis setup

  • brentn

Posted January 26, 2011 - 01:51 PM

#2

Probably because the other guys just don't have the funds to do so.

JS has soo much sponser money, they all get paid if he wins, they get paid HUGE when he wins and of course JS gets paid too. I doubt it's anything close to what his sponsers make in profit when he does win races.
Point being, they almost can spare no expense in R&D to make him .2 of a second faster on his laps.
The only limits they have, are the ones set in the AMA rule book about not changing the chasis and engine etc. Those are the only boundaries they have.

If I had a team of engineer's, ex racers and physic experts working for me and an endless amount of money I wouldn't even have a yamaha. I'd have my own custom works bike that is built from the ground up only copying a few details from mainstream bikes :thumbsup:

I'm sure that the yamaha R&D guys who had ideas but couldn't implement them in the production version of the 2011 450 that we can buy, are very happy to work with JS. They're probably putting out all their ideas that never made the final cut due to costs etc on his bike, making it even better.

Imagine riding JS's bike? WOW, makes you wonder how much different it would be to stock.

  • grayracer513

Posted January 26, 2011 - 01:52 PM

#3

Triple clamps have no effect on steering head angle. The OEM offset on a 2011 is 22mm, whereas the '09 and earlier were 25mm. You can't see that by looking.

  • Steel Panther

Posted January 26, 2011 - 04:59 PM

#4

your not going to notice 3mm unless you put a ruler to it

  • RJacks

Posted January 26, 2011 - 05:47 PM

#5

Triple clamps have no effect on steering head angle. The OEM offset on a 2011 is 22mm, whereas the '09 and earlier were 25mm. You can't see that by looking.


This is where you are wrong Gray.
Most triple clamps will not change head angle and of course we cannot buy the ones that do. But, and this is a big but, some factory teams have used a type of triple clamp and special bearing/race that does indeed change head angle. I've seen it first hand. JS7's '06 KXF was radically different and you could see it when next to the bike. There have been others too, it's a type of eccentric stem/race, but not like the ones of the KTM's that just change offset.

  • mdkcrf250r

Posted January 26, 2011 - 10:24 PM

#6

This is where you are wrong Gray.
Most triple clamps will not change head angle and of course we cannot buy the ones that do. But, and this is a big but, some factory teams have used a type of triple clamp and special bearing/race that does indeed change head angle. I've seen it first hand. JS7's '06 KXF was radically different and you could see it when next to the bike. There have been others too, it's a type of eccentric stem/race, but not like the ones of the KTM's that just change offset.


Ducati 999?

  • HRC

Posted January 27, 2011 - 12:30 AM

#7

anyone notice how choppered out Js7 has his bike setup this year? its completely different then his setup from last year,

it is also wayy off track from what the OEM sells the bike as.

a stock 10-11 yz450f clamp offset is only 22mm and if you look at JS7s bike his forks are wayy out there. i have seen 24mm clamps on a 10 yz450 and it didnt look to have the forks out that mutch futher then stock. James bike has to have something 26mm + ?

also look at out much Race sag/lower suspension link they have the rear suspension, i dont know if its because james it a short guy to have it that low or are they trying to get a different angle out of the chassis to get it to turn better.



but it you look at the other yamaha teams they arnt going to the extreems that js7 is on the rake and chassis setup



Both RC and Stewart usually have their bikes very low in the back. It looks like he has a lowering linkage and probably a lower subframe than stock.


Don´t think he has much different offset from stock though. It probably looks like that just because of the low rear.

His bike looks to be way better setup than last season´s bike ! Specially in the whoops !

  • ttr250dude

Posted January 27, 2011 - 02:11 AM

#8

Whats the benefit of lowering the rear end?

  • HRC

Posted January 27, 2011 - 03:14 AM

#9

Whats the benefit of lowering the rear end?



Mostly better straight stabilty. Takes away possible "stinkbug" feel. Tight cornering might suffer.

  • grayracer513

Posted January 27, 2011 - 08:12 AM

#10

This is where you are wrong Gray.
Most triple clamps will not change head angle and of course we cannot buy the ones that do. But, and this is a big but, some factory teams have used a type of triple clamp and special bearing/race that does indeed change head angle. I've seen it first hand. JS7's '06 KXF was radically different and you could see it when next to the bike. There have been others too, it's a type of eccentric stem/race, but not like the ones of the KTM's that just change offset.

The fact is that no triple clamp can change the head angle. In the case of the JS7 KXF, I can't say, because the only thing I ever noticed about it was how poorly it handled, and how often it blew up. When Reed was on the San Miguel team, he ran offset bearing races, but they were used to make the head angle steeper, not shallower, so as to make the bike turn better. But offset bearings are not triple clamps, and the triple clamps did not accomplish that.

Increasing head angle, or making the forks shallower, absolutely increases the tendency to push the front, and as MX bikes in general suffer from this fault more than track bikes, road bikes, and the like, there is absolutely no reason anyone would do it on purpose that I can think of. It certainly would not be to increase high speed stability on an SX course, where speeds will only rarely and briefly touch 60 mph.

Triple clamps can be made to mount the forks at an angle other than parallel to the steering tube, and this used to be done 40 years ago on some bikes, but the effect is not the same as a head angle change, nor is it very desirable. "Raking" the forks at an angle shallower than the head tube decreases trail the same as increasing the offset of a set of parallel clamps does, but it also causes the front wheel to sweep through an arc over the steering axis rather than staying centered on it. The original reason for doing it at all was to help the forks work better off-road on some bikes that were built with steeper heads. I haven't seen anyone do this in a very long time, and of course, it never did change the axis of the steering head.

A one degree change in head angle is major from the standpoint of the effect it has on handling, and I doubt that any of the pro bikes have changed it that much, or that any of them would change to a greater (shallower) angle. As far as what that change would I would challenge you or anyone else on whether you could see that. So, regardless of what you think you've seen, and what "looks radically different", I maintain that careful measurement would show that Stewart's bike, or any of the others, are not running head angles that are significantly shallower than stock to begin with, and that any such appearance is an illusion brought about by other aspects of the bike set up.

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  • tech24

Posted January 27, 2011 - 08:23 AM

#11

I didn't get a good look at his setup but last weekend he flew by RD like he was standing still in the whoops

  • tpars121

Posted January 27, 2011 - 12:23 PM

#12

Both RC and Stewart usually have their bikes very low in the back. It looks like he has a lowering linkage and probably a lower subframe than stock.


Almost the opposite of Windham's bike.

  • RJacks

Posted January 27, 2011 - 12:51 PM

#13

The fact is that no triple clamp can change the head angle. In the case of the JS7 KXF, I can't say, because the only thing I ever noticed about it was how poorly it handled, and how often it blew up. When Reed was on the San Miguel team, he ran offset bearing races, but they were used to make the head angle steeper, not shallower, so as to make the bike turn better. But offset bearings are not triple clamps, and the triple clamps did not accomplish that.

Increasing head angle, or making the forks shallower, absolutely increases the tendency to push the front, and as MX bikes in general suffer from this fault more than track bikes, road bikes, and the like, there is absolutely no reason anyone would do it on purpose that I can think of. It certainly would not be to increase high speed stability on an SX course, where speeds will only rarely and briefly touch 60 mph.

Triple clamps can be made to mount the forks at an angle other than parallel to the steering tube, and this used to be done 40 years ago on some bikes, but the effect is not the same as a head angle change, nor is it very desirable. "Raking" the forks at an angle shallower than the head tube decreases trail the same as increasing the offset of a set of parallel clamps does, but it also causes the front wheel to sweep through an arc over the steering axis rather than staying centered on it. The original reason for doing it at all was to help the forks work better off-road on some bikes that were built with steeper heads. I haven't seen anyone do this in a very long time, and of course, it never did change the axis of the steering head.

A one degree change in head angle is major from the standpoint of the effect it has on handling, and I doubt that any of the pro bikes have changed it that much, or that any of them would change to a greater (shallower) angle. As far as what that change would I would challenge you or anyone else on whether you could see that. So, regardless of what you think you've seen, and what "looks radically different", I maintain that careful measurement would show that Stewart's bike, or any of the others, are not running head angles that are significantly shallower than stock to begin with, and that any such appearance is an illusion brought about by other aspects of the bike set up.


You really don't have to explain the effects, as I full understand. But there again, the actual steering head tube angle, cannot be altered without machining and re-welding. But as for bearing races, machined clamps, or mount positions it does change the overall angle of the fork in relation to the head tube. Therfore you ARE changing the head angle in the overall scheme of things.
And no where in my post did I say any riders were currently running anything at all, all I said that you can change the head angle with the triple clamps. Or should I say fork tube angle. I've highlighted your sentence the pretty much agreed with me. Steeper or slacker, does not matter angle is changed.

  • grayracer513

Posted January 27, 2011 - 02:04 PM

#14

The sentence fragment who highlighted in the first paragraph not only disagrees with you, you missed the entire point. Offset or eccentric bearing races DO actually change the steering axis, and therefore the head angle, without cutting or altering the the frame. Triple clamps that change the angle of the fork tubes in relationship to the steering axis DO NOT change the steering axis, and the effect of these two things is very different, as I already said. Since you can take any set of triple clamps off a bike and reinstall them with offset bearings, it is the bearings that make the change, and not the clamps,

So, I repeat, triple clamps cannot alter the steering head angle/axis.

  • RCannon

Posted January 27, 2011 - 03:18 PM

#15

I found one of the guys who makes the offset bearing races and he said he would happily do a set or two for my yz 250. They were only 600.00 per set. I ordered three sets and said may name was Grayracer.....He said he could alter the fork angle "several degrees" either way. For angle, not steering angle.

  • grayracer513

Posted January 27, 2011 - 04:46 PM

#16

Cute, RC. He meant steering axis.

Only $600, huh? If I was building a flat tracker.....

  • RJacks

Posted January 27, 2011 - 05:57 PM

#17

The sentence fragment who highlighted in the first paragraph not only disagrees with you, you missed the entire point. Offset or eccentric bearing races DO actually change the steering axis, and therefore the head angle, without cutting or altering the the frame. Triple clamps that change the angle of the fork tubes in relationship to the steering axis DO NOT change the steering axis, and the effect of these two things is very different, as I already said. Since you can take any set of triple clamps off a bike and reinstall them with offset bearings, it is the bearings that make the change, and not the clamps,

So, I repeat, triple clamps cannot alter the steering head angle/axis.


I am not missing the point. More so, Changing the fork angle is where I should've been making MY point.

  • HRC

Posted January 27, 2011 - 11:58 PM

#18

I didn't get a good look at his setup but last weekend he flew by RD like he was standing still in the whoops


Whoops would be one of the places where a larger offset would benefit better handling ! For sure ! I have tried different offset on my +10 years with Honda and larger offset definitly helps going over whoops for a straighter line !

And if you look how poorly Stewart´s 2010 Yamaha handled cross the whoops and now see his 2011 bike handles whoops like a dream....a larger offset is not a stupid idea. But at the same time ( as grayracer already said) It is very very selldom a team changes the offset like that in Supercross. Usually goes for less ! There are other things than offset that you can change for straighter line stabilty. As linkage, suspension, rear wheel axle, forks in the clamps, etc etc etc....

  • RCannon

Posted January 28, 2011 - 07:30 AM

#19

Cute, RC. He meant steering axis.

Only $600, huh? If I was building a flat tracker.....


He said that he started building them for Supermoto applications. It sounded really fun to try, but the cost was about 5 times what I thought acceptable. Not unlike most motorcycle parts. The cool part was being able to tell him exactly what angle you wanted (within reason) and he would build to suit. That was also scary (how the hell do I know what angle???) and had to mean multiple sets would need to be ordered to have a valid test.

I played with offset enough on my yz 250 to realize what appeared to be logical and possible on paper, really had about 50 other thing involved.

Very similar to Grayracer talking about moving the bars forward or backward to change handling. Considering only the bike, this would not make a bit of difference. However, under real riding conditions, changes to bar position were as big of a dead as changing offset, or certainly in the league.

  • grayracer513

Posted January 28, 2011 - 07:52 AM

#20

The cool part was being able to tell him exactly what angle you wanted (within reason) and he would build to suit. That was also scary (how the hell do I know what angle???)

You would need to first build up the bike with the typical SuMo setup (lowered suspension, 17" wheels) and see where it came out in that process. Then subtract some to get at the angle you wanted. The OEM head angle is ~27 degrees, whereas an FZ-1 is 25, and an R1 is 24. Probably something like 25 would be what you wanted. The cool thing about that is that it would let you lower the bike equally on both ends rather than leaving the back end higher so as to achieve a steeper head angle.

I wonder what bearings he would use to start with, because the outer race is the one that would have to be ground, and there's not much room for that on the OEM races. Then there's the little matter of keeping them oriented correctly during the installation being that it's offset ground, the bearing race will have a front and a back, and they would need to be correctly aligned within a degree at least.





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