Poor Mans's Triple offset (grayracer input)


23 replies to this topic
  • tw557

Posted November 30, 2006 - 04:47 PM

#1

I have an 05 450f and would LOVE a 06 from all the unbelievable comments posted on here. I just can't pull it off yet so I want to get the 05 as good as possible without dumping too much into. The suspension is TBT front and rear and will be sprung for my proper weight.
I here so much talk about the steering and triple tree offset. I just can't bring myself to spend that much on them. I've contimplated an idea and can't think of too many problems with it.
I would take the top tree clamp and machine the center hole .026 oblonged toward the back. I would then either put a spacer in the opposite gap or a screw in from the end to allow fine tune. The top clamp will be offset by .026. This would equate to the wheel axle being .080 back (2mm)farther. The forks would be at a .2angle from the stem. Now the wheel offset will change during travel from 2mm offset fully extented to about 1.3mm offset at full compression. I just don't know it that would be a bad thing.
The bottom clamp easily springs the .023 needed for the top clamp to be installed. I do realize the the tripple tree is bound up a little but I think the bearings can handle it. I only have an RG3 clamp and not excited about chopping at it just yet.
Anybody see any real problems with this?

  • Ranger18

Posted November 30, 2006 - 05:20 PM

#2

I understand what you are saying, but I think you should just leave it alone. I think you are just asking for trouble. Plenty of pro's raced 05 yzf's and did just fine, just becuase the 06 is better doesn't mean that the 05 is crap, it's just not as good.

  • ncmountainman

Posted November 30, 2006 - 08:48 PM

#3

if i'm gettin' it right your changing the rake off axis of the steering stem to gain the offset that would then be variable with travel. makes sense as less offset would be needed when the forks were low in the stroke. but i think set screws and twisting the bottom clamp would not be the way to try it. maybe some sort of line hone,you'd have to do it as an assmbly with one fork tube holding the other side straight. might wanna try it with your old clamps instead of the RG3's!

  • grayracer513

Posted November 30, 2006 - 09:30 PM

#4

Just from the technical standpoint, your plan for supporting the top clamp against the stem seems inadequate. It would be better to simply bore it oversized and off center and then insert a sleeve.

Secondly, the bearings will bear none of the strain produced by pulling the forks out of parallel with the stem because that force will exist entirely within the triple clamp/fork assembly, independent of the bearings (it would be in a bind even if it were not on the bike). The binding force might, however, result in some distortion of the outer fork tube at the lower clamp.

Also, there is the fact that moving the axle back in this manner will steepen the fork angle without changing the head angle, which can cause some odd sterring characteristics.

I think a far better solution would be to buy an E-Axle from Rekluse (through ThumperTalk, of course). It's under $200, can be dialed in to suit your tastes in either direction from stock, and can be put back to stock at will, indefinitely. Remember, too, that even under the best circumstances, changing the offset will not make a pre-'06 act like an '06.

  • tw557

Posted December 01, 2006 - 07:08 AM

#5

Thanks for the input. If I had a stock top clamp It would be done already. I agree,the sleeve idea would be the best approach. I figured maybe with the setscrew holding the stem pushed over would suffice until the nut was tightened. I roadraced for many years and to straighten alot of frame issues out from buying crashed bikes to race. I did this method of oblonged holes to one side of a swingarm frame hole with a metal shim installed in the gap. I have also oblonged holes in shock mount holes then made washers with a corresponding thick protrusion sticking out the side of the washer to take up the hole gap to raise ride height. I also contemplated that with the rear shock on this bike to duplicate the Storm link. Also the rake change would be equal to lowering the front 5mm. So it is somewhat substaintial.

I have to say thanks for pointing out the E-axle. Much more cost friendly. I just might give that a try. It should act exactly like the offset triple tree.
I know it will not be a 06. One thing I have is time and machine shop useage. Just not alot of money for the toys anymore. Winter time is coming and looking to massage this bike over a bit.

  • ncmountainman

Posted December 01, 2006 - 07:16 AM

#6

i'm kinda curious as to how your idea would translate to the rider. to me it seems as though the wheelbase would lengthen(would also cock a little to the opposite side ) the more it was turned to each side and be shortest when in a straight line. that might initiate a faster turn and then smooth out if you over steered. could be good,could send you into a superman situation?

  • hackman162

Posted December 01, 2006 - 10:33 AM

#7

tw557,
Pick up some stock clamps on ebay. You can usually find them for under $20.

  • tw557

Posted December 01, 2006 - 12:03 PM

#8

I am in the process of getting a used stock set to try. I think I will machine it oblong then install a corresponding shim in the other side. "IF" this works and I see wear on the shim I will have to bore the top hole larger and off center and install a bushing. Then I could make different keyed inserts to try different offsets.

Also does anybody know if swingarm angle is a concern on MX bikes. This was a big deal on Roadracers. More swingarm angle would push the rear tire down under power from the chain pull. More angle gave more traction until it let loose then it was gone. A flat swingarm had less traction but controllable spinning and sliding. Does this issue ever come up other then just ride height for rake and trail changes?

I wish I had the chance to ride an 06, or maybe not, but the 05 seems to work pretty good. It does feel heavy but my last bike was a 99 WR400. I have pretty short legs and would lower by one inch each end cause problems or would it create a lighter feeling bike. That again always worked great for roadracing till parts started to drag.

  • Blue4Ever

Posted December 01, 2006 - 02:01 PM

#9

You may have a difficult time getting the forks into the clamps unless you do as ncmoutainman stated and line bore both clamps. You may want to reveiw KTM's design on there SXS adj clamps.

  • grayracer513

Posted December 01, 2006 - 04:21 PM

#10

Also does anybody know if swingarm angle is a concern on MX bikes. This was a big deal on Roadracers. More swingarm angle would push the rear tire down under power from the chain pull. More angle gave more traction until it let loose then it was gone. A flat swingarm had less traction but controllable spinning and sliding. Does this issue ever come up other then just ride height for rake and trail changes?

It would work the same way, pretty much, for something like a TT or flat track bike, and of course, it becomes one of the considerations in Super Moto, but in MX, the full 12" of travel is pretty much required, and the swing arm is in such constant motion that it doesn't really have any one angle you could call the "normal" angle. The closest thing to that would be more like a 5" average range.

Also, the amount of force applied to the suspension on an MX'er is going to be less for the most part than on a sport bike because of the lower power levels and the poorer traction.

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  • tw557

Posted December 01, 2006 - 04:46 PM

#11

Grey, Your explaination is what I was concidering about the swingarm angle. We had 130 hp pulling on the chain with alot of traction.
Well the offset triple tree is machined and installed. I got VERY lucky a guy at work had a stock top clamp for me to try. I went .032 offset at the top clamp which equates to about .096(2.4mm) at 24 inches down from the bottom clamp. With just the weight of the forks clamped in the bottom tree twisted the bottom enough the .032 shim slide right in the top. I hope to give a try tommorrow but weather is getting pretty rough in Pa. anymore. I can only do my little feild track. Just not sure I can do a good test without going to the track for one session with and one without. Well there is always next year.

  • ncmountainman

Posted December 01, 2006 - 08:54 PM

#12

are there any manufacturers past/present that had the fork legs unparallel to the steering stem axis for decreased rake or increased trail,but since trail is a measurement off that axis it would be variable with travel correct? headshake seems eminant?

  • grayracer513

Posted December 01, 2006 - 09:37 PM

#13

Trail varies constantly within a limited range as the bike rocks fore and aft over uneven surfaces, anyway.

  • Fastest1

Posted December 02, 2006 - 07:29 AM

#14

are there any manufacturers past/present that had the fork legs unparallel to the steering stem axis for decreased rake or increased trail,but since trail is a measurement off that axis it would be variable with travel correct? headshake seems eminant?


Alot of those Harley builds do this, however I dont think handling is an issue as much as looks. As mentioned above, why not get a set of KTM eccentircs and installed them in a stock (modified) triple? BTW do you really think there is that much of a difference between the 2 year models? Or is it just marketing hype/ justification for the price paid?

  • assfastgrass

Posted December 02, 2006 - 08:59 AM

#15

I just would like to say one thing, while upgrading to new bikes every so often is a good idea if you are competing as everything tends to wear out especially in the dirt as most of you are aware. But always remember a GREAT rider on a decent machine (all the top brand motocross bikes for years have been decent) will totally annihilate an average rider on the trickest most expensive machine out there. More practice, go to a riding school to fine tune your techniques, work on your weaknesses, improve your late braking and cornering techniques . Practice extreme outside weighting of the bike ( one tip that helped me years ago was to have the crack in your butt on the outside edge of the top of the seat in certain types of turns, this allows one to get the bike leaned over as far as possible while maximally weighting the outside peg to maximize traction) Try this and on flatter turns and even some berms this will DRAMATICALLY increase your speed while also giving you a much more secure feeling. Other things are get your weight WAY forward ( why do you think the seat extends way up the tank??) on the corners where this is appropriate. . Another useful tip that I can give out is CROSSTRAINING by riding much faster on the road than you would on a motocross track ( goes without saying that you need to do this on a race track but if not possible on uncrowded rural roads) I don't mean to go out and get a 1000 cc sport bike, A street legal supermoto will fit this bill quite nicely. This helps in that you have a much higher sensation of SPEED than those who ONLY ride on MX tracks. This does help by making your highest speeds on the mx track seem less hairy. Of course speed is relative as guys who ride mountain bikes surely know. 25 miles per hour on a tight rocky downhill singletrack can seem like 150 mph on the road.
Hopefully some of this will help some of you become better riders and racers. I know it helped me years ago.

  • grayracer513

Posted December 02, 2006 - 10:25 AM

#16

Alot of those Harley builds do this, however I dont think handling is an issue as much as looks. As mentioned above, why not get a set of KTM eccentircs and installed them in a stock (modified) triple? BTW do you really think there is that much of a difference between the 2 year models? Or is it just marketing hype/ justification for the price paid?

The question with the KTM scheme gets to be a matter of whether there is adequate material around the stem in the clamp you intend to use the idea on to support the stem holes being bored that much larger.

As to the difference between the model years, if you are asking about the difference between the '03-'05's and the '06/7, "night and day" isn't even close.

  • SMarquez

Posted December 02, 2006 - 10:34 AM

#17

Try the adjustable E-Axle from Rekluse. Suggested retail is $200. You might be able to find one discounted somewhere online.

  • tw557

Posted December 02, 2006 - 11:47 AM

#18

Well I do have to agree with everything fastgrass has to say. One reason I did well quickly in roadracing was because of motocross racing first. I don't think it is quite as good the otherway around but I am never in the best shape for motocross either. Some of the reason I want to try this stuff is half to just tinker the other half is to make it more fun and easier for my limited ability. Of any form of racing incuding roadracing I give the most rider credit to motocross.

Well I did get to do a little ride today. Not a good test really. I made sure the handlebars were the same and everything each time and I can tell a difference. It is for sure quicker to steer and I guess it feels lighter. My bumpy slimy field had me going pretty slow though. I did a little road test and felt the most difference there. I tried it with 2.5mm none then 2.5 and it is quicker and I like it better. I really need to get to a track day for a true test. It did not feel wierd. No fall in tendencies. I would say for woods single trail riding I would have no reservations with this. I'm not sure about the track yet. Unforntunately I think I'm done till spring. Maybe I'll just do it right and get the e-axle but I bet this setup got me 80% of the e-axle .

  • ncmountainman

Posted December 02, 2006 - 12:34 PM

#19

Trail varies constantly within a limited range as the bike rocks fore and aft over uneven surfaces, anyway.


i was under the impression that the measurement of trail was off the steering stem axis and if the steering stem and fork tubes are parallel that measurement cannot change no matter how much the bike rocks(at least not physically,maybe proportionately),if unparallel the measurement would change physically as the suspension acted......no? ok after consideration i now see how it would change,because the offset would be acting like a fulcrum as the bike rocks ,if there was no offset then there would be no change...only if unparallel(one day i'll finger it out!). well glad it works for ya i might just try it myself(to see if its any better than the 23mm offsets) to change the rake a little,i've still got my old clamps:thumbsup:

  • tw557

Posted December 02, 2006 - 05:22 PM

#20

mountainman, That would be great if you could give it a try. It really is simple enough. Everything is relative and I have very little to compare to. It sounds like you have tried quite a few things in the past so you could give a good comparison. I do wonder what causes tucking under and at what depth of stroke. According to my slider zipty my forks travel about 6-7 inches during straights and turns not including jumps. That means my offset changes from about 2.4mm to 1.8mm. If tucking occurs because of high trail somewhat deep into the stroke then this could work okay. I was glad of no fall in feel. My last bike was a 99wr400 which I never felt good on, high and heavy.





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