TRX250R.ORG
Riding Styles => XC => Topic started by: Victork on March 07, 2015, 09:53:37 AM
-
Time to buy some beadlocks for my build but not sure on off set. I have +2 lsr race arms and 2+2 lsr axle. What front and rear off set is ideal and how wide will it put me? Id like to stay on the wide side of xc width
-
+2's and 4-1's puts you at about 47".
-
48 inches would be considered too wide you fellas think?
-
I chose stock offset when I bought my wheels...If I had it to do over, I would go with the 4-1.
-
The stock wheels are 5.5". The offset is 3 3/4-1 3/4. I prefer 4-1's.
-
Stock width is what 46 inches?
-
About 44" in the front and 46" in the rear. Honda should've had +1 arms stock.
-
Im pretty sure my rear rims are stock silver R rims and i like that width in the woods with my +4 axle and im not sure of the front offset off hand
-
I mostly run mine with the lsr axle adjusted all the way in which I think is +1 overall. So I'm about 47" front and rear.
-
I think 47 is pretty good . So you put both of the spacers on the axle on the outside of the hub with stock offset and youre about 47 is what youre saying rk?
-
4:1 rims are the best performance geometry wise. I would go that route. 2:3 gets you free width and corner stability. But I don't think it's worth the sacrifice of bump steer. ( exaggerated bump steer.)
-
So 4+1 offset in front and rear is my best bet with the extended arms/axle it seems
-
If you are running stock height tires ,the stock offset would be best,if your running short mx tires 4+1 would work best. Wheel offset has nothing to do with bumpsteer .from the factory with stock height tires the wheels have a slight amount of scrub which gives you a feel for the terrain and makes the tires some what self centering.4+1s with stock height tires put the tires in a neutral position with no scrub and no self centering ,some people like this feel. When running short tires 4+1s correct the change in scrub and put it back to were the factory had it.look up kingpin inclination and you may understand what Im saying.
-
look up kingpin inclination and you may understand what Im saying.
I could spend all day researching atv geometry and I would still be lost lol. That's why I haven't upgraded my front end because I'm sure I would mess it up.
-
Ill check that out tonight fred. My front rims are marked 10x5 and look like 3+2 and my rear looks like oem honda D.I.D. marked 9x8 and i believe is also 3+2. The way i had my spacers the front i think was a tad wider and 48 inches but thats a vague memory. I thought it was great for fast woods racing
-
just want to be clear,Im not trying to discourage the use of 4+1 wheels ,just pointing out that they have a purpose and that the have nothing to do with bumpsteer.Bumpsteer is the change in wheel direction as the a arms go through there travel and wheel offset does not change the amount of bump they have. The affects of wheels that are too offset may be worse than bumpsteer.Also the tire height has an effect on what the offset should be.
-
You are running spacers on the front?
-
Sorry i meant the spacers on the axle. Im going to run 21in tires in the front and 20 in the rear.
-
Off set of rims will exaggerate bump steer. Anyone that says other wise does not have a clue what they are talking about.
Bump steer is all in the geometry relationships between the tie rod mounts and the a arm mounts. Wheel off set cannot fix bump steer.
But greater off set will exaggerate bump steer and feed back through to the bars.
-
I think 47 is pretty good . So you put both of the spacers on the axle on the outside of the hub with stock offset and youre about 47 is what youre saying rk?
Yes
-
If you are running stock height tires ,the stock offset would be best,if your running short mx tires 4+1 would work best. Wheel offset has nothing to do with bumpsteer .from the factory with stock height tires the wheels have a slight amount of scrub which gives you a feel for the terrain and makes the tires some what self centering.4+1s with stock height tires put the tires in a neutral position with no scrub and no self centering ,some people like this feel. When running short tires 4+1s correct the change in scrub and put it back to were the factory had it.look up kingpin inclination and you may understand what Im saying.[/QUOT
The 4-1 rims that I have measured (itp) put the center of the tire closer to the stock location than 3-2 rims.
-
Rim comparison
Stock 5.5" wide, actual offset 3 3/4-1 3/4, tire center 1" in from hub face.
Itp t-9 4-1 5" wide, actual offset 3 3/4-1 1/4, tire center 1 1/4" in from hub face.
Itp t-9 3-2 5" wide, actual offset 2 3/4- 3 1/4, tire center 1/4" in from hub face.
-
Rim comparison
Stock 5.5" wide, actual offset 3 3/4-1 3/4, tire center 1" in from hub face.
Itp t-9 4-1 5" wide, actual offset 3 3/4-1 1/4, tire center 1 1/4" in from hub face.
Itp t-9 3-2 5" wide, actual offset 2 3/4- 3 1/4, tire center 1/4" in from hub face.
that is great info and should be in a sticky. I don't run 3+2 ,even my wife can tell the difference in handling with 3+2s I bought a used ltr with 3+2s and she rode my ltr with stock rims and then she rode the other she stopped me after about a mile and told me to change out the wheels on her bike
-
I found a great deal on front and rear hiper tech 3s for 685 shipped for all 4 but the offset is 3+2 front and 3+5 rear. Honestly my only worry is being too wide in the woods and not so much on best possible handling or bumpsteer as i have a steering stabilizer. With my +2 arms and 2+2 axle what will front and rear width be, (axle adj narrow)? Never cared to pay attention to offset until now so im a newb in the offset area
-
Wheel offset has no effect on bumpsteer. Bumpsteer by definition is the change in toe through the suspension travel. As Burns stated, bumpsteer is the geometry between the tie rods, frame mounts, spindles, etc, but wheel offset is not one of the variables that effect bumpsteer. Doesn’t matter what wheel offset you have, the bumpsteer measurement will remain the same. Bumpsteer will try and turn the quad without you turning the handle bars. If you have a front end with a bunch of bumpsteer and you ride hard through a rough section, the quad will wander around.
What wheel offset does effect is feedback though the bars. A 3:2 offset wheel will give more feedback through the bars then a 4:1 offset wheel, simply because the wheel extends out from the hub further. So if something hits the outside of the wheel, there is more leverage that can be applied to the spindle, causing more feedback to the bars. So again, bumpsteer doesn’t change with wheel offset choice, wheel offset effects feedback through the bars. I guess if you have a low offset wheel and a high bumpsteer front end, then feedback through the bars could be even worse, but bumpsteer is the same no matter what offset wheel you have. I guess you could say feedback through the bars could be exaggerated with a low offset wheel and high bumpsteer front end, but feedback increases, bumpsteer stays the same.
To the OP’s original question, since you have a LSR 2+2 axle, I believe you only have two options for rear width. The widest you can make the rear is 50”, but if you swap spacers around, the narrowest you can get is 48”. For better cornering, you always want the front wider than the rear, so that limits how narrower you can make the front. With +2 arms, the only way to get the front wider then the rear is 3:2 offset wheels, from my experience with a 250R, that should get you right around 49” wide in the front. If your axle is already set to the widest position, then you will still be slightly narrower then what you are no, so should have no problem fitting through the woods you already ride through. ("Woods width" varies greatly. Some need 46, while others have no issues with 50". Just depends on where you ride.) With a 4:1 offset front wheel, the front will be narrower than the rear with your current rear axle.
It’s not the end of the world to run a 3:2 wheel, I used to swap between 4:1 and 3:2 wheels on my 250R depending on the width I wanted. Yes, there was a difference, but it wasn’t huge, I felt the extra width was well worth any extra feedback I felt through the bars. (Again, it wasn’t much, but I did notice it in some cases.) Same thing with the front to rear width. Yes, you should have the front wider, but it’s not a huge difference. I used to run my 450R as wide as possible, ended up the rear was wider. Never thought the quad cornered great, but wasn’t bad. Once I swapped spacers around to narrow up the rear, the quad did corner better, but it’s not like it went from cornering horrible to cornering great, it just improved cornering some.
Doug
-
The width you want also depends on the type of tracks you're riding or racing on. Some tracks are tighter than others.
There's a big difference between my local CRA XC courses (tighter), and the national GNCC races (more wide open). I'm at 47.5" and I like where i'm at.
Standard width frame with +2 a-arms and 4:1 offset wheels would be what I would run if I were you. Not too narrow not too wide.
I run almost identical width in the rear, maybe a hair narrower
-
So the narrowest i can get the rear is 48in? Is that 3+5 offset? Can i get the front 48in?
-
So the narrowest i can get the rear is 48in? Is that 3+5 offset? Can i get the front 48in?
My guess would be 48", but not positive on your exact axle setup. What rear wheels do you have on there now? Most common offset for a rear wheel is 3:5. Look where your axle spacers are and what rear wheels you have and measure what your current width is, from there you can figure out every possible combination with a little math. Once you figure out the rear, you will have a better idea of what you can do with the front.
Doug
-
Ok i measured a little. The rear rims i think are silver oem and look like 3 3/4+5 1/4 combined with the half inch spacers inside sits just under 48. The front was measured with the bike on the stand wheels hanging but they look like 3+2(ams are weird in the center to measure) and at the widest point which is the bottom of the tires is at 48in
-
Off set of rims will exaggerate bump steer. Anyone that says other wise does not have a clue what they are talking about.
Bump steer is all in the geometry relationships between the tie rod mounts and the a arm mounts. Wheel off set cannot fix bump steer.
But greater off set will exaggerate bump steer and feed back through to the bars.
God himself could tell you that wheel offset has nothing to do with bumpsteer and you would not believe it,I will make a video so you can see and understand it
-
Fred,
As i stated before. Bump steer is a result of the geometry relationship between the flag on the stem, spindles and A-arm mounts. Basically this will result in some amount of degrees of toe in or out as the arms cycle through the range of travel. If you use a 4:1 rim that places the center line of the rim as close to the king pin as possible, you have a certain amount of toe in or toe out with a given set of arms through the travel, some more than others. Now if you move the center line of your rim (say a 2:3) out side the king pin, and cycle the arms through the range of motion, the king pins will still move the amount of degrees as before, but because the center line of the rim is placed farther out, the rims will move more distance and faster, you will get more toe in or out because the center of the wheel is farther from the fulcrum of the king pin.
Your statement that offset does not affect bump steer is correct in the terms of geometry, has nothing to do with the inherent bump steer of a particular A-arm setup. But running more offset can make bad bump steer even worse. Or create more bump steer should i say because the center line of the rim is farther from the fulcrum. And will move more total inches in or out.
Also, because the rims have a greater leverage on the steering system since its farther from the fulcrum, it will give more feed back through to the bars. When you hit a rock or something with one wheel and not the other, you will feel more jerk in your handle bars. This again is due to the leverage or distance from the fulcrum.
I can draw a picture if you want.
Its funny how i can always be civil and respectful with you Fred, yet you cannot with me.
-
I just replied to this thread via Fred's tag.. After posting i see D Bergstrom posted what i was trying to say, and resaid just above. sorry for the repost.
-
Off set of rims will exaggerate bump steer. Anyone that says other wise does not have a clue what they are talking about.
This is your idea of being civil. You have a lot of it correct,What your not understanding is that the position of the tierods and mounting points do not change when changing offsets and therefor the bump steer doesn't change either.Im going too do some pics or video to show you what I'm talking about.
-
Lol. I have said that it in 2 posts already Fred. The total degrees of spindle change do not change because of rims. But the farther you move your offset from the center pivot point the far the the rims move for every degree of bump steer.
No need for pics. I have already spent many hours figuring out bump steer. Spent alot of time talking to Andy Maul going through the reasons and solutions. I had a front end last year that gave me a lot of bump steer.
You seem to fail to read all my posts if you think that I haven't already said. That rim offset only exagerates bad bump steer. It's not a lot, but it does. I will try to draw something up tomorrow.
-
I just did a simple calc here. But this is assuming 10 degrees of bump steer. I also assumed that the center line for the hub face was 3" out from the king pings. In reality it would probably be more than that and have a great effect. But this is what I'm trying to demonstrate basically.
As you move the center line of the rim farther and farther from the king pins, the distance traveled by the center line of the rim increases in the same degrees of motion.
(http://i158.photobucket.com/albums/t82/BurnsMGT/Mobile%20Uploads/Calc_zpsigsxaazv.jpg)
Heres what i was having problems with. I was running these 3:2 Rims, On some arms with incorrect spindles. At full extension i was getting serious bump steer. At ride height and through 80% of the travel they tracked great. Lol this is bad. Cant believe i tried to race this.
Full extension
(http://i158.photobucket.com/albums/t82/BurnsMGT/10172676_990973700449_297346869_n_zps88cd2fda.jpg)
(http://i158.photobucket.com/albums/t82/BurnsMGT/1964940_990977872089_1934508757_n_zpsf56589e6.jpg)
-
If caster is at between 4* to 7* with correct toe in and camber you'll never have bump steer as well as have steering that goes like butter. Too much caster in positive degrees the bars will not return and feel heavy, too little that's where bump steer is created, always have positive with center line of the ball joint tipped back towards the back of the bike.
-
I know this is a stupid question but i just want it confirmed. 4+1 is 1 inch narrower than 3+2 correct?
-
If caster is at between 4* to 7* with correct toe in and camber you'll never have bump steer as well as have steering that goes like butter. Too much caster in positive degrees the bars will not return and feel heavy, too little that's where bump steer is created, always have positive with center line of the ball joint tipped back towards the back of the bike.
That has not been my experience at all.
-
Kyle could I ask what your front is set up as right?
-
I always set caster between 4-5 degrees. I dont like to much because i like my steering light. But even with that set that way, you can see the bump steer in the front end that resulted in mis matched parts. The relationship between the flag on the stem and the flag on the spindles just didnt jive at full extension. My case is extreme, but does demonstrate what happens.
I dont know if its possible to have zero bump steer. And i do understand that caster can defiantly effect bump steer, if you stay in your specified range of 4-7 degrees you wont see any effect.
My experience has shown that even when you are between 4-7 degrees, you can still have a lot of bump steer.
-
I know this is a stupid question but i just want it confirmed. 4+1 is 1 inch narrower than 3+2 correct?
No they would be a total of 2" narrower for the entire front end. You will have 1" less on each side.
-
Kyle do you have a picture of the spindle tie rod out as well as the stem and tie rod mount and everything mounted?
-
I was just comparing 1 rim but i got my answer thanks
-
To get 0 bumpsteer on the r ,the tierod position on the steering flag would have to way further outward and when you do that it goes over center and the wheels will lock when turned all the way.bumpsteer is at its min from the factory.
-
Ended up going 4+1 and 3+5 thanks for the input guys
-
post pics and width measurements once you get them mounted up!
-
post pics and width measurements once you get them mounted up!
i dont think the bike will be off the stand and on the ground until the end of next month. My target race isnt until may 23rd so its not rush time yet lol
-
Victork
i didn't read the entire thread so some of this may have been pointed out.
If using a standard width frame your +2s with 4:1s will work well on today's tracks.
Not sure if you saw or not, but Rpm is making a limited run of their discontinued XC width axle. This would put you at the width you need on the rear.
The ideal setup is to be slightly narrower in the rear than the front for XC racing.