Explain Bump steer in laymans terms

[250xTrailRider]

My guess is that Bump steer is when the shock bottoms out and the arms need to travel further in order to make the turn but can someone explain "Bump Steer" in laymans terms. I see that a lot of people shoot down the 400ex arms on a 250x/ 300ex chassis due to this factor. However some guys run this setup and don't raise any complaints.

this one is going to be fun- Basically take one of the front shocks off your bike and cycle the wheel up and down like u r going through the travel. you will notice that as it is going up and down that the tire is moving backward to forward in the easiest way i can explain that is part of bump steer. as you accelerate while sitttin on your bike riding you gain toe out and as you start to brake or on deceleration into corner you gain toe in this is all part of that. bump steer is controlled by tie rod location but you can never totally eliminate bump steer just reduce it. when the tires are straight you can get it to where it is almost gone but as soon as you turn the tires and with different parts of the stroke it will be there. man i give up it hard to explain but would only take a couple of seconds to show you. dont know if this answered your question or not.

[TBD]

Allen is correct. It is a hard one to explain. Bumpsteer is caused because as the suspension goes through its travel the a-arms and the tie rods do not cycle on the same arc. Easiest way to explain it is when the arms travel from a fully extended position to full bottom the toe setting might go from a toe in setting to a toe out setting and then possibly back to a toe in setting. It depends on the model of quad to how it changes.

[bradley300]

wouldnt the polaris predators PRO steering desingn totally eliminate bump steer since the tie rods are on the same axis as the a-arms? or do i not understand that system as well as i think?

[TBD]

I'm getting ready to build arms for the Predator. I will let you know just how much, if any at all, bumpsteer it has. It does appear to be very close. What you're thinking is right.

[EASTHILL]

Bump steer is the slight turning of a wheel away from its normal direction, as it moves through its suspension travel. In reference to the front end, bump steer is associated with the tie-rod/linkage-arm relationship.


:)

[400ex28]

:eek2:

[250xTrailRider]

Ok guys. Thanks. I'll have to move the front suspension around (by hand) to see what pieces are moving where. I found this online "On competitive machines, as you lean into a corner or nose into a whoop, it feels like the quad is steering you instead of the other way around. That's unwanted toe change or bump steer." Any other input would be great. Would a steering stabilizer help reduce this? Like the ones from PEP or Scott's or GPR.

[T2RACING]

I love my stabilizer... good investment

[woodsZrider]

when riding a long time or in a long race they are life savers...:cool:

[Fred55]

Originally posted by bradley300
wouldnt the polaris predators PRO steering desingn totally eliminate bump steer since the tie rods are on the same axis as the a-arms? or do i not understand that system as well as i think?

Yes it does! it helps a lot!

[Tom TRX250R]

I have ridden a few Predators and they are probably the best quad for having the least amount of bumpsteer! Though the *** end has a tendacy to tail slide a bit too much in the turns!

[bradley300]

i think the most confusing part of "bumpsteer" is the fact that it is used to describe 2 different conditions. the one stated above, but also trail feed back (hitting a rock and having the bars jerk) is also known as bumpsteer to alot of people. the trail feed back is what the steering dampers are for

[Juggalo]

as the front suspension compresses and decompresses your front tires toe in and toe out. in case you dont know what toe in and toe out is ill give you a quick lesson in that too.

ok pretend you are looking at your quads front tires from above the suspension is not compressed at all theres no weight on the quad its just at the normal position. your tires will look like this | | pointed straight ahead right?

now toe in is when your tires point toward each other sorta like if you were to walk pigeon toed. like this / \

now toe out is just the opposite its when your tires point away from each other like this \ /

so bumpsteer is when your quad changes its toe angle from the suspension going thru its range of travel.

i hope that helped you out.

[250xTrailRider]

Thanks Juggalo. So basically we want our tires like this | | the entire time. So on a "Bump Steer" condition one tire must be pointed in (or out) more than the other tire?

[roscoe]

Originally posted by 250xTrailRider
Ok guys. Thanks. I'll have to move the front suspension around (by hand) to see what pieces are moving where. I found this online "On competitive machines, as you lean into a corner or nose into a whoop, it feels like the quad is steering you instead of the other way around. That's unwanted toe change or bump steer." Any other input would be great. Would a steering stabilizer help reduce this? Like the ones from PEP or Scott's or GPR.


A steering stabilizer will not help with true bump steer, ie the toe in - toe out as suspension moves up and down.

A stabilizer WILL help with 'bump steer' caused by a front tire hitting a rut or rock and jerking the bars around. This kind of 'bump steer' is made worse by turning the front rims around to make a wider wheel base the cheap way :) That is why it is better (although more expensive) to use +2 or extended A-arms.

I will spare you the tecnhical explanation of why this is unless you want it.

[redrunner]

He's probably gone through a set of tires by now.....:eek2:

[JOEX]

Originally posted by redrunner
He's probably gone through a set of tires by now.....:eek2:
LOL!

Old thread but good info:)