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School me on steering head off-set..

j.seims

j.seims

Member
Joined
Jun 24, 2013
Location
santa rosa
Moto(s)
aprilia
Ducati, any V-Twin
I have seen many bike with different steering head offset, some bikes have adjustable offset. I have a Aprilia RSV and a Aprilia Futura. The Futura has 5mm more offset than the RSV.

My question is what affect on steering(both low and high speed) does the steering off-set create? How would a bike handle with zero off-set?

Thank You
 
Good question. I'd like to know a real answer to that too. I know on MX bikes, they change the offset around for different purposes, but exactly who, what and why, I don't know.
 
Add more off-set and the trail decreases, quickening steering but less stability.
Take away off-set and the trail increases, slowing steering but more stability.
 
offset

as you see, the net trail is the sum of effects from wheel-tire diameter, rake angle and offset of the triple tree,

if you imagine the same diagram as in the prior post with the handlebars rotated to left or right, you might sense that the dynamic stability is affected by how the trail changes with handlebar rotation, and the offset is a key part of fine tuning the response,

as an example, at an extreme 90 degree hadlebar rotation (which never occurs in practice) the trail is 100% sideways and is due only to the offset, becasue at a 90 degree steering angle the rake has almost zero effect (there is a separate minor effect due to the front tire's finite size).

you need enough trail for positive steering feedback, but you don't want an excessively unstable system as it may create a dangerous "tank slapper"
 
has anyone here ridden a bike before and after changing offset? its not a common adjustment, almost always requiring aftermarket triple clamps. i really wonder how different the offset adjustment feels compared to a fork height adjustment.
 
stangmx13 said:
has anyone here ridden a bike before and after changing offset? its not a common adjustment, almost always requiring aftermarket triple clamps. i really wonder how different the offset adjustment feels compared to a fork height adjustment.
Click to expand...

Yeah, lots of guys do. I ran my 675 with a stock setup in 2012. I ended up running a 190 rear for a better contact patch toward the end of the season, but felt a noticeable sluggishness on turn in.

That winter I bought the Attack aftermarket triple clamps with an adjustable offset. I settled on a 27MM offset after a few track days. This increased the turn in dramatically, but changed the way the bike held a line. I ended up buying the Apex rear liner linkage, and a height adjuster for my TTX, to bring the ass back up.

After all that, I had the bike steady in a turn, and feeling really good again. The funny thing about it all though, was after I spent about $3,000 I ended up going back to the 180 SC2... However, now the bike cuts a line like a knife.
 
Not sure if I'm talking about the same thing but I lowered the front of my sv650 by letting the forks go up through the triple clamps a bit more. I could definitely tell a difference after, bike felt more responsive to steering input. Overall a welcome mod to my SV.

Am I on the same subject here?
 
Norbs said:
Not sure if I'm talking about the same thing but I lowered the front of my sv650 by letting the forks go up through the triple clamps a bit more. I could definitely tell a difference after, bike felt more responsive to steering input. Overall a welcome mod to my SV.

Am I on the same subject here?
Click to expand...

You didn't change the off-set, you changed the rake angle.
 
shouldnthave said:
That winter I bought the Attack aftermarket triple clamps with an adjustable offset. I settled on a 27MM offset after a few track days. This increased the turn in dramatically, but changed the way the bike held a line.
Click to expand...

so, how does an offset change feel compared to a fork height change?

"increased turn in dramatically" is not a phrase that makes sense to me. was the bike more responsive to bar inputs, i.e. less input was required to produce the change u wanted? did it change its lean angle faster given the same input?
 
Maybe I'm simplifying it too much, but whether you play with the rake angle or the off-set, you're ultimately playing with the trail, which greatly determines how your bike handles.
 
stangmx13 said:
so, how does an offset change feel compared to a fork height change?

"increased turn in dramatically" is not a phrase that makes sense to me. was the bike more responsive to bar inputs, i.e. less input was required to produce the change u wanted? did it change its lean angle faster given the same input?
Click to expand...


It now turns in much faster with minimal input on the bars. Lean angle, and turn in from point of turn to set is accomplished in significantly less time than with the stock offset.

It does take some getting used to for sure. It is much more easy to oversteer the bike if you get excited.
 
^^ This guy should know. He rides a 675. :teeth
 
all of this is great information. To make things more complicated how does the Bimota Tesi mimick trail. looking at there bike it has no offset and no real trail???
 
Blankpage said:
IBF: scotts steering damper
Click to expand...

IBL..in before Lou.

On the other hand, I went to a taller rear tire on my SV, fucker almost pitched me off at about 100 with a speed Wob. Different deal though, just answer in SV guy about changing there fork height.
 
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