Wheel travel, where is it measured from?

[SPP]

* edit * wikied

"Travel is the measure of distance from the bottom of the suspension stroke (such as when the vehicle is on a jack and the wheel hangs freely) to the top of the suspension stroke (such as when the vehicle's wheel can no longer travel in an upward direction toward the vehicle)"

... meaning the fork bottoms out ~20mm up from the axle casting not at the casting like other bikes (131mm stanchion showing / 110mm travel).

[Robert Taylor]

* edit * wikied

"Travel is the measure of distance from the bottom of the suspension stroke (such as when the vehicle is on a jack and the wheel hangs freely) to the top of the suspension stroke (such as when the vehicle's wheel can no longer travel in an upward direction toward the vehicle)"

... meaning the fork bottoms out ~20mm up from the axle casting not at the casting like other bikes (131mm stanchion showing / 110mm travel).

The last thing that bottoms out / stops the fork travel / ''full closed'' distance is something that we call ''cap strike''. What that means is the underface of the top cap physically contacts the top edge of the inner tube. This is normally fairly passive as hydraulic bottom out devices or rubber bottom outs have preactivated before that. Also the main spring force and secondary trapped air spring force are fairly ramped up by that stage.

It must never be assumed that ''full closed'' distance will leave no fork leg chrome exposed. In the case of the R6 and late model GSXRs cap strike occurs with around 4-5mm of chrome exposed underneath the dust seal. Or about the width of one of those funky Ohlins ride height indicators. Without my notes being to hand, in the case of the late model CBR600RR cap strike occurs with about 14mm of chrome left exposed underneath the dust seal lip. Every bike is different

Top out springs confuse the issue further as some of them are quite long and some aggressive. Just because the wheel is hanging freely in the air doesnt mean that its neccessarily fully extended. Dependent on selected fork spring rate and preload and how much the top out springs counteract that its not uncommon to be able to further push the wheel down as much as 5mm. Adding preload will ''lengthen'' that static wheel in air fork position.

[SPP]

The last thing that bottoms out / stops the fork travel / ''full closed'' distance is something that we call ''cap strike''. What that means is the underface of the top cap physically contacts the top edge of the inner tube. This is normally fairly passive as hydraulic bottom out devices or rubber bottom outs have preactivated before that. Also the main spring force and secondary trapped air spring force are fairly ramped up by that stage.

It must never be assumed that ''full closed'' distance will leave no fork leg chrome exposed. In the case of the R6 and late model GSXRs cap strike occurs with around 4-5mm of chrome exposed underneath the dust seal. Or about the width of one of those funky Ohlins ride height indicators. Without my notes being to hand, in the case of the late model CBR600RR cap strike occurs with about 14mm of chrome left exposed underneath the dust seal lip. Every bike is different

Top out springs confuse the issue further as some of them are quite long and some aggressive. Just because the wheel is hanging freely in the air doesnt mean that its neccessarily fully extended. Dependent on selected fork spring rate and preload and how much the top out springs counteract that its not uncommon to be able to further push the wheel down as much as 5mm. Adding preload will ''lengthen'' that static wheel in air fork position.

Thanks Robert... marking 14mm up makes quite a bit of difference when looking at the tie.

[Robert Taylor]

Thanks Robert... marking 14mm up makes quite a bit of difference when looking at the tie.

There are a LOT of bikes that dont use the ''full travel'' of the exposed chrome. So its dangerous to make an assumption!

[SPP]

There are a LOT of bikes that dont use the ''full travel'' of the exposed chrome. So its dangerous to make an assumption!

Mmmmm, seems silly now that did assume that. I can't be only one though...perhaps so