Steering Geometry - Thread for techies...

[David Lahey]

Here are typical numbers for 1970s trials bikes
Wheelbase 1300mm
Trail 30mm
Rake 26 degrees
Front travel 175mm
Rear travel 125mm
Footpegs in line with front edge of rear tyre tread

[aquira]

"Footpegs in line with front edge of rear tyre tread"

i dont get this

[kembro]

Trials footpegs are mounted further back than on other bikes. Looking from the side, they are mounted on the frame, either side of the leading edge of the rear tyre. Hope that helps.

[aquira]

ok i get it...

mine is about 15cm forward the rear tire edge.
but hey i just check some pics, which is obviously a scorpa

un accidentally similiar

thats why it feels so good

[David Lahey]

I think you need to look at a photo of a trials bikes which has been taken with the camera centreline at 90 degrees to the centreline of the bike and with the footpeg in the middle of the photo. The Scorpa photo you have shown has been taken with the camera rearward of the footpegs and pointing forwards, giving the illusion of the footpegs being more forward than they really are.

[PA]

Just checked my and it is 420 mm from the center line of the rear axle to the center line of the foot peg and 895 mm to the front axle from the center line of the foot pegs.

The foot pegs are around 15 mm higher than the rear axle.

[aquira]

hmm....

a 18" wheel is=457,2 which is a diameter/2 to get the radius= 228.5 center line to the edge of the rim + tyre thick which is 4"=101.6 mm

so
228,5+101.6= 330,1 (edge of the tyre)

if you said its 420 that mean it short 90mm to the edge of the tyre.

this is scorpa

i need a new frame and arm