custom swing arm

[steven_191]

for my project i think alot of hassle would be avoided by having a custom swing arm made.

im just wondering what materials are they normally made from.

i know the cagiva mito and aprilia rs125 are cast aluminium but then again there is alot of metal there.

arent some mild steel box section?

the problem i need to overcome is allowing enough space for the right suspension travel, the chain on the right hand side and the linkage actually being able to work.
speaking of linkage. am i right in thinking its job is to reduce the motion on the shock compared to the motion on the wheel. in which case its a reduction ratio.

[steven_191]

i dont really even need a linkage do i?

alot use the top brace or where the sides link together in front of the wheel as the shock mount. mounting it this far forward still reduces the shock travel

[G]

Most swingarms are steel. Regularly considerably heavier than the frame it's self.

[woodyfjr]

[steven_191]

[steven_191]

[woodyfjr]

(am i right in thinking its job is to reduce the motion on the shock compared to the motion on the wheel. in which case its a reduction ratio) the opersite.

If you think about where the shock is mounted on a modern bike in relation to a twin shock the shock would have a very short stroke.

eg: If the swingarm shock mount was say 24" away from the pivot point and say it had 8" of movement, then you fitted a shock say 12" away from the pivot you would only need it to move 4" to get the same swingarm movement.
However the shock would over heat as its doing the same work but in half the distance so this where linkages come in.

The linkage (gearing) increases the shock stroke length to allow more damping control so it would compress at a slower rate than the swingarm.
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