Custom seat

[bretts]

On a 3x1 81 frame I found the original clearance for the back wheel to guard to be 130mm yet the shock absorber travel is only 60mm
How much clearance do you think I need to leave for a custom seat?

[DiverRay]

I'd keep about 40mm, just for BIG bumps and tire growth as your speed increases. A large bump MAY cause things to flex a little, and the outside of a tire can grow about 2 to 6mm with speed. A little room for the angels never hurt.

[bretts]

So you mean 100mm in total travel and clearance?

[DiverRay]

You will need to measure the travel, and add about 4cm for clearance. Remember, the shocks mount in front of the axle, so the actual travel will be MORE than what the shock does. The correct way would be pull both shocks AFTER measuring clearance, remove spring from one shock and put it back on and re-measure the clearance. That will give you the min/max for movement, add about 2cm, and you have your space.