Hi all,

I am under the impression that, as a rule of thumb a bike should use up one third of its suspension travel when the weight of the bike plus rider compresses it.
Can anyone confirm this?

I had a custom rear shock absorber made about 6 years ago, but for a variety of reasons have only recently got around to fitting it. It was supposed to have been made with a firmer spring to cope with a lot of luggage but when I try to set the 'Static sag' as above, I have to wind the spring preload 80% of the way to wards its maximum setting, and this is with no luggage fitted.

Does this suggest that the spring that is fitted is of too low a spring rate?

As always, any thought on this are appreciated,

Thanks


Mark

You are spot on.
30% sag is the perfect setup for the bikes weight and riders weight on the bike.
The sag should not exceed 50% fully loaded.

A custom made rear shock should ideally give you:

30% sag (bike + rider) with the preload set to or near minimum if you want to have a "hard" setup for lots of luggage, two up or hard riding.

or 50% sag (bike + rider) with the preload set to or near minimum if you want to have a "soft" setup for comfortable riding one up with little luggage and being the hooligan of the town commuting to work.

I assume you did not pick up weight over the last six years :-)

Have you disassembled the shock or unloaded the spring and checked the spring's free length? Unlikely as it should not happen to a good quality aftermarket spring but it might have set whilst sitting in the box if it was fitted to the shock and preloaded.

Lecap,

Thanks for your reply.

Looking at my notes, when I made my measurements I used Yamaha's quoted rear suspension travel, but this is undoubtably not measured between the same points that I was using. I will have to have another go, but this time removing the saddle and using a ratchet strap to fully compress the rear shock.

If I get similar results, I will contact the supplier but I don't know how they will react to me 6 years after purchase!

Mark