Rear Shock Travel

[ARKNT]

Has anyone else done any measuring of the rear end travel while riding?

I find the NT rear end to be very harsh esp on square edge bumps like frost heaves and expansion joints. I decided to do some measuring to see what might help (spring change, total shock replacement). I can hear the RPMs jump up when going over these sharp bumps in the pavement so the rear end is leaving the road or unweighting it a lot. Keep in mind I'm about 155 lbs so you may not have the same problems I do.

I built a little jig to measure the travel with on a test ride circuit that has a couple of these bumps. It is a couple wooden dowel rods with one attached to the bag and the other floating in the hollow rear axle. A tye wrap moves up to mark the max travel point. If anyone wants to try this do NOT use matierial that may bind and is strong enough to get caught in rotating parts and stop them from their desired rotation.
Pics of jig attached.

My results:
It supports my idea that the rear end is too stiff for me. With minimal pre-load (3 clicks from min), I have 1.75 inches of sag with just me seated on bike. During test runs the suspension only moved 1.0 more inch.
A different spring rate (spring change) may help but I realy think the compression damping (not adjustable on NT) is too high so the real answer would be to live with it or spring (pun intended) for a new and better shock.
Has anyone replaced the rear shock with aftermarket?

ARKNT

 

[spacetiger]

Something doesn't sound right. The rear suspension has 122.5mm, or 4.82". If you sit on the bike and have 1.75" of sag, you are using up 1.75/4.82 = 36.3% of the suspension just sitting. That seems way too much suggesting you are heavy/the preload is not enough. I think a little more than an inch is right. BUT, if you ride the bike, I would imagine you would use more than another inch. What kind of riding did you do before checking? What would the reading be if you just bounced on the rear end with the bike stationary?

Here is a link for checking the rear sag:
http://www.gostar-racing.com/information/motorcycle_suspension_set-up.htm

What do you weigh?

Jerry

 

[ARKNT]

Jerry,
I'm 155 lbs so lighter than most riders. I certainly expected more travel when riding. The route I checked the travel on was highway/interstate with the mentioned sharp edged frost heave type bumps. I wouldn't try to get too technical with the numbers. The advertised 4.8" should be axle movement. That would measure correctly if the test rig is perfectly verticle. It is close but not perfect.
For your information I did measure 4 inch total travel on my first of 6 test runs. The first run included some extra road where I believe the extra travel occured (road intersection with large change in elevation).

ARKNT