NC30 Front Suspension measurement

[Old Painless]

If your forks are bottoming out they have either no oil in them or the springs are too low rate.

[Jon]

Have you got 26mm static sag with or without you sitting on it?

Loosing 20% of your wheel travel is going to make any fix a bit of a comprimise.

I use pretty much full travel braking on a bump track on a track day, (front wheel just touches fairing)

If you are getting about the right static sag and running out travel you need either firmer springs or more damping.

Drop an aftermarket damper valve and shim stack in or get the shim stack reset will help and would be my suggestion.

Other option is running firmer springs with less preload to get your static sag right.

regards
jon

[mozzi3]

Static sag is just the weight of the bike without me. I would have thought as Jon points out you would expect to be using pretty much most of the front travel under hard braking from over a bumpy surface. Otherwise you are wasting some of the travel available for keeping the front wheel on the ground. I'll have the springs out to check they are OK and replace the oil although the bike's had little use since the forks were completely rebuilt and haven't noticed any oil leaking out. Also before i changed the yokes and lost some travel now 105mm before 120mm i didn't experience the problem and when not hard on the anchors all feels good. Maybe it could be that the fork springs are not helping as they are progressive and not linear rate springs. Guess i'll have to be shipping them off to Maxton for some tweeking. The big question is whether 15% less over all travel is going to be a big problem.

[mozzi3]

Actually progressive springs should be helping.. Doh.

[CMSMJ1]

What have you done with the yokes to cause these issues - can we get a pic of it?

Bottoming the forks iunder braking is not cool..and not desirable in any way.

The cause sounds like the yokes..no need ot be messing with everything else when it is obvious that you need to solve this issue at the source.

Messing with the core handling and braking aability just to have a different lower yoke is just wrong! if nothing else, performance over looks...but safety too...and this sounds unsafe to me.

[Jon]

As CMSMJ1 says pics would be handy.

I would be aimimg at around 25mm of sag with a rider on the bike, any more than that and you are just loosing suspension travel for no gain.
The only reason have any sag is to stop the suspension topping out as often.

I run my forks the bottom of the cap is flush with the top of the top tripple clamp, run about 5mm static sag, 25m rider sag and straight rate springs.
I cant remeber what spacer length I ended up on top of my springs, i dont use my preload adjusters much they are mid way and I dont fiddle with them much as I generaly set the sag and dont try and fine tune with it.

The cable tie on my forks ends up around 20-25mm away from the bottom tripple clamp after a track day.

[mozzi3]

Obviously the problem is the yokes, not allowing the full travel, but it got me wondering how much travel most people use, and i guess the answer is pretty much all apart from maybe 10mm or so. I stripped my forks to check the springs and they are fine, (free length the same as when they went in), as it was time for a change of oil anyway. I remembered i used silkolene 10W with an air gap of 150mm. Well thanks for all the input. I need to get the yokes modified. For your info they were one off custom yokes, from a guy in the UK who has made NC30 yokes before. I'll post some photos later, as they are really nicely made.

[superlite]

I remembered i used silkolene 10W with an air gap of 150mm

The Haynes manual lists air levels of 90 mm for early model forks and 122 mm for later model forks. A 150 mm gap will be reducing your some travel for sure.

[mozzi3]

Yes it does but i'm not using original springs, i use Hagon progressives springs, they recommend 10W oil and a 150mm air gap.

Anyway i think the suspension is Ok from what has been said, the problem is only the reduced travel from the new yokes.

[Spike16]

the forks wont go all the way up to hitting the yokes, they will bottom out before then. best thing to do is when u have no oil in your forks put a cable tie on fully compress the forks and this tie here then reassemble the front end and put another cable tie on and take the bike for a ride. then you can measure the difference between bottoming out and the max travel you are using. (these will be the bottom edges of both cable ties)