Aftermarket shock lengths and geometry questions

[gavins]

Yea, no problem. I expect both shocks are the same length and that the 15mm listed above is a typo as it says it raises the rear by 35mm earlier in the text.

I'll be in the outer paddock somewhere but i saw your name on the garage list so i'll wander over after quali sometime on sat morning and let you know where we are.

[GeeTee]

The Nitron I bought for my track bike was made +15mm longer at factory to compensate for 17" rear wheel

[28hodge]

Cheers for that Gee Tee, do you run the 30 or 35 rear link?

[GeeTee]

I run the stock NC30 link

I didn't want to modify link by re-drilling as this changes the ratio

[28hodge]

So having chatted to Rick O regarding this, hers what I have come up with.

My current spec is as follows, 17” rear wheel with rs250 rear shock and nc35 dog bone. This gives me the following –

17” rear = minus 13mm ride height
160/60/17 tyre over a 150/60/18 tyre gains me back 6mm (height of the 150/60 is 90mm v the 160/60 @ 96mm)
Rear shock is 310 v the 305 of standard so I gain another 17.5mm here (5mm length x by the linkage ration of 3.5:1)
RVK link at 108mm from the 113mm VFR link gains me another 17.5mm

So my current set up gives me the following

-13 from the 17” wheel
+6mm from the 160/60 tyre
+17.5mm from the additional 5mm on the shock length
+17.5 mm from the additional 5mm on the NC30 link

Giving me in total 28mm additional ride height. Ideal (and what Maxton aim for) is 35mm gain in rear ride height. So to gain those additional 7mm of rear ride height I ideally need to gain 2mm somewhere (7mm / ration of 3.5:1)

So I need ideally a shock that is 312 in length, or as Rick pointed out a 317mm length shock and then revert back to the nc30 link.

[GeeTee]

I fine tuned my ride height using pre-load adjuster. Think I dialled in around +5mm (at shock) from the setting my Nitron was supplied with. It started to feel a bit soft and under damped at Snetterton, but seemed ok at Oulton Park a few weeks later. I've not really fiddled with damping which is still on the middle setting it came with. It's a real pain to get at the adjuster on the bike, and not a very good design to be honest. The shock's done a couple of seasons of trackday's now so probably due a rebuild & refresh at factory.