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Originally posted by andyb Couple of points, there are numerous rockers available across the ducati range, let alone stuff used for race. There are also different stroke length rear shocks, even between a bp and mono. The 749r rocker and tie rod was fitted as it is indeed the better track focussed set up, because of tougher homologation rules. If you look in the ducati catalogue, this is now also sold as an upgrade kit, including the shorter stroke shock! rather than talking about tie rod lengths, we should concentrate on using the datum tool, that is the only real way of making a comparison between bikes. Incidentally every time we adjust a chain, blow a tyre up it has the potential to alter the ride height.............best get checking! |
Rear ride height is usually used to alter head angle so for really accurate settings I'd suggest using a fork angle gauge, we do this for our DH race bikes, means you can allow for any changes in sag, front/rear ride height tyres etc and get an accurate setting with rider on bike although only at standstill. A datum tool isn't that much use , it was needed on the single sided bikes but has little relevance on the 999 where the height doesn't alter by the same amounts when the chain is adjusted, adjusting the chain on a 999 slightly alters the amount of rear wheel travel and the leverage ratio as well . The relationship between tie bar length and actual ride height remains constant (bar the small variation for that) 1 turn equates to 1.5mm and at about 1.8:1 giving or taking the small variations in progression means you'll alter rear ride height by approx 2.7mm for every turn. Accurate enough for me anyway given that wearing different clothes is going to cause 1 or 2mm more or less sag.
I wasn't aware of any different stroke lengths between mono and bip, wonder which models and by how much?? i thought they all ran 71mm stroke shocks (bar 749R) and the spring weight varied??
the 749R also has a completely different pivot point and has sheer bolts to limit wheelbase length it has a 56mm stroke shock, different rocker much higher leverage ratio and is more linear which is why it ran that different linkage and tie ba. most designs aim to keep a lower ratio as it involves more shaft travel for a given bump size which is easier to control , it would be a track thing as you don't get the same variations in road surface or conditions as road.