- Dec 20, 2011
acotrel said:I've just measured the offset of the Arces fork yoke s which were fitted to my rolling chassis when I bought it, and caused the bike to stand up under brakes and turn. The measurement is 65mm (2.6 "). I haven't checked the head angle on the frame yet, however it is an original Mk3 Seeley and should be 27 degrees. The difference in handling between the Arces fork yokes and the TZ350 yokes is extreme, you cannot miss it. I could not race the bike when it was fitted with the Arces yokes, it was simply impossibly dangerous
I understood that fairly small changes in offset make a considerable difference. (I was given 2.25" as the offset used as standard on Seeley, Rickman, Featherbeds and Commandos) I was considering trying around 2.0", but decided to build and ride first with something probably more 'neutral' since I going with longer shocks and plenty of scope for leg length adjustment. The bike is on 18" rims and last time I rode this actual one it was on 19" so plenty of change anyway...
I can see that 2.6" would likely be too much offset.....1.4" also seems extreme in the other direction and I guess what you really describe is a need to use power to steer it at all!.....so I am guessing that if you fitted 2.25" it would give you more neutral steering....might be more less 'fun', but less worrying?
Since I also now have slightly longer swinging arm I can see that I may want less offset in future....but we will see....just need an engine and gearbox in it to find out!...If I did change I don'tthink I would go less that the 1.75" DWS first mentioned...
BTW 2.6" is nearer to 66mm by my calcs and we seem to have gone over a range of different figures quoted in each post.....I noted my own error for which I apologised, I thought initially my yokes were 2.5" but rechecked my figures and corrected to 2.25".....a change from 2.25 to 1.75 is I understand significant and I guess I am surprised to see figures much outside of these in use on any period frame be it Norton Twin or 7R/G50 or Manx.