Tires

acotrel said:

Many years ago I used to race a featherbed Triton on old T1 triangular Dunlops. I fitted 18 inch rims to get good rubber onto the bike and completely buggered the handling. The bike then became exhausting to race. A lot depends on the steering geometry. Getting that right involves more arse than class. Every new set of fork yokes costs a bundle and with many frames that is not an answer anyway. With my Seeley, I was just lucky - there is no proven formula.

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Well that's why I stated the 18" rear 19" front combo that I use have exactly the same rolling radius. So this fear is negated.

If you are working on the basis of preserving rolling diameters, doesn't that mean you presume the original set-up was the best possible for the application ? Also, if the tyre sizes are different when you use different diameter rims, doesn't that mean that when the bike is leaned in corners, that alignment of the sides of the tyres is different and the handling might feel stiffer ?
My feeling is that until you try the various combinations, you won't know what the effects will be. It is all an expensive exercise, unless you look at what the really good guys are using and copy them. Then you will probably only ever be as fast as them and not necessarily faster - unless you stick your neck out further.
As I have said, my Seeley is currently very good handling. However that is more by luck than good management. When I had that handling problem, it had the potential to cost me a couple of thousand dollars to find a solution . Even buying a set of Minnovation fork yokes would not have been cheap and that probably not have been as good an answer to the one I discovered. From what I have heard from people who race them, the Minnovation Seeleys feel stiff and a bit slow in the handling department.

Is Gary Thwaites' bike a Commando or a Seeley ? If it is a Commando, copy his tyre sizes. Doug Macrae's bike might be set up for Daytona, so might be a bit misleading if you want fast handling.

acotrel said:

My feeling is that until you try the various combinations, you won't know what the effects will be. It is all an expensive exercise.

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A splendid idea Alan.

I look forward to seeing your detailed analysis of all possible permutations. When can we expect this?

Meanwhile I'll carry on using the Roadriders.

BTW, I don't think many road bike riders either have a bike like Gary Thwaites or ride like him. So I don't think copying him would be terribly relevant for most involved in this thread...

Gary Thwaites ex Commando as he is now on a Trident and still winning.