Tricked Ya! They're a pair of 16"s

Well, really, I cannot be sure what size they are... could be a set of Marchesinis?

In all seriousness now, before you do the switch, is there any chance of you getting some empirical data for a Before and After comparison of the change?

E.g. Have/will you record lap-times at your local race track of your performance on the 16/18 combination, so you can compare the-lap times to your 18/18 result?



I hear you, I had a XL500s with a 23" hoop as a demo bike for 6 months. It would roll over anything!

No I won't be doing a comparo because my bike will have a "proper" head stem angle & if I drop in a 16in wheel then the bike will become to nervous/unstable.
It occurs to me that Ducati knew that their F1 was a slow steering bike, so they dropped in the 16 to speed steering up a bit ?
Also if it's true that monjuie shock is longer, then it makes sense. they had to lift the back of the bike to maintain steering equilibrium with the std F1.
What headstem/steering head angle did you have your bike adjusted to ?

What do you propose to do? Are you planning to chop the head stem and change the angle of it?

I was suggesting that before you make any changes at all to your F3, you record your lap times with todays configuration. If you can go 2 seconds a lap faster after you have made your modifications you will hard evidence that you have improved the bike.

That we may never know for sure, but in 1983 Honda proved beyond any doubt that a 16" front was a world beater when the VF750 won (1st & 2nd places) the Castrol Six Hour "Show room showdown" for stock standard bikes and continued to wipe the floor with the opposition (who used 18" wheels) for the next two years including winning the 1985 Daytona 200. Winning races from 1983 thru to 1985, that is impressive

I disagree with Falloon that 16" wheels were "just" a fashion statement. When your opponent completely dominates for TWO YEARS with a technology as low tech as a smaller front wheel you really have to sit up and take notice . Yamaha, Suzuki and Ducati duly did take notice were soon developing strategies (possibly only sales strategies) around this new technology to catch up with Honda. That just makes more sense to me to be the reason Ducati followed suit.

Eventually evolution and the need to provide the bike riding public reason to upgrade to a new bike, 17" wheels were introduced. And the rest as they say, is history

I do know for sure that this bike was designed from the ground up to leverage both a 16" front wheel and Radial tyres (a new technology in 1985). The very different profile of the Radial tyres required many changes in the configuration of the chassis and suspension over the TT.

FYI - The theory was that the 16" wheel was lighter (because it is smaller) - less unsprung weight, which improved suspension performance, - less gyroscopic effect from the smaller radius - which made handling more nimble - an issue for inexperienced riders AND POTHOLES!

I am 99% sure they are the same length. I have a spare steel and aluminium swingarm also, so I will measure them up to see if they are they same. I think they will be.

If that question was directed at me I am sorry but I don't follow? I never attempted to change the rake of a bike. Does that involve chopping the chassis?

Hi Peter,
I'll go out on a limb here and say I'm not sure bevel MHR 18" wheels are your best choice. They are pretty skinny for an F1. The 5-spoke Oscams are tubeless type, but the 6-spoke are tube type. Both are the same widths. I think the best choice, if you insist on a 18" front, would be a set of Alazzurra Oscam wheels. They are cheap, readily available, totally drop right in, and the same style as the F1's. They are all heavy, but old magnesium wheels are no longer safe on today's crappy pavement. I also think you would find the steering would be just fine, as it is, what ever diameter front is on it. It's a street bike right? You could fine tune it, if necessary, by adjusting the length of the shock. I suspect your biggest issue with an 18" front would be a workable fender.
Bill

My marvics went to Bill long ago for use on his bevel. Now on modern 17 inch wheels with radials.

If you are building a street bike, I would recommend 17x3.5 and 17x4.5 off of a 900 ss/cr or 750 ss. With a 4.5 rear, you can fit a 160 section and clear the swingarm. The front will fit in the forks and will clear the stock front fender. You'll just need to adapt the front brakes onto your forks.

Mike, my apologies once again.
I went back & checked your full monty. You did frame/ headstem repairs, I read it as changing the rake !
So yes I intend to cut the chassis & change the rake.
Another : I was talking about the shock length, not the swingarm.
Yet another : As for evidence thru scientific testing, I am sure it has all been done before. I have read a couple or more times in these pages (somewhere) of folk taking a couple of degrees out of their rake angles.
26 degrees is very old school. - "think " turning a ship as compared to turning a dinghy.

Bill & Geoff
I agree with you that the 18's could be too skinny, but my tyre guy tells me that the race 18in's have plenty of grip.
Was hoping there would be some alum campagnolo's but ? I would not use magnesium on the road.
I checked today & there are no 5/6 spoke carbon wheels available, just a 3 spoke.
I would like this bike to be period correct if possible, but I may have to fall back on 17's
I believe that with 2 equal diam wheels you would be battling to get neutral steering with the 26 deg headstem, just by raising the rear/dropping the front. If I were running 17's then I might go for 24.5 and use the up rear/down front adjustment to get it right.
This bike will not be ridden to the local yoghurt shop & back. It has to cope with a tight mountain road near where I live - called Reefton Spur 200 corners within 19 km's
Tomorrow I will attempt to talk to 2 motorcycle engineers as the skinny 18's may have to be allowed for in any changes.
all for today folks, Peter

To me, when someone starts talking race tires for a street bike, that's a big red flag getting run up the pole.
Bill

Just to keep things in the same spirit (confusion), let's talk about 16.5" wheels now! They are cheap. Yes, I am trying to joke.

I remember constantly (gradually, over the years) modifying my 78 Guzzi Le Mans, trying to make it "better". One day I could not recognize it. So I restored it and built a cafe with the hot rod parts. Both bikes were happier. MikeV

my input at this point, now we're talking frame modifications, is that you sell the f3 to someone who appreciates its value as a lams bike and buy something later model and fit f1 bodywork to it.

you can buy f1 style tanks to go onto carby ss from a german place, and it'd probably fit an ie too as the frame is much the same.

http://www.ks-kunststofftechnik.com/pro ... aujahr-91/

or use a monster for the tt1 look

Ahhhh...... Brad just to throw some more confusion into the pot
No more french vanilla slices for you !

An I hate to admit it , but it is a good idea
There is still much to be considered Grasshopper before we can go forward.