18" rear wheel???

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I have 2 Nortons both slimlines, The 99 runs old style Avon Speedmaster/SM tyres on 19" slim std Rims ,has raised bars and weighty Craven Panniers. Handles perfectly and turns in well. Grip is a bit suspect on greasy wet roads. The Atlas has Modern tyres on 19 " Alloy rims with a WM3 on the back. Handles like a loaded truck. Would hate to have to change line mid corner. Don't ride it . Son thinks its OK , but as my brother used to ride a very bent 88 and thought it the best handling bike ever , I don't give much weight to others opinions !!.
A featerbed Norton with 19 inch wheels and the 24.5 degree rake is usually a very precise nice handling bike. I stuffed my Triton by fitting 18 inch wheels front and back to get better rubber. The bike still handled OK, but in corners became neutral and very heavy to ride fast. With the Manx motor in the featherbed frame and 19 inch wheels, the bike oversteers slightly as you accelerate when on a lean. It inspires a lot of well-justified confidence. With the twin motors, the weight is a bit further back, so the bike is not as good to ride fast.
 
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If you don't usually carry a pillion passenger, softening the rear suspension might make a Commando with 19 inch wheels handle better. As you change the trail for any given rake on the steering head, the two handling extremes are self-steering. Lowering the back makes the bike self-steer a bit more in the correct direction as you accelerate through corners. If you raise the back or lower the front, you decrease the trail, and the bike will probably tend to run wide a bit more as you accelerate out of corners, and be more difficult to tip in as you brake for a corner.
When you get the handling right, the bike should tip in easily as you brake for the corner and feel very positive as you accelerate out - on a lean.
As you accelerate, the trail increases and it reduces as you brake. So the bike steers on the throttle and the brakes. If you get into a corner too hot, you have to choose a point at which you have to stop braking and accelerate. What the bike does then, is important for your health.
Being a bit complicated for me to undestand those technical informations, I do like my Avon 120-80-18, WM3 mounted for the overall look. The Norton 19'' skinny look always promote some regurgitation for me... My next project is to lace Madass hub to a MT3.50 rim and fit a 130-70-18. Is it going to end as fatal crash for me?
 

Derek Wilson

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I run a 100/90-19 0n the front and a 120/90-18 on the rear (BT-45's). Both wheels are the same diameter, and it handles very well.

I had been running a 110/90-18 on the rear, and it did affect how well the bike turned-in in the corners, it was a bit more sluggish.

My $0.02 - FWIW
 
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Some people do not discover there bike does not handle, until they get into a corner too hot. When that happens, it is normal to gently apply the front brake. The bike slows, but as the front goes down the bike tends to run wide faster. As the speed comes off, a point is usually reached where the rider must get back on the gas and ride out of the problem, or run out of road. Some bikes tend to oversteer as the front of the bike comes up. If they do that, the bike usually turns in the correct direction. There are no double lines in the middle of a race track, but on public roads, you can end up riding into the oncoming traffic if your bike does not turn when you gas it in the corner.
 
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I run a 100/90-19 0n the front and a 120/90-18 on the rear (BT-45's). Both wheels are the same diameter, and it handles very well.

I had been running a 110/90-18 on the rear, and it did affect how well the bike turned-in in the corners, it was a bit more sluggish.

My $0.02 - FWIW
I run a 4 inch rear tyre on the Seeley and you would not know it was there. But I have changed the fork yokes which drastically altered the steering geometry in a very beneficial way. The whole handling thing is a spectrum. As you decrease the yoke offset, you move your position in the handling spectrum from 'too wrong' to 'too good'. - It is the combination of rake and trail which affects where the self-steering occurs.. If you have very steep rake, changes in yoke offset make bigger differences to the handling.
 
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Fat rear tyres do not necessarily give you more grip. They also change the alignment of the sides of the front and rear tyres, which can make the handling feel stiff.
 

motorson

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I bought an Atlas 18" rear wheel and installed it directly onto my Commando. That is when I discovered that the offset is different. Luckily I was able to center the wheel right on the bike by adjusting the spokes. I like the 18 but I'm thinking of going with a WM4 19 shouldered aluminum Acront rim.
 

gortnipper

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Being a bit complicated for me to undestand those technical informations, I do like my Avon 120-80-18, WM3 mounted for the overall look. The Norton 19'' skinny look always promote some regurgitation for me... My next project is to lace Madass hub to a MT3.50 rim and fit a 130-70-18. Is it going to end as fatal crash for me?
That is pretty wide. Doubt it would be a fatal crash, bit I do have to ask why so wide? 120 is plenty, and you could lace a WM4.
 
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" I think I've read some threads or replies, that some install an 18" rear wheel on a Commando? Just curious, how it would affect the handling? "

T. C. favoured a 16 , in the days of the 5.10 - 16 Avon roadrunner .

Wider shoulder'd keep the pipes slightly ore favourably regarding grinding . Better rear brakeing two up touring .
If it works.
Better wear with the more rubber .

These guys dunno what a Contact Patch really is these days .

081011top-i.jpg


hats a Pirelli Licorice at 3 p.s.i. , thereabouts . You can see why it might not be to hot on Tarmac .
Was the Gun soft track tyre , around 1970 .
 
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An Eighteen .

tony_smith-jpg.16840


More Rubber'll go aft ( 4.25 0 with a 4.10 fwd . Rather'n the earlier P. R. 3.00 or 3 . 60 front .


5a20f9cd03c2cfc8932816729bb7d125.jpg


It'll hook up better with better traction , in the quater mile .
 
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