Handling with 18" rear wheels.

As part of the rebuild of my 850 MK 2a I am building new wheels. The front will use a hub I've machined up from HE 30 to suit the twin disc set up I'm using. This I am keeping 19" with my current Roadrider 3.25 x 19". For the rear however, I propose to use a Honda rear disc type hub which has a superb cush drive. With this I would like to use a Roadrider 4.00 x 18" on either a WM 3 (2.15) or WM 4 (2.50) rim. This size Avon will just fit in nicely at 116mm wide. Why you are probably thinking. Well the tread depth of the 100/90/19" size is 5mm. The depth of the 4.00x18" is 7mm. As I currently get through a rear in 3000 miles or less every little helps.
Has any one tried a 18" rear wheel with this size or 110/90/18 size tyre & how does it effect the handling.
I might add that my original plan was to use the new Continental radials, but the rear 110/85/19" size which would be perfect for our bikes, is not yet available. The British importer contacted Germany and they couldn't even give a date for the start of production.
Cheers,
Martyn.

Matchless said:

As part of the rebuild of my 850 MK 2a I am building new wheels. The front will use a hub I've machined up from HE 30 to suit the twin disc set up I'm using. This I am keeping 19" with my current Roadrider 3.25 x 19". For the rear however, I propose to use a Honda rear disc type hub which has a superb cush drive. With this I would like to use a Roadrider 4.00 x 18" on either a WM 3 (2.15) or WM 4 (2.50) rim. This size Avon will just fit in nicely at 116mm wide. Why you are probably thinking. Well the tread depth of the 100/90/19" size is 5mm. The depth of the 4.00x18" is 7mm. As I currently get through a rear in 3000 miles or less every little helps.
Has any one tried a 18" rear wheel with this size or 110/90/18 size tyre & how does it effect the handling.
I might add that my original plan was to use the new Continental radials, but the rear 110/85/19" size which would be perfect for our bikes, is not yet available. The British importer contacted Germany and they couldn't even give a date for the start of production.
Cheers,
Martyn.

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Since the OD of the tire doesn't change appreciably I doubt you could feel the difference. I have always gone to a 18 inch running either a 110-90 or a 120-90 on the rear of Commandos at the first opportunity. They definitely last longer. Jim

By far most my mileage and antics on/off road on Peel Combat was on 19" WM2 front and rear 18" WM3 with 120 tire. Main thing noticed was the extra mileage of 120 size. Lessor effect but detectable when really kicking up heels was slightly more tire mass sense, so slightly more throttle and effort to steer than lighter tire but not so much to out weigh the mileage factor gained. I found it harder to break a 120 free on or off road, so I liked it better on extra powerful/lighter Peel. On my ordinary Combat the same wheel 120 stolen off Peel felt too sluggish for the power levels I was willing to run poor factory Trixie to so went back to 110 for the lighter handling and don't try to run Trixie like a racer, just economical sane mostly legal speed use. 120 rear is a bit of a fight/squeeze to work in through fender/swing arm of course. If not scratching pegs much the wider rim will give a flatter profile for a tad more mileage but I like the rounder easier to tip sense of more 'pinched' profile rear. WM3 is a tad lighter than wider rim too. I get ~4000 miles our of 110 and about 1000 miles more from 120, if throttling normal-ish and refraining from much accelerating throttle but when leaned and not using engine braking much. If mainly only throttling up while always essentially straight up then knock over 1000 miles off the center life.

For what it's worth, Norman White recommends keeping the front and rear the same diameter. 18 wm3 on rear and wm2 or wm3 on the front.

The best feeling easy balanced light on feet handling is with both ends 19 x -100 or 110 on WM2 & 3 rims to me but if power to weight and spirit enough rear spin becomes touchy on far over leans I like 120x18 on WM3 the best. Ya ain't gonna get more foot print with bigger tire or wider rim but ya do change the far over lean profile shape towards sluggishness and more sudden unpredicable let goes than on more rounded profiles that lie just outside the tolerance of company liar/lawyers. If ya can get over 130 H rated tires definitely expand to narrower profile.

elefantrider said:

For what it's worth, Norman White recommends keeping the front and rear the same diameter. 18 wm3 on rear and wm2 or wm3 on the front.

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This is the setup I've gone for on my Production Racer, with WM3 both ends - similar to my Ducati, which is pretty easy on tyres compared to my 850 Commando on 4.10H19 TT100s.
I've gone for Avon Roadriders, 100/90 front and 120/90 rear.
Maybe one day I'll finish it and report back :roll:

Thanks for the replies. At the moment I waiting to see if the 110/85/19" radial Conti's become available before building my back wheel.
Cheers,
Martyn.

My current 850 Mk III was rebuilt by Baxter's in Iowa over five years ago now, for some guy who put only ten miles on it in that time and returned it, saying he fancied a Rocket III. So they traded it for him, I saw it on the internet, bought it and imported it back here to Australia.

I am extremely happy with it and ride it everyday when it is not raining, even just to get the milk from the corner store. Then longer trips on weekends with Jenny on the back, out to wineries and restaurants etc out in the countryside. I love the precise steering (an attribute of all Nortons, or certainly should be) and the frame feels as stiff as…..well, I'll use "board" for a description.

But I am puzzled. Alloy rims are fitted, 19" front and 18" rear. Tyres are TT100's both ends. So no change to original specs bar the 18" rear diameter. Why would you do this with both tyre profiles the same? Ah La Triumph Bonneville set up in the early 70's

Out of curiosity, I phoned Jeremy at Baxter's and he wasn't sure. He said it just seems to be a thing in the USA where an 18" wheel is preferred when a Norton restoration is done.

What are you crazy yanks thinking now?? First it was handlebars so high (e.g. Roadster) where one has to stand on the seat whilst riding to reach them!!
Forty plus years later you want little back wheels??

I am not at all unhappy, and have no intention of changing anything. Because you know it is a smaller rear wheel, you might imagine that the bike looks like it sits ever so slightly lower at the rear. But I don't really think you can see it.

But I want to know, from any crazy yank in here (all yanks are crazy
Why would the bike be set up this way? Is there some perceived handling improvement?

On my last bike which my mate Pete Lynch built, we went for an 18" alloy rear wheel, but we fitted a larger tyre. On the front, also was a fatter than original tyre. That bike did not have steering as precise as this one, so I would not do that again.

Okay guys, you have approximately 24 hrs to answer my querie, before I shut this whole GOD DAMN forum down!!
Start thinking!!!

I left out the TT100 tyre sizes though you probably guessed.
4.10 X 19 Front
4.10 X 18 Rear.

24 hrs starts from NOW!!

Greater tyre choice for the rear comes to mind first!
Regards Mike

Brooking 850 said:

Greater tyre choice for the rear comes to mind first!
Regards Mike

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Yes I had thought about that Mike.
But then the Dunlop TT100's were fitted anyway?

I have absolutely no problem with the set up. Just curious. Jeremy did suggest perhaps some perceived slightly improved high speed handling.
But sounds awfully vague to me.

23.5 hrs to go boys, then this joint goes UP!!!

Mainly higher speed rating and race compound slicks only come 18" so that's what modifiers aim to mimick I guess. I've switched between 19" and 18" in same afternoon and on same familiar routes d/t flat switch out to say if just tooling around commuting its hard to tell any difference and tire width made more difference than rim dia, wider more heavy sluggish but don't let go on leans as easy so can go around faster but not necessarily quicker. Might foul on leans a bit sooner it both rims are 18" which tend to be lower ~1/2". On off road rough stuff I like the 19" a bit better but only a little more.

when I sent both of my hubs to master wheel builders, Buchanans' in California, they recommended that they build out a 19 front and an 18 rear specifically because I would have far better choice of modern tires, they also built the rear a little wider rim for the same reason.

I then talked with Heinz kegler to confirm and he said yes, as a Norton test rider, he felt a Commando simply handled a little nicer with an 18 rear and recommended that to Norton, who then decided on 19 because of the simplicity of consistency with the British tire suppliers at that time.

Finally called Metzeler here in the US who said to fit their Road Riders and to run 32 front and 35 rear psi.

with time running out, that's the best answer I can give, and I have been quite happy with that decision for the past 15 years

1up3down said:

when I sent both of my hubs to master wheel builders, Buchanans' in California, they recommended that they build out a 19 front and an 18 rear specifically because I would have far better choice of modern tires, they also built the rear a little wider rim for the same reason.

I then talked with Heinz kegler to confirm and he said yes, as a Norton test rider, he felt a Commando simply handled a little nicer with an 18 rear and recommended that to Norton, who then decided on 19 because of the simplicity of consistency with the British tire suppliers at that time.

Finally called Metzeler here in the US who said to fit their Road Riders and to run 32 front and 35 rear psi.

with time running out, that's the best answer I can give, and I have been quite happy with that decision for the past 15 years

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1up3down
Your name implies you are more interested in bedroom activities rather than riding Nortons.
But I will tolerate this……..for the moment

Yes, tyre choice seems but the most likely answer. When Pete built my last Combat, we did the same, for the same reason.
But my current Mk III comes with 18" wheel, fitted with 4.10 TT100. That's what puzzled me.

You may have just saved the forum from total annihilation but I haven't decided.
I'll see what my fancy is tomorrow morning

Phil

phil yates said:

1up3down said:

when I sent both of my hubs to master wheel builders, Buchanans' in California, they recommended that they build out a 19 front and an 18 rear specifically because I would have far better choice of modern tires, they also built the rear a little wider rim for the same reason.

I then talked with Heinz kegler to confirm and he said yes, as a Norton test rider, he felt a Commando simply handled a little nicer with an 18 rear and recommended that to Norton, who then decided on 19 because of the simplicity of consistency with the British tire suppliers at that time.

Finally called Metzeler here in the US who said to fit their Road Riders and to run 32 front and 35 rear psi.

with time running out, that's the best answer I can give, and I have been quite happy with that decision for the past 15 years

Click to expand...

1up3down
Your name implies you are more interested in bedroom activities rather than riding Nortons.
But I will tolerate this……..for the moment

Yes, tyre choice seems but the most likely answer. When Pete built my last Combat, we did the same, for the same reason.
But my current Mk III comes with 18" wheel, fitted with 4.10 TT100. That's what puzzled me.

You may have just saved the forum from total annihilation but I haven't decided.
I'll see what my fancy is tomorrow morning

Phil

Click to expand...

As an aside, real Norton gear boxes go 1down3up. You won't know this until you own a Mk III. Then you'll wonder how or why does anyone bother with those earlier excuses for a Norton with the Commando name.

Now don't anyone go upsetting me, remember I've got my finger on the big red button!!

I believe it was popular in the States 20 years ago to allow a fatter rear tire and more agressive look. That said, having two diameters front to rear is probably not the fastest way around a corner..... just ask the Harley chopper guys. And I do not think the 18" rear with 19" front is a popular choice in the UK.

Are the lights still on?

Go the 19 front 18 back WM3's
Far greater application range and brand choice from 90 front to 130 rear.
I run tt's at the moment but have choices from avons (which were excellent) to conti's (which I'm really excited about)
I have the sunn alloys on mine and love them
Don't look back

i know better than snuff a good Harley that's low in rear tall in front so my fastest combo on next Peel may be 16" rear in bias ply and 19" in radial. TC runs this combo on his long distance 850 so tell him how misguided he is as wasting time on me.

Mr. Yates, I'm sure you recall Maxwell Smarts reply to Chief Red Cloud when Red Cloud had his finger on the button...
Let 'er rip Red Cloud... that was funny!
Craig

The selection of 19" tires is better now than it was 10 or 15 years ago; there was a time when it seemed like Dunlop suspended production of the K-81 in 4.10 -19, or maybe it was just that there was wider/better rubber in 18; I used to run a 4.25-18 K81 that in my opinion was a definite improvement in both handling and longevity over the 4.10. Anyway, that's when I went to 18" rear, never regretted it. When to an Atlas rear wheel, maybe it was a very early Commando wheel but 18 inch, with the three lug nuts as opposed to those little rubber cush pads.

The difference in tire circumferences between 18 and 19 inch wheels is not that great and actually within each nominal diameter (18 or 19 inch) range you can find a variety of aspect ratios that result in cross overs of circumferences. So, I reject the idea that you should have wheels of the same nominal diameter because you can arrive at the same actual diameter by adjusting aspect ratios. And then, why should tires have the same diameter anyway? What rule, or explanation, of physics says that it's better?