Wheel Sizes Revisted

Hello All: I am new to this site, but not to Commandos, although it has been sometime. Back in 1982 I sold my '74 850 to a buddy of mine. Being an A & E for a major airline, I knew it was in good hands. About 5 years ago, he discovered Harleys and moved over to the dark side (kidding). Anyway, I offered him some cash for my old Commando, we struck a deal, and 25 years later it came home to Cheeseland.

After sitting for a year, I finally have some funds to update the bike. It hadn't been run in a number of years, and did need some work. First priorty is the wheels- and the age old question of wheel size upon rebuilding. I have heard many good discussions about 18 vs. 19 on the rear, but has anyone out there ran 18 on both front and rear with decent results? I have heard of AHRMA Commando racers running 18's front and rear, and I am interested in the effects of handling, etc. I know size of the tires will effect this as well. Just looking for some info about handling, tires sizes used, makes of tires used, etc. Will a slightly longer set of shocks speed up handling enough to offset perceived slowdown due to tire size?

The bike current has an 18 on back, so unless I spend more there, I am going to run that. Thanks for the feedback...!

Lowering the bikes front end a half inch or so should speed up the steering just a bit. Maybe through tire selection you could slow it back down again. Use a wider tire but I would not do that. Pair's of 18's are used all the time by the vertically challenged. I have never heard them wine about the handling. I started with wider tires in the 1990's and have slowly returned to 90/90's up front and 100/90 at the back. Be careful about your choosing now don't fall into a tire trap.

as someone looking to get a commando at some point in the next year or 2. either good one, to restore or a norvil restore.

this was something i was interested in too, esp as i am ony 5'6 and seat height is a concern. tho my dad had one and he is only a little taller than me(plus his had clips ons etc). i have an sv at the mo and it is a little bit of a problem esp backing the bike or when u quickly have to put your foot down on loose grave or ice etc.

too hear that it doesnt effect handling too much is good to know

I run 100/90 18 and 110/90 18 on 2.15 and 2.50 rims respectively on a Mk111 and I'm very happy with it. Running a wider tyre on the rear has kept the ride height more or less original but retaining the standard width on the front (on a wider rim) has meant that the front is slightly lower which does bring the stand pivot closer to the tarmac.

The bike does now turn quicker and I find has less tendency to patter wide on bumpy bends but that is not a problem that everybody has.

Fitting 18" rims will not make the bike an unrideable camel but neither will it turn it into a modern sports bike.

I run a 19" WM2 on the front and an 18" WM3 on the rear.
This means my rim is wider on the rear.
The width of tyre you use depends on the width of the rim on the bike.
I run AVON Roadriders, a 100/90/19 on the front and a 110/80/18 on the rear.
Do not use a 120 tyre on the rear unless you have a WM4 rim, or the set of your tyres will be wrong and result in snake like handling. A WM2 rim is good for a 100 tyre, a WM3 rim is OK for a 110 tyre, a WM4 is good for a 120. That is as wide as you can go anyway.
The mistake people make is putting a 120 tyre on a WM2 rim.
I would advise keeping a 19" wheel on the front for high speed stability.
Stuart.

I recall talking to one of the U.S. east coast Norton parts suppliers about rear tire width. He said he was developing a new wider swing arm to accommodate a 140 tire. When I pointed out that the chain is in the way he seemed stumped. Unless you offset the rim a bunch it isn't going to work. After dealing with him for three or four years I came to realize he didn't know from Shinola about Nortons. Ya', I know, I catch on quick. Also, I had another supplier tell me that you should not use a rim wider than a WM2. Screws up the handling he said. Well, I've got a WM4-18 with a 120/90 tire. It improved the handling. So much for parts experts.

My non running MKIII has an 18 rear and 19 front. I'm not sure a rear 19 will give any decent larger counter shaft sprocket, It's got a 21 t. 21T seems to be the big one.[/img]