10,000 miles

Strange, because in the ancient film of "wobble and weave" (from Dunlop i believe), the cure for weave is to lean forward. With standard footrests I would say there is very little weight on the pegs.

ntst8 said:

"The engine is an absolute delight. Pickup from highway speeds for overtaking is outstanding"

What rpm are you doing at 60 mph?

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22 tooth gearbox sprocket. Around 3000 rpm.

gripper said:

Interestingly, my Fastback has WM2 front and WM3 rear and 19 inch road riders, Koni rear shocks, rose joint head steady, vernier isolastics and Landsdown forks. Apart from the width of the rims and the rake angle (being a 1970 model) very similar spec. Hacking round the Welsh countryside is no problem but there is still a sniff of a weave at above 75mph on the straight. Probably down to my weight and rake angle I guess.

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Well, there you go! Go to 2.5 inch rims. You will notice a big difference. You have the same tyre on two different rim widths. How can that be a good thing?

gripper said:

Interestingly, my Fastback has WM2 front and WM3 rear and 19 inch road riders, Koni rear shocks, rose joint head steady, vernier isolastics and Landsdown forks. Apart from the width of the rims and the rake angle (being a 1970 model) very similar spec. Hacking round the Welsh countryside is no problem but there is still a sniff of a weave at above 75mph on the straight. Probably down to my weight and rake angle I guess.

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Your bike is similar to mine. I have an 18" rear wm3 cast rim with a 110/90/18 roadrider which is pretty close to the 100/90/19 front's diameter instead of your 19" rear. I also don't have the landsdown fork internals.

I have koni progressive shocks with adjustable damping like you do. I have jim's headsteady too and I do have a '70 frame with the 27 degree angled steering head with the early yokes which have less offset (which yields more trail than later yokes) The biggest issue regarding weave in my bike was the slop in the early model, single bolt swingarm tube. I installed the kegler clamp modification on the swingarm tube and my bike handles beautifully. I rode that bike for years and wondering why it handled so poorly, which the kegler clamps cured.

In earlier attempts to cure crappy handling, I changed to adjustable isolastics, I replaced the swingarm bushes (needlessly) and meticulously checked my previous spoked wheels for run out. None of this took away the noticable weave. All the early model bikes with a single bolt in the swingarm tube need the kegler modification or to change the cradle to the later 2 bolt swingarm tube cradle to eliminate sloppy handling.

I have a standard swingarm pivot setup. I have never had a problem with it. That tyre is too wide for your rim. Look at Avon's recommendation for the tyre. You do not get the optimum profile from that combination.
Have you ridden many different Commandos over the years?

Fullauto said:

I have a standard swingarm pivot setup. I have never had a problem with it.

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Standard... ??? you make it sound as if there's only one version of the commando engine cradle/swingarm tube design. The early commando cradle's swingarm tube with a single bolt in the center gets sloppy as time goes on. Eventually norton changed their design to have 2 bolts that pinch the swingarm shaft in the tube. The early swingarm tubes are reputed for getting sloppy over time which leads to a weave... I don't think I'm inventing this fact. I think it's well known and I certainly had improved handling by modifying my early swing arm tube to eliminate this slop.

If you have this early version of the cradle and single bolt swingarm tube and it has zero play in it, then I'm psyched for you. I have chased poor handling for years on stock 19" norton spoke rims and twin 19" dunlop TT100's. MY problem was the swingarm tube, which many early commando owners have also modified similarly and endorsed as a worthy fix. If you'ld like to deny the validity of this modification, I think you'll find a lot of people who'll say it fixed their weave issue... but don't let that stop you..

As far as optimized tire profile, I agree with you that you get a better shape by mounting a given tire on the recommended rim widths. Having the optimum tire profile gives you to maximum contact area when you lean the bike over. Certainly more area is best.

I think there's a lot of comments made that simply mounting an 18" tire on a commando automatically degrades it's handling. Unlike rim width and tire profile shape where you can show the tire's contact patch area is diminished on the less optimized rim, there's nothing scientific to show that front and rear tires on a given motorcycle that are geometrically the same, automatically make for the best handling version of that bike... Right??

In fact when you look at race bikes, are the rims and the tires in the front and back of the bike exactly the same? So what science can you point to that would explain this? If you feel this is a fact for a commando, can you explain it scientifically or are you relying on... "that's my opinion and I know more than you" ??

Honestly, I like factual explanations to consider something a fact. I don't accept opinions as fact without a reasonable explanation.

What can I say? I've never had a problem with my swingarm pivot. I regularly put some 140 weight oil in it, but that's all. Never an issue. The swingarm pivot was changed at rebuild time just because it had a bit of corrosion. Like I said, zero problems in, at that time, about 40,000 miles of my ownership. If yours was worn out, of course replacing it would fix ONE aspect of the handling package. But don't make it the be all and end all of Commando handling. I have looked at all aspects and come up with the best combination to make the best handling and behaving Commando I have ever ridden over 40 years of familiarity with Commandos.

Comparing a modern motorcycle's handling, especially a modern racing motorcycle, is the old apples and oranges argument. They bear little relationship to the dynamics of how they both work on the road. They need wide rear tyres on the rear to handle the tremendous amount of power which are put through the rear end on acceleration. The lines used are different, techniques are different and the dynamics are different. You are implying that I am saying that you need identical tyres on both ends for best handling. Where do I say that?

I'm prepared to bet that my 100/90 x 19 tyre and rim combination put more rubber on the road, AT ANY LEAN ANGLE, than your 110 section tyre on a 2.15 inch rim. If you want to go through the exercise and prove me wrong, go for it. I'm not prepared to waste my time. Until someone builds a bike like mine with all the items listed, and confirms my findings, then I'll just sit back and enjoy.

Saying that your bike is "similar" to mine, is patently false. You have some of the mods but not all.

Accepted wisdom may be accepted, but it's not necesarily wisdom.

fullauto, Your reading comprehension sucks....

I never said my bike was "similar" to yours. I said my bike was similar to grippers... look back at my previous posting. He and I both have '70 commandos and he has a slight weave around 75mph...

From what I can tell from your picture, your bike is a later model frame, so you have the improved swingarm tube, so you wouldn't have any swingarm tube problems... (but GRIPPER and I might because we both have early model frames and our cradle swingarm tubes are different than yours)

I never said that YOUR wider rims put LESS contact area on the road surface at any lean angles. In fact, I acknowledged that it is in fact true...... So I was agreeing with you.

As far as me asking you about your opinion of tire sizes, I did not imply that you made any statments about whether certain bikes were better with matching tire sizes or not. I asked if you thought there was a scientific basis for determining such a thing, because I'd like to know WHY any knowledgable person thinks that is true.... "WHY", being the operative word, because I scientific explanations of WHY leads to facts, where as answers like, "because I've been riding commandos for 40 years" isn't an actual scientific explanation of WHY....

Anyway,... I didn't mean to shit all over your thread, because you have a beautiful bike, but you jumped on my ass when I was commenting to GRIPPER, (not you) that his slight weave problem might have the same cause as mine, which the kegler modification cured on my bike...

So, your bike is awesome. I'm totally psyched for you. Sorry that I tried to give gripper a "heads up" about a flaw on our shared model year bike.

To the point made about swing arm and cradle development and changes over the years,
Andover lists the following numbers for Commando cradles early to late- 06-1411, 06-0424, 06-3146, 06-4060, 06-5140.
For swing arms there are three, listed early to late, increasing in rigidity- 06-0441, 06-4539, 06-5888.

Glen

o0norton0o said:

fullauto, Your reading comprehension sucks....

I never said my bike was "similar" to yours. I said my bike was similar to grippers... look back at my previous posting. He and I both have '70 commandos and he has a slight weave around 75mph...

From what I can tell from your picture, your bike is a later model frame, so you have the improved swingarm tube, so you wouldn't have any swingarm tube problems... (but GRIPPER and I might because we both have early model frames and our cradle swingarm tubes are different than yours)

I never said that YOUR wider rims put LESS contact area on the road surface at any lean angles. In fact, I acknowledged that it is in fact true...... So I was agreeing with you.

As far as me asking you about your opinion of tire sizes, I did not imply that you made any statments about whether certain bikes were better with matching tire sizes or not. I asked if you thought there was a scientific basis for determining such a thing, because I'd like to know WHY any knowledgable person thinks that is true.... "WHY", being the operative word, because I scientific explanations of WHY leads to facts, where as answers like, "because I've been riding commandos for 40 years" isn't an actual scientific explanation of WHY....

Anyway,... I didn't mean to shit all over your thread, because you have a beautiful bike, but you jumped on my ass when I was commenting to GRIPPER, (not you) that his slight weave problem might have the same cause as mine, which the kegler modification cured on my bike...

So, your bike is awesome. I'm totally psyched for you. Sorry that I tried to give gripper a "heads up" about a flaw on our shared model year bike.

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My mistake. For which I apologise most humbly. I don't do scientific arguments. But I do present stuff as I find it after much testing. I'm quite prepared to be proven wrong. Have been proven wrong before. I don't have a finger in the pie here, and nothing to gain. These are my findings. Prove me wrong. Scientifically or otherwise. I'm just here trying to help people make the right choices and not spend money they don't need to. The overall package is quite inexpensive as far as spending on Nortons goes, it's just money well spent.

Me again, I modified my swinging arm pivot to have two cotter pins as per the Mk3 so hopefully that would eliminate that problem. I have had 18" front and rear, 19" front was better, now on 19" front and rear. I think my problems are due to my weight and early rake angle, When two up or loaded with camping gear the straight line weave is non existent. riding long fast bends is not an issue either. during acceleration to speed there is no problem, it's the established +75 mph straight line cruise that starts the weave.
For winter I have a screen and top box on so high speed testing is always going to be iffy :lol:

In 1984 I had a standard 72 Combat Interstate, like you the weave set in (and it was frightening) at around 75mph.
I found the only thing to do was go faster and by 90 it had completely gone and the bike was stable again right up to an indicated 120 . In them days I was about 12 stone. I've since had another 5 Commandos including another 72 and have never experienced any more weaving, I'm also about 2 stone heavier now so I reckon you have a point.

I remember reading that it was a bad idea to hang heavy luggage on the back of a Commando, never took any notice of that, although the front end feels light until you are used to it.
sam

I rebuilt a Combat a couple of years ago and kept it bog standard.
With a 3.60 TT100 on the front it was pretty weavy, but when I replaced it with a 4.10 it was a lot more stable.