Type rims? and tires

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lcrken said:
I'm with Nigel here, Joe. It seems like the 100/90 Avons should work better on wider rims, but in the real world, I'm not sure you would notice the difference. I've been riding with them for a long time on stock WM2 rims, as have many others here on the forum, and they work just fine. And they get ridden very hard on occasion. I like the way the bike handles with them. It is very neutral feeling in corners. It falls into corners very easily, holds it's line properly, and doesn't push coming out under power. What more could I ask for on a street bike, except maybe better mileage on the rear?

As far as using the 90/90 on the front, I don't know what benefit you would gain from that. It would certainly work. I've seen a couple of Commandos with that combination, just never tried it myself. I raced several Commandos back in the day, and all had smaller front and larger rear tires. In fact my first race bike, a Commando PR came from the factory with 4.10x19" rear and 3.60x19" front.

Having said all that, if I were replacing the rims anyhow, and wanted to stay with the 19" size, I would go with the wider rims (in alloy, of course!). I can't see any drawbacks to following the manufacturer's recommendations.

Ken
Click to expand...

In the real world the difference is significant. More than you can imagine. I beat my gums about this and only a couple of people have actually tried it. I feel sure that if a few people with more credibility than I were to try it, that it would be the next "big thing" or "must do" in Commandoland".

It's tough being a pioneer!
 
I recently installed WM4 rims both front and back with Avon tires and can feel a real difference.They fit with all the stock fender braces on my 74 roadster.
Plus,I like the way they look,The rims were Borrani alloy that I got from Buchannans
 
YING said:
I recently installed WM4 rims both front and back with Avon tires and can feel a real difference.They fit with all the stock fender braces on my 74 roadster.
Plus,I like the way they look,The rims were Borrani alloy that I got from Buchannans
Click to expand...

Yay! A true believer!
 
Before Road Riders there were AM Super Venoms, now available in a race compound only now if at all. I used them (not the race tires) with the stock skinny rims on my MK3 and they were very good. However, try as I may I could never get the bead to seat perfectly on any of them. The raised mold line that runs around the sidewall just off the bead on all tires should have an equal space between it and the rim for the entire circumference. I could not get this. The best I could ever do was a bit of 3/4 perfect and then more space where the bead was not in quite as far. Sometimes that index line appeared sucked into the rim a bit on the opposite side. The tires wobbled just the littlest bit too at there areas. Though I've wanted too I've never tried Road Riders because they seem pretty similar to the Super Venoms and I'm guessing they would mount up in the same fashion. I think this is because the rim is too narrow for these tires and the result is not just an altered profile all around but rather an inability of the bead to seat correctly. Those who have them on stock rims have a close look.

In 1975, it was a crapshoot as to what tire came on a new Norton. It may have had to do with what ever company gave them the best deal at the time or something else but I do remember that out of a line-up of new bikes, some may have Dunlop K81's and others Avon Road Runners in 4.10 size. I just stick to K81's now, and when the profile is still nice, before the rear gets flatted, they handle great. They were the 'cat's nuts' back in the day.
 
Biscuit said:
Before Road Riders there were AM Super Venoms, now available in a race compound only now if at all. I used them (not the race tires) with the stock skinny rims on my MK3 and they were very good. However, try as I may I could never get the bead to seat perfectly on any of them. The raised mold line that runs around the sidewall just off the bead on all tires should have an equal space between it and the rim for the entire circumference. I could not get this. The best I could ever do was a bit of 3/4 perfect and then more space where the bead was not in quite as far. Sometimes that index line appeared sucked into the rim a bit on the opposite side. The tires wobbled just the littlest bit too at there areas. Though I've wanted too I've never tried Road Riders because they seem pretty similar to the Super Venoms and I'm guessing they would mount up in the same fashion. I think this is because the rim is too narrow for these tires and the result is not just an altered profile all around but rather an inability of the bead to seat correctly. Those who have them on stock rims have a close look.

In 1975, it was a crapshoot as to what tire came on a new Norton. It may have had to do with what ever company gave them the best deal at the time or something else but I do remember that out of a line-up of new bikes, some may have Dunlop K81's and others Avon Road Runners in 4.10 size. I just stick to K81's now, and when the profile is still nice, before the rear gets flatted, they handle great. They were the 'cat's nuts' back in the day.
Click to expand...

All I can say, is try Roadriders. The TT100s were great tyres. In 1973. Things have moved on. Which they have a habit of doing.
 
Yeah but, TT100s today are not the same as they were in ‘73. They look the same, but they’re made out of modern, more sticky compounds. Hence they don’t last as long (nothings for nothing).

I used to run Super Venoms, I even ran race compound on the road once or twice, but to be honest, I couldn’t tell the difference. I assume I just wasn’t going fast enough for the bennefit to be felt!

IMHO, Roadriders are every bit as good as Supervenoms ever were, and they’re my ‘tyre of choice’ most of the time.

But having said that, my T120 has modern made, period looking Avon’s (so, also made from modern compound) and that bike feels just fine too.

My point? Different horses for different courses. Tyres are like oil, there is not one universal right choice.
 
Fast Eddie said:
Yeah but, TT100s today are not the same as they were in ‘73. They look the same, but they’re made out of modern, more sticky compounds. Hence they don’t last as long (nothings for nothing).

I used to run Super Venoms, I even ran race compound on the road once or twice, but to be honest, I couldn’t tell the difference. I assume I just wasn’t going fast enough for the bennefit to be felt!

IMHO, Roadriders are every bit as good as Supervenoms ever were, and they’re my ‘tyre of choice’ most of the time.

But having said that, my T120 has modern made, period looking Avon’s (so, also made from modern compound) and that bike feels just fine too.

My point? Different horses for different courses. Tyres are like oil, there is not one universal right choice.
Click to expand...

Like I've said ad nauseum, 2.5 inch rims make all the difference. the few who have tried it, acknowledge the difference. I still think most choose rims based on looks, rather than function. Another win for form over function.
 
So what would be wrong with Avon Roadriders in 90/90-19 front and back? Going to new rims is a lot of trouble/expense. The question is wouldn't you see the same improvement that is claimed for 2.5 inch rims with the 100/90-19? The 90/90-19's would fit right and have the right footprint that was mentioned above. Right now I've got two 100/90-19's waiting to go on. When they're worn I'll try the smaller version unless someone's had experience with that and there is a good reason not to.
 
Joe Schlaberdowski said:
So what would be wrong with Avon Roadriders in 90/90-19 front and back? Going to new rims is a lot of trouble/expense. The question is wouldn't you see the same improvement that is claimed for 2.5 inch rims with the 100/90-19? The 90/90-19's would fit right and have the right footprint that was mentioned above. Right now I've got two 100/90-19's waiting to go on. When they're worn I'll try the smaller version unless someone's had experience with that and there is a good reason not to.
Click to expand...
All I can say about the 90/90 is I have one on the front of my T150. This bike also has 19" rims front and rear. The front being a WM2 like the Norton but the rear is a WM3. The rear is a 100/90 and fits great by the way. I wanted to lighten up the front a bit on this bike so opted for the 90/90. This combo works well and I have no doubts two 90/90's on both ends of a MK2 or 3 would work well too. The downside is this tire looks skinny on the Triumph front and I think would look positively anemic as a set on a Commando. And the rear would probably wear even faster than 100/90 (if that's possible) on the rear.
 
Fullauto said:
Like I've said ad nauseum, 2.5 inch rims make all the difference. the few who have tried it, acknowledge the difference. I still think most choose rims based on looks, rather than function. Another win for form over function.
Click to expand...

I don't know who you are accusing, but it's an accusitory statement. You are claiming that people who disagree with you are basing their disagreement on "the look", when in fact YOU base your claim that wider works better on your "percieved" feel of your bike's handling, based on tires and rim widths you've used previously. Very unscientific...

There are numerous scientific principles that disagree with your claims. First, a narrower front tire weighs less than your fatter tire, so there's less unsprung weight for a narrower tire which means irregularities in the road upset the bike's handling less than using a fatter tire. A wider front tire also has heavier steering, as well as having less precise handling. You forget to mention any of this...

My point ISN'T that YOU are wrong about 19 x 2.5 being a good set up for a commando. My point is that YOU ignore the science that says almost all choices have compromises.

JOE, here's a link you should check out:

https://www.motorcyclistonline.com/motorcycle-tire-width-and-traction-video

here's a link that explains why some (but not all) of what Ken says is true

http://www.bitingtires.com/tire-and-rim-width/

No doubt narrower front tires are recommended to help bikes that have sloppy handling (harleys come to mind) because the narrower tire is more precise, lighter, blah blah blah,... but those narrow tire also have a trade off too. They have a smaller contact patch areas generally than their wider rimmed, wider tire on the same bike. So,... It's all a trade off, so depending on the weaknesses and strengths of your chosen bike, you may chose a certain tire or rim width to help a certain aspect of that bike's performance, on certain kinds of roads...

Ken, my intent here is not to dismiss your claim that 19 x 2.5 is a good (and possibly the best) set up for a commando, just that the science says there are trade offs for all choices of rim and tires widths...

Ps, My bike handles well with 19 x 90 x 100 on 1.85 fronts, and 18 x 90 x 110 on 2.15 rear. which is avon roadriders on cast aluminum rims. I would never claim it's better or the best without a side by side trial...
 
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o0norton0o said:
I don't know who you are accusing, but it's an accusitory statement. You are claiming that people who disagree with you are basing their disagreement on "the look", when in fact YOU base your claim that wider works better on your "percieved" feel of your bike's handling, based on tires and rim widths you've used previously. Very unscientific...

There are numerous scientific principles that disagree with your claims. First, a narrower front tire weighs less than your fatter tire, so there's less unsprung weight for a narrower tire which means irregularities in the road upset the bike's handling less than using a fatter tire. A wider front tire also has heavier steering, as well as having less precise handling. You forget to mention any of this...

My point ISN'T that YOU are wrong about 19 x 2.5 being a good set up for a commando. My point is that YOU ignore the science that says almost all choices have compromises.

JOE, here's a link you should check out:

https://www.motorcyclistonline.com/motorcycle-tire-width-and-traction-video

here's a link that explains why some (but not all) of what Ken says is true

http://www.bitingtires.com/tire-and-rim-width/

No doubt narrower front tires are recommended to help bikes that have sloppy handling (harleys come to mind) because the narrower tire is more precise, lighter, blah blah blah,... but those narrow tire also have a trade off too. They have a smaller contact patch areas generally than their wider rimmed, wider tire on the same bike. So,... It's all a trade off, so depending on the weaknesses and strengths of your chosen bike, you may chose a certain tire or rim width to help a certain aspect of that bike's performance, on certain kinds of roads...

Ken, my intent here is not to dismiss your claim that 19 x 2.5 is a good (and possibly the best) set up for a commando, just that the science says there are trade offs for all choices of rim and tires widths...

Ps, My bike handles well with 19 x 90 x 100 on 1.85 fronts, and 18 x 90 x 110 on 2.15 rear. which is avon roadriders on cast aluminum rims. I would never claim it's better or the best without a side by side trial...
Click to expand...

Accusatory? Sorry, I don't see it, try as I might. You can talk scientific principles all you like, but, in a world of perfect theory, the theories have to be put to the test, and it may just turn to crap! Now tell me, is it unscientific to use the manufacturers own recommendation? The 100/90 Roadriders are actually MADE for 2.5 inch rims, which gives them the CORRECT profile for the tyre.

Anything else is merely a compromise!

Sorry, but like a lot of people, you seem to be relying on hearsay to back up your theories and have gone down the path of others. I've ridden a lot of Nortons with various wheel/tyre combinations and made my decision based on LOGIC!

Tell us, how many Nortons have you ridden with 2.5 inch x 19 rims fitted with Avon AM26 100/90 tyres?

Imagine if you can, the frustration of being told by people, who have gone down the path of compromise, never having ridden a bike so fitted, that what I'm saying is less than valid? Besides, the video "proof" you supplied merely backs up what I've said! The compromises only come when you use the wrong size rim!

Gimme a break.
 
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Not wishing to step on any toes in either camp, my own feeling is perhaps the stock 1.85" rims are a bit narrow for a 100/90. This is not based on handling which was fine when I had them on my bike, but rather what I considered correct seating of the bead on a Super Venom tire. This tire is admittedly not a Road Rider but I believe very similar. For me, one of the things to consider, if indeed a 2.5" rim is needed for a desirable 100/90 Road Rider, is simply the expense of switching to different rims to accommodate the tire. My original rims are perfect as are other rider' rims I'm sure so you have to ask yourself if it's worth the expense lace-up new rims just to accommodate a certain tire. Though I run Dunlop K81's on my bike, if one would want to try an Avon, this classic Road Runner is a good looking tire,,, and fit's the Norton. https://www.jpcycles.com/product/zz21091.
 
lcrken said:
I'm with Nigel here, Joe. It seems like the 100/90 Avons should work better on wider rims, but in the real world, I'm not sure you would notice the difference. I've been riding with them for a long time on stock WM2 rims, as have many others here on the forum, and they work just fine. And they get ridden very hard on occasion. I like the way the bike handles with them. It is very neutral feeling in corners. It falls into corners very easily, holds it's line properly, and doesn't push coming out under power. What more could I ask for on a street bike, except maybe better mileage on the rear?

As far as using the 90/90 on the front, I don't know what benefit you would gain from that. It would certainly work. I've seen a couple of Commandos with that combination, just never tried it myself. I raced several Commandos back in the day, and all had smaller front and larger rear tires. In fact my first race bike, a Commando PR came from the factory with 4.10x19" rear and 3.60x19" front.

Having said all that, if I were replacing the rims anyhow, and wanted to stay with the 19" size, I would go with the wider rims (in alloy, of course!). I can't see any drawbacks to following the manufacturer's recommendations.

Ken
Click to expand...

Several people like the 90/90-19 front. I tried it and was not to my taste. Stears quicker than 100/90-19, not necessarily a good thing.
 
Not wanting to take apart my perfectly good wheels, I would like to ask, "what would a 2.5 rim laced on original front and rear hubs for, say, the '74 850 cost?" In other words, buying the whole wheel. No, I'm not running out tomorrow to do this, just curious. And having laced bicycle wheels and trued them, I know that's not a simple job so you'd have to find someone who could really do it right.
 
Joe Schlaberdowski said:
So what would be wrong with Avon Roadriders in 90/90-19 front and back? Going to new rims is a lot of trouble/expense. The question is wouldn't you see the same improvement that is claimed for 2.5 inch rims with the 100/90-19? The 90/90-19's would fit right and have the right footprint that was mentioned above. Right now I've got two 100/90-19's waiting to go on. When they're worn I'll try the smaller version unless someone's had experience with that and there is a good reason not to.
Click to expand...
Joe Schlaberdowski said:
Not wanting to take apart my perfectly good wheels, I would like to ask, "what would a 2.5 rim laced on original front and rear hubs for, say, the '74 850 cost?" In other words, buying the whole wheel. No, I'm not running out tomorrow to do this, just curious. And having laced bicycle wheels and trued them, I know that's not a simple job so you'd have to find someone who could really do it right.
Click to expand...

As I said earlier in this thread, you will be well served by what you have there and if you want to try a 90/90, that may be the thing for you. Cost here in Australia is about 500 Aussie dollars a wheel, but I'm sure that it would be cheaper in the US.
 
Not expecting much notice here, but just began reading an old book, " Motorcycle Engineering" by PE Irving. Since he's the father of the big Vincent I expect many to be familiar with this publication from so long ago. Early in the book he discusses very clearly and with precission born of both solid engineering and vast experience in the development of both touring and racing motorcycles the effects of different size tires on handling.
 
Tyres today are different animals entirely to when that book was written Joe !
 
What I was refering to was not tire composition, road holding etc., but the effect of different sizes/widths on the steering geometry. One post on this thread mentions they found steering advantage to different size tires on a Norton, front vs back, under race conditions. It is this, the change in effective rake and trail, that happens when the suspension is compressed or extended or when the bike is cornered hard and the tire is no longer in contact for rake and trail as it was when rolling straight. It is interesting. He was a very good writer. Tire stickyness or flex or lack thereof isn't mentioned at this point, though he does mention the effect of underinflation.
 
It take your point on all of the above, and agree the article probably still hold a lot of value today, but it must be read through a ‘filter’ as thing s like tyre shape, wall depth, etc all effect how it works and feels on a bike. Changes in tyre technology are not only about compound.
 
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