rollagain

As far as I know, all bike tires are bias ply. Why aren't any made in radial ply?

fietsbob

Were. but I don't recall who did so..

ThermionicScott 

Too squirmy.

JanMM

The Jamis Gentry city bike I bought in 1985 came stock with Panaracer radial ply tires. As 'verified' by Wiki. https://en.wikipedia.org/wiki/Radial_tire

The tires felt a little 'funny' as I recall and I replaced them at some point. 'Funny' probably was 'squirmy'.

MikeyMK

Radial ply is good for wheels which work upright - not so good when leaning over!

CliffordK

Yet, you can have either radial or bias ply motorcycle tires.

I think the first question should be what the heck is a radial tire, and what is a bias tire.

Ok, so some reading.

https://www.bikebandit.com/blog/bias...s-best-for-you

So, a pure bias ply tire has plies arranged at crossing angles, and the same number of sidewall plies as tread plies.



This gives a fairly rigid sidewall.

In a pure radial tire, all the sidewall plies are unidirectional, perpendicular to the tire rotation direction.

Then it has some kind of a tread belt in the contact area.



Steel belts are common, but not necessarily required.

The crossed plies are supposed to have higher friction than the uncrossed plies. And, the belt around the tread can be used to help force the tire into the desired shape.

Now we get to bicycle tires. Almost all of them have crossed plies, but many have much thinner sidewalls than center tread areas. There were steel belted tires a few decades ago, but now mostly more plies and Kevlar in the tread area.

Anyway, many of the performance tires have very supple sidewalls, but still a crossed design. As well as having stiffer middle tread areas.

More central plies would have some radial tire design characteristics.

I have to wonder if there is a risk of ply separation with radial plies on bike tires, and tubes bulging out. I presume car tires have so much rubber and so stiff of plies in the sidewalls that bulge is prevented.

seamuis

JohnDThompson 

National Tire Co. in Japan made a radial bike tire for the Trek 890. They had a weird, squirmy ride quality.

Bottom line is bikes don't really benefit from radial tire construction.


https://www.vintage-trek.com/TrekBroc...AllTerrain.htm

TiHabanero

In the mid-eighties Miyata had radial tires on their top two touring bikes. They worked OK, but did not wear well. I believe they were made by National Tire of Japan.

thumpism 

Tried a pair of them back in the day and they did indeed squirm. Took 'em right off again.

Slightspeed

My 2013 Culprit Croz Blade came with Maxxus Radiale clinchers that used radial construction. The rolled very well, handled well, and wore out very quickly, probably because of a soft rubber compound. When I saw steel cords showing, I switched over to Gatorskin Continentals. It seemed the replacement price was double that of Gators. I had a high speed flat, with no drama, and the tire was still useable. Sorry but I don't have a better picture of them. These are 23s and the Gators I use are 25s, about as big as will fit. I haven't checked lately if they are still bring made.


Not my bike, but a better tire picture

The Maxxus is still available, here's a link:
https://www.maxxis.com/catalog/tire-247-143-radiale

greatscott

I had a radial tire once but it drove me crazy, it only received one station and I hated the music selection.

CliffordK

Interesting.

Old models: 22/24mm, being dumped on E-Bay for cheap.
New models: 23/25mm

It is interesting to conceptualize what keeps the tires from experiencing wind-up. I suppose it is counteracted with both tire pressure, and collapsing the belt.

However, on a bicycle, the rear tire moves somewhat differently than the front. So, the rear is constantly exposed to micro accelerations.

It would seem that these micro-accelerations would cause more wind-up with the radials than the bias tires. And, thus, on the rear, would experience more friction than the bias counterparts.

Nonethless, they should be fun tires to try out.

Slightspeed

I was very happy with the ride and handling of the Maxxus. I didn't like the fast tread wear. I think I saw steel cords showing at under 1000 miles. I know the price has dropped, but I have Gatorskins on my other bikes, so I went with them. A few years ago they were in the $80-90 range, double the Gatorskin at the time. I've always wondered what it would be like to try some new ones, again. They were fun to ride.

rollagain

Explain 'wind-up', please. I haven't heard the term before.

CliffordK

Same idea as using radial vs cross spokes on a wheel build (rear driver, or front disc brake).

The crossed spokes means that when you pedal, 1/2 of the spokes are oriented so that torque at the hub is transferred to the rim. And, half the spokes go lax.

If one had radial spokes, there would be a greater risk of twisting between the hub and the rim.

Now, I have seen a 72 spoke radial rear wheel. So, I presume with more spokes, the torque on the rim/nipples is less from the radial spokes. So, perhaps it is less of an issue with radials tires.

But, my question with a radial tire is if there would be a springy effect when one goes from the cranks horizontal power part of the stroke to the top/bottom part of the stroke.

And, whether one would actually feel that springing, whether it would impact power.

It is noted that with radial tires on cars, there is a lot of discussion about always driving them in the same direction. Of course, usually only one axle is powered.

But, with bias ply tires, people would do a right to left rotation. With radial tires, one does a front/back rotation.

Again, I have to wonder if that has something to do with the torque applied on the radial sidewall.

Or, maybe standards have changed. Looking up cross rotation now, and it doesn't seem to be considered a serious issue for radials.

ThermionicScott 

Rotation was important with bias ply vehicle tires to even out the wear. Radials naturally conform to the road better so it's far less of an issue.

And unlike with bicycle tires, modern vehicle tread patterns actually do make a difference with hydroplaning, so it's important to point them in the right direction. The construction of the tire carcass has nothing to do with it.

frogman

Wow CliffordK ! Great info !

rebel1916

Modern motorcycle tires would beg to differ.

NJgreyhead

Here's this from Jan Heine of Bicycle Quarterly, on how bicycle innovation trails automobile and motorcycle innovation:

"Radial tires have improved traction and fuel efficiency of cars and motorbikes for decades, yet today’s bicycles still roll on old-fashioned bias-ply tires. Panaracer in Japan actually made radial bicycle tires decades ago, but a lack of interest stopped that experiment before the tires could be perfected. Improved traction and better efficiency – what is not to like? "
https://janheine.wordpress.com/2019/...ikes-and-cars/

CliffordK

There is extreme interest in puncture protection and efficiency... at least with some cyclists. So, perhaps manufactures will start doing some experimenting again.

I did order some of the Maxxis tires.

Crashing in Pro races due to over inflation and slick tires?

Darth Lefty 

I tried to find some info on those Maxxis radials and the forum thread that turned up claimed they had a fiber angle of 75 degrees, confirmed by an old catalog (pdf). The theory would be that's enough away from the 54-deg hose braid bias ply angle to give more compliance but still enough to prevent the squirmy feeling if the fibers were at 90 degrees (all hoop). I wonder what Panaracer did, by comparison.