Friday, January 30, 2009

'BEADED EDGE' TIRES AND SAFETY

The word 'tire', or 'tyre' to the English-speakers, originated with the steel bands holding wooden wagon wheels together, which were forged by wheelwrights. These bands not only made for a hard-wearing surface for the wheel perimeter, but served to 'tie' the wheel and spokes together - they were literally the 'tie-r' of the wheel. The English like to think they spell things correctly but in fact the spelling 'tire' is older than 'tyre', which appeared in the 15th century. Subsequently, the word 'tire' became generic for any wearing surface on a wheel, whether a cart, bicycle, car, or a steam train, and whether the material was steel, rubber, or wooden balls bound by wire (a few of the more desperate examples can be seen in the photo below, from Munich's Technische Museum).

I'll skip ahead a few centuries to the birth of our subject, the Pneumatic tire, which supplanted the solid rubber item popular on early bicycles, cars, and motorcycles. The 'aha' moment came for John Boyd Dunlop (below) in 1887, while watching his son bump uncomfortably along a cobbled street on his tricycle.

Dunlop laid thin sheets of rubber, glued together, over the solid tires on the trike, adding an inflator valve from a football, and voila, the pneumatic tire was born. He patented the idea in 1888, and by 1889 had opened tire manufacturing plants in Dublin and Birmingham - clearly not a man to dawdle over a good idea! Another type of pneumatic tire was invented in 1845 by Robert William Thompson, but his system was too expensive for commercial production, and Dunlop gets the credit for the first practical pneumatic tire, and the first to be commercially produced. Mind you, his patent was for bicycle tires, which of course dovetails very nicely into our subject; motorcycle history (see the wonderful photo of J.B.D. enjoying the fruits of his labor, below).

Motorcycle tires of the Dunlop pattern used a very simple system to ensure positive location on the steel wheel rims of the day. High air pressure, at 40-60lbs/square inch, kept the rubber sidewalls firm against the wheel flange, which was a curved lip 0f folded steel, mated to a corresponding rubber 'bead' cast into the tire base itself (see illustration).

This method of attachment works quite well to keep the the wheel stable, at the expense of a rock-hard ride from the highly inflated tire. It has always been, since the earliest days of tire on rim, a temptation to lower the pressure within such tires, to increase the 'give' of the rubber and provide some form of cushioning against road shocks. This is fully understandable given the terrible road surfaces of the day - packed dirt or gravel were about the best one could hope for in the years 1890-1928, as the Macadam system of asphaltum-glued gravel laid in smooth beds and compressed flat were quite rare except in urban areas, which had the tax base capable of the high expenditure necessary for such infrastructure investment.

The terrific downside of under-inflation with these 'clincher' or 'beaded-edge' type tires is the possibility of rapid deflation as a consequence of a sharp blow. Of course, a 'blowout' or quick loss of air from a puncture or tear is a possibility on any inflated tire, but this early method of fastening tire to rim has the distinct charm of immediately tearing the tire from the rim if pressure is lost, as only air pressure holds the two firmly together. The consequence, Every Single Time, is a spill, as the tire magically transforms into a rubber snake hell-bent on tying itself in knots between the wheel proper and any frame or fork tubes nearby, thus locking up the wheel, which has already become an ultra-low-friction steel ski on the road surface.

Tire manufacturers developed a new type of wheel rim/tire combination around 1924 which became the standard for all automobile and motorcycle tires from then until the present day. The new system, called 'well-rim' or 'wired-edge' wheels, uses a much stiffer tire which, although far more difficult to install, does not rely on air pressure to maintain its place on the wheel rim. Thus, if deflation occurs, the tire simply goes 'flat', but stays on the rim, and the wheels continue to rotate on rubber, albeit in a wobbly/frightening manner. Still, this was a tremendous improvement in safety, and the number of crashes from deflation plummeted. Tires were made gradually thicker, heavier, and more substantial over the ensuing decades, and additions of nylon, then steel cording under the tread, and ultimately fully 'radial' tires (invented in 1946, by Michelin) for cars and, later, motorcycles were developed. New motorcycle tires are 'tubeless', yet rely on those basic principles developed in the 1920's to stay on the rim.

Falling off a motorcycle at speed really hurts, at best. I've been thrown from my motorcycle at 50 mph from a mechanical front wheel lockup, and suffered the effects for quite a while from the resultant 'high-side'; it was motorcycle jiu-jitsu, and I lost. I bring all this up after my friend James experienced a blow-out on his '24 Sunbeam, which used 'clinchers', as does my '25 Sunbeam. As fans of 'period correctness', we were quite happy that our machines retained their original equipment, and had no intention of changing over to more 'modern' well-type rims and tires, as the vast majority of 1920's machines have done. We had recently discussed proper inflation with our 'clinchers', and James stated that he was using 25lbs/sq" pressure front and rear on his Sunbeam, as the ride was almost unbearable at the 40lbs recommended pressure for the Dunlop 'Cord' tires he had installed, at great expense (they cost ~$300 each).
After James' fatal accident, a query from a distant acquantance led to a bit of mutual research into 'clincher' tire safety.

The result of this research was very sobering, and I'm posting it here in the fervent hope of obviating any additional risk when using these 80-years-obsolete tires. Using them at all is a risk per se, with their known defect of sudden detachment from the rim after deflation. But, with proper care, a greater measure of safety is possible.

According to Radco's book 'The Vintage Motorcyclists' Workshop' (Haynes, 1986), a 2.5" wide clincher tire of 24" diameter (the size of my and James' Sunbeam) at 24lbs inflation, has a load capacity per tire of 150lbs. Assuming a 250lb motorcycle, plus 175lb rider, give or take, that's 425lbs, or 212.5lbs load per tire. Thus, at 24lbs/sq" pressure, the tires are 62.5lbs OVERLOADED, just standing still.

Radco further states (see chart, above) that inflation of 36lbs equals a 320lb permissible load per tire, which gives over 100lbs of 'leeway' on the tire loading; ie, less likelihood that the tire will blow out under rapid compression, as from a large rock or sharp crease in the road. A little further investigation; in 'Dyke's Automobile and Gasoline Engine Encyclopedia' of 1927, a 'high pressure pneumatic tire' (ie clincher) should be inflated to 45lbs or more. Further still; a Society of Automotive Engineers (S.A.E.) chart of the same era lists 3" Cord-type tires (exactly the size and type of my Sunbeam) as requiring a minimum of 40lbs pressure. Vintage Tyre Supply is a primary source of the Dunlop Cord clinchers available today, as used on my Sunbeam (and James' too), but they don't list any tire pressure recommdations for these tires on their website, only for their automotive and 'well-rim' motorcycle tires. Another source of modern 'clinchers', Universal Tyre Co. lists pressures for all their tires on their website, and they recommend 60-65lbs pressure for such motorcycle tires. Longstone Classic Tires recommends a minimum of 60lbs pressure for their tires as well. This should be food for thought for anyone riding on clinchers, as I do. It is imperative that they are properly inflated, to at least 35-40lbs/sq". Under-inflation is dangerous, and could prove fatal; as risk-takers, we owe it to ourselves to be safe when it's within our power.

If you have a perverse interest in tire history, you can download a copy of the B.F Goodrich book from 1918, 'Best in the Long Run', which was used to train their sales representatives. It give a comprehensive history of tires from the earliest days through 1918. Googlebooks has made it possible to read/download the book, for free, here.

33 comments:

The Creeper said...

Wow, great article Paul. Solid information that needs to get out there to the folks running clinchers! No pun intended...

Anonymous said...

Hello Paul,
My 2 cents worth on beaded edge tyres...but I don't have a machine with them, and never have to date.
When I was active in the Vintage Motorcycle Club of Australia (NSW) Ltd, which operated out of Sydney...and I left it likely 15 plus years ago... sourcing beaded edge tyres was a problem.
It was solved by purchasing from Asia, rickshaw tyres which are clincher/beaded edge type...
Trouble is, especially after James death, one must question the sense of fitting a tyre woops tire designed for a hand wheeled vehicle to a motorcycle, then in operation forgetting about the serious disadvantages, as James did.
He in comparison to modern well-based types.
I will make enquiries of friends in the VMCC here in Sydney who still use Veteran motorcycles....
Stay tuned....
Kindest regards,
Dennis.

vintagent said...

Hi Dennis,
contemporary beaded-edge tires for motorcycles are easy to source nowadays; there is quite a market for them esp among American motorcycle collectors. I don't know who made the rickshaw tires, probably Cheng Shin, but they're all probably rubbish. Obsolete since 1925!
yours, Paul

Anonymous said...

a trick i used to use on my merkur ford was to take a stick of chalk mark the rim and tire do a couple of miles of turns to get them hot , if the line did not break i would lower the pressure 5 psi , ( calibrated gauge of course) and try again till the chalk line broke , the go up a little , ok i know your going to ask about a calibrated tire gauge , buy a good one , then take it to any Ryder truck rental depot , most have a calibration set up in the service bay , they found that they could save millions a year by correct tire pressure , so most Ryder outlets have a calibrated gauge on a air line somewhere in the service bay dave

Anonymous said...

I was wondering if glue is/was ever used? For racing bicycles, the clinchers are glued on, and I beleave that the pro pelaton use mostly clinchers.

vintagent said...

No glue. Bicycles still use clinchers, ie air pressure holds the tire on the rim, but it makes sense for them - wired-edge tires would be too heavy on a bike.

Anonymous said...

thank you Paul for the post. Never have I thought about such things with 'modern (past 100 year)' machines. Enjoyable as they are there has been developments and sometimes forgotten was the reason. Some day I might have the opportunity to ride and own a more early period motorcycle; you have made that to be a safer and more enjoyable experience. Thank you again.

Anonymous said...

Bonjour, je suis Français et restaurateur de motos anciennes; je suis entrain de reconstruire une Majestic et j'ai plusieurs demandes pour des réplicas.
La Majestic qui est sur votre blog n'a pas le bon capot moteur ( voir photo)
A bientôt peut-être

Anonymous said...

Paul,

As always, a very interesting article on the perils of riding on beaded-edge tyres. However, I note that there is no mention at all in your piece on the use of security bolts which are designed to hold the tyre onto the rim after a sudden deflation.

If you study photos of period racers in particular you will see that security bolts were common fitments. Joe Bailey's excellent 'The Vintage Years at Brooklands' shows many of the machines, especially the big twins, fitted with security bolts. For example, Freddie Dixon has a total of four fitted to the front wheel of the Brough Superior 'Works Scrapper'.

When I restored my 1925 SS100 I had the dilemma of which tyres to fit, but decided on authenticity and went for original 28" x 3" Dunlop Cords which also look superb. I found some new old stock tyres that had been stored well and fitted them with security bolts. A couple of years ago I had the dubious pleasure of putting the bolts to the test. I was riding the machine solo on a fairly smooth main road at about 60mph when the rear tube dramatically blew out. (Later inspection revealed a 10 inch split so you can imagine how sudden and loud the 40 p.s.i. bang was!) Matters aboard the machine got extremely lively, with the back end snaking around somewhat and I was hanging on praying that I wouldn't fall off (to be honest, at the time, I was more concerned about damaging the bike, especially the beautiful tank rather than me!) The machine is the only one I own which is fitted with a lever throttle and after a few seconds of weaving down the road I noticed that I was not slowing down too quickly (I didn't dare use the brakes) I am embarrassed to reveal that in all the excitement I had forgotten to shut the lever! After so doing I managed to safely coast to a halt. The bike must have run a good 100 to 200 yds on a totally flat rear tyre but it had not left the rim and I survived to tell the tale. I urge anyone who runs on beaded edge to fit them. They make tyre fitment a real pain but should you experience the same misfortune as I did they are well worth it! Cheers,

Howard.

vintagent said...

That's an excellent suggestion Howard; I'll post an addendum when I get more info on suitable security bolts.
pd'o

Anonymous said...

Paul,

I'm a regular visitor to your website now after being introduced by Dave the Photo pirate!

A very sad start to the year obviously but a great tribute from yourself.
Hopefully your current article on the development of tyres will be a useful lesson, allowing folks to enjoy the vintage bikes safely following the tragic accident with James.

Regards
Jon

Anonymous said...

Paul - I'd like to see your writing address some the interesting mechanical or engineer aspects of the machines. Please dig a little deeper. Your readers can handle it. Once you start to dig into the bowels of the mechanical development it will certainly provide interesting other correlations. Me hopes.
Pls get some close ups of characters faces every once in a while. By GOD we got'em.

Paul in Vancouver

Bibendum and I are tyred said...

Hi Paul. A bit more info on tires:

Japanese beaded edge tyres (or "clincher tires" in the USA) are made by the Okada Tyre Co. They may not make them anymore though. I've used the 26x3 size on my Rudge for around 8-10 years. They are a soft compound, and grip the road well, however they wear out after about 1500-2000 miles. I've gone through several sets, bought NOS on ebay from random sellers.

Currently, Coker manufactures clincher tires, as does Dunlop and at least one or two other companies. James used Dunlops I think. They are a harder compound than Okadas or Cokers.

Note that the all white tires were the only ones available until around 1920. They were soft and wore out quickly. Modern Cokers in white are good for maybe 1000 miles... By adding carbon black to the mixture, the manufactures made the tires last a lot longer, and led to the now-common Black Tire. And of course the cool White Wall tire. :)

Some guys do glue their beaded tyres onto the rims. I think that contact cement may work, but I've yet to try it. I haven't seen anybody using security bolts, except maybe on a rear wheel of a sidecar outfit. I do that on my Velocette, even with drop center rims.

Regarding James' accident, it seems that he didn't have a blow out. His tube still had air in it after the wreck. The guys had to deflate the tube in order to replace his tire on the rim. It appears that possibly the tire wasn't inflated enough, and it jumped off the rim after hitting the side of a bump in the road, or after the first swing of the tankslapper.

Good catch on mentioning Thompson's tire of 1845, most people don't realize that his tire predated Dunlop's by 40 years. Thompson didn't develop his, and I'm sure that his children must have winced while watching Dunlop's fortune grow and grow.

If you want to really get into arcane details, maybe another post could discuss Shrader valves or Bibendum :)

yours,
Pete in Alta California

tire sizing said...

One more item that trips up some folks:

Clincher tires are sized by the outer diameter of the tire and rim, not by the width. A 28x3 is 28" overall diameter, and 3" of tire height. Thus the rim is 28-6=22 inches. A 28x2.5" uses a rim that is 28-5=23" tall. The shorter tires are also narrower, but the 2.5 or 3" dimension is not the width of the tire.

ciao
Pete

Anonymous said...

Paul, Please go to cokertire.com for all your clincher needs! Made in Fresno of all places. Bicycles in the peloton all use sewups, the case is sewed closed around the tube, then glued onto the rim. Wait a day to use it,
put 160psi in it and chase Lance. Wired-on or kevlar foldable is the best.
Tom

Anonymous said...

Paul,
I am a new reader of your web site and the first article I read was the story about the loss of your friend James Johnson. This story came of the heels of the loss of a friend of mine in a needless accident. You have now followed up with the story on tire development. I am active in the old car hobby and we face similar problems with the period tire issue. My best friend has a 1915 Rolls-Royce which came equipped with beaded edge tires and they were a constant source of trouble. We kept blowing tires in spite of keeping them at very high pressures. The tire company would accept no responsibility and their constant refrain was "You are not keeping pressures high enough!" That was crap and Bill finally decided to have a new set of wheels made for the car that would allow the use of deep well tires. This was 30 years ago and the old Ghost has been running down the road with no troubles since then. The Silver Ghost Association runs tours all over the world for these old cars and they perform admirably. Most of the owners who run them hard have long ago updated wheels/tires and brakes to deal with modern traffic.
If your bike or car is going to be a static museum display, then fit the old beaded edge wheels. If you are going to run the machine in modern traffic, please update to more modern wheels and safer tires. The same, frankly, goes for helmets. I have a Davida Pudding Bowl helmet painted in Italian colors for use when I am playing with an early Ducati single. (Another one with the Union Jack on it accompanies the Triumph.) I will put them out for display or wear one while walking about at a meet, but I put on a proper modern helmet when riding on the public roads.
I am sorry about James as he seems to have been a true enthusiast and someone we would have all enjoyed spending time with. Even our hobbies and passions have their dangers.

Cortes
Richmond, Virginia

Anonymous said...

Hello Paul,
Thanks for the sensitive and well though out piece about James Johnson. It has helped me, and many others I am sure, to remain cognizant of the hazards of motorcycling. The use of vintage bikes and vintage equipment at modern speeds requires special care and attention as you so eloquently stated in your article in Fishtail West. Thanks again for the renewed awareness.

By the way, what does illegal p.o.s' mean?

Also enjoyed your commentary at the Vegas auction. I didn't get to buy you a beer, but I am sure that I will get an opportunity for that somewhere down the road.

We have a very active vintage bike scene here in Vancouver. http://www.bmoc.ca/newsletter.html
If you are ever in the neighborhood I will be pleased to give you a tour (on a leaky wheezy vintage bike of course)
Regards, Alan in Vancouver

Anonymous said...

I was very saddened to hear the news about James. I too had a front tire blowout with clincher rims on my vintage Harley going around the same speed. I know one thing for a fact. With clinchers, the tire goes flat in a matter of seconds. Then the tire comes off the rim. Then you go down. I was lucky to have been only banged up. Another fact that I'm sure of is that James was having adventure and living his life like one should. My sincere thoughts and sadness go out to his family.

Anonymous said...

In my search for "clincher" tires/tyres for my 1925/7 "Paris-Nice, Zhender"(Swiss, man's model[there is also a Women's/Priest model, skirts used in those days!] and only a few remaining out of a thousand built) I've come across this blog and it is very good indeed.
Here's a solution to the riding on vintage tires which I find works:
Get a cheap set of older "mountain-bike" wheels and fit them to your old m'cycle! Size matching and fiting isn't a problem and the added benefit is the rear/front wheel hub-brakes on early mountain bikes found in 2nd hand stores.My Zehnder had only a rim-brake" and belt-drive on the rear. This meant building a rim at the local sheet-metal shop for the drive-belt and attaching it to the rear wheel, and it works!
Keep your real Vintage wheels shod with a cheaper set of 'clinchers' for shows, non-mobile events, etc. For the rare riding sessions safety is assured and comfort not an issue; the looks deceive all but the very discerning. And the hub brakes ar a bonus. Where I am(Vancouver Island) there aren't all that many shows so the Zehnder stays home a lot!
Perhaps for the Vintage Runs in UK the requirement is "clinchers" be fitted and used as "original and period". A scrutiny of the Rules may reveal non-requirement Original/Period use of tires and even an "exemption" in the name of safety may be granted .
While I would happily ride the Zehnder with clinchers The loss of the bike or myself to my familial world would never be seen as comfort and soothing value in the sad event of a similar tragedy that befell your friend James. Sent in by David.

vintagent said...

Hi David,
an interesting idea, worth considering. There are other solutions - switching to later-style rims or using rim-locks on your clinchers - all of which will provide increased safety.
As far as I know, there are no 'rules' regarding clinchers at events, and modifications for safety are considered ok at events like the Legends Concours.
Thanks for the idea.
Send pix of your Zehnder!
pd'o

Derrick Trucks said...

Dunlop laid thin sheets of rubber, glued together, over the solid tires on the trike, adding an inflator valve from a football, and voila, the pneumatic tire was born.

bucket trucks

Bucket Trucks For Sale said...

¡Gran artículo! Miré una película anoche donde algún chavo los dijo que él inventó la bicicleta. ¡Fue gracioso!

Dave Barkshire said...

I've spent all evening trying to get a beaded edge tyre on! I just can't get both beads to sit in their place even after trimming the rubber on both sides. Normally my attempts at tyre fitting results in blood and paint damage but this time I've been much more careful. It would be nice if the tyre sellers and wheel builders at autojumbles could work something out so that we could get the fitted in one hit.

Used Pole Trailers said...

Gotta love the Michelin Man!

bobfleming said...

Hi Paul, Just discovered your stuff on beaded edge tyres while researching the subject. I have an original security bolt for this type of tyre on my Rudge Multi but have never seen another one. It is completely different from the well base type used now. Have you discovered a source for this type of "rimlock" in your world? VTS in England say they are unobtainable but not necessary anyway! I'd like to fit some to my other beaded edge wheels just in case. Good Luck, Bob

Anonymous said...

Hi, ive been aMarque specialist for the VMCC for 30 odd years, and you get what you pay fpr with Beaded edge tyres. You can buy rickshaw tyres, but theyre not and never were meant fot motorised vehicles. If you want to race, have a second set of wheels using wired tyres, and use the BE ones for display only. All thats between the tyre and disaster is air, and thats what keeps these tyres on the rim. Ive never had the slightest problem, but then i use the correct tyre for the job. I dont stretch them getting them on, and i dont underinflate. Because kids today dont understand BE rims, they misuse them and blame the system! Jon

rent or buy a bucket truck said...

I can tell you've spent a lot of time on this post. I love the old time pictures of bikes and stuff... takes me back to being a kid and riding whatever I could afford. Cool post.

Knuckle Boom Truck said...

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Cheap SSL said...

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Johnny said...

Great article. I am now following your blog and will share this article to my friends . Your motorcycle tire article is very interesting.

Unknown said...

I love the Vintagent and appreciate your attention to a much overlooked but important topic--both practically and historically speaking. But I fear there's some significant misinformation here. True, Dunlop lost his original patent for the pneumatic concept when Thompson's prior invention came to light. But he saved his enterprise by acquiring the patent for the wired-on tire design by Welsh. This was not a beaded edge tire, or clincher--it was the regular 'modern' configuration with a steel wire in the edge. The beaded edge tire, or clincher, was developed later by Gormully & Jeffrey as a competitive alternative, and only lasted about 30 years. Modern bicycles do not use these clinchers. They use regular wired-on tires, just like the Dunlop/Welsh, which cyclists often but mistakenly refer to as 'clinchers' in their enthusiast jargon. The steel wires do not weigh too much for 99% of bicycle use, although the small percentage of serious racers do use sew-ups or Kevlar-wired tires to save that weight. -Paul Rubenson

Anonymous said...

One consideration that hasn't been mentioned here is the lack of a really good BE tyre in
28"X 3"for Broughs, Harleys etc. If you want 26"x3" there are the pukka Dunlops which are very close copies of the originals and are reasonably substantial, but in 28 by 3 there is no Dunlop, only the Ensign which looks similar but is not the same. I fitted an Ensign to the rear of a 1925 SS.100 and found it made the bike almost unmanageable.
I tried many variation of air pressure but none seemed to suit.
On slow corners the bike seemed to sway in a most disconcerting fashion, and I concluded the the carcase of the tyre had no stiffness to it.
I replaced the Commander(now called Excelsior?) as it seemed a much stronger tyre but with a skimpy tread pattern. I cut up the Ensign to see what it was made of, the answer being not very much!
The original Dunlop 'Extra Heavy' have several canvas/nylon plies in them, the Ensign seemed to have almost nothing but rubber, little more than a mountain-bike tyre in fact. This made me worry very much for the many people who fit these tyres to vintage bikes in preference to Dunlops on the basis that they are cheaper!! My opinion was that they were dangerous and I would never fit them. I had also heard a couple of stories of these Ensigns bursting.
This brings one back to the problem of the superior Dunlops not being available in the 28" size. No doubt security bolts are needed, and they are an awful job to fit in B.E.
Despite the potential danger, vast milages were done in the vintage era on bikes. My father for one rode some 40,000 recorded miles on Scotts with BE tyres, and had plenty of punctures, but never had any accidents as a result.

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