April 01, 2015 8 Comments
Clinchers are the primary pneumatic wheel system of our time. Cars, planes, high speed trains all use forms of this proven approach to suspension and travel. In cycling as well, clinchers are the bedrock tire system. Today’s topic concerns the high pressure clincher (HPC) for road racing and performance pavement riding. Who would question The System??
When did HPC’s arise?
Before the ’70’s, bicycle clinchers had maximum pressures of 80psi and most depended on 30-65psi. They served the needs of everyday riding from commuting, to commercial delivery, to touring and recreation. Racing to win was another form of cycling. Competitors used narrow (18-25mm) tires at high pressures (7 bar/100psi+) to make wheels light, yet resistant to dents, and hopefully win races. Since the dawn of pneumatic tires, racing needs were not met by clinchers but, instead, by tubular (sew up) tires.
The mass of riders on modest pressure clinchers were well served and racers had little problem gluing sew ups or hiring mechanics to do it. For both systems, rims and tires were simple to design and flats were rare and easily fixed. What ended this happy, stable era?
In the mid-1970’s, America experienced a sudden bicycle boom, fueled by alternative thinking and, especially, a nationwide gas shortage with soaring prices. Suddenly mobs of young Americans wanted to ride bikes. Cycling didn’t have much of a role in the US besides besides grade school commuting and news boys. To get out on the roads with cars was intimidating, but less so if you rode fast. Going fast was fun and the boom focused on speed. European racing was inspiring.
Unexpected Boom Crisis
Importers found supplies of racing bikes and soon everyone was hunched over skinny tire racing bikes, riding as fast as they could. Despite some problems (neck pain, sore butts, safety, etc), one threat loomed largest: better racing bikes from Europe came with tubular tires. Few in the US knew what to do with them, no old timers in the neighborhood to mentor beginners. Tubulars were misunderstood, miss used, and became the bane of lightweight riding. They weren’t, after all, intended for general use.
An alternative to the tubular was needed quickly or the biggest American bike boom of the century faced an untimely end. Mountain bikes were still 10 years away so a new machine was not an option.
Enter the HPC. The dawn of tires and rims attempting to hold high pressures, for example IRC High Racer tires on Araya rims, was scary and loud. Tires could be mounted crooked, rims could expand with pressure, standards for fit were inadequate, tire levers bent and broke, pumps were not strong enough. HPC’s, the bastard child of an awkward historic moment?
However, the goal was clear: a system to equal the performance (pressure, weight, speed) of racing tubulars but be easier and cheaper for the masses to maintain.
40 Years Later
Where do we stand with high pressure clinchers?
(1) They are heavier and less strong by weight than tubulars.
(2) They are not cheaper, rather equal or more expensive than tubulars.
(3) They get more flats, especially pinch flats, than tubulars.
(4) Rim-to-tire fit standards are so vague one can buy a top-of-the-line tire and be unable to mount it to a top-of-the-line wheel. I would estimate 70% of riders of HPC’s do not repair their own flats. They call home. Prying off the tire and making the patch or tube insertion is complicated, requires too much hand strength, and often fails. Mechanics, like the readers of this piece, have noticed the difficulty but are not in the 70% helpless category. We are busy helping our less-able customers and riding companions. Fact is, more tubular riders with punctures ride home than their HPC counterparts.
(5) “Tubeless” systems aim to fix this but is it worth the trouble? True, fewer flats, but the rim interior is often invaded with sealant that can NEVER be removed. Bead fit is so tight that only experts can mount them. Tires cannot be inflated without compressed air. And the suggestion you can insert a tube if you flat during a ride is bogus. Putting tubes in a road tubeless system is a task virtually no one can accomplish.
(6) Making light rims in any material for HPC’s is complicated. Outward pressure of tire beads is gigantic. To withstand this force carbon rims add mass to equal the weight of aluminum rims. Huh? The circumferential pressure of HPC’s (tube or tubeless) on rims is 10X that of tubulars due to the different physics. Tons of constricting force shrinks light rims, lowers spoke tension, and deprives wheels of much strength. Is it worth it?
High pressure clinchers have had 40 years to accomplish the goal: equivalent performance, improved convenience, and lower price than tubulars. They have failed. It’s over. Good try but no win. 40 years is long enough. Believe me, I’m not alone among industry veterans puzzling over this situation.
This is not a call to return to tubulars. That’s the system that needs replacing. A new system is needed for the narrow, high pressure, racing pneumatic. Don't stop using HPC wheels. Until there is a better alternative, it’s the best we can do.
Nor does this apply to moderate pressure clinchers as in BMX, MTB, utility, and randonneur riding. Larger casings, lower pressures, and a wide variety of rims are delivering great function and value. It's also important to note that efficiencies of narrow, high pressure tires have been exaggerated. Fast, competitive riding is often better with lower pressure and larger cross sections. Jan Heine's Bicycle Quarterly (among others) has really driven this point.
Here is also not a criticism of the modern HPC tire. Taken alone, todays’s HPC’s are remarkable technology and quality. Complex and refined, tough and impressive. Same with rims. It is the system that is at a dead end for high pressure.
What to do?
(1) Separate yourself from deniers who claim HPC systems (especially tubeless) are perfect. They’re not.
(2) Think hard about alternatives. Study tubulars. Study HPC’s, both tube and tubeless. Cycling innovation begins with you.
(3) Don’t hold your breath. Innovation requires motivation (we have plenty), technology (it’s out there), and courage (well...). Structural obstacles also seem insurmountable. Tire companies are some of the largest corporate entities in cycling. Michelin, Hutchinson, Continental, Innova, Cheng Shin, Kenda, these are global chemical giants. Cycling products are trivial for them.
Why does this spill from the mouth of a wheel person? We are über proud of wheels. Anything seriously limiting their beauty and usefulness gets our attention.
Rest assured, a fearless young bicycle thinker is reading this and in due time will engineer the needed solution. I'll bet it's a wheel builder.
If my tongue-in-cheek leaves you confused or annoyed, make a comment. Then hug your bike and take a ride!
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