|
|
|
Tweet
Follow @sheldonbrowncom |
Subject: Tubular Fables
From: Jobst Brandt
Date: January 27, 2003
Why is it better to deflate tubulars between rides or is this just a silly rumor?
Yes and no. The "rumor" arises from a misunderstanding. Track tires, that are most often still tubulars, are generally inflated to more than 10 bar (150 PSI) and are dangerous if they explode. Good track tires, unlike road tires, are often made of silk with fine and thin strands that are not coated or otherwise protected.
I have seen these tires get touched by another rider's pedal and explode, or even when carelessly laid on any angular object, they can burst because only breaking a few cords is enough to start a burst. For this reason track tires are best deflated to less than half their running pressure when not in use. I can still vividly hear the sound of a tire exploding in an indoor track although I heard it only a few times years ago. It is not something you would like to have happen in your car or room.
The reasons people give for deflating tubulars are generally false and are given for lack of understanding. This is what makes it sound like an old wive's tale. Most people do it just to be doing what they think is "professional" when in fact the protected sidewalls and pressure of most road tubulars make deflation as meaningless for them as it is for clinchers.
What advantage is there in aging tubulars?
None! The aging concept arose from the same source as the "steel frames need to be replaced because they get soft with age" concept. Both were intended to improve sales during the off (winter) season by bike shops with too much inventory on their shelves. Tires oxidize, outgas, and polymerize from ultraviolet light. The concept of a tire manufacturer making a tire that cannot be used until ripened for six months from the date of purchase is ridiculous. Tires can be made to any specification at the factory. Tires are most flexible and durable when they are new. They don't improve with time and exposure to heat, light, and oxygen or ozone.
"Over-aged" tubular tires have crumbling hard, brown latex on their sidewalls that exposes separating cords directly to weather and wear, and they have treads which crack when flexed. Considering that this is a continuous process, it is hard to explain where, in the time from manufacture to the crumbly condition, the optimum age lies. The claim that tires are lighter after aging is true. Their elastomers have evaporated, making the tire brittle and weak.
Purchasing tubular tires in advance to age them is unwise, although if there is a supply problem, tubular tires bought in advance should be sealed tightly in airtight bags and kept in the dark, optimally in a freezer. For best results, use new tires, because aged tires are only as good as how little they have aged.
More Articles by Jobst Brandt
Next: Tubular Tire Repair
Previous: Rolling Resistance of Tubular Tires
Last Updated: by John Allen
