Tire size question

[Chain theory]

I have an old Worksman and according to the parts and spec page on there web site there tires are 26” x 2.125” I just bought a new set of crossroads tires at the bike shop and had them installed. After reading a related thread I thought I'd take another look at them. The ones they put on are 26" x 1.95 Does anyone think this could be a problem
The tire is supposed to rotate in one specific direction and they have the front one turned the wrong way.

[HoughMade]

Can't see it causing a problem on either front. The tires are a but smaller that 2.125s available, but 1.95s will work. As for directional- in wet conditions, maybe an issue- in the dry, don't see an issue.

[Chain theory]

Thanks HoughMade

[Mountainman]

Chain theory - kind of depends on what you are looking for in regards to your ride. The smaller tire will not take bumps as well. For riding in the dirt as we know - larger tires work better. For straight out speed on roadways - thinner tire is a little faster. You can easily turn your front wheel around so as to have both tires going with the thread in the same direction. Happy Riding from - Mountainman

[loquin]

And, you should keep in mind... per Sheldon Brown, even with slicks, it is impossible for a bicycle to be moving fast enough to hydroplane. Even downhill. The tires are too narrow, and the resulting pressure (total bike w rider weight divided by the total area of the tire surface in contact with the pavement) too high for it to ever be a problem. Slicks give the best pavement performance, as it puts the most rubber in contact with the pavement. The only reason that bike tire manufacturers even HAVE tread on street tires is because user familiarity with auto tire tread design leads people to assume that bike tire tread is important. For pavement use, it isn't. In fact, for pavement use, the more tread, the poorer the cornering and stopping performance.

[Mountainman]

slick tires -- rider must be careful - they do slip on slick surfaces more easily. Do we not think that motorcycle companies have not done much testing in regards to tires ? Taking that into account - why do most tires on new motorcycles come with at least some thread ?? Happy Riding from - Mountainman

[Chain theory]

Thanks allot guys for our input. I guess I will keep them. They were kind of pricey, but at least they look good on the old bike. I had an Honda Passport back in the early 80s. I hit a oil spot in the left hand turn lane and down I went whether I had tread or not. lol

[loquin]

slick tires -- rider must be careful - they do slip on slick surfaces more easily. Do we not think that motorcycle companies have not done much testing in regards to tires ? Taking that into account - why do most tires on new motorcycles come with at least some thread ?? Happy Riding from - Mountainman

Because motorcycles are capable of going much faster than bicycles, and their tires have much more surface area in contact with the pavement, tread is needed to channel water out from between the tire and the road surface to reduce hydroplaning.

Bike tires are very narrow, (resulting in high contact pressure) and the speed is much less. Tread isn't needed for bicycle tires on pavement.

The aircraft industry has studied hydroplaning a great deal. They've determined that hydroplaning speed depends on tire pressure, and as tire pressure increases, so does the the minimum speed needed to hydroplane. At 40 PSI, the minimum speed needed to hydroplane is 66 miles per hour; at 60 PSI, the minimum hydroplane speed increases to 80 MPH.

At high bicycle speeds, hydroplaning is just possible for car tires, but is absolutely impossible for bicycle tires.

Ref Sheldon Brown's article on tires. Scroll down to the section on tread.

Also remember that tire rubber deforms under pressure. Any slight irregularity in the road surface is 'pressed into' the tire, providing traction. If you add 'Tread', you are removing rubber that would otherwise be in contact with the road surface. The only time that I could see a tread pattern helping improve traction, would be if you are riding on a snowy road.

[Mountainman]

Good article on tires - but - I didn't see where any data from testing was done. No doubt Sheldon has a lot of good information posted - just wondering if some of it may be one man's opinion ? I hit a slightly wet spot the other day - front wheel started to slid out and stopped. I have a little thread - just not real sure that a slick would have been better ? Happy Riding from - Mountainman

[loquin]

IMO, the more rubber in contact with the road, the better. Why would drag racers run slicks if they don't provide better traction?

A slippery surface is a slippery surface. Tread or no tread. But, having LESS tire surface in contact with the surface reduces the traction on a slippery surface.

The ONLY reason that auto & motorcycle tires need tread is to channel standing water away from the tire face/road. Auto tires, in particular, need this, because a) they're flat, with a large tire surface in contact with the road, and b) they travel at a high rate of speed. This means that there's a point, at some speed, where the tire can't push all the water out of the way.

A bike tire has so little surface in contact with the road, that the contact pressure is substantially higher than an auto or motorcycle tire. And, it presents a rounded surface. this, in conjunction with the fact that there's more time (since a bike is slower than a car) to push the water our of the way.

Wikipedia mentions the formula that Brown referred to. (the actual formula is speed (in knots) equals 8.6 times the square root of the tire pressure in psi) And, they mention

Bicycles, motorcycles, and similar vehicles with a round-shaped surface toward the pavement are far less likely to hydroplane in normal road use. The contact area with the road is a canoe-shaped patch that effectively squeezes water out of the way.

And, at How Things Work, mention is also made of this.

Is hydroplaning a form of sliding friction?
Not exactly. Sliding friction refers to the situation in which two surfaces slide across one another while touching. In hydroplaning, the two surfaces are sliding across one another, but they aren't touching. Instead, they're separated by a thin layer of trapped water. While hydroplaning still converts mechanical energy into thermal energy, just as sliding friction does, the lubricating effect of the water dramatically reduces the energy conversion. That's why you can hydroplane for such a long distance on the highway; there is almost no slowing force at all.

Dan Barker, one of my readers, informed me of a NASA study showing that there is a minimum speed at which a tire will begin to hydroplane and that that speed depends on the square root of the tire pressure. Higher tire pressure tends to expel the water layer and prevent hydroplaning, while lower tire pressure allows the water layer to remain in place when the vehicle is traveling fast enough. As Dan notes, a large truck tire is typically inflated to 100 PSI and resists hydroplaning at speed of up to about 100 mph. But a passanger car tire has a much lower pressure of about 32 PSI and can hydroplane at speeds somewhat under 60 mph. That's why you have to be careful driving on waterlogged pavement at highway speeds and why highway builders carefully slope their surfaces to shed rain water quickly.

Wikipedia also mention that narrow tires, and tires at higher pressures are less succeptable to hydroplaning, and that underinflated auto tires contribute to hydroplaning.

There are lots of references to hydroplaning and speed. The only factors mentioned to determine hydroplaning speed is tire pressure. If you are approaching the speed at which hydroplaning will occur at your tire pressure, at that point, a tire's tread WILL help you out a bit, by channeling some of the water away. But, it does so by removing rubber that is in contact with the road, and thus reducing traction at all other times.