Cyclists on a Backroad

seamus wrote: »

Bicycles, on the other hand, do not routinely go above 35km/h on most roads, and the narrower tyre profile means that they're virtually impossible to aquaplane under normal conditions.

Therefore the slick -v- non-slick argument is irrelevant when it comes to bicycle tyres.

The nature of the bicycle in fact makes slick tyres safer on tarmac than wider tyres with a tread
http://www.sheldonbrown.com/tyres.html#tread

That link also has a useful table re: aquaplaning. Most skinny tyres run at between 100 and 120 PSI. Meaning that the bicycle needs to be travelling ~170km/h to aquaplane.

i was referring to racer type bikes that have narrow tyres....and these bikes on regular basis go faster than 35km/h

Technoprisoner wrote: »

i was referring to racer type bikes that have narrow tyres....and these bikes on regular basis go faster than 35km/h

No they don't.

Under typical conditions on normal roads cyclists using these bikes will typically be doing less than 35km/h. Only under race or hard training conditions will they exceed that, and even then only up to 40/45km/h, at most.

They will occasionally exceed 50 or 60km/h, but only for short bursts downhill, not for long stretches. Aquaplaning requires bicycles to travel well in excess of 100km/h.

Cars will routinely travel in excess of 80kmh, for hundreds of kilometres. Aquaplaning can occur at speeds as low as 60km/h in some cars.

that is a silly stupid post...of course the width of the tyre makes a difference...more tyre=more grip so if you are breaking it will reduce the speed easier

That's not necessarily the case. There are more factors at play than the simple width of the tyre.

I wouldn't apply for that engineering job just yet.

seamus wrote: »

No they don't.

Under typical conditions on normal roads cyclists using these bikes will typically be doing less than 35km/h. Only under race or hard training conditions will they exceed that, and even then only up to 40/45km/h, at most.

They will occasionally exceed 50 or 60km/h, but only for short bursts downhill, not for long stretches.

Cars will routinely travel in excess of 80kmh, for hundreds of kilometres.

That's not necessarily the case. There are more factors at play than the simple width of the tyre.

I wouldn't apply for that engineering job just yet.

really? and you got you engineering degree from where?

Technoprisoner wrote: »

i was referring to racer type bikes that have narrow tyres....and these bikes on regular basis go faster than 35km/h

LOL - I wish that was true! (cause it certainly isn't true for me!)

seamus wrote: »

I await your proof with bated breath.I never claimed to have one. But you seem to be claiming authoritative knowledge on tyre dynamics without a shred of evidence to back it up.
I've provided at least rudimentary links.

well looks like you need to be a physicist and not an engineer....heres a link for you to knock yourself out with explaining more tyre = more grip

http://www.physicsforums.com/archive/index.php/t-330790.html

enjoy

UnawareCaesar wrote: »

D'you really think Engineers don't study physics?

oh we are moving onto to an argument about engineers ?


it science man...you cant argue with that

Technoprisoner wrote: »

well looks like you need to be a physicist and not an engineer....heres a link for you to knock yourself out with explaining more tyre = more grip

http://www.physicsforums.com/archive/index.php/t-330790.html

enjoy

The problem with sticking some keywords into google and then pasting up the links you get back is that very often the links will contain information which completely contradicts what you're claiming.

Which is exactly what's happened in this case.

Enjoy

Jaysus, just give it up will you. Learn to know when you've got it wrong and just say, "OK, I'm wrong, I accept that".

People will respect you a lot more.

Even if, for some reason, having more tyre on the road meant better grip, the weight of the object in contact with the road has a major part in the equation. And since I don't know of any cars weighing less than 10kg, it's safe to say that the amount of grip between the road and a car tyre would be fairly similar to the amount of grip between a bicycle tyre and the road, because of the two weights verses surface contact being proportional.

Technoprisoner wrote: »

im not looking for respect.... wider tyres will give you more grip

The wider the wheel the more weight that is required in order to deform it to the road.
Bike and motorbike wheels are rounded because turning on a two wheeled vehicle requires you to shift your center of gravity into the turn in order to maintain stability. If the wheel was flatter like a car it would be much harder to maintain your center of gravity.

Hence a wider wheel wouldn't have extra contact with the ground, you are sacrificing the ability to deform the tire, and either lateral grip for very little extra horizontal grip, or the ability to turn and not fall over. Wider tires are advantageous when it comes to extremely uneven terrain, which is one of the reasons mountain bike tires are much wider. Luckily the conditions on Irish roads aren't quite that bad just yet.

The reason that motorcycle wheels are wider is to dissipate heat so the tire lasts longer, and because the extra weight means your not sacrificing as much lateral grip.

endacl wrote: »

Don't mention it.

He wasn't going to :pac:

Knasher wrote: »

The wider the wheel the more weight that is required in order to deform it to the road.
Bike and motorbike wheels are rounded because turning on a two wheeled vehicle requires you to shift your center of gravity into the turn in order to maintain stability. If the wheel was flatter like a car it would be much harder to maintain your center of gravity.

Hence a wider wheel wouldn't have extra contact with the ground, you are sacrificing the ability to deform the tire, and either lateral grip for very little extra horizontal grip, or the ability to turn and not fall over. Wider tires are advantageous when it comes to extremely uneven terrain, which is one of the reasons mountain bike tires are much wider. Luckily the conditions on Irish roads aren't quite that bad just yet.

The reason that motorcycle wheels are wider is to dissipate heat so the tire lasts longer, and because the extra weight means your not sacrificing as much lateral grip.

so what you are saying is that if you take 2 tyres both with the same rolling circumference. but you had 1 thw was 7 or 8 mm wide ...and the second was 45mm wide there would be no difference in grip. if the 2 were put on the same bike and brought up to the same wheel...if the brakes are applied on both the stopping distance will be the same?

Technoprisoner wrote: »

so what you are saying is that if you take 2 tyres both with the same rolling circumference. but you had 1 thw was 7 or 8 mm wide ...and the second was 45mm wide there would be no difference in grip. if the 2 were put on the same bike and brought up to the same wheel...if the brakes are applied on both the stopping distance will be the same?

The question is irrelevant really. On my commuter, I run 700x28's. At 110psi. I've cycled in all conditions. Never had a problem stopping. Interestingly, I've never noticed much of a difference in stopping distance from dry and sunny to lashing rain.

It has more to do, I'd say, with the mass of c.100kg in total. Not a lot of inertia built up. Even at speeds in excess of 30kph. I'll let one one of the resident mathematologists work out the sums.

If anything, I'd say the grip was 'too' good. Only yesterday I had the rear wheel hop when I braked suddenly to avoid slamming into the back of a taxi who swung in in front of me. Dry conditions at about 20-25kph.

All massive tyres would do is to increase rolling resistance, making it harder to maintain both speed and control. Although I would have thighs like Schwarzenegger, and could easily kick any taxi I came across out of my way.

I have no science to back this up. Only personal anecdotal experience. Hope this is OK?

And just for more clarity, the standard width of a so-called "racing bike" tyre is 23mm. Which is not a lot of mm's less than a commuter.