Tyres. 23 to 20mm

Tyre width is a controversial topic.

I love very high pressures, so I use 20s, but I wouldn't use them for criteriums because conering is definitely more dangerous.

Less surface area is usually faster, but only on reasonable roads, and if you go too narrow, there's a suggestion that too much deformation of the tyre will occurr, therefore making the tyre slower. 🙁 As far as I know, 21 or 22mm tyres are supposed to be the "best", which is why the most expenisive tubulars are around that width.

So, what do you do? Just experiment to see what you like.

I assume the 20mm Hutchinsons will have a higher psi rating than the 23s, so you should notice a difference in feel if you inflate them to their maximum.

I weigh about 85kg (187lbs), and I too only get about 2500-3000kms out of a rear tyre, and a bit over 4000km for a front.

these are all the sponsors of McEwan's team. Looks like they use Continental tyres.

http://www.lotto-domo.com/sponsors.aspx?lang=en

nutbag said:

these are all the sponsors of McEwan's team. Looks like they use Continental tyres.

http://www.lotto-domo.com/sponsors.aspx?lang=en

23s = good
20s = bad

Cornering ability is also dependent on how supple the tire is. If you have a very flexible (i.e. good quality - many TPI) then the tube deforms when side-loads are present, thus having more contact with the road and providing better traction.

This is also why tubulars are thinner - they conform to the road much much more than clinchers. Both because of the gluing process and the suppleness of the latex. i.e. tubulars have greater traction than clinchers at any given width and can therefore be made thinner.

Your Hutchinsons are good tires - I have never ridden them, but I would assume they operate more or less on this principle above. The only way to get to the bottom of this is test them out.

JAPANic said:

My BONTRAGER RACE X-Lite Silica tyres were starting to get hundreds of little splits on the sides after 6 months of use... not too bad but I thought that they may split open suddenly going around a bend so went to the LBS to replace them.

They may be splitting from the heat... I had my bike in the car a few times.. (never again)...Not in summer anyway...

My new tyres are French Hutchinson Carbon Comp TS Elit 700 X 20s....　190g

They were really hard to put on, and I notice they are much thinner than the BONTRAGERs... and can even notice my bike sitting closer to the ground.

My theory in the shop was less surface area on the road = faster cycling...

Now they they are on, I'm worried about cornering. Not much lee way fro leaning now....

What advantages are there in using thinner tyres and what advantages in using a standard size?

I liked the look of these new ones... Gold in color like Robbie McEwen!!!!

What brand does he use?

How many kms should a set of tyres last.

I liked the BONTRAGERS but after only 2700km they seemed to be dying quickly...

Are Hutchinson a good tyre?

As I recall, 20's were the hot thing about 10-15 years ago. Then some reports started coming out that they have more rolling resistance for riders of normal weight. So, having a thinner, more aero tire doesn't get you anything if it's offset by more rolling resistance.

Regardless of width, the size of the contact patch, and it's ability to stick to the road, is very much dependent on tire pressures. If you're an average-weight rider, running the max rated pressure will buy you poor roadholding, a harsh ride, more flats, and more rolling resistance on anything but the smoothest of roads.

The tires you bought should corner great, as long as your pressures are right.

Those hundreds of little splits your referring too happen on a lot of high end kevlar clinchers. I've seen that happen on Michelin pro race, Continental Attack/Force, and Hutchinson. I do not think heat in your car causes the splits. I have not left my bike in my car for a extended period of time, and on hot days I take my bike into work and prop it up the side of my desk. I think the constant high pressure causes the splits. I've had better results by letting the air out after I am done riding and do not leave them pumped up for extended periods of time when they are not riding. Also, over-inflation speeds this process up, even if it's only 5lbs over.

On tubtular vs. clincher, the tubular rim is not carrying any stress from the sidewall of the tire. Therefore, the rims can be made lighter. Tubular tires have more rolling resistance because the load is transmitted through TWO casing walls (tread and rim casing walls) and through the glue, all of which imposes visco-elastic hysteresis losses.

Now on the 20 vs 23, most mfg's use identical casing composition for 20 and 23 lines. Since casing stress is the product of pressure and diameter divided by twice the casing thickness, 20's should be able to take a bit more pressure than 23's. A 23 that can take 125 PSI will have a corresponding 20 that can take 144 PSI. Because of this, the contact patch length remains the same and the corresponding hysteresis losses are roughly the same. (20 * 144 = 23 * 125)

The ONLY benefit to 20's is a slightly lower aerodynamic loss.

Weisse Luft said:

On tubtular vs. clincher, the tubular rim is not carrying any stress from the sidewall of the tire. Therefore, the rims can be made lighter. Tubular tires have more rolling resistance because the load is transmitted through TWO casing walls (tread and rim casing walls) and through the glue, all of which imposes visco-elastic hysteresis losses.

Now on the 20 vs 23, most mfg's use identical casing composition for 20 and 23 lines. Since casing stress is the product of pressure and diameter divided by twice the casing thickness, 20's should be able to take a bit more pressure than 23's. A 23 that can take 125 PSI will have a corresponding 20 that can take 144 PSI. Because of this, the contact patch length remains the same and the corresponding hysteresis losses are roughly the same. (20 * 144 = 23 * 125)

The ONLY benefit to 20's is a slightly lower aerodynamic loss.

Perhaps this is all true - I see no blatant flaws in your logic (I have my doubts about the compression losses of the glue). However, these losses are completely negligible, and a 1psi difference in pressure would totally negate any of this. There are much more important performance-affecting differences between tubulars and clinchers than these.

descends411 said:

Perhaps this is all true - I see no blatant flaws in your logic (I have my doubts about the compression losses of the glue). However, these losses are completely negligible, and a 1psi difference in pressure would totally negate any of this. There are much more important performance-affecting differences between tubulars and clinchers than these.

No, I am NOT talking about the compressive effects of the tubular glue. Air has very little hysterisis and the increase in pressure from applied load is NOTHING. The clincher tire has the exact same bias angle as the tubular and the only difference is the rim on a clincher must support the outward pressure load as well as the clinching load.

I do tend to keep my tyres at full 100% pressure....will let a bit of air out in future or only usee 100% for races...

JAPANic said:

I do tend to keep my tyres at full 100% pressure....will let a bit of air out in future or only usee 100% for races...

Suggest you don't want 100% for races either. Unless you're racing on very smooth pavement, you'll have more rolling resistance and poorer roadholding running max rated pressure. High speed crit corners with the tires bouncing off the road aren't fun.

Believe you'll find 100 psi front, 105 in back with the 20's will give you a lot more grip, better handling stability, much smoother ride, and no sacrifice in speed. Will fill like a different bike....worth a try at least.

dhk said:

Suggest you don't want 100% for races either. Unless you're racing on very smooth pavement, you'll have more rolling resistance and poorer roadholding running max rated pressure. High speed crit corners with the tires bouncing off the road aren't fun.

Believe you'll find 100 psi front, 105 in back with the 20's will give you a lot more grip, better handling stability, much smoother ride, and no sacrifice in speed. Will fill like a different bike....worth a try at least.

Does body weight have anything to do with it?

These pressures seem ideal if you're a 150lb Tour rider, but what if you're a 185lb club hacker (like me 🙂 ) who pushes the rim right to the road every time you "stomp" on the pedals, when using 23s with 105psi?

nutbag said:

Does body weight have anything to do with it?

These pressures seem ideal if you're a 150lb Tour rider, but what if you're a 185lb club hacker (like me 🙂 ) who pushes the rim right to the road every time you "stomp" on the pedals, when using 23s with 105psi?

110-115 should suit most people. 105 is a bit soft.

Weisse Luft said:

No, I am NOT talking about the compressive effects of the tubular glue. Air has very little hysterisis and the increase in pressure from applied load is NOTHING. The clincher tire has the exact same bias angle as the tubular and the only difference is the rim on a clincher must support the outward pressure load as well as the clinching load.

Don't caps. I'm perfectly able to get your point without it.

If you don't mean that the glue imposes losses, then don't use "all of which imposes visco-elastic hysteresis losses," implying that the glue does contribute, along with the extra casing.

As I said I agree with you on the casing.

By bias angle, are you referring to the shifting of the tire under side load? This is not a commonly used term, so I need more info.

Any comment on the fact that these are completely negligible and shouldn't even be mentioned?

ed073 said:

110-115 should suit most people. 105 is a bit soft.

Weight, road surface and personal preference certainly play here. I like 95 front/100 rear on 23 mm GP 3000's here. I'm 168 lbs/76 kg.

Suggest people experiment with pressures to find what they like...the max rating on the sidewall likely isn't it. "Logic" tells us that higher pressure is faster, but I don't believe that's the case for most normal road surfaces.

I've taken my new tyres on a few small runs on the straight. So far so good....

Not sure if they are better or not now... I'm thinking of putting 23mm on the back and leaving the 20mm for the front... (more traction on my backside and less wind resistance up front...)... pedantic...