Question on road bike tire quality - Page 2

sogood · #16 11-06.-2008

After going through a few different tyre models, I'd say that the value on high end tyres comes in,

1) Grip. Obviously a performance as well as a safety issue.
2) Puncture resistance. Simply saves me time.

parawolf · #17 11-06.-2008

Quote:

Originally Posted by DJA

Recently on a training ride we had a long gradual downhill slope the kind you can do about 60Kph all the way and no need to brake. My friend and I stayed together all the way to the bottom. He would only get in front until I slip streamed him to catch up( he is 10 to 15 KG heavier so should be slightly quicker without slip stream). But the third guy that was with us at the top was left for dead. Even thou he peddled to try and keep up, was unable to stay with as, the differance bottom to middle range tyres that he had on. By the way we didn't try to burn him.

On such a descent, aerodynamics makes a huge difference. As a result i'd be saying that bike setup would be making a larger difference here than tyre rolling resistance.

garage sale GT · #18 11-06.-2008

Wouldn't you more experienced riders agree that one way to get more grip and a better ride would be to not run the tire at the absolute highest pressure? If you have a fine sidewall, it doesn't slow you down too much.

alienator · #19 11-06.-2008

Quote:

Originally Posted by garage sale GT

Wouldn't you more experienced riders agree that one way to get more grip and a better ride would be to not run the tire at the absolute highest pressure? If you have a fine sidewall, it doesn't slow you down too much.

The only place it comes close to making sense to run the highest pressure possible would be a velodrome. Otherwise, pressures that are too high slow you down by:

Not allowing the tire to conform to road irregularities, forcing the tire to bounce off of bumps and other such things. This causes energy to be bled off in directions other than where you want to go. The tire doesn't even have to lose contact with the ground for this to happen.
Decreasing the size of the contact patch, thus reducing corner speed.
Decreasing the temp of the tire carcass, decreasing the tire's grip.
Fatiguing the rider over the course of a long ride.

As a bonus, pressures that are too high make a tire more vulnerable to punctures and cut sidewalls. Also, if you're doing big descents, tire pressure that's too high coupled with rim heating from braking can cause the tire bead to elongate enough--or even melt--potentially causing bead failure and rapid tire deflation, followed by rapid grinding of flesh and bone on pavement.

nbfman · #20 11-07.-2008

Well, the Open Corsa was retired. Thanks to this discussion, it was on my mind to check the tire before embarking on a long climb in order to ensure a safe descent. What I saw is as attached (hope attachment works) i.e. detached patch of rubber about 1x0.5 cm in size, exposing threads underneath. As someone mentioned, the rubber layer does indeed look very thin - like noticably <0.5 mm. My spare happened to be a blue Bontrager Racelite, so I'll just to ride a while longer with a mix of tires between front/rear. Front black, rear blue looks somewhat odd, but I'll live.

One question is under what conditions would you keep riding on a tire like this? Would you change it at first sight? Would you risk another 40-50 km to get home? Would you reinforce the area with something like tape before riding any further?

Also, can you let me know what tire pressures work best for you. I always pump my tires to 120 PSI and do not like it when I can see the tire noticably bulging to both sides of the rim when riding the bike. My only reason for this is that I feel like the wheel will be more prone to rim out when I hit a bump and the feeling that it is a sign of the pressure being too low. But the other day, I was on the tail of a rider whose back tire was considerably more deformed than mine. He was a very strong rider, so I thought I may need to do more experimenting on tire pressure. Can you share how you decided on the tire pressure that works best for you?

Thanks.

kdelong · #21 11-07.-2008

Quote:

Originally Posted by nbfman

Well, the Open Corsa was retired. Thanks to this discussion, it was on my mind to check the tire before embarking on a long climb in order to ensure a safe descent. What I saw is as attached (hope attachment works) i.e. detached patch of rubber about 1x0.5 cm in size, exposing threads underneath. As someone mentioned, the rubber layer does indeed look very thin - like noticably <0.5 mm. My spare happened to be a blue Bontrager Racelite, so I'll just to ride a while longer with a mix of tires between front/rear. Front black, rear blue looks somewhat odd, but I'll live.

One question is under what conditions would you keep riding on a tire like this? Would you change it at first sight? Would you risk another 40-50 km to get home? Would you reinforce the area with something like tape before riding any further?

Also, can you let me know what tire pressures work best for you. I always pump my tires to 120 PSI and do not like it when I can see the tire noticably bulging to both sides of the rim when riding the bike. My only reason for this is that I feel like the wheel will be more prone to rim out when I hit a bump and the feeling that it is a sign of the pressure being too low. But the other day, I was on the tail of a rider whose back tire was considerably more deformed than mine. He was a very strong rider, so I thought I may need to do more experimenting on tire pressure. Can you share how you decided on the tire pressure that works best for you?

Thanks.

With a tire in that condition, I would reinforce it with heavy duty tape and probably reduce the pressure depending upon how close it was to the max limit. With that said, I would then gently and slowly ride it home. If I was going to ride past or near a cycling shop, I would probably stop in and purchase a new tire and have them mount it for me.

Concerning tire pressure, experiment with riding different pressures and see what works best for you. Tire pressure is going to be like saddles, what works for one person does not necessarily work for everyone. It is very subjective. On most of my tires, I inflate them to within 20% of the max rated inflation pressure but I weigh about 190 pounds. I max out my Bonty Race Lites but that is just because they feel better that way.

garage sale GT · #22 11-08.-2008

That tire looks fine to me unless the cords are damaged. Some tires don't have any rubber over the fabric at all except for enough to glue the plies together and they work fine. The rubber doesn't really give the sidewall any strength; it just protects the cords in the casing from abrasion. If it was on my "hard use" bike I'd glue a tube patch over it to protect it, but it might look a bit odd on a nice, new bike.

Sikhandar · #23 11-09.-2008

Remember that Vittoria & Veloflex compounds are mainly based on natural rubber, not on synthetic SBR... well, on the models I've recently analysed ;-) (opppps I couldn't tell)

Well, ok, talking about the TPI... "there are" some old industrial reports of the past decades of Vittoria R&D that record a slight dependence of the rolling resistance from the TPI. Conty recently (GP4000S) introduced an incredible amount of TPI (330!) but the standard GP4000 was 180 (also in 2009). Keep in mind that GP4000 was *good*... so I think that looking at the TPI could be useful only when choosing top end clinchers.

Veloflex clinchers ara all at 300 TPI, also the cheapest model and... the low end model (Black) it's not a clincher it's a life experience even better than a open cx, though it lasts only for 4000 km.

alienator · #24 11-09.-2008

Hmmm. I found Bridgestone slicks to be life changing, but I've never found a bicycle tire to be life changing, except for tires that free up riding time by decreasing the time spent addressing flats.

My assometer tells me that any difference in ride quality, grip, or rolling resistance between Vittoria Corsa Evo CX, Conti Sprinter Gatorskins, and even Maxxis Refuse tires is lost in the noise.

Air pressure: that's the magic ingredient.

Sikhandar · #25 11-09.-2008

Tyre pressure you say eh? Hmmm......

The effect of tyre pressure on the economy of cycling. Ryschon T W; Stray-Gundersen J Department of Internal Medicine, University of Texas, Southwestern Medical School, Dallas Ergonomics (1993), 36(6), 661-6. Journal code: 0373220. ISSN:0014-0139. MEDLINE

(their abstract ends with a triumphal: We conclude that differences in rolling resistance caused by varying tyre pressure between 552 and 965 kPa, are too small to be detected physiologically)

I'm joking anyway, this is an article that has little to do with what I intend to be the main characteristic of a tyre that is: how good is it when doing turns? (in that sense a Veloflex could be a life experience

(not a life change, though)).

nurul · #26 01-15.-2009

Quote:

Originally Posted by alienator

Tire tech has been accelerating rapidly, but perceptions don't change as quickly as the tech. When I was racing motocycles, the hot tire, a Dunlop intermediate GP rain tire, for racing would shred like crazy, leaving "snot"--balled up rubber--at the edges of the tire and all over the inside of the fenders. Years down the road, tires for the same races don't really ball up and have more grip. Same stuff goes on with bike tires.

Note the historical attachment to the wonders of tubular tires, all the while Michelin has put out tires--PR2 and PR3--that challenge those long held ideas that tubulars are the mac daddy. People'll say that tubies corner better, but that better is never quantified or described in depth. I know all my recent tires--tubie and clincher--have stuck in corners, and I also know I damn well don't want to slide them like motorcycle front tires were slid going into corners at racetracks.

While TPI is usually different between tubies and clinchers, the real significant difference is that tubie tech hasn't kept apace of clincher technology. I think that Vittoria and Veloflex--and Dugast, FMB, and Challenge--will get left behind, or at least left on the fringe, as Conti, Michelin, Maxxis, and others apply the fruits of their comparatively huge R&D budgets to their bike tires. If Bridgestone enters the market as they've suggested, it'll get doubly tough on the little guys.

There are some textiles, too, that will hit the market in the nearish future that will likely redefine what puncture resistance means. Some are classified and restricted, now, and some need for economies of scale to catch up, but they're out there, judging by what's been published in research journals.

What has been published in which research journals??