Tires - Is my assumption correct?

Everything about building wheels, glueing tubs, etc.
alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

My point is, all other things being equal, a heavy rider would puncture a corsa speed in 20km and a really light rider would probably do 1000km. It's not true that: double the weight = half the distance.

That's why I think the relationship of km between punctures and weight is exponential (opposed).

When racing you can't afford a single puncture so you better have some extra protection though.

Many people could benefit from a corsa speed in the front while racing if the roads are good. Even up to 75kg riders. It would suffer as much as maybe a 50kg rider using one in the rear.

This is just my reasoning. Feel free to disagree :lol:

by Weenie


TobinHatesYou
Posts: 1759
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

I don't think that's true either. You're basically claiming a tack is significantly less likely to perforate a thin casing under a 60kg system weight and a 100kg system weight. In both situations the probability of a puncture is very high because of the extremely high PSI at the tip of the tack. Heavier riders are more likely to pinch-flat at lower pressures, but that is a completely different failure mode.

alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

It's good we don't ride on tack infested roads.

Ironically a corsa speed run tubeless would maybe be ok but a gp4ks2 on tubes would fail, but that's another comparison.

I'm talking about moderate debris. Small gravel/glass/metal fragments. Heavy rider would push these further into the tire and faster. Maybe before they could be manually picked out after a ride and so on.

TobinHatesYou
Posts: 1759
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

The same physics applies to all the debris you mentioned. You’re talking about sharp edges/points being run over by 70 or 100kg... that weight difference doesn’t matter as much as you think it does. The biggest difference tire pressure itself makes is preventing snakebites from sag/deflection.
Last edited by TobinHatesYou on Sun Sep 09, 2018 10:29 am, edited 1 time in total.

alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Whatever you say buddy.

Next time you test a tire that you manage to puncture in the first 100km doesn't mean a lighter guy can't go 1000km without a puncture on it. It can still be a great tire for someone else.

With the same kind of thinking if you are 100kg and want to go touring. Leave those Gp4k2s tires at home unless they are brand new and you plan to ride under 500km. The risk of puncture is too great.

That's my point. Two riders can ride the same equipment on the same route but take different risk.

Nefarious86
Moderator
Posts: 2519
Joined: Sun May 25, 2014 4:57 am
Contact:

by Nefarious86

You're logic is horribly flawed based on personal bias lol.
Using Tapatalk

alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Just putting my experience out there. Anyone reading can either think about it or reject it.

Internet at it's best.

I'd love to read about your experiences. The more info the better for when dealing with the next decision.

Cheers /a

Nefarious86
Moderator
Posts: 2519
Joined: Sun May 25, 2014 4:57 am
Contact:

by Nefarious86

So you rode 100km and got a puncture. I've had one within 20km of putting a Specialized Roubaix tyre on. Your logic must mean then that 85kg guys cant ride endurance tyres too as they're 5x more likely to puncture than a corsa, which I've also punctured..
Using Tapatalk

alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Sorry, seems those tires aren't in the bicyclerollingresistance database.

Specialized only has Turbo and Turbo Cotton tested, neither of which have better puncture resistance than a common GP4ks2 that isn't too great either.

If you buy tires that you are unhappy with you can try to wear them out on the front wheel. They usually last much longer there. Saves you a few bucks not throwing them away.

I'm pretty light (65kg) and rarely mix tires. I puncture on the rear probably 3 out of 4 times. I like to try and lower my rr losses but I'd like to keep my chance of puncture even front+back. Conclusion is I probably need to go one size larger in the back and possibly one step thinner in the front. Then maybe I can arrive at 50/50. Haven't really made up my mind yet. I can't seem to wear out my tires fast enough to try different ones. I do race on corsa speed front and gp4ks2 rear but no training.

Only punctured once this year and it wasn't the fault of the tire. Snakebite. I do try to stay updated on what my friends ride and how often they puncture. They weigh 90-125kg and need different tires than what I use.

/a

User avatar
Lewn777
Posts: 315
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

OP back again. :D
So my feeling is this...
1. rolling resistance.com measurement of tire thickness is a good basic guide to how likely a tire is to puncture. This doesn't mean you can't puncture an endurance tire in 5km, or get 2000km of puncture free love from a hardcore race tire as luck always plays a part.
2. New tires are less likely to puncture than old ones.
3. Weight does play an issue, but surely it's better to measure this in bike+rider weight. This is obvious because most people pick up more punctures on the rear than front, so logically the rear takes more weight, therefore weight increases the likelyhood of puncturing.

So most bikes are balanced 60% rear 40% front.
My bike plus rider weight (clothes, shoes, drinks, spares, helmet, computer, snacks, cell phone in short everything) is 90kg. Therefore there is approx 55kg on the rear and 45kg on the front. But if I dieted and got my bike and rider weight down to 80kg I would then have a balance of approx 45kg rear and 35kg rear now meaning I would expect to have on average as many flats on the rear as I used to on the front.

I'm not claiming to be correct, because my math is horrible, but if I'm wrong please put me right in an evidence based and polite way. :thumbup:

TobinHatesYou
Posts: 1759
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Alcatraz, I find BRR’s puncture resistance test to be fairly useless. Puncture resistance changes throughout the life of the tire tread. He also doesn’t simulate the most common type of puncture I encounter...randomly shaped glass shards.

Use BRR for rolling efficiency numbers and tread thickness measurements, and not much else.

Lewn777, my rear punctures mostly come from worn tires. I’d say my puncture rate on new tires is fairly random. My weight distribution is probably 45/55 though and this is of course just anecdotal. Weight does matter, just not as much as some people think for perforations from sharp objects.

alcatraz
Posts: 1230
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

That math sounds reasonable to me but the rest of the punctures I think can be accounted by the simple reason that a front wheel can easily be steered away from surprise debris, unlike the rear.

TobinHatesYou, I think you're right but it's at least better than comparing subjective reviews. Don't have much else to go on.

User avatar
LouisN
Posts: 2431
Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

I personnaly think total weight matters, because it will inevitably influence the PSI needed for, let's say, a "balanced" ride on a said tire.
The heavier rider will have to run at higher pressure than the lighter rider to avoid such issues as pinch flats, therefore creating more "force" against road surfaces, debris, etc...
But I also agree that a heavier rider riding on lower PSI has less chance of flats than a lighter rider on higher PSI...
Anyways, that's the logic I understand....:).
Lewn777 wrote:
Sun Sep 09, 2018 9:59 am
OP back again. :D
So my feeling is this...
So most bikes are balanced 60% rear 40% front.
My bike plus rider weight (clothes, shoes, drinks, spares, helmet, computer, snacks, cell phone in short everything) is 90kg. Therefore there is approx 55kg on the rear and 45kg on the front. But if I dieted and got my bike and rider weight down to 80kg I would then have a balance of approx 45kg rear and 35kg rear now meaning I would expect to have on average as many flats on the rear as I used to on the front.

I'm not claiming to be correct, because my math is horrible, but if I'm wrong please put me right in an evidence based and polite way. :thumbup:
Depends on many factors. I maintain that focus on road is the main factor. Heck spot those objects on the road and steer away from them. If you ride in a group, ride first or don't ride too close from other cyclist's back wheels. I will repeat this but it's so obvious: Riding at lower pressure will also reduce flat risks greatly. Also riding position, and technique will reduce flat risks. It's not for all the cyclists, but riding a more aggresive position instead of an upright one will distribute the weight better between the wheels, and give you better balance. EDIT: I agree you have to push bigger watts to achieve such a change. That means in real life, you will punture a lot less if you change the above, but you will still keep punturing if you just focus just on losing a few kg. Unless this is your main motivation. In that case I encourage you to go for the weight loss. If your focus is on weight loss AND fitness gain, then you can iincrease your avg. watts, move your weight forward, and decrease the flats %.

Louis :)

Post Reply
  • Similar Topics
    Replies
    Views
    Last post