Why no puncture resistance tubes in expensive bikes?

[Saintor]

Ok... "expensive" is relative... let's say 1000$+ bikes.

I examined a few tubes in a store. I couldn't believe the difference in just thickness between the regular ones and "puncture resistant" ones. The latter has a rubber thickness of 0.030" but the regular ones looks like 1/3 of that, so flimsy.

Within one month, I got a flat tire with my new bike. I was wondering why it came with something "thin" when there are much thicker tubes. The reason of the flat was a stuck piece of glass and I can't be sure that a thicker would have avoided me this.

Anyway I learnt a lot from this incident. I am now on schrader valves (Presta are kinda hell), keep a spare tube, a small pliers and a small pump.

[vinividivici]

what

[J-Tim]

People with expensive bikes tend to use them for racing, where grip+weight outweight durability.

So for instance, Continental Gatorskin tyre which is very durable, isn't the best for racing.

You can go middle grounds, and get something like 4000s which gives you a bit of both.

[SpeedyD]

Because they're heavy. Prestas kinda hell? You kinda suck.

[VWAddict]

Presta = 'Hell'?

I see you've never gone through childbirth then!

[Saintor]

Seller:

"Don't worry sir, here is a Schrader adaptor to put over these Presta valves. No problem."

Reality:

The air inflator's nozzle at our local garage didn't fit over that no-problem-adaptor. Of course, the rear tire was too soft to ride and I lost almost one hour of my life for nothing.

I had Schrader valves for 35 years on my Peugeot for tires at 90psi. That's good enough. Here is the solution to have one less thing to worry about.



YMMV.

[J-Tim]

Seller:

"Don't worry sir, here is a Schrader adaptor to put over these Presta valves. No problem."

Reality:

The air inflator's nozzle at our local garage didn't fit over that no-problem-adaptor. Of course, the rear tire was too soft to ride and I lost almost one hour of my life for nothing.

I had Schrader valves for 35 years on my Peugeot for tires at 90psi. That's good enough. Here is the solution to have one less thing to worry about.

YMMV.

No offence,but I think you're doing it wrong. You'll probably be fine is all you do is ride between local garages, but you are better off using presta valves and a proper hand pump and possibly adding a CO2 canister if you're worried that your mini-pump won't be able to get you up to 110psi.

[merckx56]

There are so many things wrong with this thread...

[Saintor]

No offence,but I think you're doing it wrong. You'll probably be fine is all you do is ride between local garages, but you are better off using presta valves and a proper hand pump

You dont know how lazy I am. Why bother when universal schrader valves will work just fine with my garage compressor? Is there only one thing that Presta valves will do better @ 90 PSI rather than just looking cute? Just asking.

[VR6ix]

That little lock ring and the threaded valve stem can be handy sometimes... run low pressure on a mountain bike and the tire/tube can spin on the rim, ripping the valve stem off the tube. Deep-dish aero road rims have no room for a big honkin' presta valve stem.

I wrecked the little valve on a presta once, and learned from it, and still find presta easier to use than schrader. My buddy did the same thing and now swears that presta is complete crap and will never use them again. YMMV, huh?

[J-Tim]

You dont know how lazy I am. Why bother when universal schrader valves will work just fine with my garage compressor? Is there only one thing that Presta valves will do better @ 90 PSI rather than just looking cute? Just asking.

I've no idea if it does the job better or not, all I know is that Presta valve is a standard on road bikes and most mini-pumps are designed for that type.

They are not designed for people who rely on garage compressors to pump up their tyres.

As for cuteness, the reason why they are small is so to keep the hole in the rim as small as possible for structural reasons.

It seems to me that you're simply trying to find an excuse for your own arrogance and come up with a solution for a problem you created yourself.

[speedn16v]

[QUOTE=J-Tim;79203626]

They are not designed for people who rely on garage compressors to pump up their tyres./QUOTE]

I made a presta inflator for < $20 with a blowgun, and a Silca head a few years ago.

Stan's NoTubes FTW!

Dave.

[Saintor]

That little lock ring and the threaded valve stem can be handy sometimes...

This I buy.

It seems to me that you're simply trying to find an excuse for your own arrogance and come up with a solution for a problem you created yourself.

You know what to do with your insults... *sit on them hard *.

As for structural reason, no. You could actually have as many valve holes in the rim's inner surface as wires and the mechanical resistance won't suffer. It is the side walls of the rim that give it its rigidity.

[J-Tim]

This I buy.



You know what to do with your insults... *sit on them hard *.

As for structural reason, no. You could actually have as many valve holes in the rim's inner surface as wires and the mechanical resistance won't suffer. It is the side walls of the rim that give it its rigidity.

Look, you came here for an advise and multiple people have already told you but the way your thought process is going is plain wrong. If you decide to take that as an insult, that's fine with me.

[merckx56]

This I buy.



You know what to do with your insults... *sit on them hard *.

As for structural reason, no. You could actually have as many valve holes in the rim's inner surface as wires and the mechanical resistance won't suffer. It is the side walls of the rim that give it its rigidity.

That is possibly the MOST incorrect statement I've ever heard about anything remotely cycling related...and I've done this for almost 30 years.

[Saintor]

Look, you came here for an advise and multiple people have already told you but the way your thought process is going is plain wrong. If you decide to take that as an insult, that's fine with me.

You are just getting emotional for no reason. That's just dumb. There were 2 relevant questions and if you can't answer intelligently (you proved that), *pass*.

That is possibly the MOST incorrect statement I've ever heard about anything remotely cycling related...and I've done this for almost 30 years.

That's your 'impressions'. And your argument is?

[SpeedyD]

wires

Wires? What are these wires you speak of? Guy who can't even name parts correctly is now going to question hundreds of years of wheel design.

[J-Tim]

You are just getting emotional for no reason. That's just dumb. There were 2 relevant questions and if you can't answer intelligently (you proved that), *pass*.

That's your 'impressions'. And your argument is?

Oh, deary me.



Good luck with your riding.

[merckx56]

You are just getting emotional for no reason. That's just dumb. There were 2 relevant questions and if you can't answer intelligently (you proved that), *pass*.




That's your 'impressions'. And your argument is?

So, by your dumbassed logic, you can take a rim, drill 100 holes in it, yet the hoop will still retain it's structural integrity because of the sidewalls? Really?

Riddle me this then Professor, when you lace the spokes from the hub to the hoop, and those spokes are brought up to tension, is the sidewall carrying that tension? Please 'splain this to us...we'll wait...

And if the sidewall of the hoop carries all of the load, then why are the vast majority of alu rims now double-walled, and several are eyeletted?

Why is it the carbon rims usually have additional carbon material at the peak of the rim, where the spoke exits? More than a few have small washers that fit between the nipple and the inner rim surface. More than a few also use nipples that are specifically designed to lessen the pressure on that same inner rim surface, and prevent stress risers, which will eventually crack.

Please enlighten us with your expertise on rims, wheels, and wheelbuilding.

[BsickPassat]

How about replacing the, a lot of times, cheapo tires with better, more puncture resistant tires?

In my case, currently running
http://www.conti-online.com/generato...season_en.html


260 grams per tire for 700x25c with a folding bead...
which compared to the stock Spec All Condition Sport that came with my bike, are actually lighter.

[Saintor]

How about replacing the, a lot of times, cheapo tires with better, more puncture resistant tires?

In my case, currently running
http://www.conti-online.com/generato...season_en.html


260 grams per tire for 700x25c with a folding bead...
which compared to the stock Spec All Condition Sport that came with my bike, are actually lighter.

I am sure that this makes more sense than focusing on the tube and the same question could be raised. Why no puncture resistance TIRES in expensive bikes? [/IMG]

[Saintor]

So, by your dumbassed logic, you can take a rim, drill 100 holes in it, yet the hoop will still retain it's structural integrity because of the sidewalls? Really?

Riddle me this then Professor, when you lace the spokes from the hub to the hoop, and those spokes are brought up to tension, is the sidewall carrying that tension? Please 'splain this to us...we'll wait...

And if the sidewall of the hoop carries all of the load, then why are the vast majority of alu rims now double-walled, and several are eyeletted?

Why is it the carbon rims usually have additional carbon material at the peak of the rim, where the spoke exits? More than a few have small washers that fit between the nipple and the inner rim surface. More than a few also use nipples that are specifically designed to lessen the pressure on that same inner rim surface, and prevent stress risers, which will eventually crack.

Please enlighten us with your expertise on rims, wheels, and wheelbuilding.

Relax your smart-ass tone unless your goal is NOT to have a civil discussion.

For your information, there are already "100 holes" in it. I am confident that there wouldn't any problem doubling these holes in the same axis, with a larger diameter. Maybe a slightly less ultimate resistance, but hardly significant and not affecting minimum safety factor. What you refer as the point of attachment of the spokes to the rim is obviously a relatively high stressed area under shocks and is another story. Having multiple holes in a structure is common in non-critical areas. If that matters, yeah I am a registered professional mechanical engineer.

[BsickPassat]

I am sure that this makes more sense than focusing on the tube and the same question could be raised. Why no puncture resistance TIRES in expensive bikes? [/IMG]

Because it costs $$$

When you're spending at various levels $1000 or more, I rather get better drivetrain components, then thicker tubes or tires.

What's next? Complaining about why many bikes costing $1000 or more don't come with pedals?

[VWAddict]

For your information, there are already "100 holes" in it. I am confident that there wouldn't any problem doubling these holes in the same axis, with a larger diameter. ... yeah I am a registered professional mechanical engineer.

I don't want to have the OP work on anything mechanical for me.

I hold an engineering degree, as does my wife... fwiw.

[Saintor]

Because it costs $$$

Yet IMO it is a perfectly marketable feature that people would want to get at a price. I would.

I have a Giant TCX 2 2012 and the TCX 1 is 800$ more and TCX 0 1400$ more. Guess what; the standard Kenda tires on the 2400$ TCX 0 are no more expensive than the puncture resistant Continental Gatorskin. Unless they are terrible tires, I would prefer to get the Conti and God knows, maybe I would be more tempted to get a TCX 0 or 1 instead of the entry level 2 because of this appealing feature.

[merckx56]

Relax your smart-ass tone unless your goal is NOT to have a civil discussion.

For your information, there are already "100 holes" in it. I am confident that there wouldn't any problem doubling these holes in the same axis, with a larger diameter. Maybe a slightly less ultimate resistance, but hardly significant and not affecting minimum safety factor. What you refer as the point of attachment of the spokes to the rim is obviously a relatively high stressed area under shocks and is another story. Having multiple holes in a structure is common in non-critical areas. If that matters, yeah I am a registered professional mechanical engineer.

I sincerely hope that you aren't an engineer working on any critical projects that are integral to the safety of the populus, because you know exactly JACK about bicycles, bicycle wheels, wheelbuilding, bicycle tires, etc.

[BsickPassat]

Yet IMO it is a perfectly marketable feature that people would want to get at a price. I would.

I have a Giant TCX 2 2012 and the TCX 1 is 800$ more and TCX 0 1400$ more. Guess what; the standard Kenda tires on the 2400$ TCX 0 are no more expensive than the puncture resistant Continental Gatorskin. Unless they are terrible tires, I would prefer to get the Conti and God knows, maybe I would be more tempted to get a TCX 0 or 1 instead of the entry level 2 because of this appealing feature.

First of all... you bought a cyclocross bike. The Kenda Small Block 8 is designed for general purpose cyclocross conditions, not for primary use on the road. So, you complaining about punctures on cyclocross tires used on an environment that is not really intended for


the TCX1 and TCX0 are more expensive because they get better drivetrain components. That is what you're paying the extra money for, not tires.

Even if you got a road bike, it still boils down to $$$

A quick glimpse of the intended use of the Kenda Small Block 8
http://youtu.be/-3AlnzaxcXE

[VR6ix]

http://www.spinskins.com/

[SpeedyD]

mechanical

But not a structural engineer, obviously.

[BsickPassat]

Relax your smart-ass tone unless your goal is NOT to have a civil discussion.

For your information, there are already "100 holes" in it. I am confident that there wouldn't any problem doubling these holes in the same axis, with a larger diameter. Maybe a slightly less ultimate resistance, but hardly significant and not affecting minimum safety factor. What you refer as the point of attachment of the spokes to the rim is obviously a relatively high stressed area under shocks and is another story. Having multiple holes in a structure is common in non-critical areas. If that matters, yeah I am a registered professional mechanical engineer.

It is more than just the sidewalls that give the a wheel strength.

YOur rim, actually has about 66 holes in it. 32x2+2

and you should already know, each hole is its own stress riser, not to mention how the rim is joined -- that area itself is a another structural weak point. Add more holes to it... you increase the stress risers. if you had 100 holes, when you look at the von mises stress profile, they will start to overlap, which will fatigue the wheel much faster.

you probably won't see a catastrophic failure by enlarging the presta hole to fit a schrader (hopefully you have no burrs, which can wear away at tube, even if it is reinforced), as they are slightly over-engineered.

Back to rims... when you look at a cross section, the double wall boxes in the sidewalls, which gives the wheels strength, while able to reduce wall thickness to reduce weight. Without the double wall design, the sidewalls will have to be significantly thicker to handle the shear applied to the walls from the tube/tire bead, the cross section would be a U shape.



for applications where a wheel will see more impacts, wheel designers don't beef up the sidewalls, they add more to the box section

Example:


or...in the case of the rim for the cyclocross bike I ordered


and I would expect the rim cross section of your Giant TCX bike would have something similar.

There are wheels where the spoke holes don't penetrate into the rim bed


Guess what? Even stronger!!! since it lacks all the stress risers found in conventional design rims. (and no need for rim rape)

Seller:

"Don't worry sir, here is a Schrader adaptor to put over these Presta valves. No problem."

Reality:

The air inflator's nozzle at our local garage didn't fit over that no-problem-adaptor. Of course, the rear tire was too soft to ride and I lost almost one hour of my life for nothing.

I had Schrader valves for 35 years on my Peugeot for tires at 90psi. That's good enough. Here is the solution to have one less thing to worry about.



YMMV.

DOing it wrong anyway. A drill bit doesn't create a perfectly round circle. An oblong circle will concentrate stress on certain areas of the stem, instead of a a more consistent load around the stem.

YOu should be drilling to a size slightly smaller, then use a straight reamer drill bit to get to the final size. (you won't find that in the PE exam)

[BsickPassat]

P.S. Don't bring the TCL attitude over to the Cycling forum.

The Cycling forum is a nice & relaxed that requires almost no moderator oversight.

[merckx56]

and the down has been smacked...

[username]

when I first got into biking beyond having a 20"-er when I was a kid, I didn't get presta valves and the durability vs. wieght tradeoff of road tires too. I even drilled out some MTB rims for shrader valves. Its ok, everyone makes mistakes

[mrothwell]

I'm loving this discussion BTW.

[BsickPassat]

how come bikes costing $1000+ don't come with Stan's Notubes Sealant? (whether in the tubes or tubeless)?