What Wheels?

[no.one.knows]

Thanks johan, something i keep reading about and obviously get the wrong info. never knew they had less rolling resistance. now i know!!! cheers

[Johan Bornman]

Snip snip snip.....

 

What i don't understand is that after all the marketing hype from Easton about the marvelous threaded spokes on both sides and how an elbow joint is the achilles heel of a wheel' date=' their latest generation wheel is about as straight forward a wheel can get and does away with all the fancy stuff. I bet this new wheel costs about half as much to produce though.
[/quote']

 

They got caught up in their own marketing hype. The elbow and thread are about equally vulnerable. If the spoke approach angle at the rim veers too much off the 90 degree mark, then the thread is more prone to breakage than the elbow.

 

A good wheelbuilder who understands the residual stresses in a spoke knows how to make the elbow durable enough for a 200 000 km life.

 

In my view, that's a life-time.

 

The best wheel (for all-round use) is a standard wheel i.e. one with elbow spokes, cross spokes, standard serviceable hub, standard ALUMINIUM rims and .....sorry Peter.....clinchers.

 

For special purposes, wheels need to veer off these fundamentals, but then always at the expense of strength, durability, braking performance, serviceabillity and of course, cost.

 

Strangely enough, just about any wheel is stiff enough and stiffness is therefore never an issue, no matter what the design or materials.

 

Strong, light, cheap - choose two.

 

JB

 

[Christie]

Hi JB

I struggle to understand the fundamentals of what you are saying. OK, I understand why soft glue will result in a amount of lag under acceleration or deceleration. However, I would think that the lag is small, as I have recently locked up my wheels in a race and the skid stripped the outer compound completely off the rear tubby, exposing the underlying puncture proofing, but the tubby stayed attached to the rim. This leads me to conclude that the bond between the tubby and the rim is fairly strong in the rotating direction.

Secondly, at a constant speed, inflated to the same pressure, would the the rolling resistance not be depend mainly on the difference in the outer compound from tyre to tyre? At a constant speed, the lag due to soft glue should not have an influence.

Thirdly, my clinchers can be inflated to 8.5 bar, while my tubbies can go to 15 bar. So in a very hypothetical sense, I would think a tyre inflated to 15 bar has less rolling resistance than one at 8.5 bar. I say hypothetical, because in reality I only pump the tubbies to 12.5 bar, because I'm too lazy to pump them to 15 and the harder the tyre, the bumpier the ride.  

Christie2007-11-04 13:38:40

[Christie]

I agree with the negatives you list regarding tubbies: hard to repair, expensive.

 

[PokerFace]

15 bar!!!! WOW!!! Wouldn't that be a reason why tubbies are less likely to puncture?

[Johan Bornman]

Thanks johan' date=' something i keep reading about and obviously get the wrong info. never knew they had less rolling resistance. now i know!!! cheers [/quote']

 

Rules of thumb for rolling resistance:

 

1) Clinchers are better than soft-glued tubbies.

2) Wider, up to 28mm is better than narrow.

3) Harder is better than softer, up to +_ 110 PSI, then the benefits flatten out dramatically.

4) Silica-based* tyres have slightlyless RR than carbon-based tyres.

5) Thinner tubes improve RR because it is the thickness of the tyre and tube together that causes RR.

6) RR is so small in modern bicycle tyres that you shouldn't bust your head about it. It is in the order of three or four grams of pressure per 40kg wheel load.

 

 

* Silica tyres: silica is sand and as you know, you can get coloured sand. Hence the various colours of silica tyres. All coloured tyres nowadays and most black tyres are silica-based, simply because they cost less to manufacture. Silica has a slightly better RR but pays for that in poor wet performance and poor grip. The latter is not an issue since most of us are too scared to lean far enough to slip out.

 

There is a new fashion in tyres, no doubt cashing in on  the love for all things carbon, to label some tyres as Carbon tyres. These are nothing other than old-fashioned black tyres. All car tyres contain carbon and all bicycle tyres used to get their black colour from pure carbon until silica came along.

 

Silica tyres perform so poor in the wet that they're banned from cars. Smart wanted to match their cute two-seater For Two cars with colour-coded cars but the DIN standard put an end to that and they're now stuck with carbon tyres like the rest of the motoring world.

 

Then, about four years ago, Avocet came along and put the words Carbon 12 (standard carbon isotope) on their tyres and caused a stir in the US. However, Avocet is so small, that it had no market impact and it is still a marginal tyre supplier. Now Continental (I believe) started marketing Carbon tyres this year. I say marketing, because Continental's black tyres used to be carbon-based until the colour fad came along. I have no doubt that it'll create the same stir that the Kevlar revolution created.

 

Carbon was first discovered in the century before last to be the perfect additive to raw rubber for making rubber tyres last and last and last.

 

I am now waiting for someone to market a Carbon 14 (rare isotope of carbon) tyre and claim a puncture resistant, glow-in-the-dark, ever lasting product.

 

This is not too far-fetched. What is even less far-fetched is that they'll convince the cycling population that there is benefit in this. The benefits will go something like this: Stronger, Lighter, Stiffer, Faster.

JB

 

 

[PokerFace]

[quote name=Johan Bornman

... 

This is not too far-fetched. What is even less far-fetched is that they'll convince the cycling population that there is benefit in this. The benefits will go something like this: Stronger' date=' Lighter, Stiffer, Faster.

JB

 

 

[/quote]

That could be the marketing for almost any cycling related article!

[Icycling]

The Yak - how tall and heavy are you? This can impact on the wheels you choose!

[Johan Bornman]

[

Christie Writes:

 struggle to understand the fundamentals of what you are saying. OK, I understand why soft glue will result in a amount of lag under acceleration or deceleration.

 

The RR doesn't come from what you describe as lag under acceleration. It comes from a movement between the tubbie and the rim. Just like a car's squealing sounds on a smooth floor gives away the fact that the tyre moves in relation to the floor, a tubbie's aluminium oxide in the contact area proves to us that a tubbie squirms against the rim, something that a clincher doesn't do, since it's attachment is much more secure. The energy losses happen underneath the tyre, against the rim.

 

Christie:

 

However, I would think that the lag is small, as I have recently locked up my wheels in a race and the skid stripped the outer compound completely off the rear tubby, exposing the underlying puncture proofing, but the tubby stayed attached to the rim. This leads me to conclude that the bond between the tubby and the rim is fairly strong in the rotating direction.

 

Johan: There is no perceptable lag. I.e. the rim doesn't rotate ahead of the tyre. We're not strong enough for that. As I said, it is squirm at a different level.

 

Christie:

 

Secondly, at a constant speed, inflated to the same pressure, would the the rolling resistance not be depend mainly on the difference in the outer compound from tyre to tyre? At a constant speed, the lag due to soft glue should not have an influence.

 

 

Johan:

 

 All things being equal, the tubbie has more RR due to the squirm. We assume outer compounds are the same.

 

Christie:

 

Thirdly, my clinchers can be inflated to 8.5 bar, while my tubbies can go to 15 bar. So in a very hypothetical sense, I would think a tyre inflated to 15 bar has less rolling resistance than one at 8.5 bar. I say hypothetical, because in reality I only pump the tubbies to 12.5 bar, because I'm too lazy to pump them to 15 and the harder the tyre, the bumpier the ride.  

Johan:

A clicher can withstand less pressure because the bead will lift and let the tube escape with a  big bang.

 

However, the last few bar, from 8.5 upwards produce massively diminishing returns and just hurt your body.

 

JB

 

 

[BikeMax]

 

You are correct about the lower rolling resistance of the best clinchers' date=' but tubular rims give a significant weight advantage, tubulars puncture far less frequently and also handle better. On top of that a punctured tubular stays on the rim and you in turn on the bike.

 

For a race wheel and tyre combination I would choose tubular rims and wheels over clinchers 100% of the time.

[/quote']

 

Hi Peter

 

From measurements I've seen, just about any quality clincher of the type that anyone would fit to a bike will give lower rolling resistance than a soft-glued tubbie.

 

I don't understand your puncture claim though. The two tyres and their tubes are essentially the same construction, materials and thickness and both will puncture equally easily given the same puncture object. There's nothing inherent in a tubbie that makes it more resistant to penetration.

 

Weight advantage I'll grant you... "significant" I'll arm wrestle you for.

 

Better handling???? I don't understand. Both handle the same and an unglued tubbie in the case where you just punctured and replaced it, rolls off in corners.

 

I believe the only reason tubbies still exist is because it is still difficult and expensive to make an all-carbon clincher rim and tubbies give the manufacturers a cheap way out. As long as the myth of the superiority of tubbies exist, they'll ride it to the max.

 

The pro peleton is rife with superstition and myths and tubbies are one of those who just seem to stick no matter what.

 

Besides, tubbies are a dog to repair by anyone's standards.

 

JB

 

 

 

 

 

An interesting study done here;

 

http://www.rouesartisanales.com/article-1503651.html

 

Rolling resistance is minimally different in my opinion but I would still argue that pinch flats are reduced on tubulars (and my anecdotal experience backs this up) and that due to the shape and profile of the tubular (more like a rear motorcycle tyre) that handling through corners is superior. Safety once unctured is an issue and tubulars will provide a safer platfrom if at speed.

 

That having been said - 400 odd grams is a significant weight saving at the rim in my book.

 

[Willehond]

Oooh, you don't want to say 'at the rim' like it is better than saving weight anywhere else on the bike with JB around...

 

Bound to be a reply

[sias]

Ja-nee asb Bikemax! Moet net nie s? dis beter om gewig op die wiele te spaar as op enige ander deel van die fiets nie! Dis al bespreek ad nauseum!

Tubbies ry baie lekkerder en kry definitief nie soveel "snakebites" soos clinchers nie.

[Johan Bornman]

An interesting study done here;

http://www.rouesartisanales.com/article-1503651.html

Rolling resistance is minimally different in my opinion but I would still argue that pinch flats are reduced on tubulars (and my anecdotal experience backs this up) and that due to the shape and profile of the tubular (more like a rear motorcycle tyre) that handling through corners is superior. Safety once unctured is an issue and tubulars will provide a safer platfrom if at speed.

That having been said - 400 odd grams is a significant weight saving at the rim in my book.

 

Aaaah. Pinch Flats. Yes, less pinch flats purely because of the shape of the rim. General puncture resistance, the same for equal thickness of tyre and tube, irrespective of whether it is a tubbie or clincher.

 

However, the inflated shape of a tubbie and clincher are exactly the same - i.e. a perfect cylinder. Obviously the clincher is not perfectly cylindrical on the underside, where it follows the rim's shape, but for calculating the contact patch and RR, it is a cyclinder.

 

Both these tyres are constructed like pressure hoses, with high tensile strength cords intersecting at 35.27 degrees when inflated.

 

Just like you don't want a pressure hose like the one you use at a garage to inflate your car tyres, to become fat and short when pressurised, you don't want tyres to change shape as the pressure increases.

 

Therefore they are designed so that the force on the cords in the wheel's direction of travel equals the inflation pressure X the area of the inner diameter. 

 

In other words, the tyres are designed so that they "inflate" up to when the cord angle is 35.27 degrees and then remain stable, irrespective of the pressure.

 

Both tubbes and clincers are made like this, which means their inflated shape is exactly the same, hence handling remains the same. They're both perfectly cyclindrical on the side that matters.

 

I had a look at the study you linked in. It was performed by Continental and not peer reviewed, which worries me should I have to trust the data for some or other important reason such as brand comparison.

 

Continental did a few things right, amongst others, do the test on a smooth steel drum. This is the only way to standardise the surface - anything roughter only adds to the base RR.

 

They could have done better by publishing the slip-out angle and mentioned whether the tyre in question is made from carbon black or silica. This would have shown us that the slip-out angle is far smaller for silica tyres.

 

They did pick up that narrower tyres increase RR - good.

 

I don't go for the emotive language though, especially the intro paragraph where they talk about the most underrated aspect being RR. I think most of us should just forget about it after taking care of the base factors - pressure, size and compound, and go for a ride.

 

JB

 

 

 

 

 

 

[buckstopper]

Nou gaan hijack julle weer die thread, al is dit meer interesant. Yak doesn't have the bucks for tubbies, period. Wheels are about compromise as JB and Brad Hunter (who put Velomax on the map says). At 1477gm the Orion 2's provide 24/28 spokes an awesome ride (clinchers) tempest quality hubs. They are also stiffer than the Ascent at 1428gm 18/24 spoke about R5500

2 other alternatives, Tempest 2 clinchers 1570gm 18/24 spoke, awesome wheel about R6500

Ksyrium SL also fairly light and very stiff and responsive, not as good as the above wheels in crosswinds. Don't require rimtape so there is a 40-50gm saving there. About R6500

 

Dura Ace 7800, a bit heavier at 1700gm, lovely aero wheel to ride, rolls beautifully, good enough to ride a break. expect to pay R4500-R6000 

[Kiwi]

Get some Ksyrium clinchers, even the latest ES version can be got second hand for R4500. They are light and tough, look at any European cyclocross races and you even see then used there!

There may be some bargains for brand new sets soon too as they have just be superseded by a new version call Ksyrium SL which we don't have here yet.

If you go tubbies then get some Tufo tub tape, no more glue and you can stick another tubbie on on the side of the road and it wont roll off allowing you carry on at full speed.

[Christie]

I think from the discussion we can conclude that:

1. tubbies do not have lower rolling or puncture resistance when inflated to the same pressure as clinchers.

2. deep section tubbies are more aerodynamic & lighter than clinchers. The effect of this on performance may not be as big as marketers want us to think, but they will feel different, enough to put a smile on your face, at least.

 

IMO if you dont want to save a bit longer / spend more on tubbies, keep your current wheels. Spending R5k on other clinchers wheels wont make a big difference. If you are dead set against tubbies, rather spend the money on other bike stuff then.