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Questions about purchasing bicycles and parts

Postby Dave A » Wed Sep 19, 2007 7:30 pm

This exact same thing happened to me this time last year when i was in the market for a new bike.
Come September, the suppliers have run out of this years stock, and generally have no idea when next years will be available.
In effect, there is a 2-3 month vacuum.

I am staggered that this is common practice, amongst all makes.

Can you imagine a car company operating like this :shock:
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by BNA » Wed Sep 19, 2007 8:32 pm

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Postby MountGower » Wed Sep 19, 2007 8:32 pm

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Last edited by MountGower on Tue Feb 15, 2011 7:49 pm, edited 1 time in total.
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Postby Blybo » Thu Sep 20, 2007 3:02 pm

MountGower wrote:benalc81 wrote:
There are a lot of misconceptions regarding this. Some people think that a thinner tyre is faster. This is not the case. The fatter the tyre, the less rolling resistance it has. This is beneficial up to between 25-30kph, after which it's lower aerodynamics causes it to drag slightly more. Both these factors will not be felt by the rider.

Another misconception is that the increased pressure usually held by the thinner tyre makes it faster. This is chronically and massively overstated by most people.

I have Michelin Transworld City commute tyres. They are like sports car or motorbike tyres with the water dispersing grooves and are quite wide at 26x1.95. They run at 67psi so most people would think they are wide and slow. On my road bike I run quite expensive Vittoria Diamante 700x23c tyres at 130psi. My mountain bike is 2kph slower on the flat and up hills alike. They are the facts. As I said earlier, I have happily ridden over 100km on my mountain bike and loved it. Then there are the times I have after a tyre change and hit the bush.


I'm confused as you said many are. I've just replaced a 26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre @45psi for a Schuwable tyre like your commute tyres but in 26x1.5 @90psi.

The difference is chalk and cheese in effort to me. I also changed my computer at the same time so I'd rather not compare speeds but I'm doing the same commute in the same time allowing for daily variances at a much lower output level.

I would logically have thought a smaller contact patch achieved by a thinner tyre at the proper pressure should have significantly less rolling resistance plus as you mentioned the narrower tyre would have a slightly better aerodynamic profile.

Please explain why this perceived substantial benefit to me is a figment of my imagination. I'm not trying to flame you here, it just doesn't make sense to me. Also... if you can climb at the same speed on your MTB as your roadie either it is an extremely light MTB or your working harder to maintain that pace.
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Postby europa » Thu Sep 20, 2007 3:16 pm

Blybo wrote:I would logically have thought a smaller contact patch achieved by a thinner tyre at the proper pressure should have significantly less rolling resistance plus as you mentioned the narrower tyre would have a slightly better aerodynamic profile.


This is where it starts getting complicated.

The comparison made between a thin tyre and wide tyre is usually stated as being 'at the same pressure'. At the same pressure, the thin tyre has a long, narrow contact patch. The wide tyre has a short, fat contact patch. Comparing the two, you get less rolling resistance with the short, fat contact patch, ie, the wide tyres.

However, what I haven't seen demonstrated (and possibly because I haven't read the articles correctly), is comparing a fat tyre at its optimum pressure with a thin tyre at its optimum pressure - this would be a fat tyre at something like 45-60 lb depending on the tyre and the thin tyre at something like 100-130 lb. There we may see some differences.

Pumping your tyre up until it is rock hard does not produce less rolling resistance, and I forget the reasonning now. If I remember correctly, you are best pumping your tyres to a pressure that allows the tyre to flex a bit. Coincidentally, this also gives a comfortable ride so I've gone to the practice of working out the max pressure that gives me a comfortable ride (as opposed to that 'riding on wood' feel of a very tight tyre).

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Postby Aushiker » Thu Sep 20, 2007 3:24 pm

Dave A wrote:This exact same thing happened to me this time last year when i was in the market for a new bike.
Come September, the suppliers have run out of this years stock, and generally have no idea when next years will be available.
In effect, there is a 2-3 month vacuum.

I am staggered that this is common practice, amongst all makes.

Can you imagine a car company operating like this :shock:


Yep very frustrating and bloody poor customer service and they wonder why we shop online overseas!

I emailed four stores yesterday re the Felt. Only two replied. Makes you wonder why the bother have websites and email addresses.

Felt do not even have the 2008 bike specs available yet I can get one ex the East apparently. All Felt are doing is encouraging me to go back to Giant.

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Postby Aushiker » Thu Sep 20, 2007 3:30 pm

Blybo wrote:I'm confused as you said many are. I've just replaced a 26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre @45psi for a Schuwable tyre like your commute tyres but in 26x1.5 @90psi.

I think you are comparing apples with oranges here. MG is comparing apples and apples. What I mean is you are referring to your experience going from a knobbly tyre to a slick, MG is talking about a fat slick against a thin slick.

I would expect your experience as you have changed the tyre design on the bike.

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Postby europa » Thu Sep 20, 2007 3:38 pm

Aushiker wrote:
Blybo wrote:I'm confused as you said many are. I've just replaced a 26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre @45psi for a Schuwable tyre like your commute tyres but in 26x1.5 @90psi.

I think you are comparing apples with oranges here. MG is comparing apples and apples. What I mean is you are referring to your experience going from a knobbly tyre to a slick, MG is talking about a fat slick against a thin slick.

I would expect your experience as you have changed the tyre design on the bike.

Andrew


And what Andrew didn't say (but implied), is that going from a knobbly to a slick is dramatic :D ... unless you're in the mud :roll:

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Postby Dave A » Thu Sep 20, 2007 4:26 pm

Aushiker wrote:Yep very frustrating and bloody poor customer service and they wonder why we shop online overseas!

I emailed four stores yesterday re the Felt. Only two replied. Makes you wonder why the bother have websites and email addresses.

Felt do not even have the 2008 bike specs available yet I can get one ex the East apparently. All Felt are doing is encouraging me to go back to Giant.

You obviously havent tried buying an Orbea then.

One of the many reasons i bought the Felt was the fact i got delivery before Christmas.
Having a website showing the 2008 bike, and actually being able to buy the bike are two very different things.

And dont bother with emails, ring the store instead.
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Postby Blybo » Thu Sep 20, 2007 4:30 pm

Without being rude here you both missed this bit
26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre


It was basically a full width MTB tyre with slick tread.

I believe I am comparing fat apples with thin apples :P although maybe I could of made it clearer :oops:
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Postby europa » Thu Sep 20, 2007 4:35 pm

Blybo wrote:Without being rude here you both missed this bit
26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre


It was basically a full width MTB tyre with slick tread.

I believe I am comparing fat apples with thin apples :P although maybe I could of made it clearer :oops:


The off road experts will have to confirm this, but I think that these are among the worst offenders for tyre performance ... but maybe I'm thinking of something else.

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Postby Blybo » Thu Sep 20, 2007 4:39 pm

europa wrote:The comparison made between a thin tyre and wide tyre is usually stated as being 'at the same pressure'. At the same pressure, the thin tyre has a long, narrow contact patch. The wide tyre has a short, fat contact patch. Comparing the two, you get less rolling resistance with the short, fat contact patch, ie, the wide tyres.

However, what I haven't seen demonstrated (and possibly because I haven't read the articles correctly), is comparing a fat tyre at its optimum pressure with a thin tyre at its optimum pressure - this would be a fat tyre at something like 45-60 lb depending on the tyre and the thin tyre at something like 100-130 lb. There we may see some differences.

Richard


Thanks for clarifying that. Seems pointless to compare the 2 at the same pressure as they are designed to operate at different pressures although I'm sure quantifying results at optimum pressure would be scientifically more difficult. The pressure figures I quoted for my tyres were both around 10% below the maximum recommended.
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Postby Birdman » Thu Sep 20, 2007 4:40 pm

europa wrote:
Blybo wrote:Without being rude here you both missed this bit
26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre


It was basically a full width MTB tyre with slick tread.

I believe I am comparing fat apples with thin apples :P although maybe I could of made it clearer :oops:


The off road experts will have to confirm this, but I think that these are among the worst offenders for tyre performance ... but maybe I'm thinking of something else.

Richard

I'm not an offroad expert but from searching the forum i have noticed that people have a strong disregard for the semislick tyres.

Mitch.
SOME PEOPLE ARE LIKE SLINKYS. NOT REALLY GOOD FOR ANYTHING BUT THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.

Until next time...
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Postby Bnej » Thu Sep 20, 2007 4:53 pm

europa wrote:Pumping your tyre up until it is rock hard does not produce less rolling resistance, and I forget the reasonning now.


It does, but don't do that. If and only if you are riding on perfectly smooth tarmac where you don't have any traction issues or bumps to roll over, you can get faster rolling with really high pressure. The contact patch shrinks, the sidewall flexes less, and as such the tyre will roll better.

But the difference is smaller the more air you put in. On a real road you'll lose the benefit you get because your bike will be vibrating constantly and you will have poor traction as the contact patch is so small.

I know someone who runs 160PSI on 23mm tyres on road, you can hear everything rattle around even on smooth roads. It's just not worth it.

Iif you want a comfortable ride at lower speeds, run a 1.5"/32mm tyre or wider. If you want a fast, light tyre for rough roads, use a 28mm tyre. If you want to go fast on good roads use a 23mm or 25mm tyre. If you're doing a time trial you can go narrower but only if you're serious.
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Postby Blybo » Thu Sep 20, 2007 5:03 pm

europa wrote:
Blybo wrote:Without being rude here you both missed this bit
26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre


It was basically a full width MTB tyre with slick tread.

I believe I am comparing fat apples with thin apples :P although maybe I could of made it clearer :oops:


The off road experts will have to confirm this, but I think that these are among the worst offenders for tyre performance ... but maybe I'm thinking of something else.

Richard

You may be thinking of something different, I can't link as yet as I haven't been a member long enough but they are called town & country and can be seen on Continentals uk site under city and touring tyres.
If this was what you were thinking I'll have to have stern words with my old LBS as they were sold to me as commuting/high performance tyres. At the time I bought them I thought skinnier tyres on a MTB looked silly and I still do to a point; but with the Around the Bay in a Day coming up I thought I needed all the help I could get :oops:
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Postby Bnej » Thu Sep 20, 2007 5:07 pm

The Continental Town & Country is not a bad tyre. They are made for rough roads and gravel/dirt so they are not as fast as some slicks, but they are a solid choice for a fat road tyre.

The good thing (among many good things) about fat slicks is you still can take them off road, just as long as you're a bit careful about how fast you go and the conditions of the surface.
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Postby Blybo » Thu Sep 20, 2007 5:26 pm

Bnej wrote:The Continental Town & Country is not a bad tyre. They are made for rough roads and gravel/dirt so they are not as fast as some slicks, but they are a solid choice for a fat road tyre.


Thanks Benj, I understand from performance car ownership that construction and tread materials in tyres can have an effect on performance/speed but getting back to my original point I'm surprised that MountGower suggests that the difference in speed performance between a MTB with moderate width slicks and a roadie with narrow slicks is overstated by most. I would have thought that there is a heap of difference, hence buying a bike for it's intended function.
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Postby europa » Thu Sep 20, 2007 5:33 pm

Bnej wrote:The Continental Town & Country is not a bad tyre. They are made for rough roads and gravel/dirt so they are not as fast as some slicks, but they are a solid choice for a fat road tyre.

The good thing (among many good things) about fat slicks is you still can take them off road, just as long as you're a bit careful about how fast you go and the conditions of the surface.


See, wait long enough and someone who knows what he's talking about comes along :D Thanks Bnej.

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Postby Blybo » Thu Sep 20, 2007 5:40 pm

Well the lycra has come out of the locker and it's time for my commute. I'll look in again tomorrow.
Cheers all,
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Postby Bnej » Thu Sep 20, 2007 9:05 pm

Blybo wrote:Thanks Benj, I understand from performance car ownership that construction and tread materials in tyres can have an effect on performance/speed but getting back to my original point I'm surprised that MountGower suggests that the difference in speed performance between a MTB with moderate width slicks and a roadie with narrow slicks is overstated by most. I would have thought that there is a heap of difference, hence buying a bike for it's intended function.


When you get a bike tyre there's a wealth of choices to make, you can go for light weight, puncture resistance, low rolling resistance, road traction, sidewall toughness, dry/wet performance, on/off road performance, comfort... you just can't get a tyre that's perfect at everything.

WRT to the speed difference, it is and isn't overstated. I certainly see more disparity in my speeds than 2km/h (more like 5 with my bikes & rides). 2km/h average might not sound like much but it's 33m every minute - if you're chasing someone they'll pull away pretty fast. If you're on your own doing a commute though, it's not that big - you don't go twice as fast or anything.

It depends a lot on the bike, the tyre, the way you ride, the terrain, road quality, etc. And of course, you can make up for whatever the bike lacks with more fitness.
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Postby Mulger bill » Thu Sep 20, 2007 9:46 pm

Bnej wrote:The Continental Town & Country is not a bad tyre. They are made for rough roads and gravel/dirt so they are not as fast as some slicks, but they are a solid choice for a fat road tyre.

The good thing (among many good things) about fat slicks is you still can take them off road, just as long as you're a bit careful about how fast you go and the conditions of the surface.


On my third set now :) , I'd call them more comfort road oriented, with a reasonable off road capability, great for urban riding. You can squeeze a bit more than 45psi in there too if you feel that way.

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Postby Aushiker » Thu Sep 20, 2007 10:00 pm

Blybo wrote:Without being rude here you both missed this bit
26 x "standard knobby width" city/country (slick centre and small tread on shoulders) Continental tyre


It was basically a full width MTB tyre with slick tread.

I believe I am comparing fat apples with thin apples :P although maybe I could of made it clearer :oops:

You are correct I did missed the specifics. My apologies for that.

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Postby Blybo » Fri Sep 21, 2007 10:18 am

Mulger bill wrote:
Bnej wrote:The Continental Town & Country is not a bad tyre. They are made for rough roads and gravel/dirt so they are not as fast as some slicks, but they are a solid choice for a fat road tyre.

The good thing (among many good things) about fat slicks is you still can take them off road, just as long as you're a bit careful about how fast you go and the conditions of the surface.


On my third set now :) , I'd call them more comfort road oriented, with a reasonable off road capability, great for urban riding. You can squeeze a bit more than 45psi in there too if you feel that way.

Shaub

Yep I reckon they are great tyres and will be putting them back on the MTB when the around the bay is done and dusted, 1 month from today! I'm hoping that doing a 100k ride will convince SWMBO that we do need Roadies or flat bar roadies as she is already talking about doing the full 220k bay ride next year :shock:
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Postby Bnej » Fri Sep 21, 2007 10:28 am

If you do the full 220 you need to get good road bikes. It's a really really long way to go on flat bars.

Plus, road bikes are shiny. ;)
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Postby stryker84 » Fri Sep 21, 2007 10:32 am

Bnej wrote:If you do the full 220 you need to get good road bikes. It's a really really long way to go on flat bars.

Plus, road bikes are shiny. ;)


While flat bar roadies are the more road oriented hybrids, some even coming close to road bikes in design, they're not roadies simply with flat bars, there is some difference in geometry etc. Yes, you'll want a proper road bike for the full ATB distance, both for the drops and the performance.

And yes, road bikes ARE shiny. ;)
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Postby Blybo » Fri Sep 21, 2007 10:35 am

Bnej wrote:WRT to the speed difference, it is and isn't overstated. I certainly see more disparity in my speeds than 2km/h (more like 5 with my bikes & rides). 2km/h average might not sound like much but it's 33m every minute - if you're chasing someone they'll pull away pretty fast. If you're on your own doing a commute though, it's not that big - you don't go twice as fast or anything.


33m per minute brings it into perspective a bit more as still being significant but the 5km/h you mentioned sounds more realistic to me and I do understand all tyres will have strong and weak points.

I'm not doubting the facts that MountGower used to illustrate his point, I just don't think that the argument used is relevant to the point he is trying to get across, given that people looking for knowledge on this forum would be observant enough to make sure they correctly inflate their tyres regardless of size.

I would however agree with MountGower and suggest to the OP a decent MTB with Town & Country or similar tyres until a more informed decision can be made with maybe 12 months riding under his belt. He could even look at buying a second hand set of MTB wheels and have a set for commuting and a set for off road/recreation use.
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