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Discussion Starter · #1 ·
There are a lot of opinions about tire width and its impact upon average speed, with the latest prevailing wisdom that the advantage of narrower tires is over-inflated (so to speak).

Although this is probably the case for a rider in optimal condition under optimal conditions, I was wondering what it would be like for me. I'm older and quite a bit slower than most people, for a variety of reasons I won't bore you with.

For the last few months I have been riding off and on road with Clement XPLOR MSO 40mm X 700. (Prior to that I used the 35mm XPLOR USH, but these seem to handle the rough trails I ride much better, without paying a significant on-road penalty.) So for laughs, I put Clement 28mm on-road tires on the bike today, and took it out for a quick shake-down ride. Despite riding more cautiously (and slower on the downhills), I gained a little bit over 12% in speed relative to my best time on a local six mile loop near my house that involves about 700 ft of climbing. In terms of absolute speed, I am still quite slow on this loop (11.8 mph), but I think this is a significant increase given it was hotter today, I was more tired, I was more cautious on the downhill portions, etc.

Getting the new tires on the rims was kind of an ordeal and I ruined a tube. Changing the tires on a per-ride basis seems impractical. Maybe I do need a second set of wheels... assuming this trend holds up on more rides. (Unfortunately, riding these smooth tires on gravel is not my idea of a good time, so it screws up my commute.)
 

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You changed the width, but you also changed the resistance by removing knobbies from the tire. Too many variables to declare narrower tires are faster.

Sent from my XT1565 using Tapatalk
 

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Discussion Starter · #3 ·
Well, I suppose I could find some 28 mm knobbies, but then there would probably be some other uncontrolled variable (different chevron pattern, different brand, different color, different width-adjusted tire pressure). Since it is a completely anecdotal observation, I don't see any point in bothering, since it isn't going to be generalizable.
 

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You could just enjoy the ride. The few times I found gravel on my 25 mm tires I felt fairly uneasy about it.

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Discussion Starter · #5 ·
It was more of an experiment than a lifestyle change. I need the gravel tires pretty much on a daily basis. (BTW the tread on the rear gravel tire is worn smooth.)
 

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You changed the width, but you also changed the resistance by removing knobbies from the tire. Too many variables to declare narrower tires are faster.
^^^This^^^

Probably the biggest difference in rolling resistance is with knobbies vs. slicks. This will make a much bigger difference than tire width.

Rather than looking for narrower knobbies, why not try wider smoother tires. Not necessarily slicks, but wider city/hybrid tires like these below. The Kenda Kwest in 700x40c are probably wide enough to handle your gravel roads with some due care, but roll really nice:

http://www.amazon.com/Kenda-KWest-K193-Cross-Bicycle/dp/B00IEZI07I
 

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Discussion Starter · #7 · (Edited)
I'm not really interested in narrow knobbies. It was just a suggestion on how I could do a better controlled experiment.

What I really found interesting was that the 28 mm slick tires made climbing easier and a wee bit faster. Whether this is due to the width per se, or some other aspect of the tire, like the tread pattern, isn't that important to me.

I have those Kendra's on another bike (a commuter I gave to one of my kids). They are a bit leaden and unresponsive.
 

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What I really found interesting was that the 28 mm slick tires made climbing easier and a wee bit faster. Whether this is due to the width per se, or some other aspect of the tire, like the trad pattern, isn't that important to me.
Slick is faster than treaded on pavement, irregardless of width.

I have those Kendra's on another bike (a commuter I gave to one of my kids). They are a bit leaden and unresponsive.
Really? Are you talking about the Kenda Kwest? I found just the opposite. What tires are you comparing them to?
 

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Discussion Starter · #9 ·
Today I did a much harder 15 mi ride. My increase in speed relative to the last time I rode this (a few days ago) on 40 mm knobbie tires, was only 3%. Today was a lot hotter, I talked with some guy a bit who was in the process of dusting me, even though he was ca. 15 year older and recovering from an ankle injury more severe than mine. But I have concluded that normal ride-to-ride uncontrollable variables like outside temperature and solar exposure, who you might say hello to along the way, etc, at least to me, are probably more significant than the differences between these tires. Since I really have no need to go incrementally faster, I think I would be wasting money on a second wheelset if I got it for the purpose of swapping around tires. I may go back to the 35 mm XPLOR USH, splitting the difference (they are on my wife's bike, and she wants the 28 mm ones, so everyone will be happy).
 

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Discussion Starter · #11 ·
Yeah, sorry about that. They are Conti Touring.
 

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But I have concluded that normal ride-to-ride uncontrollable variables like outside temperature......
Oh definitely. As much as I don't mind the cold and dislike the heat, ironically, I find I perform better in warmer temps. I believe this is because breathing is easier.
 

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Discussion Starter · #14 ·

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You changed the width, but you also changed the resistance by removing knobbies from the tire. Too many variables to declare narrower tires are faster.

Sent from my XT1565 using Tapatalk
I also think it has more to do with reduced overall rolling resistance over 'aerodynamics'.
 

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I only use GP4000 23mm and when I get on a bike with anything else I immediately notice the extra drag.
This is most certainly true when it comes to a lessor tire, but there are plenty of comparable, or superior, tires that could prove this to be overstated.
 

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This is most certainly true when it comes to a lessor tire, but there are plenty of comparable, or superior, tires that could prove this to be overstated.
Since going fast isn't cool anymore every time I get on someone else's bike it has wider tires. I haven't tried any other new 23mm racing tires. In a few days I'll be putting a lot of miles on my dad's new bike with Compass 32mm tires that the shop guy claims ride really well on good pavement. We'll see...
 

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Discussion Starter · #19 ·
I took the skinny little anorexic 28 mm tires back off and put the 40 mm knobbies back on. They are so much easier to put on, that alone warrants taking a (possible) 5-12% speed penalty.
 

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I'd get a second wheelset, or at least another rear wheel. It's always good to have a back up, or at the very least, something for an indoor trainer (if you use one).
 
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