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Myths in cycling: wider tires are slower

renehersecycles.com

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Re: Myths in cycling: wider tires are slower

#51

Post by dahart »

louthy wrote: post #2

If that were the case, surely Tour de France riders would use wider tyres to gain more grip going around corners, especially in time-trials or stages with sprint finishes. Doesn’t a greater surface area touching the floor means more frictional effects when pushing against the road?

> Doesn’t a greater surface area touching the floor means more frictional effects when pushing against the road?

Good question because at first I thought it might be negligible due to the tire normally being in a state of static friction relative to the road. But some quick searches showed me that rolling resistance is related to how large the contact point is, like you suggest, along with a variety of other factors. https://en.wikipedia.org/wiki/Rolling_resistance

I don’t know how reliable this is, but googling brought me to this site which compares bicycle tire brands according to rolling resistance on their test machine. Apparently, some 25s have all the 23s beat. If true, the variability range for bicycle tires is a lot wider than I expected. https://www.bicyclerollingresistance.com/

Re: Myths in cycling: wider tires are slower

#52

Post by haswell »

jaypeg25 wrote: post #48
haswell wrote: post #12

This is one of the reasons I love the emergence of the "Gravel" category of bikes. They look and have geometry similar to a road bike, but they have enough clearance for nice fat gravel tires. I ride in Chicago (shitty roads, potholes & construction are everywhere), and love that I can put nice 38mm+ GravelKing Slick tires on the bike, and still have no problem keeping up with most road bikes. I've gotten funny looks…

I bought a Specialized Diverge over a year ago. It was mostly to commute to and from work, but also to have the ability to take gravel paths and trails on the weekends. It's been awesome but friends have suggested I take off the stock tires and add some new ones. Is it really worth it? The tires are already fairly fat already, at least compared to road bike tires.

The Diverge was on my shortlist when I got the Topstone. At the time (2019), I think the Diverge defaulted to skinnier smoother tires. Can’t remember which tires specifically.

The Topstone shipped with some pretty knobby WTBs that definitely had an impact on rolling resistance. If your tires are knobby/optimized for off-road, putting a slicker tire (the GK slicks are quite popular for good reason), I suspect you’ll notice quite a difference, but I’d look more at the knobbiness than the fatness if you’re considering a change.

Also worth noting that some knobby tires have a hard line down the middle that keeps resistance minimal until you start to turn, at which point you hit the high traction portion of the tire. Takeaway: even if it looks knobby, it might not be as slow as it looks.

32mm+ is already getting into “fat” territory for a road bike, and for me personally, 38mm seems to be my sweet spot.

Re: Myths in cycling: wider tires are slower

#53

Post by plorkyeran »

jaypeg25 wrote: post #48
haswell wrote: post #12

This is one of the reasons I love the emergence of the "Gravel" category of bikes. They look and have geometry similar to a road bike, but they have enough clearance for nice fat gravel tires. I ride in Chicago (shitty roads, potholes & construction are everywhere), and love that I can put nice 38mm+ GravelKing Slick tires on the bike, and still have no problem keeping up with most road bikes. I've gotten funny looks…

I bought a Specialized Diverge over a year ago. It was mostly to commute to and from work, but also to have the ability to take gravel paths and trails on the weekends. It's been awesome but friends have suggested I take off the stock tires and add some new ones. Is it really worth it? The tires are already fairly fat already, at least compared to road bike tires.

The Pathfinder tires that come stock on recent Diverges are pretty widely regarded as not just the worst part of the bike, but a sort of bafflingly bad choice because they aren't even cheap. If you're looking to spend some money upgrading your bike, they're a good place to start.

Re: Myths in cycling: wider tires are slower

#54

Post by [deleted] »

at-fates-hands wrote: post #24
aeharding wrote: post #14

Earlier quoted context omitted.

Do you have a source? Anecdotally I've found clipless to make my power transfer more efficient. Some quick googling shows this seems to be true: "Mean power output was higher using clipless pedals ( = 617 watts, SD = 112) than toe-strap ( = 572 watts, SD = 77), and flat ( = 566 watts, SD = 83)." [1] [1] https://scholars.fhsu.edu/cgi/viewcontent.cgi?article=1118&c...

I was a life long flat pedal rider. Started working at a bike shop during college and one of the first things roadies told me was they are indeed much more efficient because you can push AND pull on your pedals - generating a lot more power and making the ability to sustain that power a lot easier.

[deleted]

Re: Myths in cycling: wider tires are slower

#55

Post by salty_biscuits »

soperj wrote: post #5

Another one is that clip in pedals make you faster.

No data other than anecdotal but totally agree. I use flats on my road bike and look like an idiot but I go just as fast. I prefer to be able to wear normal shoes so I have less to carry. The whole "you can push while you pull" thing makes no sense, my quads are way more powerful than my hamstrings and you never need that much force when pedalling anyway, cardio fitness is always the limiting factor for me, not leg strength/power.

Re: Myths in cycling: wider tires are slower

#56

Post by kazinator »

periheli0n wrote: post #8

Years ago I switched from 1" tyres to 2.5" inch ones for my commuter bike and I can confirm that they are not slow at all... as long as you ride in a straight line! As soon as you turn, they suck up all momentum. The fact that they provide decent straight-line rolling even at 2bar pressure is nice though, especially in a city where cobblestone paving is common. Fat tyres provide some suspension, and a ton of grip. St…

I completely believe you, but the issue is likely not width per se.

Might it be that your tires have a smooth profile down the middle for going in a straight line, but edges that have a more aggressive tread pattern, which engages the road surface when you tilt into a turn?

There are true fat road slicks that have the same smooth profile all over.

I think, tire pressure is also a factor in turning because of the way the tire deforms on the rim. If you have the pressure way down (which you can easily get away with in 2.5 inches), that could be a factor.

Re: Myths in cycling: wider tires are slower

#57

Post by soperj »

louthy wrote: post #47
soperj wrote: post #5

Another one is that clip in pedals make you faster.

You can pull up and push down. Also if you get a pro fitting then the position of your foot will be optimised to get the max power through the pedal. Anecdotally they’re faster.

Foot placing definitely, I love clipped in shoes for that. You don't pull though. I can ride equally as fast on flats, as I can clipped in. I've gone on 80km bike rides with people who are clipped in while I'm using flats, and it's the same. Clipped in is more comfortable, in my experience, it's not faster.

Re: Myths in cycling: wider tires are slower

#58

Post by TheAlchemist »

Is the data available somewhere ?

It doesn’t match my experience at all. I have a road bike and a gravel bike - same quality range (gravel slightly higher). At low speeds, that may be true - the difference is negligible. But at higher speeds / power outputs, the road bike beats the gravel hands down - by a significant margin (big enough to be felt, without a power meter)

Re: Myths in cycling: wider tires are slower

#59

Post by soperj »

mumblemumble wrote: post #23
soperj wrote: post #5

Another one is that clip in pedals make you faster.

Huh. I had never heard anyone say that, per se . For my part, I like clipless pedals because they ensure that my feet are positioned optimally, which reduces fatigue and strain on my joints. Which, in turn, probably does mean I can maintain a faster pace for longer, but it's not like I've ever timed myself. Back when I was mountain biking, I also liked them for better control over the bike, and easier mount/dismount…

I also like them for feet placement. They just aren't faster from my experience. It was not something I expected.

Re: Myths in cycling: wider tires are slower

#60

Post by louthy »

soperj wrote: post #57
louthy wrote: post #47

Earlier quoted context omitted.

You can pull up and push down. Also if you get a pro fitting then the position of your foot will be optimised to get the max power through the pedal. Anecdotally they’re faster.

Foot placing definitely, I love clipped in shoes for that. You don't pull though. I can ride equally as fast on flats, as I can clipped in. I've gone on 80km bike rides with people who are clipped in while I'm using flats, and it's the same. Clipped in is more comfortable, in my experience, it's not faster.

I’ve done many 100 mile+ sportives and have done both pushing down and pulling up.
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