Wheel Aerodynamics

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Mep
Posts: 516
Joined: Fri May 28, 2004 4:11 pm

by Mep


TobinHatesYou wrote:I used to think 25mm would be ideal particularly for racing until I started actually doing it. bm0p700f, it’s clear to me you don’t race at all. For any remotely lumpy race right now I am using 202s with 28s, reserving my 5.6s with 25s for only the smoothest courses and non-technical crits.

Reduced fatigue = free speed
More stability = free speed
Confident cornering = free speed

Even TT/Tri guys are switching to 28s.

And of course all of this applies to daily riding as well.
What's your combined weight with the bike? That's as important a consideration when deciding on tire width as the roads you're riding. For example, it would certainly be overkill recommending 28s for my wife whose system weight is 50+kg.

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TobinHatesYou
Posts: 12458
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Mep wrote:
Wed Apr 24, 2019 10:35 pm

What's your combined weight with the bike? That's as important a consideration when deciding on tire width as the roads you're riding. For example, it would certainly be overkill recommending 28s for my wife whose system weight is 50+kg.

It's not overkill.

I weigh anywhere between 59-62kg. My bikes weigh 6.4 and 7.6kg. I pump my 28s to ~60psi. The amount of impact energy a 28mm tire can absorb over a 25mm tire is pretty damn significant.

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pdlpsher1
Posts: 4016
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

Yeah I agree that comfort = free speed. It’s also psychological as well. A nice comfortable ride is like having a gentle tailwind on your back. I’m more inclined to push a higher wattage with a tailwind than I can with a headwind. It’s all in the head I know but psychology plays a huge part in cycling. My bike is custom and designed with comfort in mind.

I got my 32mm GP5K non-TL today. But these will go on the tandem. Currently I have 28mm GP5K at 90psi. I plan to run the 32s at 80psi. The 28s measure out to 30mm on 21mm internal rims. I imagine the 32s will be 33-34mm wide.


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Mep
Posts: 516
Joined: Fri May 28, 2004 4:11 pm

by Mep

TobinHatesYou wrote: It's not overkill.

I weigh anywhere between 59-62kg. My bikes weigh 6.4 and 7.6kg. I pump my 28s to ~60psi. The amount of impact energy a 28mm tire can absorb over a 25mm tire is pretty damn significant.
Good to know, we all have our own preferences. Go too wide and the bike feels slow. It's a strange sensation, but I don't appreciate it when my supposed race bike starts to feel like a tank.

Etienne
Posts: 374
Joined: Tue Aug 23, 2005 11:41 am
Location: France

by Etienne

Mep wrote:
Thu Apr 25, 2019 2:22 am
Go too wide and the bike feels slow. It's a strange sensation, but I don't appreciate it when my supposed race bike starts to feel like a tank.
It's all about sensations, and sensations are very personnal ... I am one of those who consider that wider tires and lower pressures makes me faster because when there's too much road rattle, I tend to switch off my effort and/or be less efficient. I only appreciate narrow tires on perfectly smooth tarmac, hence 10 to 20% of my riding time.

My road bike's clearance doesn't allow 28 tires ... but I tried some on other bikes and find myself fast enough on them ... I assume tires are not fast by themselves of course.

But at the same time, I have riding mates who prefer narrow tires and high pressures, because they feel faster ... so it's just a question of personal preference and the psychological factor is probably very strong when it comes to cycling performance.

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