Weight vs. Aero for a gravel racer

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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PMC
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Joined: Wed Nov 12, 2014 1:22 pm

by PMC

For wheels your tire profile/size can take what is an aero rim with a 25-27mm road tire and erase most if not all the aero benefits. When I was looking at doing a deeper disc wheelset for my Warbird a couple years back the builders I talked to basically said it was a waste as the real world benefits aren't there.
I ended up with a shallow and light carbon rim that is tubeless and haven't regretted it, especially now that there are really good tubeless options.

You'd be better off putting some stubby clip on aero bars on your rig and getting comfortable on them. I added some lightweight carbon Deda bars when I did Gold Rush 110 in the black hills a couple years back and was significantly faster over the last 20 miles where you could really use them.

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wheelsONfire
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by wheelsONfire

If you could get a gravel bike lighter, it would serve you better than aero.

Let's say you ride more trails and even some light tracks. The lighter bike is more nimble and that would be better.

There is however some issues going too light.

It's way more easy you crash when you ride on gravel. Loose over hard in corners, mud etc etc.

You wouldn't want the bike to crack if you fall. Lighter carbon bikes often uses more brittle carbon and also much thinner walls.

A good idea when you ride gravel is to ride tubeless because you can use lower tire pressure.

Anyway, you'd want to bring a small bottle of sealant (possibly even a spare tube), a C02 inflator and stripes to insert in tire in case of a hole/ tear.

This also add some weight. And if you like me, buy a Lauf Grit you end up with another issue for lighter weight.

The fork weights something around 900 grams +. (The aero features on Grit is probably none existent.)

But the Grit helps with a few things. You don't suffer neck/ shoulder and hand fatigue. You also have better traction and this is greatly appreciated descending or cornering....

or if you happen to bump into something!
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Ltyarbro42
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by Ltyarbro42

tilf wrote:Rolling Resistance > Aero > Weight

If your tire is too narrow to float on whatever surface you are on, then everything else is lost. Aero next since it seems there is always a headwind no matter where you go. Clip on aero bars are half for the aero advantage, part to getting your hands some rest from washboard, and part someplace to hang things off of. Weight is important, but mostly in choosing what to bring/not bring in the longer unsupported races.



From an engineering perspective, this is be-all end-all. I apply the same to mtb's and it seems to hold up.

Cheetahmk7
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Joined: Sat Aug 20, 2011 2:09 am

by Cheetahmk7

Ltyarbro42 wrote:
tilf wrote:Rolling Resistance > Aero > Weight

If your tire is too narrow to float on whatever surface you are on, then everything else is lost. Aero next since it seems there is always a headwind no matter where you go. Clip on aero bars are half for the aero advantage, part to getting your hands some rest from washboard, and part someplace to hang things off of. Weight is important, but mostly in choosing what to bring/not bring in the longer unsupported races.



From an engineering perspective, this is be-all end-all. I apply the same to mtb's and it seems to hold up.


Except the order is mixed up. Rolling resistance is small compared to aero drag.

For a 29 MTB tyre at 29 km/h its around 30 watts spent on rolling resistance. Aero drag is likely to be in the order of 200 watts.

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Tomstr
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by Tomstr

It's not just watts, if you'd ride over asphalt then yes but gravel riding is about the idea that you don't know where you could end up. A big part of that is the terrain itself that could be paved or a mountainbike trail or everything in between.

In order to deal with that you need to make sure you can;
A actually cross the terrain while riding
B do so efficiently.

Given the distances aero is on my mind, since there is little climbing or getting the bike back up to speed weight is only C priority.
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Marin
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by Marin

The weight differences in a bike will make very little overall difference in performance. 1kg off the bike is a lot, but it might be 1.5% of the total weight you're moving, and will only come into full effect on climbs.

Aerodynamics are very important, but are determined mostly by the rider, with the bike making almost no difference again.

The only major factor determined by the bike alone is rolling resistance.

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