I currently use the Bont Riot Tri shoe (till half distance, fast flying mount), or my road shoe, a NW (full distance, no flying mount), pic below.
How much time (ballpark, educated guess) would I save if I switch to a Mavic XCR Ultimate? I’m talking full distance at about a 5 hour effort (36kph).
That strap is pretty hideous, so I am going 4 watts. There are some rough estimating methods, like 1 watt saves about 3-4 seconds over 40k, so about 20 seconds on an IM per watts. Total then is between 1 and 2 minutes.
I’ll say this after having tested many shoes on many people including some “aero” shoes.
Not all shoes are aero no matter what their claims.
Personally I’d go with the shoe(s) that are the most comfortable. Riding 3.5h with hotspots and numb feet is no fun. ymmv
If been doing a lot of CFD work on shoes lately and will be heading to the wind tunnel soon.
I can tell you that small differences in things like sole shape, last shape and toe shape can make big differences. It’s impossible to judge the aeroness of a shoe by looking at it. Covering the boas may reduce drag but the shape of the edges of the sole may increase it more.
…Assuming the shoes let you push the same watts, for the projected time. That means same power efficiency, comfort level, etc…
Louis 
That strap is pretty hideous, so I am going 4 watts. There are some rough estimating methods, like 1 watt saves about 3-4 seconds over 40k, so about 20 seconds on an IM per watts. Total then is between 1 and 2 minutes.
It’s worth looking at my A2 thread: https://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Aero_Testing_in_the_Field_and_in_the_Tunnel:_My_Trip_to_A2_*UPDATED*_Now_with_MORF_Data_P6247199/?page=-1;t=lyhqrtwysjhezyk
It might be worth looking at my A2 Thread
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It might be worth looking at my A2 Thread
So, 5W @ 0 yaw, and 0W @ -10 yaw, compared to some super sleek shoes.
FWIW I have the same Riot TRs and the length of extra strap was insane. Maybe I have skinny feet?
I recently bought some super adhesive velcro and extended the strip on the shoes so the straps can be fully tucked in. It looks much neater and there’s more velcro engagement; no idea on aero performance though, but it can’t hurt.
I currently use the Bont Riot Tri shoe (till half distance, fast flying mount), or my road shoe, a NW (full distance, no flying mount), pic below.
How much time (ballpark, educated guess) would I save if I switch to a Mavic XCR Ultimate? I’m talking full distance at about a 5 hour effort (36kph).
I like those. They don’t look cheap!
The straps were crazy long on mine too.
It might be worth looking at my A2 Thread
Ya I remember your shoe experience. I have seen a bunch of the Simmons stuff from speedskating and while it is really nice, the tops seem to be very flat. I sort of figured that might be why they didn’t work well for you. However, now that I go back and look at the pictures, you can see that your foot is pretty flat throughout your pedal stroke. So ya, good example of the total failure of the eyeball windtunnel.
