Are aero bikes noticeably faster?

Than a otherwise very good non aero bike?

You alway read in the bike mags about how the latest aero bike is x watts quicker in testing and noticeably faster when out riding etc etc and I’ve always called bull turd. I’m firmly in the camp that they are at best going to be seconds quicker over a fairly large distance, and whereas I fully buy in to marginal gains on a tt bike, when it’s all about racing against the clock, for normal road bikes it’s fairly pointless

However today I was riding with a chap I’ve competed against a few times in TTs and hill climbs, and I’ve always beaten him. Today however he’s out on one of the latest generation aero bikes and it was really quite a struggle keeping up. For context I definitely wasn’t having a bad day, and ride a 2019 tcr with 60mm wheels… ie not a slow bike

Got me thinking, maybe there is something in these aero bikes..

It’s marginal gains, a more aero position will make much more difference which is perhaps what he is now riding in due to the new bike

They do help to hold the speed better, but expect the rider position, aero helmet and non-flappy clothing has as much to do with it.

I’ve recently bought a ‘semi aero’ road bike (Super Six). Stock wheels aren’t great or deep but it holds speed better than my old bike – it is noticeably stiffer – even though it’s slightly heavier. With better wheels it’ll fly.

I think I agree with your orignal belief, OP – minimal gain from the bike’s slippiness (though as said it might force rider into a pretty aero position which would make much more difference IMO)

However today I was riding with a chap I’ve competed against a few times in TTs

Maybe his TT setup is worse than yours ? (less aero and/or else he just can’t get comfy)

and hill climbs

I seem to remember you’re light with a good P to W. Maybe he’s not got quite the same ratio ? Was yr ride today fairly flat on the bits where you struggled ?

Yes; 3-4km/h average speed faster for the same cadence and power output

i had a go on a low profile in the early 90’s. it was fast. i overtook an allegro on a dual carriageway. one of the best days on a bike i’ve had.

Yes; 3-4km/h average speed faster for the same cadence and power output

They are in now way 3-4km/h faster for same power, unless your average speeds are 200kph.

Notice the watt gains are typically stated for a speed of 45kph

A high number I have seen in testing is 90 seconds over an hour so for an average rider at 20mph that is 0.5 mph.

The aero claims are pretty much complete rubbish, I went from a steel road bike to a fancy aero bike just over a year ago, my ride times, average speed etc haven’t changed at all.

It’s more about your position on the bike, than the bike itself.

It will be the combination of bike plus rider position. He may have got a decent bike fit as well which will potentially give gains in power as well

Or it’s an ebike

3-4km/h average speed faster for the same cadence and power output

if that’s true, TAKE MY MONEY!

it seems trek (who I presume optomised the tests to try and sell bikes) claim ~0.5mph as well

https://blog.trekbikes.com/en_UK/2020/07/15/how-much-does-bike-aerodynamics-really-matter/

so it’s probably in that region or slightly lower.

eta : a bit of reading suggests aero wheels may add the same again?

A high number I have seen in testing is 90 seconds over an hour so for an average rider at 20mph that is 0.5 mph.

Even 0.5 mph will be noticeable if you’re riding with them, as you ‘ll just drop back unless you ride harder. And over an hour averaging 20mph if one rider is doing 20 and the other 20.5 the ‘faster’ rider will have a 2700ft advantage (AKA approx a kilometre).

Or is my maths wrong?

No, your maths is right, but you seem to have made it unnecessarily complex.

If the speed is 0.5mph different it’s the same as how far you’d go if you were doing 0.5mph for an hour. ie Half a mile.

I’ve switched from a previous generation Supersix Evo with 50mm wheels and round tubes to a new TCR with 42mm wheels and a more aero profile. Same riding position etc. Aero cockpit on both. Very similar weight.

Totally unscientific, but I have been getting PB’s all over the place on the Giant. This could also be down to stiffness or any number of other factors.

Sometimes dropping a wad of cash on a new bike can inspire you to ride more, maybe your competitor has just gotten fitter?

A high number I have seen in testing is 90 seconds over an hour so for an average rider at 20mph that is 0.5 mph.

I’d say that’s significant and enough to be noticeable. I have to try quite a bit harder to get an extra 0.5kph on a ride.

In a word no it’s not noticeably quicker. Especially since you have aero wheels and a semi aero frame. More likely he was on a good day and you weren’t on top form.

The gains the bike manufacturers claim are based on wind tunnel tests and the figures quoted are often compared against the most non aero bike they can find. Riding in a group there’s no difference. Riding solo in a road bike TT you may be a handful of seconds quicker due to the aero benefits. That may make it worthwhile if it means a win rather than a 2nd place.

shave your legs and a set of tt bars if it troubles you that much.

As people have mentioned the big fleshy lump on top of the bike is where the biggest gains can be made.

What bike was he on before? Aero wheels, frame, cockpit and a better aero position would quickly add up if he was decidedly un-aero before.

I’d say that’s significant and enough to be noticeable. I have to try quite a bit harder to get an extra 0.5kph on a ride.

Yes it is noticeable. Your overall time over an hour will be 90 seconds better (at most) so any PBs you had now have a 90 second advantage (all other things being equal)
If riding with someone else it will be noticeable.

If riding on your own then not really noticeable in feel alone and only noticeable when looking at the data.

Not important to me, I just ride for fun and a PB is only a PB for the the same given bike.

Sometimes dropping a wad of cash on a new bike can inspire you to ride more, maybe your competitor has just gotten fitter?

Yep its very rarely the bike that’s making a difference..New bike and a new keenness or the wheels make a nice whiish noise at high speeds that he likes hearing..

Or you were just having an off day.

Its why you should drop the money on a nice shiny bike for motivation it never gets easier you just get faster(or fatter).

Yes, it’s definitely noticable. I would say around 1mph gain going from a decent ‘normal’ road bike to a decent aero road bike.

When I go from my steel Genesis Equilibrium to my S Works SL7 I go from around 19mph to 20.5mph for normal riding on average, obviously there’s a big weight saving there too. TT bike (even on the tops) is similarly fast but still heavy.

i had a go on a low profile in the early 90’s. it was fast. i overtook an allegro on a dual carriageway. one of the best days on a bike i’ve had.

Best thing I’ve read all day.

Mine is faster than the non-aero bike it replaced, even with 30mm wheels it was faster; I had 30mm wheels on the non-aero bike.

The thing I notice is (granted I have carbon 48mm wheels on the aero bike, but they’re lighter than the 30mm alloys on the previous bike) is that it holds speed much better on those long draggy sections of road that you get between the fun bits.