Aero Gravel question / perspective

The spirit of Grav-lo-cross. No but seriously, cyclocross and gravel go here!

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sigma
Posts: 695
Joined: Mon Apr 02, 2018 4:12 am

by sigma

I've been watching the trend toward aerogravel bikes with interest. I read the Swisside piece and subscribe in general to aero is better for speed certainly over weight in most cycling situations. I also subscribe to the idea that the rider position is what inevitably matters most followed by wheels. My first gravel bike was the Open UP. I enjoyed it but set it up in a very upright position with a much shorter stem than I normally would ride. It was a good ride but nothing spectacular yet I would often feel a little beaten up riding it on the Utah gravel, so I added a redshift stem and swapped my 700 wheels to 650b. Much better overall.

My second gravel bike was the Factor LS. Truthfully I bought it because Factor was offering a sweet deal at the time (remember those days!), it seemed a bit lighter than the Open, and a bit more racy overall. I again went with a shorter stem and a higher setup but interestingly I have slowly migrated this setup much more closely to my normal endurance geometry for road. So a bit lower and longer and I find it much more engaging. I am also faster on it probably just because of my riding position, so my biggest complaint about the bike is really the tire clearance is a bit limited for around here. I have been thinking about an upgrade and trying to decide which route to take. I started with the wheels and picked up a deeper gravel set. I think I have the geometry sorted out from my rider position, but I can't get my head around how frame aero attributes are really going to make much of a difference once I have a 700X42 on the front of the bike. For instance, the Factor Ostro Gravel looks interesting but probably for a few different reasons than Factor intended. I like the attachable TT style bars for the long straight sections of gravel and I like that the bike can potentially do double duty as a road bike with deep wheels and thin tires plua be able to handle wider tires than the LS. However, if I toss the aero frame aside as being worth anything once I have wide tires, would I lean more toward something like the Crux as an exclusive gravel machine? Other bikes on my list are the BMC Kaius and Ridley Kanzo Fast. Curious what the collective thought is here. I am planing to do some of the midwest 100 mile style gravel races this spring, so that's probably promtping my interest.
Lots of bikes: currently riding Enve Melee, Krypton Pro, S Works Crux, S Works Epic Evo, SL7.
In build: SW SL8

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Chaunch
Posts: 33
Joined: Tue Jun 01, 2021 12:10 pm

by Chaunch

This may help. Would be interested in your thoughts...https://www.youtube.com/watch?v=u7WBPnh8ukE

warthog101
Posts: 872
Joined: Wed Sep 25, 2013 10:05 am

by warthog101

Chaunch wrote:
Sat Dec 24, 2022 10:40 pm
This may help. Would be interested in your thoughts...https://www.youtube.com/watch?v=u7WBPnh8ukE
I liked it.
Seat slammed forward to open the hip angle in an aero position.
2x road train. More driveline efficiency with less cross chaining and smaller jumps between gears.
In terms of time saved weight is placed last behind aero, rolling reistance and driveline efficiency.

Didn't so much agree with his rolling resistance advocacy for larger tyres

https://www.bicyclerollingresistance.co ... comparison

However he did go on to say aerodynamic efficiency losses from larger tyres made the larger goers a poorer choice.

Greg0rE
Posts: 24
Joined: Sun Feb 28, 2016 11:41 am

by Greg0rE

I'm also in the market for an aero gravel bike (had a Venge that got Lufthansa'd and fancy a bike for all terrains). Really like the look of the BMC Kaius but it doesn't appear to be available as a frame set sadly. The Ostro looks great but is meant to be an exceptionally harsh ride on rough terrain. Also liking the look of the Scott Addict Gravel Tuned

boots2000
Posts: 1393
Joined: Mon Oct 15, 2007 9:28 pm

by boots2000

Do you want the aero gains for racing in specific? Or just because?
Also- Are you going to get a new bike anyhow?

If I was in the market for a new gravel bike, the Ostro gravel woud be on my my short list. Because if I am getting a new bike, why not have more aero. At the same time, the Ostro gravel isn't heavy (or light), has plenty of mounts, good geometry and takes big tires. Those are all my requirements.

That said, I feel like much of the aero is diminished once you put on a race number and fat tires.

I already own a 2022 Crux, so it would take a bit to get me to change. The Crux is that good.

sigma
Posts: 695
Joined: Mon Apr 02, 2018 4:12 am

by sigma

I think I agree with a lot of Dylan's statements but could sum up my opinion like this: if I took a normal non-aero gravel bike and slapped on aero TT bars to give me a good position, with wide tires, I think I am basically as aero as the Ostro Gravel. The OG however has the added advantage of being quite aero if you have narrow tires, so doing double duty is better and it has many other desirable gravel features. However, the ride reports of the harsh ride with the Ostro are probably holding me back until I can try one out. I am a bit surprised at these since the Ostro itself is known to be a very compliant ride.

@boots2000, the aero gains are really for racing - something I am returning to after a long hiatus this spring. I will be on two circuits. Midwest gravel - packed paths and relatively flat courses where aero / wind play a large role, (you can run 38s and be comfortable hence my occasional thoughts around just using a racy road bike that can handle bigger tires) and rocky mountain utah style gravel - so wide wide tires and lots of technical features with punchy climbs and gradient. I think I will get a new bike anyway since I have crashed the Open enough times to warrant a change. My shortlist is the Crux, Ostro, Addict, and Kaius so far. Maybe an Argonaught if I really feel like splurging. I still have to investigate the Italian offerings too more thoroughly.
Lots of bikes: currently riding Enve Melee, Krypton Pro, S Works Crux, S Works Epic Evo, SL7.
In build: SW SL8

Michenfelder
Posts: 13
Joined: Sun Feb 21, 2010 1:40 pm

by Michenfelder

I've had an Ostro gravel for ~3 months now. I bought it to use as a road and gravel race bike in 2023. So far I've been very happy with it. Full Dura Ace 12 speed and roval wheels has it at 16.0lbs ready to ride on the road. Gravel set up is just under 17.5lbs. I bought it because the geometry works for me, the frame is ~900g, and it uses a threaded T47 BB. I love the clean look of no exposed cables and as you point out the ability to cleanly install aerobars will certainly help ride faster. I am coming off a tarmac SL7 and the factor does not give up much if anything on the road...

sigma
Posts: 695
Joined: Mon Apr 02, 2018 4:12 am

by sigma

Michenfelder wrote:
Thu Dec 29, 2022 1:42 pm
I've had an Ostro gravel for ~3 months now. I bought it to use as a road and gravel race bike in 2023. So far I've been very happy with it. Full Dura Ace 12 speed and roval wheels has it at 16.0lbs ready to ride on the road. Gravel set up is just under 17.5lbs. I bought it because the geometry works for me, the frame is ~900g, and it uses a threaded T47 BB. I love the clean look of no exposed cables and as you point out the ability to cleanly install aerobars will certainly help ride faster. I am coming off a tarmac SL7 and the factor does not give up much if anything on the road...
Great color. Thank you. How do you find the compliance of the bike?
Lots of bikes: currently riding Enve Melee, Krypton Pro, S Works Crux, S Works Epic Evo, SL7.
In build: SW SL8

stevesbike
Posts: 324
Joined: Thu Oct 24, 2019 5:33 pm

by stevesbike

I personally think buying a 'quiver killer' bike is always going to involve compromise - the Ostro gravel, for example, is never going to handle on the road like the Ostro road and it's not aerodynamically optimized in the same way as the Ostro road (for one, the tube profiles don't involve cleaning up flow around the wheels like the Ostro road).

As far as aero for gravel goes, there's also a lot of marketing hyperbole. On the one hand, Graham Shrive at Factor is on the record saying aero for gravel doesn't make much sense, but then market pressure led to the Ostro gravel - to compete with the Aspero S and to move away from other bikes at the 3k frameset pricepoint. In gravel, there's not much difference between the 3k pricepoint and 5k and some tradeoffs - personally, I prefer a simple setup for gravel and ease of travel to races, so less integration (and I prefer mechanical for gravel, which is both lighter and easier to service on the road at races).

Michenfelder
Posts: 13
Joined: Sun Feb 21, 2010 1:40 pm

by Michenfelder

I'm 137lbs so I find most carbon bikes stiff and this one is no exception. I just did a 128 mile road ride on it with LOTS of climbing and I was VERY happy with it. I certainly wasn't beat up any more than I would have been on the SL7. I honestly don't think the Ostro gravel gives up much on the road and I'll disagree with Stevesbike in that I would NEVER want mechanical on a gravel bike. Electronic all the way for me.

m3bas
Posts: 94
Joined: Wed Dec 01, 2021 7:23 am

by m3bas

I'm also in a simlar position and tossing up between the Ostro Gravel as a do it all bike or non-Sworks Crux as gravel only.

My only thought around aero gravel frames is the front number they make us use- surely this kills most of the aero gains in the frame?

stevesbike
Posts: 324
Joined: Thu Oct 24, 2019 5:33 pm

by stevesbike

Michenfelder wrote:
Mon Jan 02, 2023 10:25 pm
I'm 137lbs so I find most carbon bikes stiff and this one is no exception. I just did a 128 mile road ride on it with LOTS of climbing and I was VERY happy with it. I certainly wasn't beat up any more than I would have been on the SL7. I honestly don't think the Ostro gravel gives up much on the road and I'll disagree with Stevesbike in that I would NEVER want mechanical on a gravel bike. Electronic all the way for me.
The Ostro Gravel is not aero-optimized for the road - the aero shaping is mainly to minimize frontal profile, so it's not aero-optimized as a road bike. Again, as a quiver killer it's clearly a compromise. I race on a ONE except for mountainous races - it's more aero optimized than the Ostro road. I race on a Felt FR with rim brakes at events like Haute Route Alps (it weighs 5.8kg). For mountainous gravel events like Rock Cobbler I still race on a Felt FX FRD which weighs 7.2 kg (with pedals), so over a kg lighter than the Ostro with the lightest electronic setup (it has clearance for 40mm tires rear and larger front, ). If I were to replace it, I would buy a non S-works Crux and put on Ekar or another light mechanical 1x setup, which is lighter than an S-works and about half the cost. 1x electronic doesn't make much sense to me on gravel since it just adds weight. Also, since I fly to a lot of gravel races, I don't want an integrated handlebar setup, which is a hassle to fly with. Of course Dylan Johnson is going to rave about the Ostro - they sponsor him. I like Factor bikes and own one, but the gravel aero segment is clearly sales/marketing driven.

Michenfelder
Posts: 13
Joined: Sun Feb 21, 2010 1:40 pm

by Michenfelder

Dylan is sponsored by Factor - he has the choice to ride an LS or an Ostro. He races the Ostro every time even in hilly races and he does so with heavy GRX...

Cinch (as much as I hate to even mention them) will be on the Factor Ostro Gravel in 2023. They can ride whatever they want...

I do not believe that there is no benefit to having an aero gravel bike. That being said, we should all ride what makes us happy and if chasing weight is more important to you than aero, I understand and appreciate that.

robeambro
Posts: 1829
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

Michenfelder wrote:
Wed Jan 04, 2023 1:59 pm
Dylan is sponsored by Factor - he has the choice to ride an LS or an Ostro. He races the Ostro every time even in hilly races and he does so with heavy GRX...

Cinch (as much as I hate to even mention them) will be on the Factor Ostro Gravel in 2023. They can ride whatever they want...

I do not believe that there is no benefit to having an aero gravel bike. That being said, we should all ride what makes us happy and if chasing weight is more important to you than aero, I understand and appreciate that.
In theory they both can ride whatever they want, in practice they will ride whatever is the latest and shiniest new toy. Just like Boswell has been riding Diverge > Crux > Diverge STR. The latest bike needing the marketing push is always the best tool for the job.

Only exception to this rule is Canyon, where their 'gravel race' bike is presumably so bad and ugly that nobody rides it (see Mvdp, Stetina, etc - nobody rides the Grail).

by Weenie


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stevesbike
Posts: 324
Joined: Thu Oct 24, 2019 5:33 pm

by stevesbike

Michenfelder wrote:
Wed Jan 04, 2023 1:59 pm
Dylan is sponsored by Factor - he has the choice to ride an LS or an Ostro. He races the Ostro every time even in hilly races and he does so with heavy GRX...

Cinch (as much as I hate to even mention them) will be on the Factor Ostro Gravel in 2023. They can ride whatever they want...

I do not believe that there is no benefit to having an aero gravel bike. That being said, we should all ride what makes us happy and if chasing weight is more important to you than aero, I understand and appreciate that.
The big difference between the Ostro Gravel and LS is the geometry - the LS has much more road-like geometry especially in terms of reach while the Ostro is a lot longer in terms of front center, reach, and wheelbase. It's even a lot longer than the Aspero in terms of reach (to the point that I'd have to size down to get a workable stem length and it looks like some of the sponsored riders do too). If you were to choose either one in the same size, you'd get a very different handling bike, which would address the more skittish nature of the LS especially in technical stuff.

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