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Ultra Wide Reserve 40 I 44 Gravel Wheels are More Aerodynamic, Guaranteed for Life

Reserve carbon wheels 40 44 GR
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It looks like gravel wheels are about to get even wider. The new Reserve 40|44 GR wheels are 27.4mm/27.mm wide. That’s the internal width, not external. That makes them wider than some current XC mountain bike wheels, though that kinda makes sense with how gravel bikes are being ridden these days.

Reserve states that the added width allows the rims to accommodate tires up to 50mm wide, with the recommended tire range listed as 30-50mm in width.

More than just being super wide, the 40|44 GR claims to be super aero as well. While Reserve was founded by Santa Cruz Bicycles in 2014, they’ve gradually made their way from MTB, to gravel, to Pro Tour road racing with Team Jumbo Visma in 2022. Given that Santa Cruz / Reserve and Cervelo are now both owned by PON, the collaboration makes sense and it has allowed the two very unique brands to work on a unifying project – aerodynamics.

Using what they call “exclusive Turbulent Aero wind tunnel testing,” the Reserve 40|44 GR shape was validated with simulated real-world airflow. They go into more detail here, but it seems that the wind tunnel can create turbulence that you would typically only see in a real-world environment, which helped them create a rim profile that is fast in the real world, not just in the wind tunnel.

The result is a wheelset with slightly different profiles. The front is a 40mm depth with a 27.2mm internal width, while the rear is a bit taller and narrower at 44mm deep and 27mm internal. Externally, the rims measure 36/34.4mm wide, and both run 24 straight pull spokes. Those spoke holes are internally reinforced to resist pull-out with specifically engineered carbon plies that Reserve has developed over years of building carbon rims for mountain bikes.

Rather than use a hookless design, Reserve uses what they are calling “semi-hooked”. There is a definite lip around the edge of the rim, and it allows the rims to offer an 80 psi maximum pressure which seems pretty high for a rim this wide meant for gravel bikes.

The 40|44 GR wheels are only offered in one build with a Centerlock DT Swiss 350 EXP hub set with a 36t ratchet. At the time of launch, they are offered with HG or XDR freehub options. That means if you’re running the new Shimano GRX 12 speed 1x group, you’ll have to purchase a Microspline freehub separately. Note that the new Shimano GRX 12 speed group is split on its freehub use – 2x groups still use HG freehubs, while 1x use the Microspline.

Reserve 40|44 GR Actual Weight

With claimed weights of 425g and 445g for the rims, the complete wheels check in at 684g for the front and 791g for the rear. Those weights are with tape and the included Fillmore valves installed, so it seems the wheels are well within the claimed weight of 1444g for the set.

Reserve 40|44 GR Initial Review

Reserve sent over a set of the new wheels, and I was excited to check them out – mainly because I wanted to see what riding a rim this wide would feel like on a gravel bike. Out of the box, the rim tape on both wheels needed some attention. One wheel had the valve hole punched in the tape so it was an oval that the Fillmore valves wouldn’t seal. The other had the end of the tape lifting up, so both rims required some extra tape to be added to offer an air-tight seal. We’ve seen similar issues on other brand wheels from time to time, so it’s not a Reserve specific issue. Just be sure to inspect your tape before installing the tires and valves, and if there’s an issue Reserve will help you out.

I was also planning to run these wheels on a bike with a GRX 12-speed 1x drivetrain which required a Microspline freehub. As mentioned above, Reserve isn’t offering a Microspline option yet, so I sourced my own. It was an easy swap, and the hubs were ready to go.

It’s still pretty wet outside, so I opted to install some WTB Raddler 700c x 44mm tires I had on hand. While the first tire bead was a little tight to install, the second bead went on easier without tools. With some sealant in the tire, the beads seated very easily, immediately sealing without any additional effort.

When I’ve used the Raddlers previously, they’ve never quite measured a true 44mm. But on the 40|44 GR wheels, they measured 44mm almost immediately. One thing is for sure, rims this wide will impact the shape of narrower tires. On the Raddlers, the tread ends up fairly flat, with the widest point of the tire being the sidewall by a large margin.

On my first few rides, the 40|44 GR wheels are easy to love. In my opinion, the Raddlers aren’t a particularly fast tire, especially on pavement. Yet when mounted to the Reserve wheels, they feel faster than I remember. Coupled with the carbon rims, the ride quality is fantastic – which is only accentuated by the quiet freehub of the DT Swiss hubs. I don’t mind loud freehubs on the mountain bike, but on the road or gravel, I find the louder hubs more intrusive.

I can’t say that the wheels felt particularly aero, but the sense of speed and stability seems to reinforce Reserve’s claims. Considering that these wheels are guaranteed for life with free replacements, I would not hesitate to buy these for daily use even though they’re the perfect option for your next gravel race.

reservewheels.com

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threeringcircus
threeringcircus
1 month ago

These look really nice. DT 350s are my favorite hubs of all time. Still, the price is nuts considering the excellent options from direct to consumer outfits like BTLOS.

Evan
Evan
1 month ago

1800 USD is ridiculous now? Don’t go over to the cadex site…

Those DTC Chinese brands also have premium wheelsets around that price point, so apparently your criticism could be leveled at them as well. But I don’t think you can make an apples to apples comparison between rims because there’s really no way to know the quality (impact resistance, QA, etc) of the carbon, but 1800 for wheels with actual customer support is not at all unreasonable.

Kelvin C
Kelvin C
1 month ago
Reply to  Evan

Huh! Cadex brand is a spinoff brand from Giant. You can get Cadex-branded products from anyone who distributes Giant bikes. Cadex wheels are also on pro tour bikes…if you don’t know, now you know.

Karl
Karl
1 month ago
Reply to  Evan

I would say it is quite a lot for these. Not really light, no real aero benefit. What do they offer that you can’t get for $800? They can’t even get the rim tape on, so I wonder what attention they pay to the rest of the wheel.

You could get two superb pairs of handbuilt wheels for the same price.

Semi-hooked…? Please, this nonsense just needs to stop.

Robin
Robin
1 month ago
Reply to  Karl

Can you show the data that demonstrates these have “no real aero benefit”?

Karl
Karl
1 month ago
Reply to  Robin

I think you need to show they have a benefit if that is the claim.

Robin
Robin
1 month ago
Reply to  Karl

That’s funny because I didn’t claim anything: you did. So you must have knowledge or data in front of you. I’m interested in seeing the data from which you drew your conclusion. After all, objectively analyzing data is how science moves forward and how we improve out knowledge. I was looking to learn from your data.

Can you do aero analysis by just looking at a photo and a few specs? Is an assumption the same as aero analysis?

Again,I was hoping there’d be an opportunity to learn from aero expertise and years of experience.

Karl
Karl
1 month ago
Reply to  Robin

Added to that…

Also, you need to realise that any aero benefits are only ever going to be seen at higher speeds. Considering gravel is a relatively low speed format, compared to track or road, the aero benefits are likely to be minimal and only on those that can maintain high speeds (+20mph) for long durations (essentially a Pro level rider). If you are Dylan Johnson it may make more sense. Most of us aren’t.

Terrain will play a massive part though on what you can achieve in terms of speed. Open and flat course would perhaps work. Again, you would need to provide data that these wheels are indeed giving that benefit – otherwise it is marketing. What they are saying here is that is has been developed and tested with wind tunnel testing. That means nothing in terms of how it performs. I can put any rim in a wind tunnel and now say I developed it with wind tunnel testing and add a term (Turbulent) that is not defined.

Overall, do you go aero or light, if you assume both are equally durable (probably the #1 requirement)? Personally I would go light for gravel, as I do for MTB, where the terrain is often slow, requires lots of braking and accelerations up to speed again. The accelerations are what kill you. Indeed their best XC wheels focus on light, strength and compliance. For most gravel riders, I’d be focusing on that too.

I would be very happy if Reserve send me and our team a set of XC28’s to test for a season of British Nationals and European 3 Nations Cup – I sure can’t afford them. Pretty sure that won’t happen though.

Robin
Robin
1 month ago
Reply to  Karl

Really, only at higher speeds? How is it then that a rider with aero wheels riding at 15 mph over the same course as someone riding at 25 mph will save more time over that same course as a result of that apparent aero benefit that you think is negligible?

How is it that people who are actually aerodynamic engineers or who work in that field analyzing such data say something different than you?

At what speed airspeed does the “aero benefit” switch on? I guess it must be like a Heaviside function ( step function) in that it suddenly switches on, much like a light switch, at a certain speed….Interesting.

Karl
Karl
1 month ago
Reply to  Robin

Wow.. angry man.
The writer said he felt no aero benefit. And you need to go back to school on aerodynamics. Speed has a massive impact on the benefit you will see. I’ve literally no idea what you are saying above. It’s incoherent. Look at the hunt ex-employee below. Why do the test at 32km/h? The benefit increase with speed and duration. But even then their wheels only improved by 6 seconds on a 312km course.

Don’t bother replying. I won’t be reading it again. Enjoy your wheels. Calm down.

Sirclimbalot
Sirclimbalot
1 month ago
Reply to  Karl

But… You’re missing the potential motivation factor. Like I could work up to 20+mph pro speed if I bought these…no problem. Just kidding, totally agree that those reserve 28s on an XC rig make way more sense, and under serious purchase consideration.

Robin
Robin
1 month ago

I have a set of the 40/44 road wheels, and I love ’em. With tape but no sealant, they hold ridable pressure for 2-3 days (just testing, not actual riding without sealant). The warranty is great, and the use of mini-hooks makes me confident that I’m not gonna have a tire suddenly blow off the rim.

Evan
Evan
1 month ago

I’ve yet to see convincing evidence that aero matters at all on 35mm+ knobbies. I would like to be convinced one way or another though.

Maybe you could buy these to run 34mm slicks, but I think that defeats the purpose of 27mm internal. (Actually, what is the purpose compared to 25mm?)

Probably still a nice wheelset and not so light at to be scary.

Luisa Grappone
Luisa Grappone
1 month ago
Reply to  Evan

You can find an explanation on the aero advantages of having wider rims also with wider/knobby tires at this link.

https://cdn.shopify.com/s/files/1/0686/6341/files/Revised_HUNT_42LGD_white_paper_1.pdf?v=1638959216

That was my work for years when I was the Engineering Manager for the wheels programs in HuntBike Wheels. If you have time you can read the white paper and understand a bit more.

Karl
Karl
1 month ago
Reply to  Luisa Grappone

32kmh is a very ambitious speed for most riders especially on gravel very 312km.

A saving of 0.05 of a watt equating to 6 seconds over that distance is within the margin of error. Against a non aero but lighter set on the actual course would be an interesting comparison.

Evan
Evan
1 month ago
Reply to  Luisa Grappone

Thanks Luisa! That comment is better than expected content! But the paper does not address my question. It says “Test two (leading) aerodynamically developed rims commonly used in gravel racing from ENVE and Zipp, and the new HUNT 42 Limitless Gravel Disc”. As is probably expected, the results of 3 nearly identical wheels is nearly identical. But you did not test against either a 60mm+ wheel (which would be expected to make a difference if aerodynamics actually matter) or a shallower, boxier rim, or you did not publicize your results if you did. Though there is some graph at the top (figure 1) that appears to be unrelated to the rest of the paper and doesn’t specify a tire or even the “non-aero” rim under test. Surely more details would have been shared if they supported the thesis that the sponsor of the “study” wished to promote. The silence is deafening as they say.

So yea, you can see why this the paper seems like a big smoke screen and I’m still not convinced that aero wheels matter for gravel. But surely body position and skinsuits will have some impact.

Rémi
Rémi
1 month ago
Reply to  Evan

To be fair to Hunt, they published a study showing exactly what you desire : HUNT Engineering Paper – Gravel: Does Aero Matter?

BTW, this paper is cited in Luisa’s work.

Linc
Linc
1 month ago

Wait. 2x Shimano 12 speed? What’s this now?

Ssel
Ssel
1 month ago

The guaranteed for life has t&c’s.

Or at least in singapore, they only replace/rebuild destroyed rims. Doesn’t seem to be a 1 for 1 exchange
I had to pay to true my set of dt 240 reserve 28s.
Forgot to ask if you had to pay for rebuild fees if a rebuild with new rims were needed or what would happen if the hub went kaput instead. Would they refer me to DT Swiss instead?

Karl
Karl
1 month ago
Reply to  Ssel

Trek has the best wheel support. Will replace damaged wheels free of charge.So far had to replace 3 wheels, the free replacement is not fully covered cost if you break that but they give a great discount, usually 30-40%. They even supplied me with an upgraded Pro wheel because they didn’t have an Elite line in stock. No extra cost.

Emo
Emo
1 month ago

Light Bicycle has a similar set of wheels available, for a lot cheaper. WG44. 30mm internal / 40mm external / 44mm depth. Looks like a very interesting option and I know Light has a good reputation.

tabs
tabs
1 month ago

I don’t think there is any such thing as DT 350 EXP hubs, unless it’s exclusive to Reserve and being announced here and now (doubtful).

Around the time the 240 was “upgraded” to EXP, DT Swiss released the updated DT 350 shell and it included a 36T ratchet as standard (unlike 18T as before).

The EXP mechanism is exclusive to 180 and 240 currently, not backwards compatible to old 240 or 180 hubs, and I don’t believe it’s offered anywhere for 350. I’d bet Reserve is probably just using the newer but-still-not-EXP 350 design and got carried away trying to pump up the ad copy with the latest DT nomenclature.

tabs
tabs
1 month ago
Reply to  tabs

And I should add, in the pictures the hubs look bog standard and have no EXP labeling where such exists for 180 and 240.

Sirclimbalot
Sirclimbalot
1 month ago

Makes sense to me.. but I still have a pair of 25mm wide reserve wheels on my hardtail. They have over 10k miles, and the bearings on the 350s lasted almost 9k miles – more fun from these than I ever imagined. So… Not gonna run out and buy these today, but if I was building up something new it’s a consideration.

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