Ok, so don’t laugh but I’m noodling on an idea. 40-45ish deep, 30ish wide internal mtb wheels, laced with aero spokes.
You’ll say at mtb speed this won’t matter, but the racing around here is getting upward of 20-22mph average over a 2ish hour mtb course. Sometimes it’s spent off the front alone, but often times at least in the flatter races, there’s little tree cover and it gets WINDY.
Recent testing has bought into question how much tire width affects aero wheel gains.
What do we think? I’ve got some shallow carbon wheels I’m running right now and could potentially do some Chung testing if I can find a mfg who’d make such a thing.
And yes, I know I’m at the ridiculous end of the cycling spectrum, I don’t need the eye rolls.
In my entirely unkowledgable opinion it’s a low hang fruit of a gain. I’m sure I’ve seen studies that aero makes a difference even at lower speeds and on open sections saving watts is saving watts.
I don’t quite understand why we didn’t see that at Leadville, there were fork fairings so why not some deeper wheels? Hell, wheels are easier to get than fairings. I say try it!
Tbh the person you need to poke with the big book of ideas is Dylan, he’s down for all sorta wierd experiments!
There is a rule of thumb that aero wheels should to be at least 100% as wide as the tire, and better to be 105%+ as wide, for good aero performance. Narrower than that, and separation of air flow behind the tire significantly reduces aero performance. That’d be pretty wide rims for 2.2 to 2.4” tires.
I would say that fairings are easier to get or make then a wheelset that meets the criteria (IE your brand doesnt have something to try or their is not something on the market “yet”), but any savings is savings.
That is for maximum aerodynamic benefit, a aero shaped rim with a bulbus tire “will” still see some benefit downstream with airflow and stability….. maybe just not as much as you hope for.
The shape and length such as a 55mm could help reorganize the wake. There could be a serious downside to mud being stuck to the rim possibly.
I talked with a wheel builder about this a while back and their theory was that most XC tires disrupt the airflow enough that a deep section wheel wouldn’t make much of a difference. The airflow around something like a Dubnital or Mezcal isn’t quite the same as a slick tread like a GP5000.
Hah! No, but long stretches can end up in a peloton and these guys like to push the pace up. Cat1/elite field are quite fast round here. Long mtb races do include a little bit of tarmac as connectors though too.
I’ve got a buddy who laced up some zipp xplr wheels with MTB hubs. I would do the same if $ were no object. Definitely not the recommended use for those rims, but I think they would be great for the long marathon events I do where there is a lot of time in the wind and not that much really chunky terrain. I’d definitely run them at leadville where aero is such a big factor on much of the course. I probably abuse gravel wheels more than I do MTB wheels, speeds are generally much higher and there are more big unexpected hits when you can’t see your line in a pack.
I think it was Silca that did some testing on the gravel side with MTB tires on deep rims and they do make a difference. I can’t remember the numbers, but I do remember that the Race King 2.2 on a wide/deep rim (maybe hunt?) tested surprisingly well for aero, as good as many gravel tires in the 40-45mm range.
I have a deep wheelset, the one teddygram mentioned above. I ride them on my dropbar hardtail. I don’t know if I’d ride them on my E8 though. Have you considered inner bar ends? Might even make more of a difference than a deep wheelset. You mention fast speeds in a group - are you at the front the whole time? Seems more like a solution in search of a problem?
Do you know of any DIY fairings so far to be 3d printed? I wonder how they are attached to the fork and if somebody (with more aero experience than I have) has some recommended wing shapes. I would like to try them on my SID 32.
I wonder the same. Total shot in the dark, but I’d guess that it’s a combination of multiple factors -
Tradition/style - As crazy as it sounds, I think the MTB side of the sport might be slower to change and accept new things than the road side (which is saying a lot). In particular, I don’t think most MTB riders believe in the “voodoo” of aerodynamics. And to be fair, it’s not as big of a factor in MTB compared to road and gravel.
Durability vs. weight vs. compliance - A deeper rim is going to add weight and might add significant weight if it’s got to be built stronger than a gravel wheel. And if you beef it up too much, it’s probably hard to keep the wheel compliance and it becomes too stiff. For me, I think any of the current wide/deep gravel wheels would be robust enough for the MTB racing I do, but I wouldn’t run them on my trail bike where the rims are constantly being abused. And some MTB courses are probably rougher than the stuff I ride with my trail bike.
Bike companies like to keep things “in their lanes” from a marketing/sales perspective. For sponsored riders, I’m not sure the big brands want their MTB athletes riding a wheel that isn’t sold as a MTB wheel.
Again, all speculation. I think it’s dumb that they aren’t being used on some courses. But I also think it’s dumb that forks and frames aren’t aero optimized as well. It wouldn’t be near as impactful as aero optimization for gravel and road, but I still think it’s coming for MTB eventually.
I think part of the reason is at least when riding in loose rocks are where you are turning over chunk, mtb wheels already get scratched and dinged up the side, and the taller the rim the more likely that is to happen. Still an interesting idea though
The only production (Prototypes) that I have seen are Blackbox and Rad which are sister companies to Rockshox and Fox (BB=RS, RAD=Fox). That doesn’t mean someone with a 3d printer and some time couldn’t print some of their own.
Honestly sounds like you just need a flat bar gravel bike. If it is so untechy and flat that 20 mph is an average, then I think you should get yourself a gravel bike and convert it.
This is a great idea. If I was doing it, I would go all out. 3D print the farings as they did at Leadville.
The main reason this does not exist is that it probably rides like a crab on any kind of bumpy terrain. Try it and let us know!
For what it’s worth, Jonathon mentioned deep/wide wheels on the latest podcast as something he expects to see at Leadville this year. Sounds like it’s something he’ll be considering. I’d be very surprised if we don’t see a decent number of pros rolling them.
