why are front fenders cut so high at their trailing end? isn't that where the spray is generated?



most bikes i see (mine included) with a mud flap practically has it on the ground and to me, with good reason. if the goal (above) is purpose related, why not skip the whole thing?

and i will wage JH's back end gets a stripe too.

so much i don't grasp about this hobby . . . .

Blocking junk from getting into and around your headset and fork crown is kinda nice. Makes sense for MTBs especially.

The fenders on that picture though? I really dont know why they are even mounted. I am sure Jan has some 'science' that 'proves' those specific fenders improve aerodynamics(even though he is on a bike with round steel tubes) or something like that.

The back one might be shielding the ST/seatpost junction. I just noticed how low the front part of the rear one goes. The location could be about protection from something other than moisture.

Also, if you going to mount one, mount them both. Got to be matchy-matchy.

The front fender looks like its mounted backward, the short part you see sticking behind the headtube/fork interface area seems like it should be out front. I'm thinking its to keep the handlbar bag off the tire(?) rather than having to buy a new front rack or different bag. I have no idea what's going on with that rear fender, it looks pretty useless to me.

In this case this is done by Jan Heine for aerodynamics, not splatter reduction.


short excerpt
That’s where the Rene Herse’s fender fairings come in. (They may look like shortened fenders, but they are not intended to keep the rider dry.) By shielding the tops of the tires from the airstream, they reduce the wind resistance. Now the airstream is hitting the fender fairing—which moves at 36 mph—rather than the tire at 72 mph. We optimized the shape of these fender fairings in the wind tunnel, until they decreased air resistance by 1-2%—almost as much as a set of aero wheels on a racing bike. In road racing, fairings are illegal, but these rules don’t apply to most gravel races.

full link https://www.renehersecycles.com/aero...-gravel-bikes/

may be of interest
https://www.renehersecycles.com/spec...xl-rene-herse/


https://www.renehersecycles.com/oreg...od-or-madness/

No, it is generated all along the circumference of the tire, starting at the rear of the contact patch, dispersing (more or less) tangently, with more uniformity in heavy downpours v wet roads...
#Pedalantic

i only can tell time with digital

Digital tells you the time. Think about it, mannnnn!

Called it.
Good job Jan, you slightly reduced the inherent poor aerodynamics of your wide tire round tube steel frame bike.**
Clown.

How many dynes are we talking?

Yeah, cause the bikes aerodynamics are important when you are riding sitting way up and you have a grocery bag up front...

What your times for Oregon Outback or Outbound XL? Jan's times and those of other riders on similar seem to support there is something there. pretty sure ol Jan has spent more time testing and in wind tunnels than your have

not bad.

this turned into a BF pissing match quicker than most.

Skip the fenders... Nice Bike!

If you read what he wrote, he explains the whole thing. While yes aerodynamics are going to be different on a gravel bike they are still important while racing at least to some degree and improving things even if slightly will be an advantage to those who haven't. The reason that Team Sky/Ineos whatever had such boring wins is the marginal gains, they do help even if boring or maybe a touch silly to some.

He explained the rando bag being faster then having a bunch of bike packing bags as it is an easy carry all with easy access rather than fiddling around with where you will put something during a control or stop. Plus at least according to him it might help a bit simply because it is blocking your pedaling so less turbulent air.

The bike is hot! Curved fork blades, lots of chrome, under DT bottle and old school pump on the seat stays. What's not to like? Got that Vintage K5 Blazer/Power Wagon/Scout vibe going. The only thing missing is an old school number hanger on the TT. It definitely looks like a bike a Hardman would be riding.

My time for each was about treefiddy.

Are you claiming the aero improvement is actually significant?
Are you claiming I can't find his claim to be dumb when paired with a very unaerodynamic frame and bike setup just because he is a talented cyclist who has completed long rides?


Like really, what is your point here because your response doesn't actually counter what I posted.
The guy's 'science' has been taken to task over and over again for years now. The guy's bike is objectively un-aero so doing a bunch of wind tunnel work to improve a specific area of airflow is...goofy.

On a related note- I have 35mm deep rims on a steel frame. Marginal gains despite starting at a distinct disadvantage to purpose built products can be seen all the time on bikes. Jan is ko different. If he wants an aero setup, then get a legit aero setup.

If he actually wants marginal gains, then ride a bike that is designed to reduce drag more than the bike he is riding there. And use wheels that are more aero. And use tires that are more aero.
Etc etc.

But anyways, to address your comments in red...
- I agree that a bag in front of your bars is easier to access while riding. One could just fill their jersey pockets and use a top tube be to bag as well to get the same eay access benefit.
- Saying something might help a bit is far from saying something will help and showing it helps thru actually good testing. Jan struggles from time to time with the actual good testing part of things.
- Is that rando bag actually blocking his pedal motion? I have a 139 basket and bag that hovers as close to the front tire(fender, really) as is possible and that massive setup doesn't block my pedal motion at all because the basket and bag are well above where my feet are.
- a rando bag can improve aerodynamics in very specific instances and comparisons. Getting into a super compact tuck is one such instance...but you then look like this guy...



Jan talks about the aero benefit and limited application in an edit to a post on his site. Of course it's an edit instead of just in the initial article...it's Jan and he is a modern day salesman who only clarifies once enough push back is felt(by way of responses which no longer exist for his articles).
https://www.renehersecycles.com/aero...ando-vs-racer/

It's pretty dishonest of him to state that his handlebar bags reduce aerodynamic drag when, by his own admission, they actually increase aerodynamic in all positions except an extreme tuck that he can't hold for very long.

I read what he said, I just don't agree with it.

I have no sympathy for anyone who wouldn't question that adding a bunch of flat frontal area improved aerodynamics on a bike. Snake oil salesmen's kids have to eat and go to college too....

What you actually should do is read the published research on all of this. Bicycle Quarterly is open and honest in their data and the results. Instead you shout form the sidewalk without anything other than your beliefs. Heine has proven a number of beliefs in the bicycle business to be wrong, starting with the fact that narrow, high pressure tires are not faster like we all assumed they were.

The published research you are citing is shown in this thread- both links and direct quotes from articles on the website.

The published research shows...
- that fender setup is not even as aerodynamicly beneficial as some race wheels(so a 40+mm rim).
- that bag in front is a detriment to reducing wind resistance when in cross winds, when climbing, and when on flat road.
- that bag setup is only aerodynamicly beneficial when in a super compact tuck(with your hands apparently on the stem, if the pic is to be believed).

^ those are things Jan has said.
And then you need to add in the reality that if aero gains are important...just ride a bike that has a frame profile meant to reduce drag, and use a tire/wheel combo that provides comfort while also reducing drag.



Again, this is stuff that Jan has concluded from his research and is posted in his articles.

ok my post was a bit more snarly than needed, mea culpa

I guess I don't understand the dissing of Jan. yes he is iconclastic bordering on eccentric, and I don't buy everything he does, but I do think he is sincere and he bikes the talk himself, but is not a luddite.

His bigger tires are not slower (to some logical point) have been embraced by tour de france riders with many riding 30mm (with more like 32 measured tires)

his moto style fenders for aero, are not for sale so he is not hawking that

his focus is long solo rides like the long gravel rides and paris-brest-paris so aero is in that context of having to bring things along

but the key point is he rides what he is pitching, and gets some top times. Is it the rider, the experience the gear? as always a bit of both. will it work for everyone, probably not....especially super thing flexy frames and bigger riders like me

Ok.