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  1. #1
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    Fenders in wind?

    Does a lack of fenders really help a bike handle better in wind?

  2. #2
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    I suppose it would, but I've never noticed a difference. They add nothing compared to me sitting on top of the bike.

  3. #3
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    I can absolutely feel the difference.

    but who cares, I'm also wearing a giant stuffed backpack. It's not a race, as long as you can get where you're going safely.

  4. #4
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    I can't say that I've noticed much of a difference.

  5. #5
    I Ride for Donuts
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    I have noticed a difference when I'm in a stupid-strong crosswind and I happen to have the knobbys on the bike...the rear fender gets a nice gust of wind and GAK hits the back tire, a knob on the tire bounces it back GAKGAK and then the wind pushes it back GAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGAKGA K ... it's like a superfast game of ping pong.

    I hate everything about fenders other than the fact that I hate everything about not having fenders when it's sloppy out.
    You have no excuse for driving to work
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  6. #6
    Fat-tired Roadie
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    On my road bikes, I can see how it would make a difference in theory but I don't notice a difference.

    My MTB has high-clearance fenders without stays. Not very effective at keeping my legs dry, but they still help and they don't catch sticks and things. So for me, a good compromise off-road. If they move around in a cross wind, I don't hear it.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  7. #7
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    Bicycle Quarterly did some testing in a wind tunnel. For the type of fenders they use (long, full coverage aluminum jobbies), the addition of fenders actually *decreased* the wind resistance. This was in a wind tunnel with a dyno, which allowed the rider to pedal the bike--possibly, the turning wheels had some relationship to the effect of the fenders.
    WTB: Specialized AWOL frameset, XL

  8. #8
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    Quote Originally Posted by seat_boy View Post
    Bicycle Quarterly did some testing in a wind tunnel. For the type of fenders they use (long, full coverage aluminum jobbies), the addition of fenders actually *decreased* the wind resistance. This was in a wind tunnel with a dyno, which allowed the rider to pedal the bike--possibly, the turning wheels had some relationship to the effect of the fenders.
    Did they try the headwind at different angles. If not, they only tested calm, wind directly behind or in front conditions. I have suspected the scoop of the rear part of full fenders might be sail like with the right quartering wind.

    BrianMc

  9. #9
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    Even if they tested just riding into a headwind, no one rides in a perfectly straight line, especially guys commuting through traffic. I can absolutely feel the wind messing with the bike when I have fenders on.

  10. #10
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    Took mine off this weekend to get bigger tires in there. Didn't notice much of a difference. But, I have the luxury of using a car when the weather is bad. If you are like me, then I would say take them off. If you have to ride every day and that is your only option, leave them on.
    Austin Mountain Biking and worldwide travel pictures:

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  11. #11
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    My take on the original question was that he was asking more about handling (like in crosswinds) than about drag. Maybe he`ll come back on and clarify? Either way, I don`t notice a difference, but I`m sure its there. Besides everybody having different sensitivity to things like that, the efect will be different depending on the bike and the fenders involved.

    Quote Originally Posted by CommuterBoy View Post
    I hate everything about fenders other than the fact that I hate everything about not having fenders when it's sloppy out.
    Well put
    Recalculating....

  12. #12
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    The Alternative

    I would have liked some fenders for the ride home last night. This was all from riding on a dirt road.Fenders in wind?-2013-03-25-18.11.25.jpg

  13. #13
    I Ride for Donuts
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    ^^ I live on a dirt road. So there you go. Necessary evil.
    You have no excuse for driving to work
    (unless you don't have studded tires)
    (no excuse for that either)

  14. #14
    Squeaky Wheel
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    Let's look at this a little differently.

    I have full coverage fenders on my commuter. Front fender is about 3' long, rear fender is about 4' long. Assuming the OP was asking about a crosswind, fenders increase the surface area that the wind would push against on my bike by about 1" (probably less, but I'll round up) all along their length which would mean that by installing fenders I added about 84 Sq. inches of surface area to my bike.

    Now compare that 84 sq. inches to the surface area of my body and my bike...I am 73" tall and let's say that from the side on average I am 12" wide (some parts wider than other, haha). Let's add another inch for clothes, helmet, etc. That multiplies out to a little more than 1000 sq. inches of surface area for the wind to push against. I am not going to measure the surface area of my bike, but just looking at it - wheels, frame, cranks, cassette, pannier the surface are is going to be way, way more than 84 sq. inches.

    So, would you feel a difference in handling with fenders in the wind? Maybe. On my setup fenders are going to add less than 5% surface area from the side which I *think* would be worst case. If I was not using full coverage fenders the addition would be much less than 5%.

    From actual experience - and I am very much in tune with my bike (heck, I spent almost 500 hours on it last year) - I cannot feel any difference in handling from having fenders on my bike. Of course YMMV.

  15. #15
    I Ride for Donuts
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    Another other way to look at it is that usually on my ride to work, with wind comes rain and wet and road grime. The OP's question was "Does a lack of fenders really help a bike handle better in wind?"

    When I can see, my bike handles better in the wind. When I have fenders, I can see. So I'm going to say no, a lack of fenders doesn't help with the handlng
    You have no excuse for driving to work
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  16. #16
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    At some angles the fenders will provide angled tail winds with more area to push on. An narrow head wind angles they could act like scoops. At a bit wider like airfoils and a slight forward thrust like a boat sailing at an angle to the wind, and full cross wise, they would add some side thrust. I think my deep vee rims would add more side thrust. The very deep carbon road rims would be much higher in side thrust.

    I notice more difference off line of uphill. Not much added weight, but they are added weight.

    BrianMc

  17. #17
    Squeaky Wheel
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    Quote Originally Posted by CommuterBoy View Post
    When I can see, my bike handles better in the wind. When I have fenders, I can see. So I'm going to say no, a lack of fenders doesn't help with the handlng
    LOL. This is the answer that matters!

  18. #18
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    Actually, I was talking about heavy cross winds, which are common here. Like 20mph plus. Rain isn't common, but rocks are dirt are.

    Wind regularly gets over 40mph here. Can't go cycling in that but have to up to 25mph at times.

  19. #19
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    ^^ In a heavy crosswind, I'd say the floppy-ness of the fenders is a major factor. My 29er PB Cascadias start dancing like plastic sails in 25mph wind if the angle is right.
    You have no excuse for driving to work
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  20. #20
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    Mine don't flop significantly in cross-winds, gusts to 20-30 tops. There's a little motion at the bottom of the front fender but I've otherwise got them secured pretty well. SKS longboards, I think.

    I did get an interesting oscillation in my front end care of the wind/fender interaction a few weeks ago. It was neat.

  21. #21
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    I haven't had them flopping around. I was worried about them making the bike hard to handle, not flopping around.

  22. #22
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    Quote Originally Posted by austin_bike View Post
    Took mine off this weekend to get bigger tires in there. Didn't notice much of a difference. But, I have the luxury of using a car when the weather is bad. If you are like me, then I would say take them off. If you have to ride every day and that is your only option, leave them on.
    Some people choose to ride every day.

  23. #23
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    Subjective assessments of fenders and wind

    Lacking a power meter, wind force and direction data, I have tried to assess my bike's handling subjectively in winds with and without fenders.

    Buildings, woods, and creek valleys can affect the local wind direction versus the general one. This makes the assessment a bit tougher. By picking days where I was riding into the wind without landscape factors, the bends in the road gave me angles from head on through slightly to either side, and to full crosswinds. I got three days of good assessment with the fenders in April. Only recently has the wind cooperated and given me a third day in the right direction. Winds varied form 10-20 average speeds. I tried to stay in the 75-80% pulse range as a crude measure of somewhat constant power output. I monitored my speed and the wind angles.

    With no fenders I was slowest with the winds straight ahead. Speed increase as the road turned and the wind came around with the fastest when the wind was broadside. So If I was making 14-15 into the wind, it dropped to 10-12 at about 30 degrees to the wind and increase up to about 17 with a full cross wind. I could feel the gusts a bit when the winds were at 90 degrees. Nothing scary. But more than I get with no fenders. With no fenders the speed went up as the wind moved from full ahead to broadside as you'd expect.

    So even with tightly fit fenders, there are shallow angles of a mostly headwind where the fenders act as spinnakers catching and sailing at an angle to the wind adding a rearward thrust. The tailwind effect on the front part of the rear fender was not as noticeable, as the rear of both fenders would be factors. If this all averaged out, it would not matter. But good days/bad days and myriad other factors don't allow speeds overall to be used to compare these rides. My impression is that there is some gain on the return leg, but the main treat is keeping rain and road kill and worse, off me.

    YMMV

    BrianMc

  24. #24
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    "Fenders in wind?
    Does a lack of fenders really help a bike handle better in wind?"

    Yes. No. What?
    No more so than not having a lack of other limited and unnecessarily useful components.

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