Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling Do you enjoy centuries, double centuries, brevets, randonnees, and 24-hour time trials? Share ride reports, and exchange training, equipment, and nutrition information specific to long distance cycling. This isn't for tours, this is for endurance events cycling

Fender width

Old 03-21-19, 12:59 PM
  #1  
mtb_addict
Senior Member
Thread Starter
 
Join Date: Jun 2011
Posts: 3,985
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 3015 Post(s)
Liked 32 Times in 28 Posts
Fender width

So, I read that Jan Hein did wind tunnel aerodynamic testing to prove that "the overall effect of the full fender and (small) mudflap neither increases nor decreases the wind resistance of the bike."

But I notice his picture show he use very skinny fenders that seem to barely cover the tire's width.

So, the question is how much does wide fenders slow you down? Lets discuss.
mtb_addict is offline  
Old 03-21-19, 01:33 PM
  #2  
rhm
multimodal commuter
 
rhm's Avatar
 
Join Date: Nov 2006
Location: NJ, NYC, LI
Posts: 19,076

Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...

Mentioned: 438 Post(s)
Tagged: 0 Thread(s)
Quoted: 1538 Post(s)
Likes: 0
Liked 12 Times in 11 Posts
I think part of his argument is that fenders increase drag in some areas, but the part of the front fender that covers the top part of the front of the front tire reduces drag, so the net effect is negligible. That makes sense to me, but my front fender hardly goes down the front at all, so I doubt I get any advantage there.
__________________
I put new leather on ruined saddles like Brooks, etc. You can reach me by private message.
rhm is offline  
Old 03-21-19, 01:33 PM
  #3  
GadgetGirlIL
Senior Member
 
GadgetGirlIL's Avatar
 
Join Date: Sep 2017
Location: Lisle, IL
Posts: 269

Bikes: 2003 Litespeed Vortex, 2017 All-City Mr. Pink, ~1997 Trek Multitrack 700

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked 5 Times in 5 Posts
Given my frontal surface area and my preference for sitting more upright due to lack of flexibility in my lower back, the width of fenders is certainly not making me go any slower than I already do.
GadgetGirlIL is online now  
Old 03-21-19, 01:51 PM
  #4  
rando_couche
Senior Member
 
Join Date: Jul 2013
Posts: 1,058
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 133 Post(s)
Likes: 0
Liked 12 Times in 10 Posts
How many angels can dance on the head of a pin?
rando_couche is offline  
Old 03-21-19, 08:38 PM
  #5  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 14,959

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 86 Post(s)
Tagged: 0 Thread(s)
Quoted: 1785 Post(s)
Liked 34 Times in 28 Posts
We ride our tandem year 'round, fenders in winter, none in summer. We have normal over-width fenders and a big rear mudflap. I don't notice a difference. I used to keep track on Strava - winter trim and summer trim - but quit when it became obvious that it made no difference. Of course that's on a tandem. Still, clothing, position, and tires will make the most difference. For sure you'll be faster if more comfortable, so fenders are good, especially long and large mudflaps on the front fender.
__________________
Results matter
Carbonfiberboy is offline  
Old 03-24-19, 09:06 PM
  #6  
Spoonrobot 
Senior Member
 
Spoonrobot's Avatar
 
Join Date: Jul 2006
Posts: 3,179
Mentioned: 55 Post(s)
Tagged: 0 Thread(s)
Quoted: 986 Post(s)
Liked 25 Times in 21 Posts
The wind tunnel testing was mostly nonsense. I've never seen anyone run a fender like the one in the test and the results would most likely not replicate with any off the shelf fenders. It's the same as how a rear saddlebag that was wider than the rider's hips was used as proof that front handlebar bags have less drag than rear saddlebags. Nonsense.



Like wide tires and handlebar bags, I believe there is additional aero drag due to fenders but over most distances it's negligible. Would I run a fender in a time trial or a race? No. For a 300k+? I debate quite a bit as I know from experience having fenders adds anywhere from 15-25 minutes over 200k. Usually I take fenders but if it's going to be completely dry I have foregone them in the past.

But for most of my everyday riding bikes the difference is small enough that it's just noise. On particularly windy days I do notice the difference in the effect of gusty headwinds when using fenders on the same bike vs when fenders aren't installed. If a 10-15-20mph cross wind is obviously affecting the bike more with fenders does it not stand to reason that wind directly from the front has an effect as well
Spoonrobot is offline  
Old 03-25-19, 12:30 PM
  #7  
ThermionicScott 
hungry
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 18,508

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers)

Mentioned: 68 Post(s)
Tagged: 0 Thread(s)
Quoted: 2025 Post(s)
Liked 95 Times in 79 Posts
^ I was a little incredulous after reading that article as well. It would seem that anything additional that you put in the wind has the potential to add drag, even if it's in front of or behind something else.

I don't have any data to prove it, but I feel like I have to work a little harder with fenders on. It may just be in my head.
__________________
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is online now  
Old 03-25-19, 05:10 PM
  #8  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 18,240
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 33 Times in 30 Posts
the first year I rode with fenders was a bad year for me anyway, so I have no point of comparison. But I don't think fenders really slow me down much. I like fenders a lot, so I think I will stick with them. I think the best part about fenders is not getting wet when the rain has stopped but the roads are still wet.
unterhausen is offline  
Old 03-25-19, 05:23 PM
  #9  
jlaw
Senior Member
 
Join Date: Mar 2018
Posts: 626

Bikes: 2015 Spec. AWOL Elite, 2007 Spec. Roubaix Elite, 2003 Spec. Big Hit 2, 1998 VooDoo Zobop, 1985 Trek 410, 1984 Trek 620

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 216 Post(s)
Likes: 0
Liked 35 Times in 21 Posts
Originally Posted by mtb_addict View Post
So, I read that Jan Hein did wind tunnel aerodynamic testing to prove that "the overall effect of the full fender and (small) mudflap neither increases nor decreases the wind resistance of the bike."

But I notice his picture show he use very skinny fenders that seem to barely cover the tire's width.

So, the question is how much does wide fenders slow you down? Lets discuss.
Fenders slowing me down - now that's funny!

My mountain bike shorts and long sleeve sun shirt flapping in the breeze is probably a bigger issue - but I'm not a racer. However, I do enjoy keeping up with my Lycra-clad buddies on their carbon bikes while I spin along on my vintage steel frame with fenders and DT shifters. I will admit to riding in the drops frequently and hiding behind other riders to reduce my wind exposure! And there are some riders who I couldn't keep up with no matter what I was riding, fenders or no.
jlaw is offline  
Old 04-02-19, 07:46 PM
  #10  
Road Fan
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 14,203

Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 801 Post(s)
Liked 6 Times in 6 Posts
Originally Posted by Spoonrobot View Post
The wind tunnel testing was mostly nonsense. I've never seen anyone run a fender like the one in the test and the results would most likely not replicate with any off the shelf fenders. It's the same as how a rear saddlebag that was wider than the rider's hips was used as proof that front handlebar bags have less drag than rear saddlebags. Nonsense.



Like wide tires and handlebar bags, I believe there is additional aero drag due to fenders but over most distances it's negligible. Would I run a fender in a time trial or a race? No. For a 300k+? I debate quite a bit as I know from experience having fenders adds anywhere from 15-25 minutes over 200k. Usually I take fenders but if it's going to be completely dry I have foregone them in the past.

But for most of my everyday riding bikes the difference is small enough that it's just noise. On particularly windy days I do notice the difference in the effect of gusty headwinds when using fenders on the same bike vs when fenders aren't installed. If a 10-15-20mph cross wind is obviously affecting the bike more with fenders does it not stand to reason that wind directly from the front has an effect as well
If I recall, Heine also was claiming that the long forward extension reduced water being thrown upward by the tire. Upward into the rider's face - one of Heine's goals for a good fender setup was to not throw water into the face, because road water could be contaminated by some really nasty and disgusting stuff. Of course it was also about protecting the drivetrain against dirt thrown back by the front wheel's rooster-tail, and other matters of foot and frame contamination.

Last edited by Road Fan; 04-02-19 at 07:52 PM.
Road Fan is offline  
Old 04-03-19, 04:50 AM
  #11  
rhm
multimodal commuter
 
rhm's Avatar
 
Join Date: Nov 2006
Location: NJ, NYC, LI
Posts: 19,076

Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...

Mentioned: 438 Post(s)
Tagged: 0 Thread(s)
Quoted: 1538 Post(s)
Likes: 0
Liked 12 Times in 11 Posts
If you're getting a spray of nastiness thrown up from the road, it's probably the bike in front of you that needs better fenders. To protect the drive train etc, you need a really good mudflap on the front fender.

One of the drawbacks of fat tires is that they displace a lot of water, and the mudflap has to be wide enough to catch it.
__________________
I put new leather on ruined saddles like Brooks, etc. You can reach me by private message.
rhm is offline  
Old 04-03-19, 07:05 AM
  #12  
Bandera 
~>~
 
Join Date: Mar 2013
Location: TX Hill Country
Posts: 5,806
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quoted: 1037 Post(s)
Liked 62 Times in 38 Posts

I've ridden the same 4 mile false flat for time on a variety of machines over the years.
Oddly enough the 2nd fastest time set in the '17 season was ridden on my winter/wet bike replete with full mudguards, box section 32 hole wheels, heavy 28mm tires and a cheerful bell.
Not exactly the ideal aero TT set-up but end of season fitness and the mind-set to lay down a stout time trumped light weight, lower position and aerodynamics on all but one full-on ride.

Fit = Fast.


-Bandera
__________________
'74 Raleigh Internat'l. '77 Trek TX900 FG. '90 Vitus 979. '10 Merckx EMX3. '13 Soma Stanyan
Bandera is offline  
Old 04-11-19, 12:23 PM
  #13  
ascherer 
Senior Member
 
ascherer's Avatar
 
Join Date: Jul 2007
Location: Manhattan
Posts: 1,032

Bikes: 1987 Mercian Pro, 1971 Raleigh International, 1971 Peugeot PX-10E, 1966 Raleigh Sports

Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 254 Post(s)
Liked 18 Times in 12 Posts
Originally Posted by Bandera View Post
Fit = Fast.


-Bandera
Boom!
__________________
1987 Mercian Pro, 1971 Raleigh International, 1971 Peugeot PX-10E, 1966 Raleigh Sports
ascherer is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
NJAgent020
Charity Events
2
04-05-17 09:20 AM
bikeallday26
Charity Events
2
08-13-15 03:28 AM
Mambwe
"The 33"-Road Bike Racing
5
07-24-03 06:08 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.