Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

What effect do fenders have on speed?

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

What effect do fenders have on speed?

Old 12-20-15, 07:52 PM
  #26  
Northwestrider
Senior Member
 
Northwestrider's Avatar
 
Join Date: Apr 2006
Location: Gig Harbor, WA
Posts: 2,470

Bikes: Surly Long Haul Trucker, Gary Fisher Hoo Koo E Koo, Dahon Mu P 24 , Ritchey Breakaway Cross, Rodriguez Tandem, Wheeler MTB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Just an observation. Many small aircraft have fenders over their tires, ( fairings ) they are put there to reduce drag and increase speed, they are shaped differently though . On the other side of the coin, TDF and other racers never have fenders , likely for the same reasons .
Northwestrider is offline  
Old 12-20-15, 07:53 PM
  #27  
Northwestrider
Senior Member
 
Northwestrider's Avatar
 
Join Date: Apr 2006
Location: Gig Harbor, WA
Posts: 2,470

Bikes: Surly Long Haul Trucker, Gary Fisher Hoo Koo E Koo, Dahon Mu P 24 , Ritchey Breakaway Cross, Rodriguez Tandem, Wheeler MTB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Bob Ross View Post
However much they slow us down, it's not enough to be worth soaking wet shoes & ass.
+ 1 , agreed
Northwestrider is offline  
Old 12-20-15, 07:56 PM
  #28  
B. Carfree
Senior Member
 
Join Date: Jan 2010
Location: Eugene, Oregon
Posts: 7,048
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 509 Post(s)
Likes: 0
Liked 8 Times in 8 Posts
Originally Posted by Homebrew01 View Post
And what about all the extra weight too !!
Since you're not getting soaked from the water on the road you might make up for the weight of the fenders by wearing less clothing. It could be a wash.
B. Carfree is offline  
Old 12-20-15, 08:02 PM
  #29  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,405

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2012 Post(s)
Liked 1,098 Times in 665 Posts
Originally Posted by jamesdak View Post
No, no.... What I'm trying to say is that my bikes with fenders are different than the "race" bikes I ride for the PRs I track. Fastest century, fastest descent top speed, fastest 10 mile, fastest 20 mile, fastest time up any given MT, etc. etc. Most PRs, except for the climbing ones, are held my my beat up old 2000 Lemond Zurich.

My point is that it's not fair to compare my CX and MB to any of my road bikes since the road bikes are built for speed and not fenders while the CX and MB have a different purpose. If I could get some will fitting fenders on the Zurich I would not expect to see any measurable effect on the bike.
Interestingly, one of my fendered bikes is an '02 Lemond. I usually keep the RR MkIIs on it, but I suppose I could take them off, put on the Powertap wheel set, and do some back-to-back testing of my own...in the name of science.



Alternatively, you could take the fenders off your bikes and ride as you would otherwise and check that. I don't think it need be restricted to road bikes; if there's extra drag, there's extra drag.
chaadster is offline  
Old 12-20-15, 08:11 PM
  #30  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,919
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 585 Post(s)
Liked 570 Times in 228 Posts
Originally Posted by Homebrew01 View Post
I really doubt it.
You're demonstrably wrong.
RChung is offline  
Old 12-20-15, 08:12 PM
  #31  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,919
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 585 Post(s)
Liked 570 Times in 228 Posts
Originally Posted by chaadster View Post
Would that be an "undemanding use" of a power meter, or would it fall in the advanced user camp?
Advanced users count as "anyone."
RChung is offline  
Old 12-20-15, 08:29 PM
  #32  
jamesdak 
Senior Member
 
Join Date: Aug 2010
Location: Utah
Posts: 7,536

Bikes: Paletti,Pinarello Monviso,Duell Vienna,Giordana XL Super(2)Lemond Maillot Juane (2) & custom,PDG Paramount,Serotta CSI,Fuji Opus III,Davidson Impulse,Pashley Guv'nor,Evans,Fishlips,Prologue TT,Y-Foil,Softride, Tetra Pro, CAAD8 Optimo,Klein Quantum II

Mentioned: 135 Post(s)
Tagged: 0 Thread(s)
Quoted: 1915 Post(s)
Liked 2,020 Times in 945 Posts
Originally Posted by chaadster View Post
Interestingly, one of my fendered bikes is an '02 Lemond. I usually keep the RR MkIIs on it, but I suppose I could take them off, put on the Powertap wheel set, and do some back-to-back testing of my own...in the name of science.



Alternatively, you could take the fenders off your bikes and ride as you would otherwise and check that. I don't think it need be restricted to road bikes; if there's extra drag, there's extra drag.
Sweet Lemond! Hmmm, maybe if I ever get the Zurich back from the friend who "borrowed" it I can try those on it.

I honestly think there's too many factors that figure in to really test this real world. If it helps, the fastest avg speed on my normal 20 mile route I've ever held with the CX bike happened this month with the fenders and the 700 x 30 C tires on it. Yet my conditioning is not as good as previous years, it was just a "perfect" day.
__________________
Steel is real...and comfy.
jamesdak is offline  
Old 12-20-15, 08:45 PM
  #33  
kbarch
Senior Member
 
kbarch's Avatar
 
Join Date: Aug 2014
Posts: 4,286
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1096 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Depends on the conditions, and whose bike they're on. In wet conditions, someone who might not be able to keep up without drafting may be more inclined to do so if the rider in front has a rear fender.
kbarch is offline  
Old 12-20-15, 08:49 PM
  #34  
Homebrew01
Super Moderator
 
Homebrew01's Avatar
 
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Posts: 21,717

Bikes: Old Steelies I made, Old Cannondales

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1103 Post(s)
Liked 632 Times in 434 Posts
Originally Posted by RChung View Post
You're demonstrably wrong.
For example ??
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.

FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
Homebrew01 is offline  
Old 12-20-15, 08:58 PM
  #35  
f4rrest
Farmer tan
 
f4rrest's Avatar
 
Join Date: May 2008
Location: Burbank, CA
Posts: 7,986

Bikes: Allez, SuperSix Evo

Mentioned: 38 Post(s)
Tagged: 1 Thread(s)
Quoted: 2870 Post(s)
Liked 26 Times in 22 Posts
Fenders definitely look slower.
f4rrest is offline  
Old 12-20-15, 09:01 PM
  #36  
Homebrew01
Super Moderator
 
Homebrew01's Avatar
 
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Posts: 21,717

Bikes: Old Steelies I made, Old Cannondales

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1103 Post(s)
Liked 632 Times in 434 Posts
Originally Posted by chaadster View Post
I presumed he was referring to power meter testing, and yes, I think the numbers would show a difference, but as I said, obviously some setups would be worse than others; were the tires to fill out to the edge of the fender width, and were there little gap between tire and fender, would be an ideal setup, I think.
I wouldn't argue fenders don't slow down a rider, and it may be measurable. But the post was about noticing that fenders are slowing you down.

"I doubt it slows us down enough for anyone to notice a difference ."

How can a rider notice they are going a tiny bit slower than they would without fenders ?
Someone can confidently determine, by feel, that they would be going some small percentage faster ?
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.

FYI: https://www.bikeforums.net/forum-sugg...ad-please.html

Last edited by Homebrew01; 12-20-15 at 09:56 PM.
Homebrew01 is offline  
Old 12-20-15, 09:13 PM
  #37  
woodcraft
Senior Member
Thread Starter
 
woodcraft's Avatar
 
Join Date: Apr 2012
Location: Nor Cal
Posts: 6,015
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1813 Post(s)
Likes: 0
Liked 918 Times in 566 Posts
I've been reading BQ for about two years, so I missed the fender findings.

Certainly an obvious place to look.
woodcraft is offline  
Old 12-20-15, 09:22 PM
  #38  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,405

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2012 Post(s)
Liked 1,098 Times in 665 Posts
Originally Posted by Homebrew01 View Post
I wouldn't argue fenders slow down a rider, or that it may be measurable. But the post was about noticing that fenders are slowing you down.

"I doubt it slows us down enough for anyone to notice a difference ."

How can a rider notice they are going a tiny bit slower than they would without fenders ?
Someone can confidently determine, by feel, that they would be going some small percentage faster ?
Well, there are different ways to "notice," right? For example, rather than noticing your speed difference at any given moment, it may be a perception of effort over a segment, or over a total ride. But, for me, noticing is also looking at the ride data and assessing how I did, so yeah, measuring is noticing, to my mind.
chaadster is offline  
Old 12-20-15, 09:53 PM
  #39  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280

Bikes: Nashbar Road

Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2933 Post(s)
Liked 336 Times in 224 Posts
Originally Posted by chaadster View Post
Well, there are different ways to "notice," right? For example, rather than noticing your speed difference at any given moment, it may be a perception of effort over a segment, or over a total ride. But, for me, noticing is also looking at the ride data and assessing how I did, so yeah, measuring is noticing, to my mind.
It's not that hard for me to notice .2 mph difference when I'm at a threshold effort, and I'd imagine that racers training seriously would be even more attuned to it. So I don't doubt that someone could notice tiny differences in drag while riding. The effect of fenders would be some fraction of that in my estimation, depending a lot on the particular fenders.
wphamilton is offline  
Old 12-20-15, 11:37 PM
  #40  
woodcraft
Senior Member
Thread Starter
 
woodcraft's Avatar
 
Join Date: Apr 2012
Location: Nor Cal
Posts: 6,015
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1813 Post(s)
Likes: 0
Liked 918 Times in 566 Posts
Dr Isotope notices the difference:

"I'd love a stiffer set of cranks, but have yet to find anything affordable to fit my needs. Picture is also well out of date, and the shorty fenders have gone the same way as the full fenders I ran originally. They're just too annoying to keep clean, and even that short front fender still caused noticeable drag. So away they went. A closer-to-now photo."

From the hot-or-not thread. Couldn't manage to get the pic over here.
woodcraft is offline  
Old 12-20-15, 11:51 PM
  #41  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 18,280

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

Mentioned: 108 Post(s)
Tagged: 0 Thread(s)
Quoted: 3300 Post(s)
Liked 1,241 Times in 917 Posts
No, we don't notice a difference with or without fenders on the same bike. I'd guess that mudflaps should make a difference, but we don't notice it.
__________________
Results matter
Carbonfiberboy is offline  
Old 12-21-15, 01:37 AM
  #42  
Long Tom
Senior Member
 
Join Date: Jun 2013
Location: Go Ducks!
Posts: 1,549
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Bob Ross View Post
However much they slow us down, it's not enough to be worth soaking wet shoes & ass.
Ok, we can stop now.
Long Tom is offline  
Old 12-21-15, 02:33 AM
  #43  
K.Katso
Gold Member
 
K.Katso's Avatar
 
Join Date: Jan 2010
Location: Haarlem, Netherlands
Posts: 1,313

Bikes: Pinarello Dogma F8, Pinarello Bolide, Argon 18 E-118, Bianchi Oltre, Cervelo S1, Wilier Pista

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Why don't you do back-to-back rides over the same course with and without fenders, then upload the data to cyclingpowerlab.com's CdA estimation tool and find out what aero difference it makes?

I may be the lone dissenter here, but I don't see any value in fenders. I live in a wet climate, and pretty much NOBODY has fenders on their race bikes here. Only on commuters. If you're worried about the performance impact of your fenders, just take them off.
K.Katso is offline  
Old 12-21-15, 07:16 AM
  #44  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,405

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2012 Post(s)
Liked 1,098 Times in 665 Posts
Originally Posted by K.Katso View Post
Why don't you do back-to-back rides over the same course with and without fenders, then upload the data to cyclingpowerlab.com's CdA estimation tool and find out what aero difference it makes?

I may be the lone dissenter here, but I don't see any value in fenders. I live in a wet climate, and pretty much NOBODY has fenders on their race bikes here. Only on commuters. If you're worried about the performance impact of your fenders, just take them off.
Sure, not everyone rides in the conditions, and in such a way, including frequency, to make fenders valuable.

Assuming by "race bike" you mean a road bike (I don't believe any road race sanctioning body permits fenders, so install/removal for a true race bike would be annoying), what you describe is the same here; most people don't use fenders.

Even in climates like mine, where we get more than 2x the annual precipitation you get in Haarlem, many do not use fenders.

Yet for me, the value is clear. Fenders reduce my bike cleaning time, keep my clothes from getting stained, increase my comfort, keep me warmer, and let me see better (eyeglass wearer) by reducing spray.
chaadster is offline  
Old 12-21-15, 08:20 AM
  #45  
PepeM
Senior Member
 
PepeM's Avatar
 
Join Date: Apr 2015
Posts: 6,861
Mentioned: 180 Post(s)
Tagged: 1 Thread(s)
Quoted: 2739 Post(s)
Liked 119 Times in 59 Posts
I'm considering putting fenders on my road bike because cleaning it every time is a pain in the arse.
PepeM is offline  
Old 12-21-15, 08:32 AM
  #46  
Marcus_Ti 
FLIR Kitten to 0.05C
 
Marcus_Ti's Avatar
 
Join Date: Sep 2014
Location: Lincoln, Nebraska
Posts: 5,331

Bikes: Roadie: Seven Axiom Race Ti w/Chorus 11s. CX/Adventure: Carver Gravel Grinder w/ Di2

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 2349 Post(s)
Liked 405 Times in 254 Posts
Originally Posted by f4rrest View Post
Fenders definitely look slower.
Only if you're not riding hard enough. All bikes not ridden look equally slow. All bike ridden hard enough look fast.
Marcus_Ti is offline  
Old 12-21-15, 09:25 AM
  #47  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,919
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 585 Post(s)
Liked 570 Times in 228 Posts
Originally Posted by Homebrew01 View Post
For example ??
Oh, sorry. I didn't realize I'd hit "post" on that. I thought I'd hit "cancel."
RChung is offline  
Old 12-21-15, 09:27 AM
  #48  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,919
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 585 Post(s)
Liked 570 Times in 228 Posts
Originally Posted by chaadster View Post
Well, there are different ways to "notice," right? For example, rather than noticing your speed difference at any given moment, it may be a perception of effort over a segment, or over a total ride. But, for me, noticing is also looking at the ride data and assessing how I did, so yeah, measuring is noticing, to my mind.
Right, the post I was responding to didn't restrict "noticing" to "without instrumentation."
RChung is offline  
Old 12-21-15, 09:35 AM
  #49  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,919
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 585 Post(s)
Liked 570 Times in 228 Posts
Originally Posted by wphamilton View Post
It's not that hard for me to notice .2 mph difference when I'm at a threshold effort, and I'd imagine that racers training seriously would be even more attuned to it. So I don't doubt that someone could notice tiny differences in drag while riding. The effect of fenders would be some fraction of that in my estimation, depending a lot on the particular fenders.
I recently worked with someone who was attempting a record on the track. As you probably know, no visual display is allowed during record attempts (you can record and review later but during the attempt itself you're only allowed to see lap count on a chart at the side of the track). Over the course of extensive practice and testing at the targeted pace, the rider became so attuned to internal assessment that small differences in effort for pace due to changes in drag became "noticeable." But that's an unusual case. I took "noticing" more loosely.
RChung is offline  
Old 12-21-15, 09:35 AM
  #50  
Wilfred Laurier
Señor Member
 
Wilfred Laurier's Avatar
 
Join Date: Feb 2013
Posts: 5,063
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 646 Post(s)
Liked 282 Times in 206 Posts
I did some group rides this summer with and without fenders, about the same speed and skill level of riders. I was able to keep up equally well with as without fenders. I think my own conditioning and energy level had a bigger impact than the fenders.
Wilfred Laurier is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.