djb

you silly man. Pauvre con.
;-)

Six jours

Pissing into the wind is a hobby of mine...

djb

yet with fenders, your pant legs wouldn't get a dark spot on them.
See non believers, another reason for using them. Never be socially embarrassed again.

sstorkel

Fenders are great in the rain. My touring bike uses 700c wheels and fenders increase the potential for toe overlap problems. If I'm not expecting rain, I leave the fenders a home...

mm718

I am fenderless. I don't have an issue with a brown mud stripe because my tent poll bag sticks out a few inches off the back of the rack. If it rains my drive train needs cleaning anyway... Happy to save that 1.4 lbs in weight and avoid the hassles that some have reported with fenders. I also don't like the look of fenders.

Western Flyer 

I am amazed it is almost 5 to 1 favoring fenders! I have never kept track or even noticed, but I would have thought it would have been 1 to 1 at most.

Walter S

That's not my experience. Get cover during a shower and you can ride right afterwards without getting at all wet with fenders on. Without them you get soaked without any water falling from the sky. And if I ride in the rain it is so much better to get myself and my bike wet with water instead of covered with mud. And for a short lite rain I hardly get wet in the least as I remind myself how nice it is to have fenders.

staehpj1

I wouldn't read the results as 5 to 1 against using fenders. Remember that the question was not "do you favor fenders". Rather it was a guy who uses fenders already asking if he should take them off for his tour. It seems to me that isn't the same question at all. If asked whether I favor using fenders myself I would have said no, but given his question I suggested that in his case it probably made sense to leave them on.

Western Flyer 

I see what you are saying. In that case I should change my vote. The added wind resistance slows touring cyclists down a bit so I don't look quite as slow and I can draft them on rainy days without getting water and mud sprayed in my face. So yes, everyone should keep their fenders on.

LeeG

Depends

If the roads are dry you don't need then.

Lasse

Won't slow down the bike according to wind tunnel tests: https://janheine.wordpress.com/2012/0...orld-bicycles/

Western Flyer 

I’m skeptical of their claimed results. I would like to see their test data along with photographs.

Lasse

Western Flyer, test data would indeed be interesting to see, although I don't doubt mr Heine's integrity. Maybe you should send him a mail and report his reply? There should also be more details in the Bicycle Quarterly issue mentioned in the blog entry.

Burton

You can take the fenders off for shipping. Depending on where you're headed - you may or may not need them. If I was touring the Cabot Trail - they'd stay on. In the Sudbury area above the Great Lakes - I wouldn't bother with them.

Western Flyer 

I don't either, just the test results. It is when I am riding downhill at speed and I see my front fender bending and distorting I gotta think there is some resistance going on.

djb

I suspect that is one loosy goosy front fender---mind you, to be completely honest, I have never glanced at a front fender going downhill at speed, my eyes are elsewhere. My fenders are narrow ones (for prob up to 32 max tires) and have a much narrower and closer frontal area than larger fenders--maybe this is a factor as mine seem not be close to moving around. Put it this way, Ive never noticed my fenders moving around with big gusts of wind or whatever when Im going at slower speeds and would be more likely to see the front fender move around out of the corner of my eye.

I too wonder also about the results, but do not have any aero expertise, so wat do I know. I did however find the Bike Quarterly 15% tire deflection article to be overly low in what is an optimum pressure for a given rider and bike weight-specifically about how a tire feels at their recommended settings whilst going around corners fast, working the tire.
re the aero effect mentioned in the article, I don't really understand why a rear fender would have more drag than a front, as they claim that the rear cancels out the benefit of a front fender.
All I know is that last summer on downhills tucked in with roadies near me, I could never match their coasting speed on my cross bike, rear fender, rear rack, cantis etc--dunno if its a mass thing (Im a light guy), an aero thing, a wheel hub, tire thing? maybe all mixed in together, but it was frustrating as I like to go fast.

Lasse

I think Heine forgot the word 'section' after 'rear fender'. That would make the sentence I quoted make more sense:
"The front section of each fender shields the tire and reduces the wind resistance, while the rear fender section increases the aerodynamic drag. The two effects cancel each other."
It's quite obvious I'd say, looking at the first part of the sentence.

So it's not the rear fender that increases the drag but the rear part of each fender, in contrast to the front part of each fender which shields the tire. Since the front fender has hardly any front section shielding the tire, the front fender on its own would have a negative effect on aerodynamics, in contrast to the rear fender which is almost completely shielded and must have a positive effect to cancel out the negative effect of the front fender. Or in other words: usage of a rear fender would make your bike more aerodynamic. This is just theory though, Heine would be able to confirm or correct this based on his tests, I assume.

Either way, the point is that well fitted fenders have a negligible effect on the total aerodynamics of a bike with rider.

neil

If you've ever had the briefest exposure to aerodynamics, the test results make intuitive sense. The fender is a partial coverage wheel fairing. Fairings are used in race cars because spinning disks are not very aerodynamic, so getting them out the wind is a net benefit. Fenders, of course, aren't designed to act as fairings, so the open sides would also grab some wind at the same time. Thus the test result "effects cancel each other out." It's certainly possible that at different speed and wind directions, one effect may overcome the other, but we're talking very small impacts.

As with all things on bikes, though, the effects we're talking about are small. When you're racing and cutting down weight and air resistance by the slightest amounts can change your finishing time, it might matter. But like adding the extra 250g does not substantially change the weight of a loaded touring, the aerodynamic adjustment isn't much worth worrying about. Your panniers are already providing a nice big sail.

djb

thats the end of the line isnt it? Panniers are just great big honking wind grabbers, all the rest of talk of weight and wind resistance of fenders is such a small amount compared to bags, especially at the speeds we usually plonk along at (I guess weight can be a factor if one is really picky).

re the "less gunk on drivetrain" theory, I believe it but others can decide for themselves.

Western Flyer 

I have had some exposure to aerodynamics and I am still skeptical. Perhaps I should use a less inflammatory word like "puzzled" because I am not questioning anyone honesty or integrity or even expertise in conducting the tests.

I don't use front panniers, although I do have a small handlebar bag and a six pack cooler over my front wheel. I cut my rear pannier profile down by about 30% each side but that was more for negotiating single track when touring than aerodynamic considerations.

Six jours

I have a bike with plastic fenders. The front one flutters quite a bit at any speed much beyond 30 MPH. But my other bikes have aluminum fenders. The "race" bike has very narrow and light fenders (mounted with very thin stays) that move a tiny bit at very high speeds (40+ MPH). The other bikes have wider aluminum fenders that don't deflect at all (at least to the naked, watering eye) at 50 MPH and beyond.

A spoked bicycle wheel is a lousy object from an aerodynamic POV. The idea that drag could be lessened by fairing it makes perfect sense to me - as long as your fairing isn't wobbling around in the breeze too!

djb

side wind gusts are likely the reason we dont see that stuff around, pushing us around too much would be dangerous.

Six jours

Oh, I was just referring to the fenders as a fairing. I have a bit of experience with fully-faired recumbents: very fast, but far more exciting that I generally care for!

djb

re drag aero and all, it must be pretty neat in one of those fully faired recumbents, just from the faster speeds from the same effort. They are the sort of thing that would be very cool to try, but they are pretty rare. Must be very very cool riding those record breaking speed ones, the tear drop jobs that are fully enclosed (must be hotter than hell in em tho)

Six jours

I managed a velodrome, years ago, which periodically hosted the HPV geeks. I cadged rides whenever possible. Some of those bikes would go 40 MPH without much effort, but boy, in any kind of a breeze you put so much work into keeping them upright that you could scarcely remember to pedal!