Cycling UK Forum

Pigeons, have a cat!

https://janheine.wordpress.com/2018/01/ ... -you-down/

Sort of sounds reasonableish, but i guess it depends on how far forward they go, how fst and how close! But whether its right or not, its a good enough excuse for me

I'm convinced, and have been convinced for years, that my Mercian runs better without mudguards. I would say that all my previous bikes did too though I wouldn't even consider ever riding the Moulton without mudguards due to the muck generated by small wheels.

No mudguards = quieter and faster.
Given the choice, I would ditch them.

Air getting under the mudguard and swirling about the stays has got to reduce forward motion. OTOH most of our riding is at speeds where this makes no difference and i've had mudguard clad bikes exceeding 70kph on more than one occasion!

I guess it's all relative.

I'm convinced, and have been convinced for years...

... that it makes no real world difference either way unless you're at the pointy end of a race or timetrial, and even then it might not!

My average speeds are pretty consistent across my bikes and speeds only vary with route and on-the-day performance. The minor weight differences between them have little effect, and I think the guards have even less effect than that. Tyres and body position trump most other factors by an order of magnitude or more.
I'm quite happy taking mudguarded bikes out on semi-fast club runs (20mph average) and don't feel they're slowing me down or any disadvantage, even when dry, but I do absolutely hate a wet ride with no guards, and probably go slower on those rides just due to sheer volume of water being sprayed in my face and general discomfort!

What I do know is that most of my mudguarded rides (not all) are in crappier weather which can make a mental difference to perceived (and actual!) effort. Also, many people only run guards on bikes with correspondingly heavier duty slower tyres which could also play a part in that.

I think Jan loves to bang his drum though, and for him and his riding even if guards did slow you down a bit it would be worth the compromise, others may have different opinions as to whether they are 'worth it' or not. But I do tend to agree that they don't really slow you down for normal riding, but I'm not sure I'd go so far as to say they speed you up or that you should strap them on for your next TT!

In summary, I think guards are mostly irrelevant to speed, other factors outweigh any small impact they may have.

Hmm well looking at the detail of the test it seems that the rear part of a guard does add drag, and it seems likely that a decent sized mud flap which you typically need with something like the SKS guards will add even more (I notice the test specifies a "small" mud flap). The only advantage you seem to get is if the front part of the front guard extends beyond the top of the wheel (and I suspect need to closely follow the shape of the wheel at this point), very few guards I see in typical use do that. So I'd say that they do slow you down at least a little.

More to the point I suspect that the build up of mud and other crud that I seem to get get on my local roads, that is often enough that it will be rubbing on the tyre will definitely be slowing me down! Still probably better to be a little slower than be covered in that crud!

I read somewhere (but can’t remember the source) that tummy upsets are common in the tdf peloton are thought to be caused by road dirt. Yuk.

Interesting that Jan Heine finds that a portion of front mudguard in front of the brake improves aero dynamics and that it may yet make an appearance in the Tour de France.
It made an appearance in the 1930's on the bicycles of Gino Bartali and some others.
I'm not sure of the purpose but it probably wasn't the outcome of wind tunnel tests.

ANTONISH wrote:...finds that a portion of front mudguard in front of the brake improves aero dynamics....

well it may lower drag in a straight headwind but that is not the same thing as 'improved aerodynamics'. Often there is no free lunch; the benefit may only be appreciable if the tyre is fat and/or heavily treaded, the mudguard is an unreasonably close fit to the tyre, and it may come with various unwanted effects such as worse drag and/or stability in crosswinds.

Note that 'dustbin fairings' on racing motorcycles were banned because they had some unintended downsides that caused some nasty accidents.

In general the answer to the question 'are you slower with mudguards?' is simple; 'yes'.

cheers

Brucey wrote:In general the answer to the question 'are you slower with mudguards?' is simple; 'yes'.

Unless you don't ride if it's wet, or value comfort when the road is wet.

I still wonder about making full front wheel fairings for the trike, with 'splitters' inboard (to keep inward spray to a minimum, nowt to do with aero)
I do know that there is little chance of me ever doing it though

I have them fitted but am thinking of taking the front one off, however the rear stays, got fed up with my back getting wet from the spray.

Rusty Rider wrote:I have them fitted but am thinking of taking the front one off, however the rear stays, got fed up with my back getting wet from the spray.

Do you like wet feet, then?

ANTONISH wrote:Interesting that Jan Heine finds that a portion of front mudguard in front of the brake improves aero dynamics and that it may yet make an appearance in the Tour de France.
It made an appearance in the 1930's on the bicycles of Gino Bartali and some others.
I'm not sure of the purpose but it probably wasn't the outcome of wind tunnel tests.

If a front mudguard doesn't reach a few inches ("few" depending on clearance) forward of the top of the tyre, wheel spray is on an upwards trajectory as it leaves the tyre and may blow back into your face.
Back in the 30's there were a lot more gravel roads, and the water in the face would have been muddier than is usual today.

Just a possibility.

Rusty Rider wrote:I have them fitted but am thinking of taking the front one off, however the rear stays, got fed up with my back getting wet from the spray.

Frame tubes aren't fat enough to stop all spray so your chest will get wet, to a degree that depends on how straight you ride, and your legs from what splashes off the down tube. Your transmission will also get mucky.
A crudcatcher type downtube mudguard will likely be even less aerodynamic than a regular mudguard.

I told you my chrome fin mudguard extending in front of the brakes was aero!

Interesting views no doubt, personally for winter use de facto guards, summer.. rarely.. might use a clip on splash if its wet roads on a longish run.. never felt the effects of guards slowing me down in winter, more usually the brisk or strong north, east, or west wind is the culprit turning a nice sunday 30 miler in feeling as if you have done 60..as for mudguard noise Mike, they ain't fitted right.. mine are silent and my cycle buds also.. it takes more than an hour or more to get them correct... as someone on here claimed a while back he could do it in 15/20 mins.. ballix.. they wouldn't do for me.. will