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TECH NEWS
whyte_glencoe_-_rear_mudguard.jpgMudguards are MORE aero: study shows that optimum drag reduction is achieved with mudguards on
Ever been reluctant to stick your mudguards on for the winter through fear of losing out on sweet aero gainz? Well according to a new study you can fear no more and keep them on year round, because the results shown that drag can actually decrease with mudguards on your bike.
16 of the best mudguards for any type of bike
It's long being thought that mudguards affect the aerodynamics of a bicycle in some way or another; and if you think about it, more coverage and a smooth surface over your tyre could in theory make for better aerodynamics. The study in the SAE Mobilus engineering journal - titled 'Effect of Fender Coverage Angle on the Aerodynamic Drag of a Bicycle' - explored the effects of various types of mudguards that provided wheel coverage from 60° through to 270°. Using a validated computational fluid dynamics (CFD) model in SolidWorks Flow Simulation, the model predicted that aerodynamic drag coefficient reduced with mudguard coverage angles of up to 135°, and started to increase thereafter.
An analysis of the effect was carried out at velocities of 6 metres per second (m/s), 8 m/s and 10 m/s, and the results were found to be similar to the CFD predictions, with the minimum aerodynamic drag coefficient at 135° occurring in all the cases. The researchers eventually concluded that there was indeed an observed optimum decrease in drag coefficient - the bike with mudguards had 4.6%, 4.5% and 4.6% less drag than the bike without mudguards at 6 m/s, 8 m/s and 10 m/s respectively.
We're not too sure what type of bike and what type of mudguards were being used in the study, but are currently doing some digging to get further info about the methods used. In the meantime, there are some mudguards already out there specifically designed to be more aero than without, such as the Null Winds Aerofender shown above - they even claim the fairing outperforms any aero wheelset in strong headwinds, and will net you an advantage of between 10-20% in headwinds compared to bare wheels.
Jack has been writing about cycling and multisport for over a decade, arriving at road.cc via 220 Triathlon Magazine in 2017. He worked across all areas of the website including tech, news and video, and also contributed to eBikeTips before being named Editor of road.cc in 2021 (much to his surprise). Jack has been hooked on cycling since his student days, and currently has a Trek 1.2 for winter riding, a beloved Bickerton folding bike for getting around town and an extra beloved custom Ridley Helium SLX for fantasising about going fast in his stable. Jack has never won a bike race, but does have a master's degree in print journalism and two Guinness World Records for pogo sticking (it's a long story).
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15 comments
Going to get some mudguards and smash those KOMs.
My personal study shows that mudguards are optimum for not having a stripe of sh*t up your arse and back.
Useful info. I've always wondered whether mudguards would be a little more aero than without due to the speed at the top of the wheel being twice that of the speed of the bike.
Presumably the top 135° is not enough to stop spray flicking up into people following? Leading edge aero cover is probably less important that trailing edge though. I believe reducing the trailing negative pressure void/wake and getting air to re-attach smoothly is the key. Maybe a Kammtail rear-edged spray catching is optimal?
For some time I've wondered whether mudguards in the pro peleton would reduce the number of respiratory problems riders suffer from.
I've never dared to express this publicly for fear of ridicule
Don't know about the link between mudguards and respiratory problems but, given the fact that you aren't going to get laid, you might suffer fewer sexually transmitted diseases.
Are you kidding? Mudguards are the definition of cool!
I've found that not spraying water into the face of the person behind me, or having water sprayed into my face by the person infront of me has a positive effect.
YMMV
Damn, another excuse gone...
As is often the case, the Jan Heine fellow (of Bicycle Quarterky magazine) made tha case for mudguards being more aerodynamic, some time ago. Here is his article, which contains a fair bit of info and discussion about it:
https://janheine.wordpress.com/2018/01/16/myth-3-fenders-slow-you-down/
He employs the word "fenders" but as he is a Yanker he must be forgiven for this poor English.
Cugel
Excellent. What with this news and the Lotus track bike, it looks like in a couple of years I might be able to pass my year round commuter off as a bang on trend aero model. "Yeah, the seatstays meet the top tube to help re-attach the airflow, and those Chromoplastics save me 10 watts".
That exposed wheels aren't particularly aerodynamic is old news for anyone outside the roadie crowd.
Most of mudguards people use are too short at the front of the fork and not very well fitted (big gaps) hence the anegdotes about mudguards being slower.
https://janheine.wordpress.com/2018/01/16/myth-3-fenders-slow-you-down/
There's a crucial sentence in the first para that doesn't make sense - is there a "with" missing from this?
Alway felt mudguards act like a sail catching a pocket of air, like opening your jacket it balloons open.
Anecdotal evidence from ME, says conventional mudguards slow you down a bit. Full coverage aero design probably do work, but we are not all trying for land speed records whilst commuting or winter riding-keeping water from wetting rider and keeping bike cleaner are the function of mudguards
This is my experience, when the rear mudguard eventually cracked and failed (SKS bluemels) mid-ride, I had to stop and remove the rear mudguard and the remaining journey being both ligher and more lively made me think hard about living without the mudguards, it didn't last long however since the next rainy day made me order a new pair of mudguards for next day delivery.