
My relationship with mudguards is tumultuous, they have saved and ruined bike rides in equal measure.
The best mudguards/fenders for gravel bikes are well-fitted and sturdily made. They reduce wheel spray for you, as well as preventing grit (and worse) from getting into your eyes and mouth. Mudguards will also protect your back and feet from the worst of the wet and muddy stuff on a ride and extend the life of your kit by reducing contact with grit-degrading debris.
The flipside, however, couldn't be worse: mudguards that rub tyres no matter how much adjusting is done, create a front-wheel trip hazard when undertaking more technical sections, and actually damage paintwork or frame materials from abrasion friction.
Testing a pair of Zéfal Shield G50 gravel bike-specific mudguards on the Fara F/Gravel in mid-winter felt like a game of roulette on wheels.
Construction

Designed specifically for gravel bikes, the plastic (Technopolymer) front and rear Zéfal Shield G50 mudguards are, according to the brand, suitable for 650B/28"/700C tyres. To ensure the best fit for your size wheels, the guards have adjustable lengths, with three mud flaps of 20, 60 and 120 mm lengths to choose from.
Measuring 55mm wide, Zéfal say the Shield G50 mudguard is capable of providing coverage for tyre widths of up to 48mm, which will fit all bar the largest of gravel bike tyres.
Two robust stays secure each guard in place. These stays connect via adjustable herth joints to rubber pads, similar to old-fashioned brakes. They are fastened to the bike's rear seat stays and front forks using a silicone-coated hook-and-eye strap. According to Zéfal, these straps should fit tube diameters of 10 to 55 mm at the front (210 mm long) and 10 to 32 mm at the rear (130 mm long).
Compared to the slender stays on other clip-on brands, such as the SKS Speedrocker fenders these look positively industrial and would not be out of place on a suspension bridge.
This simplistic design does mean the guards are rather chunky in size, the front measuring 461 x 54 x 210 mm(L/W/H) and the rear 660 x 54 x 210 mm (L/W/H), with the 120mm mudflap on. The weight tips the scales at 195g for the front and rear 250g (with mud flap 120 mm).

Fitting
When it comes to fitting mudguards, I generally adopt an 'expect the worst and hope for the best' approach. So, I was pleasantly surprised to discover how easy it was to fit the Zéfal version. Using just a small cross-head screwdriver and a 5mm Allen key, the fitting took less than 30 minutes.
It would have taken 20 minutes had I been able to locate the tiny screwdriver required to change the adjustable flap size, please note - it's not part of an average bike tool kit set up.
The robust design means minimal twisting out of shape, making fitting on one side and then the other a breeze. My hesitations about pairing the pad shape with the tubing shapes on the Fara F/Gravel seemed unfounded. While not exactly glove-like, they felt very firm once secured with the straps.
Once that was done, the guards were angled and the herth joint tightened to secure them in place. Thanks to its gear-like construction, the joint stayed in place while I tightened it, making the Sheild G50's the quickest, easiest, and neatest mudguard fitting experience I've ever had.

The Ride
No matter how easy it is to fit a pair of mudguards, the real test is whether they stay put once on.
I was pleased not to hear any evident rattle of rub on the maiden voyage, but that was just a quick road loop to preempt the usual fender faff re-fit requirement of first rides.
So far, so good, but riding on relatively smooth road surfaces compared to the off-road terrain of UK-style gravel was going to be a big ask for any mudguard, especially a clip-on.
Next up, I started to venture onto more adventurous surfaces. On cinder trails and more benign off-road rides, they again proved rock solid.
The mudguards proved to do a great job at deflecting the muck and spray front and back, as well as a semi-decent job of protecting the bike, although if you really want full seat tube and drivetrain protection you'll need to look in the direction of something like the Portland Design Works Full Metal fenders.
Confidence growing, I braved a truly epic off-road adventure to really put the Shield G50's to the test on some more gnarly Peak District (UK) terrain, when my daughter and I decided to take on the well-known 'Pike'.
A mother and child on drop bar bikes hauling their way up an increasingly technical climb isn't something most hikers, bikers - and, in one instance, a farmer - witness too often. All had forewarned us about how challenging it was up ahead, and questioned if we really were on the proper bikes to tackle such terrain.
Undeterred we pressed on. While some of the more challenging sections saw us adopt a hike-a-bike approach, I was so surprised at how well and far I was able to get. The shorter style of mudguard at the front voided the risk of foot overlap, vital on these front wheel twitching sections.
On the faster sections, I wasn't even aware of their impeding progress, perhaps the fastest riders out there would perceive a slowing of speed due to their drag, but mudguards are designed for comfort. If going fast is always your aim, then you might find something like the Ass Savers' Mudder Mini fender is probably the best option for you.
The proverbial elephant in the room, however, is a mudguard spray etiquette for other riders. As with all clip-on guards, their short design will mean that a rider behind will likely be worse off for sitting on your wheel. But bear in mind these are specifically for gravel use, where wheel sucking is more the exception than the rule.
Value and Conclusion
I must admit, I initially judged the Zéfal Shield G50 mudguards by looks when they landed with me. They aren't the most alluring pair of guards on the market, but when have mudguards ever been particularly attractive? I'd personally forgo looks over ability and performance any day of the week.
The only thing that makes them ick for me is their impact on the rider behind, and I'd struggle to use them on a group ride. Other than that, they are top-notch.
Easy to fit, true staying power and doing an excellent job of rider protection for the reasonable price tag of £40/$59.00 for the set.