I have fitted quite literally hundreds of mudguards during my time as a cyclist. That might sound like exaggeration, but I swear it’s true.
Some of that’s down to my own bikes – most of which have mudguards – but it’s largely thanks to my time spent preaching the good word of the mudguard evangelists while working as a mechanic in a perpetually damp Edinburgh bike shop.
Our poor customers left the shop having spoken to me, feeling mudguards weren’t optional – they were practically compulsory.
And with good reason – we all know mudguards keep you drier, protect your drivetrain and generally make riding in bad weather tolerable. I’m sure they thanked me when splish-splashing along a cobbled vennel.
But my commitment to the way of the fender is lifelong. My dad’s dad taught him that no meal is complete without chips – along with that nugget of culinary wisdom, my father passed on to me the equally valuable belief that no bike is complete without mudguards.
Over the years, I’ve learned what makes the difference between a noisy, half-baked setup and mudguards that disappear into the background – quietly doing their job, rattle-free, for years.
Here are my hard-earned tips for fitting mudguards properly, so you too can enjoy dry-bum bliss.
1. Be patient
Even the best-designed mudguards are fiddly to fit – don’t rush it. A slapdash job means wobbly stays, uneven tyre lines and countless rattles.
For alloy mudguards, especially, set aside a couple of hours the first time around. Once you’ve got the hang of it, or you’re refitting after summer, it’s much quicker – but patience is your friend here.
I advise changing your mindset before committing to the temple of dry bum. Treat the job as a pre-winter afternoon project, and indulge in the pleasure of a job well done.
2. Do your research
Patience must also be employed before you fit anything – mudguards aren’t one-size-fits-all.
To start, profiles vary. A round guard might hug a road tyre beautifully, but look awkward or rub on a gravel bike. Conversely, fenders with a flat profile often suit chunkier tyres better.
The shape also really matters. Round guards tend to channel water down and away, but in muddy conditions, they can clog more easily.
Equally, some mudguards will simply suit some bikes better than others.
We sold dozens of entry-level Trek Domane road bikes in the aforementioned bike shop. This was in the rim-brake era, and we found the slightly narrower, rounder profile of SKS guards suited the bike far better than Trek’s own-brand fenders.
On the other hand, a bike with flat seatstay and chainstay bridges might suit flat-profile mudguards and enable you to eke out a few extra millimetres of clearance.
Good mudguard manufacturers will provide detailed measurements that you can cross-reference with your bike. Consult these closely and don’t rush the buying decision. You might also find your local bike shop has advice for your specific bike.
3. Pick the right material
Mudguards broadly come in two flavours: alloy and plastic.
Each has pros and cons, and choosing the right one depends on how you’ll use your bike.
Alloy guards look fantastic, last for years and can be more easily repaired if damaged. They also tend to be available with higher-quality hardware and spares, which means you can keep them running almost indefinitely.
They aren’t always the best solution, however. If you park your bike in a crowded rack, an alloy guard will not appreciate being bent or squashed. Plastic guards, by contrast, will more easily shrug off knocks, flex rather than bend, and are generally easier to swap between bikes.
If you want longevity and don’t mind them being a little fussier, go alloy. If you’re rougher on your bike, or want something more forgiving, plastic might be the smarter choice.
4. Go as wide as possible
Your frameset will dictate the maximum size of mudguard you can fit, but my rule of thumb is simple: go as wide as you can.
Even if your tyres are narrower than the guard, a wider mudguard gives you more clearance for mud, a margin for error in setup and the freedom to fit bigger tyres later.
Done neatly, it rarely looks odd, and the pay-off in coverage and practicality is worth it.
There’s really no good case for going narrow, unless you’re utterly obsessed with the perfect fender line, but even that’s possible provided the difference between tyre and mudguard width isn’t cavernous.
5. Prep your threads
Mudguard eyelets live a hard life. They’re continually blasted by spray, salt and grit. If you don’t look after them, they’ll seize solid and turn removal into a nightmare.
Before fitting, chase the threads with a tap if you can. This ensures the bolts go in cleanly. Then, when you fit them, absolutely smother the threads in grease or antiseize.
Wipe away the excess once it’s tightened, and you’ll have peace of mind knowing the bolts won’t seize and the guards will still be removable come summer.
Prep is even more important when fitting guards to a bike with hidden eyelets.
Referring back to the Domane, Trek’s neat banjo-bolt style mudguard mounts made for clean lines in the summer, but the grub screws used to cap these eyelets seized with alarming ease.
In summary, ‘clean those threads and grease liberally’ is a good rule to live your life by.
High-quality fasteners are also essential. As with bottle-cage bolts, I recommend stainless steel cap head bolts with a good, deep 4mm socket for most applications.
I refer back to my previous point on being patient and encourage you not to skip this boring, five-minute step – it will save hours of swearing in the long run.
6. Kill the rattles
Mudguard rattles put off many from enjoying a life less soggy. Once they start, they’re all you’ll hear, and they make people conclude wrongly that mudguards are inherently awful.
The truth is, rattles almost always come down to setup. Stays too long? Bolts not tight enough? Clearances slightly off? Those are your usual culprits. Take the time to adjust and readjust until everything lines up neatly – again, patience.
If you’ve done all that and there’s still a buzz, damping contact points can work wonders.
I like to stick on a bit of thick, rubbery, transparent greenhouse repair tape where the mudguard touches the chainstays or fork crown. It’s a simple hack that silences most niggles and helps protect paint.
Small off-cuts of bar tape can also be used where there’s a larger gap to bridge. This is most useful to fill the gap between the mudguard and the underside of the fork bridge.
But don’t ignore persistent wobbles or clattering – that almost always means the fit isn’t right. Keep tweaking until they’re silent. A properly fitted set should be fit and forget.
7. Buy guards with spares available
Cheap guards are a false economy because once a stay bolt, flap or clip breaks, you’re usually out of luck. No spares, no fixing and straight to landfill they go – very depressing stuff.
Better brands, though, sell spares for everything – from bolts to stays to mudflaps. This means you can keep a single set of guards alive for years.
At the time of writing, I have a set of alloy guards that have survived eight years and three bikes of riding, simply because I could replace a stay or a bolt when needed.
If you want your guards to last longer than a season, choose a brand that makes spares readily available.
8. Don’t be afraid to modify
Sometimes, a mudguard will fit almost perfectly, but not quite – that’s where a little modification comes in.
Small tweaks – a wee cut here, a reprofile there – can make the difference between endless frustration and a neat, silent fit.
Common mods include trimming a slot to clear a front derailleur, gently reshaping a guard to clear tight chainstays and adding a supplementary stay to stiffen up a long front guard.
Manufacturers might officially discourage this, but if you do a neat job with the right tools, there’s rarely any downside. A rotary tool such as a Dremel, in particular, is worth its weight in gold for this sort of fettling if you need to make a neat cut.
9. Mud flaps are not a crime
Yes, they look dorky, but mud flaps are the quiet mark of a deeply committed winter rider likely to gather admiring nods from those in the know.
They extend the coverage of your mudguards, stop spray from soaking your shoes and prevent your riding chums from cursing your existence when they sit on your wheel in January. Some more traditional cycling clubs even insist on them, and with good reason.
You can buy aftermarket ones, or go classic and cut up a washing-up bottle. Either way, wear them with pride. They’re not dorky – they’re practical, effective and charming in an old-school way.
