Posted by: audaxing | June 19, 2010

The Bikes Weakest Part

Last weekend I was doing a test ride of my 400km audax event, the Avalon Sunrise. It runs for the first time next weekend
The ride went fine, it seems a great route to ride during the night and the way the dawn breaks is excellent.

However, there is inevitably some poor roads and unexpected hazards, such as the rough B road between Hinton Charterhouse and Midford on the way to Bath.

The road itself is very rough which is a pity as it makes the splendid downhill slightly less enjoyable
As the road is making whatever vehicle you are using buzz quite well. It is understandable that the lines across the road to alert traffic to the approaching 30mph limit have to be quite pronounced to make a “bump” to wake up drivers
On a bike at high speed they are a bit nasty! I couldn’t jump over all of them as they were in groups of three, although I did try.

Shortly after my bikes rear wheel started making an odd noise. Yes, it was the mudguard rubbing. AGAIN

On almost every long audax ride I do, regardless of the care and attention I lavish on them, the mudguards play me up. They do not usually fail completely. Normally the fault is a tiny loosening and misalignment. But this leads to rubbing against the wheel. The rubbing is annoying, wastes pedal power and could possibly damage the tyres. It is mostly annoying however.

I usually try and ignore the problem and press on. However, on long rides little annoyances can drive you crazy. So on this ride, as usual, I had to stop and try and fix it. There were three stops. First time I didn’t notice that the retaining bolts were loose but realigned the guards. Second time one retaining bolt had fallen off. I used a rubber band as a temporary fix. Third time I attempted to replace the rubber band with a bolt and some washers. I found this wasn’t going to work with the spares I had with me and then swapped back to the rubber band again. I estimate these stops cost me approximately 20 minutes

So why are mudguards so prone to failure like this? It strikes me that they are designed to be firstly light, secondly flexible and thirdly cheap.

They are lightweight because road cyclists like stuff that is light over stuff that is built to last
They are flexible because there is a slight variation between bikes and the materials used have to be able to fit in with the differing mounting points and tyre sizes.
They are cheap because there is apparently a limited market for high end mudguards. Expensive high end bikes simply do not have them

The lightness and flexibility conspire on the road. If the bike runs over rough road then the rattling will often work something loose. If the bike is leaned against a fence and the mudguards catch on something then they can easily be bent out of shape. The part of the mudguard that actually protects the rest of the bike from the tyre is often made from a light plastic material. This light plastic material can be brittle under some circumstances and show a clean break.

So what am I going to do about this? Some people favour attaching their mudguards using only cable ties. They do not undo and fall off like nuts and bolts. I do use these for some of the attachments on some of my bikes. It is true that they have some kind of advantage over nuts and bolts. But I have seen even a double cable tie break and the attached mudguard being left free to flap and annoy!

The mitigation plan I have in mind is two pronged

Firstly, obtain some of the worlds only “high quality” mudguards. Most mudguards are made from plastics with steel stays and bridge. The SKS mudguards are considered to be the best of this sort. The SKS mudguards have stainless steel fittings and the plastic is mouldable with heat but not simply with bending.
I already use these. However, as noted above, plastic is light but not absolutely ideal.
There are a few mudguards made from aluminum. This does seem better but aluminum is quite a soft metal and prone to bending.

So I have found a source for some French mudguards which are made from stainless steel. The maker is Gilles Berthoud. These are possibly the strongest guards available.

Giles Berthoud Stainless Steel Mudguards

The second part of the plan is something I should have done before the 400km ride mentioned above. I will use a Loctite thread locking product. If you haven’t come across this before, here is an excerpt from the Loctite 222 datasheet:

LOCTITE® 222 is designed for the locking and sealing of
threaded fasteners which require easy disassembly with
standard hand tools. The product cures when confined in the
absence of air between close fitting metal surfaces and
prevents loosening and leakage from shock and vibration

It’s special glue for nuts and bolts. I aim to use this on all fastenings.

Yes, buying new mudguards and using exotic engineering substances on them may seem like an overreaction.
But I have had enough of mudguard failure and I need to fight back, stop it happening again


  1. still love my Salmon Super Profil aluminium guards, and replaced the one when it broke due to a severe stone jam-age. I seem to never have to adjust/align them, the fixings are superb.

    your father in law would have explained loctite threadlok to you years ago should you have asked – he was using it in motorbike engine building when he was knee high to a grasshopper! 😉

  2. I think that it was for reasons like these that the French “Constructeur” bicycles had mounting points for the racks on the mudguards. In fact, they were all designed as an inter-connected design rather than just lots of bolt-on bits.

  3. I have Berthoud stainless steel fenders on my bike and I love them. The sturdiness and good coverage more than compensate for the slight additional weight. (Mutatis mutandis, that’s why I use a Brooks Flyer sprung saddle too.)

  4. […] The Crud mudguards are supplied as a kit of front and rear guards with fittings. The front and the rear mud guard are in 4 pieces each. The two largest parts join together underneath the brakes. Then they are attached to each other with a bolt. The guard is then attached to the brake bolt with a cable tie. I am not the most mechanically adept person and it is probably a good job I’ve spent many hours fixing mudguards. […]

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