Mudguards broken

[silva]

A solution I found as working for vibration-caused damage is to put rubber or any energy absorbing (by deformation) material inbetween the mounts.
Aluminium rivets are crap in this application - the plastic from the mudguard frets them out from the inside, gradually causing more wiggling room, and exponential because the distance (amplitude) of the vibration increases and this in turn increases the fretting.
I solved this a couple times along a steel bolt+nut+2 big washers to spread out the pressure over the plastic + 2 old innertube rubber cuts sized to the washers with a hole for the bolt in them. The steel of the bolt is more resistent to the plastic of the mudguard, and the rubber avoids the need for a high torqued bolt that may crack the plastic despite the washers. Small diameter bolt - big washer combinations on themselves doesn't suffice since the washers then are thin and deform themselves, voiding the purpose of a washer. The rubber brings grip / movement resistence, and absorbs (part of) vibration energy.

btw, today I saw a left behind inner tyre along the road. I made a U-turn to pick it up. Inner tyre rubber has a thousand applications in the nonprofessional (read: cheap) part of the human world. I use it everywhere. Even my big backpack/frame has some rubber cut washers at the shoulder straps because I discovered the steel bolt heads that fix the straps to the frame were fretting out the top of the aluminium frame tube. I put 3 rubber washers inbetween both mounts and no more fretting out since.

 

[Ming the Merciless]

Cable ties and duct tape are a permanent fix in my book. At least until they fail again in such a way that they just can't be bodged any more.

Agree

 

[SkipdiverJohn]

3M duct tape 2" wide x 50 mtr currently on offer in Lidl for £2.49 a roll, silver grey or black. I came out with two more rolls the other day and I only went in there for some pizza slices!

 

[Ajax Bay]

the bracket holding my rear mudguard had snapped,

This bracket will succumb to metal fatique eventually. Always carry a cable tie for such (and other) purpose.

45mm and wider guards are much stiffer and last much longer.

Maybe. My 35mm one (SKS Chromoplastic, rear) has split half way across where the seatstay bridge bracket will have provided a stress riser - duct tape and turning round the bracket to support the break has lasted 4000+km with no rise in noise and no loss of efficacy.
Bear in mind, for normal (ie rim brake) wheels, 35mm is the maximum mudguard width road calipers can take 'between' the two legs of the caliper (clearances vary as the brake blocks wear down).
PS ETA: These mudguards have done more than 25,000km, and showing signs of wear from crashes and general use - I am retiring them, and I have their replacements (SKS Bluemels 35mm) ready to fit.

 

[Threevok]

It may be a bit late to mention it, but has anyone considered making their own brackets from Thermoplastic ?

I've used it on and off the bike for a variety of (non-heat critical) applications, where fettling of old brackets etc just doesn't cut it

 

[Ajax Bay]

The final fitting action for a mudguard chainstay bracket is to squeeze the (normally) 4 legs tight against the mudguard sides (with pliers). How would this work with a thermoplastic bracket?

 

[Threevok]

The final fitting action for a mudguard chainstay bracket is to squeeze the (normally) 4 legs tight against the mudguard sides (with pliers). How would this work with a thermoplastic bracket?

To be fitted in the same way, I would assume with your fingers, while the plastic was still hot an manageable. Although, if the mudguard itself is plastic then (providing the surfaces are clean) it will stick anyway.

However, the reason I mentioned using thermoplastic, is that you can come up with your own custom alternative to the existing fastenings, rather than emulate them

 

[Tom B]

What guards are they? I have some Sks spare fittings kicking about and I think you can buy spare fittings for Sks.

 

[Richard A Thackeray]

- cable ties tend to be made from some plastics that becomes brittle and breaks, I started to use nylon/polyester ropes and just tie it with knots, and before make a few loops around anything to facilitate a tight knot.

On an old work/winter bike, after the rear-most stay mount rusted apart, I used the green 'garden twine' (maybe 1996?)
It was still there, when I passed the bike on to @Milzy ealier this year

- if you drill holes in a mudguard, round off or better - melt (soldering iron) the edges of the hole or they may wear through the ties or ropes.
- take into account that anything harder can fret out aluminium, so keep some distance, or put some buffering material (alike inner tube rubber) inbetween, as a wrap. Bonus is it will absorb vibrations (and avoid consequential noises)

I wish I'd spent some time cleaning the 'guard properly, & siliconing the joint/holes, as road-grit works its way through & runs down the 'guard

- duct tape, and any tape, is crap when you have to dismount something, the ugly glue remainders are hard to remove and solvents may damage frame paint. Inner tube rubber is very elastic and thus easy to make a tight knot in it.
Of course it may not look cool...

I used an off-cut from an old bottle at first, but it moved, so cut up an old inner-tube

 

[Milzy]

I can’t get over that twine was so old. It looked like it had been fastened on yesterday.

 

[silva]

Silicone requires thorough pre-cleaning and careful appliance (no mess - rubbed out to thin ends) in order to make it lasting in bicycle circumstances.
I cut out rounds from rubber, doublefold them, cut out a boltsized half circle or any other (ex tie wrap) half form from the doublefolded, open them again, result is some rubber washers. Those I put inbetween. It absorbs vibrations and it blocks road grit / anything from getting through. Another benefit is that if the mount gets a bump / hit, the rubber allows some movement and any movement absorbs energy so may avoid a crack.
I did the same for that on-top-of-rear rack basket (in meantime I mounted a bigger one) from my avatar bike picture. Not any tight/short connection. It's mounted with ropes and leather or 100% polyurethane (avoid any other pu % - it's peeling off crap / dirt sticking around) belts. If it bounces against something / receives a hit, it all allows some movement and the damage (in the sense of breakages) is minimal and easy/cheap repair. Drawback is that the wiggle room may allow heavier luggage to move abit. But this can be compensated for by using more of the elastic ties, and the extra also serve as backup in case of some breaking.
No scraping off silicone/glue whatever.

Some prevention also avoids work, I have had (quite expensive) mudguards that didn't need any mounting except for a folding of some lips around the fenders. This is made possible by within the rubber present thin steel strips. But the (used kind of) rubber is locally stretched apparently beyond its longer term holding capacity / elasticity: it quickly shows lots of cracks and through these cracks water reaches the thin steel strips, that are ALSO stretched and probably developed some micro cracks, so even more prone to oxidation (the water passes eventual zinc plating).
On top of that, producers chosed to make some holes in the rubber, precisely on those weak locations. Alike they don't want the mudguards to have a long life (hurah sales figures). Can't find any other reason for those holes.
Result is that the mudguards disattach to end somewhere along the road, depending on weather conditions just some months later. The best mudguards (and alot in life) are those you make yourself, preferrably with waste (read: cheap) as source material.

All details and its just mudguards but ohwell, it makes life easier if you don't have to waste time and bucks / mess around instead of doing/spending what you wanted to do/spend.