Do mudguards need to be wider than tyres?

[Nick H.]

All the popular mudguards seem to wrap right around the tyres. http://road.cc/content/buyers-guide/216720-14-best-mudguards-any-type-bike-keep-dry-when-its-wet-guards-race-bikes But BITD lots of people used those flat, narrow steel Salmon mudguards which went just to the edge of the tyre and no further. In fact I can remember seeing some which were narrower than the tyres...tho that might have just been an optical illusion.



Were the Salmons OK for keeping off the rain? Most of the water gets flung off the centre of the tyre...how wet do you get if the mudguard doesn't go to the edge of the tyres?

Carbon fibre Gilles Berthoud mudguards were also v narrow. They're not made any more, and the current GB steel mudguards are much wider.

With all the current emphasis on aerodynamics it seems that unnecessarily wide mudguards are behind the times.

[Torslanda]

Aero or wet arse.

Pick one.

[Brucey]

IME whether crud comes off the wider parts of the tyres depends on how lumpy they are, i.e. smooth tyres throw less crud at the edges. Also whether the contact patch extends near the edge of the tyre makes a difference too, because that part of the tyre may not get dirty/wet.

Regarding aero drag, there is a school of thought that says that if the mudguard is tight-fitting the drag is minimised. However this also makes rubs (annoying) and snarl-ups (v dangerous) more likely too.

cheers

[bobb]

The Salmon style guards were always a compromise designed to fit frames that had very little clearance - something manufacturers are fortunately less obsessed about these days. Those guards would still throw a whole bunch of shit sideways all over your irrate clubmates on a winter ride.

Certainly, nobody has invented the perfect mudguard yet, but worrying about being aero is way down the list of improvements. About 99% of cyclists never go fast enough to even start considering what benefits they might get from a slightly different mudguard....

[hubner]

I reckon the mudflap is the main cause of additional drag.

[Duckfoot1606]

A bit like cars with wheels and tyres that are too big/small for the available space looking bit odd, I think the same applies to bikes to - there’s a “right” combination of mudguard and tyre size, with the former wider than the latter. In the eye of the beholder, of course.

Given my general state of decrepitude these days, dry feet/backside trumps a style (aero) statement any day of the week 😀

A

[Nick H.]

I want to make some. I'm thinking 1mm foamed PVC, maybe with spokes as stays.

[Brucey]

14g spokes are about 2/3rds the thickness of typical mudguard stays (2mm vs 3.2mm) and this makes them a small fraction of the bending  stiffness (which goes with the cube of diameter IIRC). Plus the stays have to be longer than typical spokes are.

I made a set of mudguard stays with 3/32" diameter (because I had a reel of the correct wire) and they are noticeably flappier than any other set of mudguards I have used.

FWIW a while back I found myself eyeing up some PVC cable trunking (about 25mm wide) and concluding that the 'lid'  might make a plastic version of a salmon type mudguard.



Note that the grooves in the section might

a) prevent the worst side-spray and/or
b) make a handy place to stash a dynamo wire or a stiffener of some kind.

Now, PVC doesn't weather that well and you might need to stiffen it with something along the back.  However provided you can deal with these things the scheme does have one major attraction; cost.  A 2m length of trunking costs peanuts (slightly over £2 in screwfix for example) and would be enough for a pair of DIY mudguards. In the event of a prang, another £2 will furnish you with the material for a repair, provided the stays are still usable.

Genius or madness? I don't know yet because I have not put the plan into action....

cheers
 

[blackburnrod]

When I was an impoverished schoolboy in the 50s we made mudguards from a section of an old clincher tyre and the metalwork from defunct celluloid (Bluemels) guards.Cheap,robust and didn't rattle.

[Frank9755]

If you make some then bladed spokes would be much better for aerodynamics than round wire sections normally used.  But vibration would be very bad.

[Kim]

The best solutions to mudguard vibration appear to be small diameter wheels and, where possible, anchoring the rear mudguard to a luggage rack.

[Brucey]

FWIW I also found myself eyeing up  a knackered golf umbrella, with thoughts of mudguards in my mind. The reason? Said umbrella had ~3.5mm dia carbon fibre struts in it, holding the canopy up....

 These could make excellent mudguard stays, (and there were about a dozen of them, so enough for a full set plus spares in a single brolly) but as usual the devil is in the detail; how they are fixed at the ends would make all the difference. I don't think that eyebolts would be a good method BTW; I favour some thin-walled stainless tube bonded over the ends and clamping/welding them in some way.

cheers

[Nick H.]

I'm going to start with an attempt at stayless 'guards.  1mm foamed PVC is so light that it will be interesting to see what happens. It will probably be too floppy so the Mk 2 model would have a stiffener.

[andrew_s]

Salmon guards were OK if used with slick race tyres, but less good if there was much in the way of tread, which encouraged water to come off the tyre before reaching the centre.
Still not as good as proper full-size mudguards, of course.

I've seen a bit of PVC trunking cover strip used as a mudflap on a narrow mudguard with narrow tyres, but I'd expect it to be too stiff for an actual mudguard unless you can bend it to a suitable shape without introducing twist etc, probably using heat.

[nobby]

I'm going to start with an attempt at stayless 'guards.  1mm foamed PVC is so light that it will be interesting to see what happens. It will probably be too floppy so the Mk 2 model would have a stiffener.

Corex can be cut for mudguards. House sale signs provide enough.