Mudguard Safety

[Ubert767]

I have recently replaced Panaracer TG 1.75" tyres with Mondial 2.0" tyres on my MK1 Raven Nomad and this results in reduced clearances between tyres and SKS mudguards.
Is it recommended to fit SKS security fixings to the front mudguard stays (http://www.sjscycles.co.uk/sks-secu-clips-for-front-mudguard-stays-per-pair-prod666/π) or is it thought that there is little risk, in the event of wheel lock-up due to debris, because the mudguard anchor point on the front forks is above the axle?
 Thanks.

[Andre Jute]

404 -- link not working on my iPad.

I use Securiclips with P65s and Big Apples fitted very closely together. No problems in seven years. Necessary? Who knows? Depends on where you ride. It's an extra layer of peace of mind.

[David Simpson]

Here is the correct link:
http://www.sjscycles.co.uk/sks-secu-clips-for-front-mudguard-stays-per-pair-prod666/

- DaveS

[Ubert767]

Apologies for link error and thanks so far.

Rob

[Danneaux]

Hi Rob!

For more urban and on-road use, I prefer no less than 5mm between tire and mudguard, and take care to add a little extra clearance at the lower end and also make sure my stays are attached higher up the fork.

For touring in autumn leaves, on gravel, rough roads, and general expedition touring, I prefer no less than 10-12mm clearance between the tire and mudguard.

I've attached three photos below, showing what happens to the mudguard stays when leaves or other debris jam between the tire and mudguard.  If the stays are attached to the dropout near the axle, the radius of the stays is less than the tire, and so the mudguard will be drawn onto the tire, jamming it and causing the front wheel to lock.

If the stays are attached midway up the fork -- mine shown here are attached to my lowrider bosses, rather than the dropout eyelets -- the 'guards will be lifted away from the tire, reducing the chance of a jam-induced wheel lockup.

Because of the geometry of the higher attachment point, I have not felt the need for releasable SecuClips on my bikes with 'guard stays using higher anchor points. Of course, Thorn bikes are configured with mudguard stay anchors well up the fork for this very reason.

Best,

Dan.

[Andre Jute]

Thanks, Dave. No problem, Rob. Very clever, Dan; you clearly paid attention in geometry class.

[Ubert767]

Many thanks for your explanation Dan, truly an example of "a picture equalling a thousand words".
Thanks to Andre also, I'm all for "peace of mind".
Grateful to all.
Rob

[mickeg]

Dan, it never occurred to me to mount the fender stays on the rack mounts like that.  Good idea, thanks for posting.

Many front fenders have gone from a stay system where there are two attachment points on the fender to only one on each side.  I have no examples of crashes to cite, but just looking at them and thinking about how they might deform if an obstruction got in there, I think the two stay system is inherently safer than one set of stays if using plastic (flexible) fenders.  Thus, when shopping for fenders I have never bought the single stay versions.

On the clearance between tire and fender, if using a knobby tire that could grip an obstruction better than a smoother tread, I use as much clearance as my fork crown will allow except on my Nomad where it would allow a lot more clearance than I think is needed.  In the first photo, you can see a bit of gap between my knobby tire and fender, this is the largest tire I ever run on this bike when using fenders.  In the second photo, you can see I have a small spacer between fork crown and fender, but it is pretty small.  The same tires are used in both photos.

[Danneaux]

...when shopping for fenders I have never bought the single stay versions.

<nods> I had much the same view, but found with a mid-mount, single-stay mudguards/fenders can work well, thanks to the stiffer bracing of a shorter stay (moment arm). Much depends on where the stay bridges are attached to the mudguards, and how rigid the fender blade is.

For example, the PlanetBike fenders on my unnamed, 32 year-old gravel grinder-in-the-making have but a single stay, yet are as rigid as the dual-stay (ESGE, pre-SKS) Chromoplast models shown earlier -- all due to the shorter stays. Same model, same mid-fork mounts, placed not far from where Thorn places their stay-mounting bosses.

I don't like the aesthetics as well as stays connected near the dropout, but the practical, structural, and safety benefits of an anchor well up the fork trump appearance for me -- except on my Rene Herse replica, which "has" to look "right".  Sloping top tubes were a stretch for my aesthetic senses also, but those seem to go well with midfork stay mounts, so all is good. The overall look has now grown on my and looks "normal" with greater exposure.

Thorn have carried many of the benefits from the fork to the rear fender by mounting much shorter stays to the rear rack, either on tabs (Thorn Expedition rack) or via P-clips (Tubus Airy). The result is much quieter mudguards that stay nicely in place. Just one more of the many well-thought and executed details that make Thorn a "complete solution" in my mind. I am thinking if trying a similar setup on a problematic installation where rear mudguard stays in a conventional location would interfere with the lower pannier retention fins. Unfortunately, the stays on those mudguards are "doubled" on a single mount, so it will require some thought before plunging ahead.

Best,

Dan.

[il padrone]

Fender stays on the Thorn Nomad Mk II are already a few inches up the fork blades. Enough to give clearance if the mudguards get blocked up.

[John Saxby]

My Raven has 26 x 1.6 Supremes, and VO 650B alloy mudguards.  The front fender stay (ooops--mixing my regional vocab there) is no more-or-less parallel to the ground.  For the first 18 months of its life, it angled up to the mid-fork threaded boss at about 45 degrees -- at that time, the stay was mounted very low on the mudguard.  I preferred the stay closer to the horizontal, so cut 10 cms off the bottom of the mudguard, and redrilled the alloy to remount the stay.

The protection against crud offered by the front mudguard and mudflap seems unchanged.

I confess I didn't consider possible safety implications. (Fortune favours the clueless, perhaps?)

There's a good amount of vertical clearance both fore and aft, as you can see, and I've never had much stuff get stuck in either wheel, except for occasional big dry leaves. 

[Danneaux]

Unless there is some distortion caused by perspective, I think you'll be fine with your fender (mudguard) stay in the position shown in the photo, John.

All the best,

Dan.