Thorn Audax. SKS mudguards and Ambrosio fork

[Philb]

Hi All. When I brought my Audax Mk 3, I modified my SKS p35 muduard to suit the original fork by drilling out the front eyelet to put a bolt through. I've since changed my fork to the Ambrosio carbon and brought some new SKS guards with the front brake eyelet intact.

I'm finding this new mudguard nearly impossible to attach to the bike. The eyelet on the new front muguard seems to be thicker steel that I remember the older one being. I'm using Shimano R650 .

Has anyone else had this problem?

[Danneaux]

Has anyone else had this problem?

Yes, I have, Phil. SKS did "uprate" their brackets on some models. I really think they changed all of them, and whichever we see or get just happen to reflect old or new stock.

I believe what you need to solve the problem is a pair of "Sheldon Nuts", brought to market at Sheldon Brown's urging (they were being cobbled-together by individuals and LBSs here some time before this version hit the marketplace via ProblemSolvers). Basically, they're an extended nut for a recessed front brake, and will allow use of a standard allen bolt to mount the fenders through the eyelet, thin or thick. I have a link to them at SJS Cycles for you here: http://www.sjscycles.co.uk/problem-solvers-sheldon-fender-nuts-per-pair-prod18687/

Photo of them in use, here: http://problemsolversbike.com/products/sheldon_fender_nuts/

Hope this helps.

All the best,

Dan.

[Philb]

Thanks Dan.
I thought I might need another part, just couldn't get the allen key nut to grip the bolt after trying for an hour.
Thanks aigain.
Phil

[Danneaux]

...just couldn't get the allen key nut to grip the bolt after trying for an hour.

Ohhhhh, boy, Phil. A whole hour! How frustrating! I've "been there" myself on similar projects and they just leave one drained and left with the feeling you'd like to beat something to oblivion. My own little version today involved trying to swap a hard drive in a laptop. The "sled" carriers were identical, but the forward part of one drive's blade connector array was .2mm too long to clear the laptop's connector. I swapped a half-dozen drive sleds, I removed the drive bay, I did everything but stand on my head. I finally got it in -- and without forcing it once! -- but man, did it ever put up a fight. When I finally got it in place, about all I could do was chuckle weakly and shake my head at the tight tolerances.

Sorry you had a similar fight with the SKS fender eyelet. The good news is, the Sheldon nuts will likely fix you up right. If you ever sell the bike or fork, keep them for another installation. They make removals and re-installations a breeze! Best of all, they're really secure and give a nice, solid grip on the male half of the brake bolt so you won't have to worry only a thread or two has caught.

All the best,

Dan.

[NZPeterG]

Only an Hour I have looked for hour's to find a bolt dropped into a Motorcycle motor  Yes some one dropped a bolt into a 1000cc Motorcycle motor  I had to remover the motor, about to pull motor apart 
Only to find it on the floor  Life

Pete...
 

[Philb]

It was a long hour!

[Andre Jute]

It was a long hour!

LOL! My wife has me so well trained that when she sees me crawling around on the floor, she immediately puts on her glasses and joins me, saying, "How big is it?"

[triaesthete]

Phil
I've done this.

Beware the problem solvers bolt as the pic Dan links to shows it on a steel fork and it appears to be seating on it's  upper shoulder on the outside of the fork crown (as is normal for steel crowns).

On the Ambrosio Momentum fork it needs to seat on the step at the bottom of the brake nut hole, the same as the original brake nut does. The shoulder should then clear the outer face of the crown as it is not flat and not meant for load bearing.

I think the 2010 onward  Momentum fork had a thicker crown in this area than it's predecessors. Thorn used to list an own brand  widget for Audax mk3 carbon fork/mudguard builds but the shoulder was too low for it to work properly on the 2010 fork. It is no longer on the website. I bought one and had to modify it a little by raising the shoulder: electric drill held in vice and judicious use of a file sufficed in the absence of a lathe.

Beware also that whatever nut you use has sufficient thread engagement with the brake centre stud. Shimano make normal nuts in two lengths to ensure this, The nut supplied with my R650 caliper was fine for the steel fork but would have been to short for the carbon one. Same applies to mudguard adaptor replacements. I think there are likely to be bending and fretting loads in this area so you can't bodge a solution.

If this makes your head hurt it is probably worth calling Thorn as they must have a solution for current carbon fork builds on the mark3.
Best wishes
Ian

[Danneaux]

Ian,

A really, really good addendum to my post and much appreciated by me, at least. Nice job! 

All the best,

Dan.

[Philb]

Thanks all for the advice. I've ordered a 22mm problem solver brake nut and I hope that fixes the problem. When I recive it I'll add to the post as other owners must have the same problem.

Cheers Phil

[NZPeterG]

All the best I hope it fixes your mounting.
I know it's some time's a big pain fixing the small thing's

Pete..
 

[Philb]

And expensive 16 AUD for that nut!

[Philb]

Just letting everyone know that the 22mm 'problem solver' extended brake bolt worked although it might be easier to get wet!

[Danneaux]

Terrific followup, Phil! Well done! Man...spendy little things, aren't they? Still, when only one solution presents itself -- and riding is held hostage -- well worth it in money and effort.

Glad this nut worked for you, and a worthwile caution for others with slightly different forks by Ian in there as well.

All the best,

Dan.