Originally Posted by 79pmooney

Those are for recessed brakes. Narrow end is the recessed hut, Bigger end is threaded one size larger (and you may have to drill fenders, etc. for it). The large size is also milled for a 6mm allen wrench and goes on just like the regular recessed nut except that one size larger on the wrench. Pretty ingenious. I have them on two bikes.

Edit: if clearances are tight, you can run tiresavers backwards. IE front saver pointing back. (You'll have to re-bend the mount part but that isn't hard.) Drawback is that the saver will now scrape dust into hour headset. Either use lots of a marine grease on the lower bearing (so much it oozes out the first few rides) or cut an inner tube to about 3/4s of an inch and slide it over the headset (pulling the fork out). (Or use a mini fender except that won't work because of your clearance issues unless you are ready to jump though anther hoop, cut the mini fender and use a River City bracket.)