The bike I recently purchased was advertised as "full rack and fender braze on"....but there is only one mounting hole on the dropout. The bike I have is a disk brake model and required the "L" shaped mounting bracket. I was able to use a longer screw to mount both in the same hole, but am starting to see some bending of the bolts.

The only solution I can think of, and I haven't checked that I actually have clearance to be able to do, is to relocate the fender mount to the inside (rim side) of the frame with a nut to hold it onto a longer bolt.

I didn't know if there is some manufacturer out there making some novel solution to the issue?

If you can, mount the rack's leg to the inside (against the dropout face) of the fender strut. That puts less bending moment on the bolt from the rack's load.

Mount the rack first,up against the dropout/brazeon....Make the rack shear the bolt,not bend it.

If the bolt is bending, odds are that the rack supports were mounted outside the fender stays. The fender stays put almost no weight on the bolt but the rack supports put all the weight of the rack plus its load on the bolts. The closer the rack supports are to the bike frame the less the bolts will bend

I Have my rack attached to the Frame and the Mudguard struts attached to the rack .

If you bend bolts you chose too butter soft a steel Bolt. & ignored them getting loose.

fenders on the outside, and I like a leather washer between

1. It's not moment of inertia that matters here; it's shear strength.
2. Actually, shear strength doesn't matter very much either. The bolt supplies the normal force. The friction between the rack and frame is what holds most of the weight.
3. It's usually not possible to mount a rack on the inside of the dropout. The smallest cog on the cassette is in the way.

Put the fender strut on the outside of the rack, use washers, and tighten the bolt well.

You misinterpreted what I wrote. When I said put the rack inside against the dropout face, I meant inside the fender strut but on the outside face of the dropout. Of course you can't put the rack leg on the inside face of the dropout for just the reason you noted.

I think you all missed this in my OP:

"The bike I have is a disk brake model and required the "L" shaped mounting bracket. "

It is impossible to mount that bracket inside, or even the fender mounts as I thought might work. There is no room.


The bolts are not loose and they are made of the standard stainless/chrome/whatever that comes in the mounting kit with. I am not having a similar problem on the wife's bike, same rack (Topeak Explorer), same bolts, just no fenders.