Show me your 700c wheeled, disc brake equipped, hub geared bikes with a rack.

If a rack bolt works loose your boned . Itll see high dynamic loading.

Id be looking towards that for issues ….. Or cheap stainless bolts supplied with most racks – the shiny silver ones !! I prefer nice hi tensile surface rusty bolts anyday.

Never had an issue with a single rack ever and as far as i know none of my customers did either Also try and stick a nyloc on the back if possible to prevent it coming loose but with modern deraileurs this isnt always possible.

Could be the bolts right enough.

The end is still stuck in my 29er frame 😀

I always use grade 8.8 for the bottom fixings with a bit of thread lock. That kills both potential problems at source. I have a Tortec Ultralite rack for my Day One, just haven’t fitted it yet as I’ve been using an old MTB to commute with and that’s already fully sorted.