Dumb Rack Question

[Bill56]

Just bought a new Topeak Explorer Rack for my new-to-me LHT, first rear rack on this one. The bike is about 3 years old.

Issue is the bolts supplied by Topeak (which I believe are M5s) feel like they're stripping the threads in the rear eyelets. They're going on too tight.

I can't imagine one of the most popular racks in biking ships with bolts that don't fit one of the most popular touring bikes.

Did I just pick up some paint in the threads? Should I just force the fit? Could the eyelets and bolts be mismatched?

Thanks.

[DanE]

There is a good chance there is paint in the threads if there has never been anything installed on those eyelets before. I would run a tap through the threads before I just forced the bolt through.

[Bill56]

Thanks. What's a "tap"?

[DanE]

A tap is a tool used to cut threads into metal fittings. Most likely the threads in your eyelet are already in place but clogged with paint. By running the proper sized tap through the eyelet it will cut through and remove the paint and leave nice fresh threads ready to receive the bolt. You will need the proper sized M5 tap, perhaps a tap handle to hold the tap and to turn it, and some oil to lube it when you run it through. As usual, YouTube is your friend on doing household tasks: https://www.youtube.com/watch?v=KVnN4jiB7Gk

[Bill56]

Thank you. Sounds adventurous...

[DaveB]

There is a good chance there is paint in the threads if there has never been anything installed on those eyelets before. I would run a tap through the threads before I just forced the bolt through.

There more than a chance that there is paint in the eyelet holes, it's a near certainty.   I've built up two Surly frames and installed racks on both and both needed to have the eyelets cleaned of over spray before the bolts would thread in properly.   I didn't have a proper M5x.8 tap so I improvised by filing a couple of longitudinal grooves down a regular M5 bolt to act as flutes.

[paddleboy17]

You might check ans see if your bolts are too long.  The sensation that you describe matches what would happen if the bolt were hitting the far side of the tube before seating.

[CanvasAndSteel]

You might check ans see if your bolts are too long.  The sensation that you describe matches what would happen if the bolt were hitting the far side of the tube before seating.

This would not be the issue, as the OP is talking about eyelets in the dropouts (or maybe the little braze ons on the seat stays), not mounting holes in a tube.