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I have a number of mount holes and bottle cage holes that I am not using. Overtime the hardware has fallen out and I would like to replace it. However, I can find any replacement hardware at shops online. Does anyone know of a good shop for this and what sizes I need?

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    Replace what hardware? Bottle cages are fairly generic. And screw holes are screw holes. Any hardware store will be able to supply screws that fit the holes. (Just be sure the screws you get are metric.) Oct 13 at 23:58
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    Just go to a LBS Oct 14 at 1:14
  • Most bottle cages are usually sold with the required screws.
    – Carel
    Oct 14 at 8:48
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As with most things in cycling, its probably a metric M5 x 0.8 bolt in the bottle cage mounts. There's a small chance its a M4 x 0.7 if its a fancy race bike, or an imperial thread if it is older than the 80's

Coincidentally this M5 thread is the same as a cleat bolt on most clipless shoes.


Your other mount holes are probably the same M5, though some manufacturers may use M6 for a rack/carrier mountpoint for the extra load/forces.

A M4 or even a M3 could be used on a mudguard/fender mount because they need a smaller hole and carry less weight.

Light mounts haven't been a thing for decades, so it could be anything.


Any hardware shop will have metric bolts these days. You don't want them too long if you're just blanking off a hole. Best thing to get is one of those plastic box assortments of 300 pieces, so you have plenty of spares.

Downside, they're not generally that strong, so I might buy some high-tensile bolts if fitting a rack to a bike.

They will be made of steel too, so if your bike is aluminium then get some copper assembly lube/clay. Otherwise you can use normal grease on the threads, and either way wipe off the excess.

Remember to clean and dry the hole before sealing them up.

Lastly, you might go for hot glue instead of bolts. Sitting flush in the hole hot-melt glue will be more aero and less noticeable. I've got some sticks of black hot-glue for this, have not yet had a need for them though.

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    The advantage of having a bike shop sell you the bolts is that they should sell you ones appropriate to the task. As Criggie suggests, bolts for things like racks and (especially) brakes will have different strength requirements, so a (weaker) stainless steel bolt might be fine for bottle cages and conveniently corrosion-resistant, but not strong enough for other components.
    – Armand
    Oct 14 at 2:23
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    Plastic/nylon bolts are often used for plugging attachment holes in frame tubes or forks that don't carry loads. It avoids water or dirt ingress.
    – Carel
    Oct 15 at 7:39
  • @carel excellent point. Even a patch of duct tape would keep dirt out, and comes in different colours too.
    – Criggie
    Oct 15 at 9:37

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