Bottle Cage insert, thread size?

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Anton de Lacey</i>

If you mean the mount inserts which take an M5 bolt then you will need a 4.20tap.
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This is not so. The thread will be either M4 or M5, not sure which without checking, (I think most are M5, but I sem to recall my Colnago C40 was M4). I digress.

So you need either an M4 or an M5 tap.

The 4.2 you mention referrs to the size hole you need to drill before you tap it M5. i.e. you drill with a 4.2mm dia drill bit. The equivalent core size for an M4 hole is 3.3mm, so you use a 3.3mm dia drill.

I've been Thamed !!

I've re-cut a few bottle cage bosses that were corroded or painted. Some are M4, some M5.

Try your M4 tap and then see how well an M4 bolt fits. If it won't screw in nicely (flops about), it's probably an M5 boss, so try your M5 tap. If the M5 tap binds, drill through with a 4.2mm drill and then run the M5 tap through. You <i>will</i> now have an M5 boss!

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