Adding Pins to a non-pinned Chainring

Wasatch5k said:

Would it be possible to add your own pins to a cheap 8 speed chainring.
I was thinking of drilling some holes, tapping them and
semi-countersinking some screws (about 1mm sticking out) in the same
pattern as a Shimano chainring. I would not have the ramps and special
shaped teeth, but it still might help with the up shifts. Has it been
done? Will it work?

n

I have done this. I used 4, 3mm x 5mm long flat head hex screws (aka
Allen bolts) in roughly the same orientation as the Shimano pins. I
drilled and threaded the holes, then screwed the bolts in as tight as
possible. This left about 0.5mm exposed. I then cut off the excess
thread (opposite the bolt head) with a Dremel tool.

This was on a FSA 39 tooth chainring used as the middle ring on an
Ultegra triple. FSA sells a ring specifically for this purpose:
http://www.biketoolsetc.com/index.cgi?&d=single&&item_id=FS-RR39M
but, like a doofus, I ordered the double ring instead. My adapted ring
has worked fine for two years, though.

Jeff

On 19 Jul 2005 16:30:45 -0700, "Wasatch5k" <[email hidden]>

Quoted message said:

Would it be possible to add your own pins to a cheap 8 speed chainring.
I was thinking of drilling some holes, tapping them and
semi-countersinking some screws (about 1mm sticking out) in the same
pattern as a Shimano chainring. I would not have the ramps and special
shaped teeth, but it still might help with the up shifts. Has it been
done? Will it work?

Given how well the pseudopinned sprockets on the Walgoose work, I
think you have a good chance of success. Those Goose rings have pins
that are nothing more than formed pimple-shaped bumps; they look like
spots where a center punch was employed from the opposite side with
the material sitting over a drilling in the support surface that the
bump formed itself into. Your proposal should make a better "pin"
than that.

I say "Go for it!"
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Werehatrack said:

On 19 Jul 2005 16:30:45 -0700, "Wasatch5k" <[email hidden]>

Quoted message said:

Would it be possible to add your own pins to a cheap 8 speed chainring.
I was thinking of drilling some holes, tapping them and
semi-countersinking some screws (about 1mm sticking out) in the same
pattern as a Shimano chainring. I would not have the ramps and special
shaped teeth, but it still might help with the up shifts. Has it been
done? Will it work?

Given how well the pseudopinned sprockets on the Walgoose work, I
think you have a good chance of success. Those Goose rings have pins
that are nothing more than formed pimple-shaped bumps; they look like
spots where a center punch was employed from the opposite side with
the material sitting over a drilling in the support surface that the
bump formed itself into.

A production engineer would refer to such formations as
a "half shear". Makes sense, since the material is halfway to
being completely sheared - that is, punched completely out
of the sheet.

Quoted message said:

Your proposal should make a better "pin"
than that.

I say "Go for it!"