Dia Comp Downtube Ratchet Shifters

[Big Paulie]

I just installed a set of downtube ratchet shifters on my San Marcos.

[Big Paulie]

Sorry, my above post was published before it was completed...

The crank gear level seems to slip "downward" into the smaller rings
as I ride.

Thoughts?

[William]

Your left side shifter doesn't have quite enough friction to hold the front derailleur in position so it gradually slips down to a smaller ring.  

What I've noticed with those shifters is the bolt is a little long, and it prone to bottom out in the hole that it threads into before really tightening the shifter mechanism.  I take care of that with an additional thin washer, like the one that came with your shifter.  Another way is to file down the bolt a mm or so.  Or just use a shorter allen head bolt first and convince yourself that is the problem.

Let me know if that doesn't make sense

[Big Paulie]

Thanks William, makes sense... :)

[Matt Beebe]

I had the same issue with silver shifters, and ended up shortening the bolts by about 2 threads with a hacksaw and a file, which fixed the problem.