Here's a link to information on S-A triggers and toptube controls, includind instructions for modification for use with fixed hubs (it's a downloadable PDF file-about 2 minutes): http://www.users.globalnet.co.uk/~hadland/6triggers.pdf If that doesn't work, go to this link and scroll down to "triggers": http://www.users.globalnet.co.uk/~hadland/gill.html
Best regards,
Wes Gadd
Unionville,CT