KB12

Hey, so Im converting my fixed Trek 330 back to its original state. I have most of the original parts except the freewheel and rear wheel. I found a Suntour alpha freewheel (6 speed) that appears to be like the one that was originally on the bike. If I find an old 6 speed wheel can I take the freewheel off and put my new freewheel on it? If I buy a 7 speed wheel would it work with the 6 speed freewheel? Also my derailleur is indexed so would I need a special chain? Thanks for any help you can give

EatMyA**

your shifters are indexed.

If you switch to friction shifters such as bar-end/barcon shifters you wont have a problem.

if your shifters are 7 speed shifters you will need a 7 speed freewheel for the shifting to work.

KB12

my shifters are 6 speed

Bill Kapaun

Another caveat is the ols SunTour freewheels had an odd cog spacing, compared to Shimano.
Read the part about
Mixed Sun Tour/Shimano Indexing


https://sheldonbrown.com/harris/freewheels.html

HillRider

Both standard 6-speed (not "Ultra") and 7-speed freewheel hubs are 126 mm OLD so they can be used interchangably.
As noted, the indexing for Shimano and Sun Tour were different so you should match the brand of 6-speed freewheel with your shifters if you want to maintain proper indexing.

KB12

This would work as an indexed freewheel right?

https://cgi.ebay.com/Suntour-Alpha-AP...d=p3286.c0.m14

DannoXYZ 

Sure, but only with Suntour shifters and derailleurs. Even then, they still have to be from the same generation. Suntour's 6-spd freewheels changed cog-spacing throughout the years.