SunTour to Shimano Upgrade

Quoted post said:

Originally posted by Ian Puleston
Hi,

I have a bike with a SunTour 6-speed gear system and I'm trying to work out mny best route to upgrade the gearing on it. I want to get to 7-speed or better with STI brake/shifters.

My girlfriend recently bought a used bike with SunTour 7-speed gears and she just had it upgraded. The guy who did it replaced the shifters with new Shimano 8-speed STIs and replaced the rear derailleur with a used Shimano 105, but didn't change the SunTour freewheel. I'm assuming this works because according to Sheldon's website Shimano 8-speed gears have 4.8mm spacing and SunTour 7-speeds have 4.8 or 5mm spacing, so if hers is the 4.8mm then it should be compatible with the Shimano 8-speed STI shifters - correct?

So, if I replace my SunTour 6-speed freewheel with a SunTour 7-speed one (the frame is wide enough to take it) then I should be able to do the same to upgrade my bike to Shimano 8-speed components with STI shifters. Any problems there?

My problem if I'm correct so far - I can get a Shimano 7-speed freewheel on eBay, but is there some way to tell if it is 4.8 or 5mm spacing other than trying to get the seller to measure it? Anyone know the standard spacing on a SunTour Winner-Pro 7-speed freewheel?

And one final question - if I go the other route and get a Shimano 7-speed freewheel, I believe that I can use any Shimano 7, 8 or 9 speed 105/Ultegra derailleur with it, but the shifters will need to be Shimano 7-speed, and 8-speed will not work. Correct?

Thanks,
Ian

Shimano 7 speed index is 5.0mm and 8 speed is 4.8mm. Close enough that 8 speed shimano shifters and correct RD usually work with an index capable 7 speed freewheel. There was no 4.8mm spaced 7 speed shimano frewheel. Pre 9 speed DA shifters and RDs have to be used together, otherwise any other shimano SIS RD will work with any other shimano shifter. Campy 8 speed cog spacing was also 5.omm but you have to use a campy RD with them.

Quoted post said:

Originally posted by boudreaux
Shimano 7 speed index is 5.0mm and 8 speed is 4.8mm. Close enough that 8 speed shimano shifters and correct RD usually work with an index capable 7 speed freewheel. There was no 4.8mm spaced 7 speed shimano frewheel. Pre 9 speed DA shifters and RDs have to be used together, otherwise any other shimano SIS RD will work with any other shimano shifter. Campy 8 speed cog spacing was also 5.omm but you have to use a campy RD with them.

Umm, as usual, I impressed with any post you make, boudreaux. But, tell me, how or why on earth do you know this sort of thing off the top of your head?

And given that you seem to have a preternatural gift for techinical specifications, shouldn't you have been picked up by the CIA or DOD for foreign military assessment by now?

Look, are you a doubleagent, or what?