mazdaspeed

My hub had a 6 speed suntour freewheel, which has been replaced with a 7 speed shimano one. The shimano's smallest gear hits the chainstay/dropout though. I was told by many different people that a 7 speed would drop right in and work, but it seems like it's way too wide. Do I need to go back to a 6 speed or can it be adjusted? It seems like dishing the wheel that far would make it so it doesn't fit anymore.

Sixty Fiver

You may have been talking to the wrong people...

You need to add a spacing washer to the drive side to provide adequate clearance and a little re-dishing of the wheel will also be required.

All in all...it's a pretty simple upgrade.

krems81 

Usually there should be enough room to replace a 6 speed w/ a 7 speed. Check to make sure its threaded on all the way.

If so, you problem is axle spacing. take freewheel off, and you'll have to take off the drive side axle locknut. This requires cone wrenches.

Add a spacer (maybe 3mm?) behind the locknut on drive side. It would be adviseable to remove a spacer from non-drive side, unless you have extra room in your drops for a wider OLD (over locknut distance). If you have quick release, you'll probably HAVE to remove spacers from nondrive side equal to what you add on drive side. Then the wheel has to be redished a bit. Not a problem it can be done, but its not really a process to explain here.

Best bet: find your community shop with open shop hours. I'm sure there will be folks ready to help you out, or bring it to your friendliest local shop, and they'll probably at least explain to you whats being done.

HillRider

One other possibility, was your 6-speed freewheel an "Ultra-6"? Sun Tour made some very narrow 6-speed freewheels that were the same width as a 5-speed. A 7-speed would be significantly wider than an Ultra-6.

mazdaspeed

I'm actually not sure, it was 1986 suntour sprint.

Retro Grouch 

If you're willing to accept as reality "You can never change just one part on a bicycle," you'll be right way more often than you're wrong.

Al1943

I made a similar upgrade for a friend and had to replace the axle with a slightly longer axle and also had to make some changes to the spacers. In this case it was not necessary to change the dish, YMMV.
The conversion did work well and was very inexpensive.

Al

mazdaspeed

I think I'll take it to a shop and see what they say. There is still one shop here I haven't tried, but the rest are useless. We'll see how it goes. If not I'll just buy a 6 speed freewheel

oldbobcat

I'm surprised at how far this discussion has gone without actually talking about axle lengths--well, actually, the span that fits between the dropouts.

Traditional 5-speed is 120mm, traditional 6-speed (same spacing between cogs) is 126.5 mm. Around the mid 70s Shimano and Sun Tour independently introduced a spacing that allowed an extra cog for each given spacing, so 5 could do 6 and 6 could do 7. They each had a proprietary name for it, they were oddly compatible, at least as far as chains went, and pretty soon other manufacturers came up with their own versions and chains for them.

So the first thing to do is measure the axle on your hub to see what kind of freewheel you can put on it.

Gonzo Bob

If your current 6sp is an Ultra-6, a standard 6sp will also be too wide. Ultra-6 freewheels are about 26mm wide, standard 6sp are about 30mm wide, and 7sp are about 32mm wide. If you need to respace and redish for a standard 6sp, you might as well go with the 7sp you already bought.

rmfnla

Ain't it the truth!