Bicycle Mechanics - swapping 6sp freewheel suntour vs shimano

i'm moving this question from the C&V forum to here for some insight:

I tried to swap out my Suntour 13T-21T 6 speed freewheel to this (http://harriscyclery.net/itemdetails.cfm?ID=782) 14T to 28T Shimano freewheel.

However, the width of the Shimano freewheel is such that the smallest gear rubs on the chain stay. In other words, the axel is not the first thing the chain stay hits, it is the smallest gear, which makes peddling difficult :notamused:

Does this sound familiar? I suppose i need to find a suntour freewheel, or did i not crank down on the new freewheel enough?
Thanks.

Suntour made an "ultra" 6 speed freewheel which was narrower than the shimano you bought, but I think the solution is to actually get a 7 speed freewheel.

Check this out:

http://www.sheldonbrown.com/cribsheet-spacing.html

"Regular" 5-/6-speed 5.3 mm

Sun Tour "Ultra" 6-speed 5.0 mm

Sun Tour "Accushift" 6-speed 5.5 mm

7-speed 5.0 mm

You probabaly had a suntour ultra 6 speed and now have a regular 6 speed which is .3mm wider. A 7 speed ought to be the same width as your 6 ultra.

so just to clarify, i'm talking about the total width of the freewheel, from the highest gear to the lowest, not the spacing between each gear.

Oh yeah, I was thinking backwards.

Well I dunno. I was able to redish and respace an old wheel that had a 5 speed on it to take a 7 speed and it had 126mm spacing (it wouldn't have fit otherwise), maybe you just need to do a little of that.

Suntour made an "ultra" 6 speed freewheel which was narrower than the shimano you bought, but I think the solution is to actually get a 7 speed freewheel.

Check this out:

http://www.sheldonbrown.com/cribsheet-spacing.html

"Regular" 5-/6-speed 5.3 mm

Sun Tour "Ultra" 6-speed 5.0 mm

Sun Tour "Accushift" 6-speed 5.5 mm

7-speed 5.0 mm

You probabaly had a suntour ultra 6 speed and now have a regular 6 speed which is .3mm wider. A 7 speed ought to be the same width as your 6 ultra.
That's not right. An Ultra-6 freewheel was the same width as a regular 5-speed freewheel and fit in a 120 mm spaced frame.

A 7-speed freewheel is also narrow spaced but fits in the same width as a 6-speed standard spaced freewheel and requires 126 mm dropout spacing.

The dimension you quote are the distances between adjacent cogs, not the overall freewheel width.

Aha! so the thing to do is to measure the width of my frame. if i have 120mm spacing, than i have an ultra6 and it would make sense that the standard shimano 6 (for 126mm spacing) would not fit.

You need a narrow-spaced 6-speed or 5-speed freewheel if you don't want to re-space and re-dish your rear wheel. A Shimano SIS freewheel will have "standard" spacing so it will be too wide.

i think we have gotten to the bottom of it. I measured and found that i have 120mm spacing for the rear. Therefore, a standard 6 will not fit. Thanks for the help!

i think we have gotten to the bottom of it. I measured and found that i have 120mm spacing for the rear. Therefore, a standard 6 will not fit. Thanks for the help!

Do you have a steel frame? If so, those 6mm are easy to come by.

Indeed, I have a steel frame. but i hesitate to go through the "process". i think i will try to search for a 6 speed ultra freewheel, or a 5sp...

thanks though!

You can try placing a spacer under the DS lock nut to gain a bit of clearance.
How much do you need?