Inconsistent spacing on Shimano 6 speed freewheel (MF-TZ20)

Andy Wilson

Hello,
Can someone tell me if the spacing on a 6-speed freewheel is meant to be different between sprockets 5-6 than it is between the others, or have I got one with an incorrect spacer?

I thought I’d done enough internet searching to be satisfied that standard 6-speed freewheels used the same spacing (5.5mm) as 5-speed freewheels, but this Shimano MF-TZ20 that I’ve just bought has surprised me. Whilst most of the spacing on it appears to be 5.5mm, it’s definitely bigger between the two highest gears and nowhere on the web that I’ve come across mentions this; sites such as Sheldon Brown’s just state that the spacing is 5.5mm, which understandably I took to mean between all of the sprockets.

I was planning on using it with my existing Shimano 5-Speed index shifter, whilst having the choice to set it up to use either sprockets 1-5 or 2-6.

cooldad

Try it and see.
Five speed shifters? Haven't seen one of those since I was in high school, 40 odd years ago. What are you using it on?

cycleclinic

have you measured the spacing. sayiing it looks different is one thing but measuring it to be different is the way to know. Beside a 5 speed shifter should be friction and if it is index make it friction and problem (if there is one) is solved.

The spacing looks O.K to me in that photo.

Andy Wilson

I take it no-one knows if the gaps between sprockets on a 6-speed freewheel are meant to be the same?

thecycleclinic wrote:

have you measured the spacing. sayiing it looks different is one thing but measuring it to be different is the way to know.

I used the shanks of drill bits as a guide.
A 3.5mm bit fitted nicely into the first 3 gaps, was a tight fit on the fourth and had a lot of slack in the fifth.
A 4.0mm bit wouldn’t fit into any of gaps except the last one, which it did quite comfortably.

thecycleclinic wrote:

Beside a 5 speed shifter should be friction

I disagree with that statement- I’ve been using this 5-speed indexing shifter for decades, it’s original to the bike and it does an excellent job.

thecycleclinic wrote:

if it is index make it friction and problem (if there is one) is solved.

I understand that freewheel spacing wouldn’t be an issue with a friction shifter but I much prefer index to friction.

thecycleclinic wrote:

The spacing looks O.K to me in that photo.

Are you saying that the gaps should be the same between all of the sprockets and to you they appear to be that way in the photo, or are you saying that the gaps aren’t meant to be the same and in the photo they appear to be as you’d expect?

cougie

What made you check? I've never even thought about this. Does it work?

cooldad

The spacing should be the same AFAIK.
But why not just get a 5 speed freewheel, they only cost about £10. Less faff and mental strain.