How To Modify a 7 Speed Freewheel

[blown240]

Modifying a Freewheel:


Many Massif and Dolomite owners want to put an easier gear on their bikes. This is easily done by swapping on a Megarange freewheel. The problem with the megarange freewheel is that is has a big, 10 tooth, jump between the 2 largest cogs.


On my 6 year olds Massif, this jump was way to big, so I set off to make the steps between cogs smaller, this is how I did it:


First off here is a picture of the stock Massif freewheel, and the Megarange freewheel that I bought from my LBS.

Here is a picture of the megarange freewheel I took off of my wifes bike:

Notice that the 2 megarange freewheels have the same size cogs on them, but they are very different:


NEW:

OLD

The new style megarange freewheels will not work for this modification because the 3 largest cogs are pinned together and cannot be easily taken apart. And if they are taken apart, the 34 doesnt have splines.

So make sure that the megarange freewheel you have doesnt have the pinned larger cogs.


Here is the breakdown of the 3 freewheels:


Stock Massif (and probably Dolomite)

28, 24, 22, 20, 18, 16, 14

NEW Megarange:


34, 24, 22, 20, 18, 16, 14

OLD megarange:


34, 24, 22, 20, 18, 16, 14

HOW TO DISSASSEMBLE:


Its pretty easy to do with common tools.



Screw the freewheel to a block of wood using the teeth to hold the freewheel in place. Using a screwdriver, or a punch, and a hammer, tap the lockring to unscrew it.

THE MODIFIED FREEWHEEL:


once you have a pile of cogs and spacers, time to reassemble it. I used as many of the Shimano parts as possible and here is the result:


34, 28, 24, 20, 18, 16, 14


putting the 28t between the 34 and 24 is the best way to go:

Let me know if I need to explain any of this more. Hopefully this helped...

 

[LukeTheJoker]

Great write up, thanks! Much better and no doubt easy way to hold the freewheel in place with the wood and screws method than the two old chains method, that is just a recipe for skinned knuckles...

Any chance @blown240 of you also explaining how you made that massive one on your first Beast? Was is 14-42 tooth?

Luke.

 

[mikeeebikey]

10 teeth in the rear! That is like a 30 tooth change in the front!

Nice write up.

 

[blown240]

My first beast has an 11-42 cassette.

Here is a link to the build thread:
http://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/diy-42t-cassette-cog-842237.html

 

[LukeTheJoker]

My first beast has an 11-42 cassette.

Here is a link to the build thread:
http://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/diy-42t-cassette-cog-842237.html

Thankyou! Added to my favorites! Very nicely done and far simpler than I had imagined!

Luke.

 

[blown240]

Small update on the Megarange freewheel mod:

I installed it on my boys Massif and it works great.

The only issue was that the derailer cage touches the rim when in the lowest gear. This was easily solved by trimming the corner of the cage off with a pair of side cutters. The metal cuts very easily.

NOTE: this is not an issue with the Dolomite. Only the Massif due to it's smaller wheels.