Thursday, January 5, 2012

The Miche Conversion Cassette

A conversion cassette is a way to make Shimano and Campagnolo play together. One common conversion is to use Campagnolo shifters with an otherwise Shimano drivetrain; these are referred to as a Shimergo. The primary reason is Campagnolo has a more positive shifting mechanism, which tends to last longer and is rebuildable. Shimano on the other hand makes cheaper and mored varied cassettes and very well made freehubs. The conversion uses a Campagnolo 10 speed shifter and a Shimano 9 speed drivetrain. The conversion is made possible by re-routing the rear derailleur cable called “hubbub” routing. I put a conversion together using the hubbub routing and it works very well (see the above Shimergo link).

Next I decided try a conversion cassette as another way to combine different components, maintain 10 speeds and to test the quality of the shifting. Unlike the hubub routing, a conversion cassette uses both Campagnolo shifter and rear derailleur. Campy and Shimano have different splines, so you can’t put a Campagnolo cassette on a Shimano freehub; further Shimano and Campagnolo use different spacing so a conversion cassette would use a Shimano spline with Campagnolo spacing (or visa versa). One way to do this to buy one ready made; Wheels Manufacturing, IRD, and American Classic all make a form of a conversion cassette; the one thing they have in common are they are very expensive; $200+. The one exception is Miche. Miche makes cassettes with individual cassette cogs and spacers. While they don't advertise building a conversion cassette many have suggested that it would be an easy conversion to simply use the Shimano cogs with the Campagnolo spacers.So, I mounted a Campy 10 speed rear derailleur and I needed to make the front derailleur 10 speed friendly again. Campy 9 speed compatible 10 speed front derailleur have a spacer that
clicks into place and I removed it as I was running a 9 speed chain drivetrain; it was a simple procedure to install it again.

Next I bought a Miche Shimano spline and spaced 10 speed cassette; it’s cheaper to buy a complete cassette than 10 individual cogs. At the same time I bought 7 Campagnolo spacers (the Shimano
spacers are red and the Campy’s are blue). I then switched out 7 the 7 Shimano spacers for Campagnolo spacers. The reason there are not 9 is the first and last cogs have integral cogs; the fact that they are on the ends of the cassette mitigate any issues with the different spacer width.

I installed the Miche conversion cassette on the Shimano freehub and one thing was immediately evident, the cassette had grown by 1.19mm. (The Campy spacers are .17mm wider than Shimano’s). The result was the end 12t cog did not connect with the splines. I tightened the lockring while holding the cog in place and after a few turns I could feel the cog connecting with the splines and I was able to continue to tighten the lockring without out the cog turning. Now I had mounted the Miche cassette with the Shimano spacers and even with a 1mm spacer behind the cassette, the cog connected with the splines, so I know it was very close. Further this is not unusual with some 10 speed freewheel combinations, so unless you are the type that uses the last cog regularly and exert a lot of pressure on it such as sprinting, it should not be a concern. I also noticed that the derailleur cage was very close to the spokes when the chain was in the last big gear. This is also not unusual for 10 speed drivetrains, especially Miche who has the last gear offset toward the spokes. The general rule is, if the derailleur is not hitting the spokes it will work; in my case the cage had about 3-4mm clearance, which I find acceptable.

After adjusting the rear derailleur, I took the bike for a test ride and the conversion cassette worked pretty well; it should be noted that one should not expect the near flawless shifting that comes from a Shimano or Campy cassette. There was however, a rough shift in the area of the 6 and 7 cog (smallest to largest). While on the 6 cog, he 7 cog was trying pick up the chain for a few revolution and then would settle down and stop. I was able to adjust this out with the barrel adjuster by turning it down as far as possible while the derailleur was still shifting from the first to second cog, but the shifting felt flat. Somewhere in the back pf my memory, I remember reading that Campy used different spacing between some cogs. I looked it up and sure as heck Campy places a .14mm wider cog between 6 and 7 (the other 8 spacers are 2.41; the spacer between 6 and 7 is 2.55). Since the Miche spacer is actually 2.26, I needed a 2.40 spacer to account for the wider spacer. This of course is in all practicality the same as a standard Campy spacer; and having a few in my parts box I used it to replace the Miche 2.26 spacer between cogs 6 and 7; it is an optical illusion that it looks thinner, the OD of the spacer is simply smaller.

The difference was remarkable for such a minor tweak. First the shifting felt more positive on all the gears not just cogs 6 and 7. Second to keep the rear derailleur cage away from the spokes, I set the stop as close as possible, which resulted in an increased effort to click the shift into the end gear (this may also have been due to the spacing). Well, .14mm apparently moved the indexing outward and the shift now feels the same as the rest.

There is another method of making Campagnolo and Shimano play together using a shifter adapter called a Shiftmate.This little gadget uses two tiny pulley wheels to change the shifter cable pull. Not only does it work for Campagnolo and Shimano cross platforms, it allows one to mix and match shifters and cassettes of different speeds and manufacturer. I currently have one that allows the use of my Campy 10 speed shifters with a Shimano 10 speed cassette. After riding with the campy spaced cassette long enough to determine it was working very well, I replaced the Shimano spacers and installed the the shift mate on your left. I was a little tricky getting it right, but if you read and follow the instructions exactly, it appears to be working very well. I will update after several road rides. FTF

Two weeks later and about 300 miles later the shiftmate has yet to miss a shift; thi sis the way to go.

But back to the Miche Conversion Cassette; if you want to know if you can make a conversion cassette with a Miche cassette the answer is a resounding yes; as long as you are willing to put up with slightly inferior shifting and pay attention to the details. And it is certainly cheaper than a new wheelset and the other conversion cassettes..

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