Yesterday I wrote about putting a compact crank on my road bike.  Today I changed the gearing on Anne’s road bike so she would also have lower gearing.  She already had a triple crank with a 12-27 cassette so the only way to get lower gearing would be to add a mountain bike type cassette on the rear, which means also the need to change to a mountain bike rear derailleur.  There was one complication because Anne had 10 speed shifters on her bike and all mountain bike components are 9 speed.

You can not just use a 9 speed cassette with 10 speed shifters because the cable pull between gears is different.  When I bought my new compact crank for my bike, I also purchased an XTR rear derailleur because it was also on sale at Performance and there was also a 12 hour period with 20% more off.  Cost for the XTR was only $80, a steal.  From my prior experience I knew that I needed a “top normal” type.  Newer mountain bikes use a “low normal”.  Derailleurs are defined by the normal position of the derailleur (that is the resting position), either the top gear (smallest cog) or the lowest gear.

I checked with the bike club for recommendations.  Most of those responded recommend using an IRD product. They make a 10 speed 11-34 cassette.  I was not too anxious with this approach for a couple of reasons.  First I had tried that cassette, on loan from a friend, on my road bike before last year’s Everest Challenge.  I was not happy with how it shifted so I took it off and did the event last year with my double crank and regular road cassette.  Second the price for this cassette is about $170, which is a lot more than a Shimano XT cassette that would shift better.

When you have a triple crank having 10 speeds is a bit overkill because you get a lot of duplication in gearing.  I feel that most people with a triple who also want mountain bike gearing would have been happy to stay with 9 speeds but Shimano didn’t go that route with their road components.  There is talk that they will come out with a 10 speed mountain bike group, but that is not yet the case.

One club member suggested I look at a product from Jteck Engineering, called the ShiftMate.  I emailed the company and got a reply to my questions within an hour.  After studying the concept, it seemed like a great way to go so I ordered online from them, cost of $35 plus $6 shipping.  They shipped to me by priority mail.

This device is two concentric pulleys that the derailleur cable routes around.  The difference in the diameter of the two pulleys is such that the cable pull from the 10 speed shifters is increased to match what the cable pull from 9 speed shifters would do.  This allows you to use a 9 speed cassette.  The device arrived last Saturday.   I took a look and it seemed to be a clever approach to a common issue.

Today I decided to tackle this project.  I started by removing the cable from the existing Shimano 105 rear derailleur.

Next I removed the chain from the bike.

After I removed the existing 10 speed derailleur, I attached the new XTR derailleur in it’s place.

I cut the cable housing shorter so it would fit better, then threaded the cable back through the housing and then through the ShiftMate.

Next I removed the road cassette from the rear wheel and replaced it with a Shimano 11-34 cassette.  I had purchased a new XT cassette for our tandem during the recent sale but was not planning to use that until later this year.  Since we use our tandem more than Anne uses her single bike, I decided to do a swap and put the new cassette and chain on the tandem and move the tandem’s rear cassette and chain over to Anne’s bike.

The final step was to connect the cable to the rear derailleur and make the final adjustments.  Since the shifter has 10 stops and the cassette has only 9, I used the low stop on the derailleur.

A short test ride on the street showed that things were shifting smoothly, just as you would expect if the bike had 9 speed shifters.  Since I used some components from our tandem, the total cost was only $80 for the XTR and $35 for the Shiftmate, for a total of $115.  If Shimano does come out with a 10 speed 11/34 cassette, I can always switch to that and most of my investment will still be used.

Later in the day, we went for a ride to make sure that it shifted okay while actually climbing.  Anne reported that it worked just fine.

Categories: Cycling Equipment
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