Friday, August 19, 2011

The Phoenix Project - Shimano Ultegra 12/27 CS 6500 9 Speed Cassette

Background on The Phoenix Project is available here and here.

Having long ago selected a Shimano compatible freehub for the rear hub, it is about time to get a cassette on it.

I actually spent quite some time dithering around with this as selection of the cassette is completely intertwined with crankset selection.

The number of speeds is also a factor.  In the case of The Phoenix Project, we opt for 9 speeds.  There are a couple of reasons for this selection.

First, 9 speeds is about the highest number of cogs that average riders can use in the the friction mode without excessively fine motions needed for rear derailleur trimming.  Some riders report no problems with 10 and even 11 speeds, but the curve starts breaking sharply at 9 or even 8 speeds.

The shifters for The Phoenix Project have friction and 9 speed indexing modes, so a 9 speed cassette keeps options open for using in index mode.

9 speed cassettes are still supported by the cycle industry in a wide range of quality and tooth counts.

Finally, 9 speed chains, unlike 10 or 11 speed chains, are as robust and long lived as 8/7 (and less) speed chains.

The Ultegra level is the sweet spot, in my opinion, for overall value in terms of quality, price, and durability.  Although I have several new Ultegra 12/27 9 speed cassettes in stock, I also happened to have one that only got used for about 3 rides, so I went with that:

I can't think of a whole bunch of cute things to say about cassettes, so rather than bore readers with a bunch of gratuitous ratings snarkery, lets talk turkey about the 12/27.

As noted above, the choice of crankset informs cassette choice and since the beginning of The Phoenix Project I have been wrestling with this issue.  More specifically, the issue has been whether to go with compact double or a traditional triple.

I really want to love wide range compact doubles, but I keep getting back to a couple of issues.   For this bike, intended as a versatile all-rounder, I want a very wide range and especially so on the bottom end for pulling loads up steep inclines.

Most compact doubles go no lower than a 34 tooth small ring.  With a 27 or 28 big cog in the rear, the limit of typical road derailleurs, that translates to a low of 32 or 33 gear inches, clearly inadequate for loaded hill climbing.

If we decide to go to MTB/Trekking derailleurs, we can consider something like the Shimano HG61 12/36 cassette.  With a 34 small front ring, that starts getting into acceptable hilly/loaded low range of 25 gear inches.  But for the type of loads I sometimes pull along with my advancing age, it is still a little borderline.

This got me interested in the new Sugino OX801D Compact+ crankset, which allows a choice of either a 110 or 74 bcd inner ring.  I got so interested in this that I actually ordered one in a 46/30 configuration and mounted it on the Trek 620:

The Sugino crankset is a beautiful piece of work and is quite flexible with the 110 or 74 mm inner ring options.  With a 30 tooth inner ring and a 36 large cog, one gets a stump-pulling low gear of 22 gear inches.

The problem, though, is that the 12/36 cassette has a lot of big jumps between the gears and the large jump between the front rings inhibits a lot of back and forth between the front rings.  Plus, the 36, or anything larger in the rear than 27 or 28, then rules out a lot of fine derailleur choices.  So all of a sudden the compact double is still imposing various compromises. None of these compromises are fatal, but it just seems like there are a lot of nagging issues, the sum of which seem like lots more downside than having to trim a front derailleur when shifting from the big ring to the middle on a triple.

Thus, at this point, I've finally decided to go with a traditional 110/74 triple.  Despite all the compact double hype, and they do have many virtues, they still don't completely replace a traditional triple for heavily loaded riding.

One could counter that I could fit a 24 or so small chainring in the front on the Sugino and still keep the 12/27 in the rear and get a good low gear and tight ratios.  That is true, but then the front shifting becomes dicey with a jump of of 20 or more teeth.  
I may ride this Sugino for a bit on the Trek 620, but it will likely end up on my wife's bike, as she lets me carry all the heavy gear and a compact double makes more sense for her as she also finds triples a bit vexatious.

Running Tally

$3015 USD

We carry forward $2955 USD.  Although this particular cassette was slightly used, new ones can be had as low as about $60 USD.

The Sausage Factory

1 comment:

Alex said...

With regard to rear derailleurs and very large gear ratio differences, I run a campagnolo chorus long cage rear derailleur on a shimano 12-36 10 speed cassette. I also have a campagnolo chorus triple crankset with chainrings 50/40/30. The rear derailleur can shift (relatively) comfortably between a 30-12 combo and a 50-36 combo without stretching the cage too much. I guess all i'm saying is don't pay too much attention to manufacturers recommendations with regard to how much slack the derailleur can or can't pull.