"For those of you interested this kind of thing, I built a 14-28 cassette this weekend for use with a stock nine-speed Ultegra triple and STI shifting. It worked perfectly on a test ride to Piermont this morning.
Shimano chainrings are specially designed and machined to shift smoothly and quickly with STI, but the stock 42-tooth middle ring and 52-tooth outer ring produce higher ""high"" gears than I can use, when combined with either 12-25 or 13-25 cassettes. Plus, the lowest gear ratio on the middle chainring, produced with the big 25-tooth cog on the cassette, is too high for me to climb all but fairly modest hills, so I'm forced to shift to the granny chainring more than I prefer. But I really like these cassettes because the spacing between adjacent gears is pretty close.
I tried to improve (lower) the gearing with smaller chainrings, but they just didn't shift as effortlessly as the Shimano rings. The shifting wasn't really bad, but it wasn't fast and smooth, either. In particular, the shift from the middle ring to the granny was slow, despite my best efforts to fine-tune it. And, unfortunately, Shimano doesn't make smaller rings for its triples.
I tried a compact double, too, because it's much easier to set up a double to shift smoothly, and I actually built up the 14-28 cassette for use with the compact crankset's 34-48 chainrings. With this configuration, I got low gears for climbing hills, and closely spaced gear ratios, but at the expense of the top end! I basically ended up with nine very close low gears on the inner ring - not so useful, in practice.
Finally, the ""ah ha"" moment, when I realized I could use the big 42-52 Shimano rings with the 14-28 cassette and get a nice range of gears, low gears for steep hills, and much more useful gears for cruising and climbing moderate hills. The icing on the cake is the superb shifting - as easy as any double.
I built my cassette from an Ultegra 13-25, a 14-tooth end cog, and a 28-tooth loose cog. I removed the 13 and 14 cogs and one spacer from the small end of the cassette and substituted the 14-tooth end cog in their place. Then I added the spacer and 28-tooth cog to the other end of the cassette. Easy! I ordered the cogs from Harris Cyclery.
If you have a triple on your 700C bike (650C and MTB bikes are different) and are frustrated by the gearing, you might consider building a new cassette. Have fun!"
Custom cassette
"Tony, great setup and story. I'm overwhelmed by your website and the stuff you've put together ... but the the inner chain ring on a Shimano road triple is 74 BCD and the smallest size available is 24T.
http://sheldonbrown.com/harris/chainrings.html
I have a 24T on one road crank and a 26T on the other. A ""chain shark"" to keeps the chain in place on down shifts.
My rear cassettes are standard 14-25T Tiagra and Ultegra (30 grams lighter and $30 more expensive).
My fronts are 48/42/26 and 46/40/24.
(I spin a lot.)
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PS> For those with $$ to burn and not enough titanium in their life, these guys make custom cassettes and chainwheels -- as well as many other neat toys.
http://www.actiontec.us/ticog.htm
http://www.actiontec.us/ti&steel.htm"
Neile - thanks for your comments. Actually, I meant that Shimano doesn't make smaller rings for the middle and outer positions for its road triples. I guess the D-A triple uses a 39 middle, but the selection is still limited.
As you do, I also use a smaller than stock inner ring - either a 26 or 28.
"Another option would be to build up carbon or high end aluminum MTB crank (110/74 BCD) and use a stock ""corn cob"" cassette.
http://www.raceface.com/components/cranks/deus-crank.htm
http://www.sram.com/en/truvativ/mountain/cranksets/stylocarbon/carbongxp...
Outer 40-61T
Middle - 32-46T
Inner - 22-36T
http://sheldonbrown.com/harris/chainrings/110.html#74
http://sheldonbrown.com/harris/chainrings/74.html
Truvativ also makes nice chainring sets at reasonable prices."
...are titanium (at least that's what i was told - i know the groupo i bought came with an all-titanium cassette).
don
12,13,15,17,19,21,23(24),26(27),30.
Start with a Shimano 12-27 or SRAM 12-26, throw away the 14. Put a 30t cog on the hub followed by the cassette (minus the 14, of course). Exceeds Shimano's extremely conservative double rear derailer capacity but works fine anyway, though the Shimano cassette works better than the SRAM making the 13->15 shift.
Disclaimer - the derailer location is what determines whether or not this works. Some people have had success with a 32t cog and a DuraAce double RD, others can barely shift into a 27.
Anyone ever make a 9 speed 11x25 that works?
"Back in the old days (8 speed), I used to take a 12-21, pull off the 21 and substitute a 26. That would give me a 12-13-14-15-16-17-19-26. With a 53-39 I'd have all the combos I needed and a ""bailout"" 39-26 to climb anything steep. I didn't have to make the shift from the 21 to the 26 too often, and once in the 26 I usually stayed there, but the shift was always crisp and clean.
Now with the factory bolted cassettes this seems impossible. If you have a suggestion for something similar, let me know."
The 9 speed Shimano HG70, also known as 105, 12 -23 cassette (12-13-14-15-16-17-19-21-23) which comes screwed together for convenience, but can be disassembled by removing the three screws (1.5mm Allen wrench) and you can substitute a 26 for the 23 if you wish. It's only the higher end cassettes (Dura Ace, Ultegra) which use the spiders to save weight for the larger cogs and can't be taken apart.
what about the 11?
If you take a Shimano HG70 (105) 9 speed 12-25 (12-13-14-15-17-19-21-23-25), you can get an 11t first position sprocket + lock ring (from Harris) and remove whichever cog you don't want to make an 11-25.
Thanks; Seems a little too good to be true, but I might give it a try this winter. I often thought there might be a reason Shimano might not sell them- maybe the shifting is not as crisp?
In my experience, the shifting is not as crisp when you remove cogs from the middle of a cassette. It works, but there's a lag and some grinding before the shift takes effect.
I've combined the 13-14-15-16 cogs from a 13-25 with the 17-19-21-24-27 cogs from a 12-27 and that worked OK, but the one time I tried to insert a 16 into a cassette, the shifting was not smooth. And the one time I removed a 16, the shifting wasn't great either.
The 11-25 looks hard to do. There are stock 11-23 and 12-25 cassettes, so you might want to change your chainrings to get the ratio you're looking for - either at the high end (with the 11) or the low end (with the 25 cog).
Why do you want an 11-25?
"There are times when I ""spin out"" in the 53x12 (115) and I find myself wishing I had the 53x11 (125) so I could really put down the hammer. However, I live with this inconvenience as it's really nice to have the 39x25 (41) or even a 39x27 (38) for some of the steeper hills upstate or in New England. I've thought about going to a CD with a 50/34 in the front and an 11/23 in the back (118 to 38), but that would only be a modest improvement over the 53/39 - 11/27 setup that I have(115 to 38). A triple is out of the question as it would clash with my carbon wheels :)
All in all, I'm pretty happy with my current set-up. Just wondering if anyone had successfully built a functional 11x25."
Abstract Several studies have suggested that the most economical cadence in cycling increases with increasing workload. However, none of these studies have been able to demonstrate this relationship with experimental data. The purpose of this study was to test the hypothesis that the most economical cadence in elite cyclists increases with increasing workload and to explore the effect of cadence on performance. Six elite road cyclists performed submaximal and maximal tests at four different cadences (60, 80, 100 and 120 rpm) on separate days. Respiratory data was measured at 0, 50, 125, 200, 275 and 350 W during the submaximal test and at the end of the maximal test. The maximal test was carried out as an incremental test, conducted to reveal differences in maximal oxygen uptake and time to exhaustion (short-term performance) between cadences.
The results showed that the lowest oxygen uptake, i.e. the best work economy, shifted from 60 rpm at 0 W to 80 rpm at 350 W (P<0.05). No difference was found in maximal oxygen uptake among cadences (P>0.05), while the best performance was attained at the same cadence that elicited the best work economy (80 rpm) at 350 W (P<0.05). This study demonstrated that the most economical cadence increases with increasing workload in elite cyclists. It was further shown that work economy and performance are related during short efforts (~5 min) over a wide range of cadences.
Will you translate that statement into English? :)
Basically, it says as power demands increase, greater efficiency occurs at higher cadences than lower. Implicit then is higher cadences allowing greater sustainability during situations requiring higher power requires, such as on a climb.
...most people just like to get out and ride. :)
don
