Triple chainrings and gearing
Hoopdriver
Posts: 2,023
I am building up a light touring bike and have a N.O.S. TA Zephyr triple crank and am trying to sort out gearing. I'm using an XT front mech and bar-end shifters. I'd like to use 48-34-26 and am wondering about the 14-tooth step from outer to middle. I've checked the Shimano tech specs and in the fine print they appear to recommend a 12-tooth minimum step-down, although all the chainsets I see offered have 10-tooth drops from outer to middle.
My expedition tourer has 46-36-24, and I've a roadbike with a (Campag) compact chainset of 50-34, so clearly a 16-tooth drop is feasible. It seems to me that my proposed 48-34-26 ought to work, And the total range is within the 22-tooth capacity of the mech. And that of the rear mech as well. But shifting with triple chainrings is imprecise science so I thought I'd ask and see if anyone had any real life experience either with this particular ratio, or 14-toot drops between outer and middle.
I suppose since I am using TA chainrings, with their one-tooth increments, I could always use 47-35-26 and keep it to a 12 tooth drop.
My expedition tourer has 46-36-24, and I've a roadbike with a (Campag) compact chainset of 50-34, so clearly a 16-tooth drop is feasible. It seems to me that my proposed 48-34-26 ought to work, And the total range is within the 22-tooth capacity of the mech. And that of the rear mech as well. But shifting with triple chainrings is imprecise science so I thought I'd ask and see if anyone had any real life experience either with this particular ratio, or 14-toot drops between outer and middle.
I suppose since I am using TA chainrings, with their one-tooth increments, I could always use 47-35-26 and keep it to a 12 tooth drop.
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Comments
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Often, the only way to find out is to try it. My tourer has 50-40-24, which is quite a jump from middle to inner and a wide range for the mech to handle. The text books said this was beyond the capacity of the mech (Shimano 500cx) but it has proved to be faultless in shifting over these past 17 years or so.0
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I have often used TA Carmina or Zephyr with 26/36/46 TA rings. This gives a good range for light touring in hilly terrain.0
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Thanks for the responses. It looks as though the 48-34-26 is at least worth a try; if you can get a 16-tooth drop between middle and inner to work faultlessly, Weejie, the 14-tooth drop I am thinking of ought to work.
I seldom use the inner and so the range 48-34 on the outer two should give me the general flexibility for light fast touring, with the granny ring in reserve. I'll be using a 12-27 road cassette on back, since I do not like the look of the big dinner-plate 32 and 34 MBT cogs.0 -
I run a 52/42/26 chainset with a tiagra front mech, XT rear mech and Campag 10 shifters without any problems, I have also run the same chainrings on a full 105 set up. Give it a try, rules are meant for breaking
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