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Minimum difference in tooth count between chainrings

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Minimum difference in tooth count between chainrings

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Old 01-29-17 | 03:07 PM
  #26  
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From: Pittsburgh, PA

Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

Originally Posted by AlexCyclistRoch
That is the true definition of 'credit card touring'; one where you have the money to pay somebody else to move your luggage, so that you don't have to carry it. You also do not need to be limited by a set schedule if you have a day of bad weather, or you decide to change your route in the middle of your tour.
OK, you define it your way.
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Old 01-29-17 | 10:33 PM
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From: SoCal

Bikes: 2014 Bruce Gordon Rock&Road, 1995 Santana Visa Tandem, 1990 Trek 520, 2012 Surly LHT

I am running step-and-a-half on several bikes as follows

Bruce Gordon touring bike, 44-36-22, using a Shimano XTR FD-M900 (old 8 speed from about 1994, designed for maximum large chainring of 48T, minimum difference of 8t between and middle chainrings, and a maximum capacity of 26T large to small chainrings).

Co-Motion Touring, 46-38-24, using a Shimano XT FD-M735 (old 7 speed from early 1990s, designed for maximum large chainring of 48T, minimum difference of 5t between and middle chainrings, and a maximum capacity of 26T large to small chainrings).

Santana Visa Tandem, 52-44-28, using a Suntour XC Pro FD-XP00-GHX (old 7 speed from ??, designed for maximum large chainring of 48T, minimum difference of 8t between and middle chainrings, and a maximum capacity of 24T large to small chainrings).

The trick with all these older front derailleurs is they have a small inner plate. Yes, they may not have as crisp a shifting as newer derailleurs, but I have good shifting with non matching chainrings. These and other front derailleurs from the same era are available used on e-bay. Not much can go wrong with these so even used are perfectly functional. I also understand that of the modern FD, the Shimano FD-CX70 works well.

The problem can be matching older derailleurs with brifters. I am using Campagnolo Chorus shifters and they work perfectly shifting across the full triple crankset. If using bar end shifters, the front shifter is friction, and are ths compatible with any and all FDs.
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Old 01-30-17 | 10:05 AM
  #28  
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From: Erie Penna.
I run 45-42-24 X 12,14,16,18,21,24,28,32,36. The 42 45 shift is as smooth as glass and 45 with that rear cassette gives an almost perfect half step. Better than the 46-42 combination if I remember. 15 usable gears without duplication and a very simple half step pattern.

One thing not mentioned is what a difference the tallest gears have in feel with a very straight chain line.

I had plans to modify my FD if I liked the setup moving the outer plate down to look more old school. But it shifts so well I see no reason to mess with it.

Here is a thread with pictures of mine if you want to see it.

https://www.bikeforums.net/touring/85...8-32-36-o.html
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Old 01-30-17 | 11:03 AM
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From: Erie Penna.
Originally Posted by HillRider
What this says is the bike seems to be geared as a "credit card tourer" meaning it is lightly loaded and you carry only extra clothes and sleep in motels and eat in restaurants. Hence the need for a "credit card" and you can get away with fairly high gears. The opposite is "loaded touring" where you carry a tent, sleeping gear and cooking gear as well as your personal stuff. Loaded touring bikes typically have much lower low gears.
I don’t know about the OP’s 30t granny and what cassette he has but both of those are inexpensive to change as I did going from a 30-42-52 crank and a 11-32 cassette to the 24-42-45 crank and a 12-36 cassette. I agree tour bikes like my Windsor Tourist are set up too high for being practical as a loaded tour bike as sold.

The OP uses his it sounds about the same as I do when he uses it as an around town bike. Depending on what kind of hills he has dropping the granny to 24 or 26 makes it much more of a hill climber loaded or not. The 52t ring though always seemed too high to me for touring or not touring in a heavier bike like this. I don’t miss not having a 120 GI high gear even on down hills.

Point being with the smaller granny, larger cassette and the 45t big ring I got an evenly spaced gearing running from 17.7GI to 101GI giving me 19 proportionately even spaced gears or 21 useful gears as the only hard shift of them all is from the granny to the middle so I left a 2 gear overlap in the pattern there. That shift has to be a soft shift the rest including the 42-45 shift work fine under power even. I just back off a smidgen doing a half step.

With gearing like this the bike could be used around town grocery getter, credit card touring or loaded touring. What it won’t be is a competitive ride bike for group rides and such. I find a touring bike the perfect bike for a lot of people that might not ever go on a tour.

It would be great if the bike came with the 42-45 half step with the 30t granny and a FD cage made for the task and a cassette that gave half steps in the range I got. It is almost like they have a bunch of old road triples and they use them up on these tour bikes.

Like the OP I thought a long time about tossing the 52 and putting a bash guard on there. I’m glad I didn’t.
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