Quattro Gearing

The original Quattro gearing was a triple chainring and an extended Capreo block with a custom derailleur. Although this worked OK, I didn’t trust it to take me all the way across the USA.

Custom Derailleur

Tensioner

I decided to fit a standard short cage 105 derailleur, with an extra custom tensioner to take up the slack.

The gearing for ROAM was 72T, 60T & 45T chainrings and a standard Capreo 9 speed block, 9T, 10T, 11T, 13T, 15T, 17T, 20T, 23T & 26T.

Front Wheel Drive

This gives a top gear of 72x16/9 = 128” (10.3m) and a bottom gear of 45x16/26 = 27.7” (2.23m), which is a range of 462% but I was badly over-geared on hills over 10%.

Sliding Gears

What I would like to try is a single chainring and a straight chain line. The extended block slides left and right on some kind of spline and the tensioner is fixed.

Aiming for a gear range of 500% based on the Capreo block, there are three relatively simple options.

Gear Number	Capreo 9 Speed Block	Shimano HG61 Block	Custom Sprockets	Result
1	9			9
2	10			10
3	11			11
4	13	12		12
5	15	14		14
6	17	16		16
7	20	18		18
8	23	21		21
9	26	24		24
10		28		28
11		32		32
12		36		36
13			40	40
14			45	45

This gives some nice close ratios for racing but I discard most of the expensive Capreo Block.

Alternatively

Gear Number	Capreo 9 Speed Block	Custom Sprockets	Result
1	9		9
2	10		10
3	11		11
4	13		13
5	15		15
6	17		17
7	20		20
8	23		23
9	26		26
10		30	30
11		34	34
12		39	39
13		45	45

This gives slightly wider ratios but is physically narrower and nothing is discarded.

Alternatively

Gear Number	Capreo 9 Speed Block	Shimano Sprocket	Custom Sprockets	Result
1	9			9
2	10			10
3	11			11
4		12		12
5	13			13
6	15			15
7	17			17
8	20			20
9	23			23
10	26			26
11			30	30
12			34	34
13			39	39
14			45	45

This gives nice close ratios for racing and as many gears as a Rohloff Hub!

They all give a top gear of 72x16/9 = 128” (10.3m) and a bottom gear of 72x16/45 = 25.6” (2.06m).

For any future tours I would probably reduce the chainring to say 65T.

Giving a top gear of 65x16/9 = 115.6” (9.31m) and a bottom gear of 65x16/45 = 23.1” (1.86m).

9T Selected

 

45T Selected

It was easier to make an MDF mock-up of the tensioner shape and position, than to try and draw it on the computer.