100 or mm chainstay entension

[super slim]

I Have a Silvio V 1.0 with WTB drop bars, and a triple crankset with 153mm cranks, that I am thinking of installing a 100 mm or 150 mm chainstay extension on.

I am 6"1" tall with a 1175 mm (46") x seam measurement.

The BB is currently 630 mm above the ground with 700C 28 tyres, and the bottom of the seat joint with seat cushions is 600 mm.

Is the 100 mm or 150 mm, the best size.
What effect will this have on the derailer?

Super Slim

 

[randyspann]

100mm

- I am useing the 100mm extension. I'm 6'6" tall and this raised the BB about 6 inches. Worked out very well for me! Did not affect the front derailleur. You will, however have to lenghten the chain.

 

[Doug Burton]

What's your x-seam?

Or use the C-Seam measurement, the distance between the seat bottom joint and the center of the BB axle.

Set a yardstick to this distance, then raise the BB end of the yardstick vertically. This is the arc your BB will probably follow if you install the extension.

Generally, the extension will not be vertical, so if you multiply the extension length by the sine of the angle your carbostays make to the ground, you can closely estimate the increase in BB height. 100mm is about 4 inches, 150mm is about 6. So if the extension was vertical, it would add 6 inches to the bb height. If your carbostay ends up at about 45 degrees, you'll increase BB height 2 or 3 inches, depending on which extension you install.

The front triangle will be a little more open, so you'll probably have to move your front derailleur one mounting point to the rear.

 

[super slim]

100 mm extension on Silvio

I have bought and installed the 100 mm extension, with a new longer chain, and it is fantanstic, as now NO more upper leg pressing into the edge of the seat, better aerodynamic position, and lots more space above the front wheel to add a bag for pump, 2 tubes, multitool, and tyre levers. It now feels funny riding the Quest when needing to take a big bag to work.