SRAM 3 SPEED GEAR with the FRONT DERAILLEUR -example

EXAMPLE & EXPLANATION OF CHART WITH FRONT DERAILLEUR OPTION

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BROMPTON SRAM 3 SPEED GEAR CALCULATIONS with the FRONT DERAILLEUR OPTION

Standard
	inches

Notes Sprocket ratios other than the Brompton Standard ratio

Brompton Standard Wheel Size

The "Actual" physical wheel diameter size

Data
Entry
Area

REAR Sprocket

The number of teeth in the Rear sprocket (You will be allowed to vary this)

SMALL Chain Ring

The number of teeth in the Small Front Chain Ring (You will be allowed to vary this)

LARGE Chain Ring

The number of teeth in the Large Front Chain Ring (You will be allowed to vary this)

Small Chain Ring Resulting Sprocket Ratio

The resulting sprocket ratio with the SMALL chain ring engaged

Large Chain Ring Resulting Sprocket Ratio

The resulting sprocket ratio with the LARGE chain ring engaged

Resulting Small Chain Direct Drive Wheel Size

	inches
	inches

The resulting WHEEL SIZE in Direct Drive with the SMALL chain ring engaged

Resulting Large Chain Direct Drive Wheel Size

The resulting sprocket ratio with the LARGE chain ring engaged

REAR HUB GEAR SELECTION

Resulting Wheel Size

lWith SMALL Chain Ring Engaged …

1st gear

RESULTING WHEEL SIZES with SMALL Chain Ring Engaged

With Rear Hub 1st gear engaged

2nd gear

With Rear Hub 2nd gear engaged (direct drive)

3rd gear

With Rear Hub 3rd gear engaged