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  • Home
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The two speed is an obvious choice to save weight, but with the limited gears you need to pick you options well as you can easily be left churning a massive gear or spinning out too quickly! 

It is very common to increase the chainring size, 60t seems to be the biggest option without too many issues. Larger hits the front fork hook / the chainstay. On my personal bike I have used a 122mm BB to stop the chainring contacting the chainstay when folded. 

The stock ratio / MPH for RPM/cadence of 90 is - 3.38-4.5 / 15.1-20.1 mph.

Ratios/speed for alternative ring sizes;

56t - 3.5-4.67 / 15.6-20.8mph 
58t - 3.63-4.83 / 16.2-21.6mph 
60t - 3.75-5.00 / 16.7-22.3mph

The BWR with 50t has a gear range of 302%, ratio of 1.99-6.03 with MPH per 90 RPM (cadence) at 8.9-26.9mph.

So with a 60t x 12/16 you would need to pedal at 108.5 RPM to equal a BWR hub using 50t 13/16 at 90 RPM.  ​
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  • Home
  • Shop
    • Accessories
    • Brompton Bicycles
    • Components
    • Conversions / Servicing
    • Drive Chain Parts
    • Frame Parts
    • Service Parts / Tools
    • Sturmey Archer Parts
    • Tubes / Tyres
    • Wheels / Wheel Parts
  • Servicing
  • The Basics
    • A Line
    • C Line
    • C Line Electric
    • P Line
    • P Line Electric
    • T Line
  • Weights
    • Stock Bikes
    • Frame Parts
    • Components
      • Braking
      • Easy Wheels
      • Handlebars
      • Mudguards
      • Saddles / Seatposts
    • Transmisson
      • Bottom Brackets
      • Chainsets/Chainrings
      • Pedals
      • Shifters
      • Tensioners
    • Wheels/Wheel Parts
      • Front Wheels
      • Rear Wheels
      • Hubs
      • Rims
    • Tyres/Tubes
  • Tech Info
    • Bearings
    • Brompton Electric
    • Cable Lengths
    • Chain Lengths
    • Gear Ratios / Ranges
    • Hope Technology
      • Front Hubs
      • Rear Hubs
    • Datasheets
    • Notes
    • Paint Codes
    • Serial / Frame Numbers
    • Sturmey-Archer
    • Torque Settings
    • Tyres
    • Wheel / Wheel Building
  • Modifications
  • Contact