Brompton G Line Transmission We have 11 products.

Subcategories

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  Brompton G Line Bottom...

  Brompton G Line Bottom Brackets

  What is a bottom bracket?

  It sits in the bottom of the bike frame and contains ball bearings - the crankset attaches to the bottom bracket - and it means that when you pedal the pedals drive the chain to push the rear wheel around

  Is it the same as a standard 16 inch wheel Brompton?

  The Brompton G Line uses a different length spindle on the bottom bracket when compared to the standard / traditional 16 inch wheel size Bompton folding bike

  • 16 inch wheel - 119mm length spindle 
  • G Line (20 inch wheel) - 123mm length spindle

  The extra length means that the chain will clear the wider tyres on the rear of the bike

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  Brompton G Line Chain...

  Brompton G Line Chain Tensioners

  Due to the fact that the bike folds - the Brompton uses a chain tensioner to help keep the chain tight so that it doesn't fall off!

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  Brompton G Line Chains

  Brompton G Line Chains

  The Brompton G Line (the 20 inch wheel version of the Brompton folding bike introduced in 2024) comes by default with a 54T front chainring

  G Line chain lengths

  114 links is what is used on the default 54T chain ring 112 links would be used if you changed from 54T to 50T to reduce the gearing 110 links would be used if you changed from 54T to 44T to further deduce the gearing

  We currently only stock the one length of chain - but if you order and add a note with your chainring size we can cut the length to chain as requested before shipping

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  Brompton G Line Chainsets

  Brompton G Line Chainsets

  The Brompton G Line actually uses the same chain set and chain rings as the traditional 16 inch wheel Brompton folding bike - this chain ring is available in 3 sizes:

  • 44T
  • 50T - the default for the G Line manual version
  • 54T - the default for the G Line Electric

  Changing the chain ring to a smaller (or larger on - though this seems to be rarely done is a simple job - but will need a change to the chain length to cope with the new ring size)

  We made the above video to show how easy it is to change the chainring size - it was filmed on a Brompton 16 inch wheel bike - but the process of changing the chainring is exactly the same on a G Line

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  Brompton G Line Pedals

  Brompton G Line Pedals

  When the Brompton G Line was launched in 2024 it came with new (not used on any previous Brompton) flat mountain bike style platform pedals. Though the came with a twist - the left hand pedal is removable (to reduce the folded size) and can be clipped into the back of the front fork for storage

  Is this the only pedal that will fit a G Line?

  The G Line uses the same crankset as a standard 16 inch Brompton C Line - so any pedals that will fit that (which is most bicycle pedals these days) will fit the G Line - so you have a choice of different types available

  • Brompton specific pedals - with one removable / folding
  • Mountain bike flat pedals
  • Touring pedals
  • SPD (clipless pedals)

  So if you don't want the stock pedals on your G Line - you can easily change to your favourite style

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  Brompton G Line Sprockets

  Brompton G Line Sprockets

  The Brompton G Line uses a Shimano Nexus sprocket 

  As standard it comes with a 20 tooth sprocket

  If you want to reduce the gearing slightly - a 22T sprocket will fit

  When riding at a cadence of 70 rpm in the lowest gear with a 20T sprocket you will be going 9kmh
  If you increase the sprocket to 22T and pedal at a cadence of 70 rpm your speed would drop to 8.1kmh

  Note on increasing longevity of your sprocket:

  Keep it clean - as dirt accumulates on the sprocket and is mashed by the chain, it will wear out both the chain and the sprocket. Keeping it clean will extend the life of both!