Which sprocket(s) do I need for my Brompton?

Which sprocket(s) do I need for my Brompton?

Over time chains and sprockets wear out. Due to the workhorse nature of the Brompton and the fact that the drivetrain is closer to the ground than on larger bikes (it picks up more dirt / grit), and the fact that it only has one or two sprockets to pared to 7-11 on a mountain bike for example,  they can wear even quicker.

If you are replacing your rear sprocket(s) then we recommend replacing both the chain and the sprocket. We describe it as an old married couple - they get comfortable with each other and wear at about the same rate.

So remember - if you replace the chain alone then the chain may well slip - and the same if you replace just the chain.

Which sprocket(s) do I need?

Well, as you are changing the chain AND sprocket, then it's the 3/32 sprocket you'll be wanting!

Note: If you fit a narrow chain 3/32 to a wide sprocket 1/8, the chain may not sit properly on the sprocket - so the chain will appear to be too short.

The sprocket you need depends upon your rear wheel and on whether you also want to replace the chain guard and circlip (which holds the sprocket / sprockets) in place.

Which splines?

Brompton sprockets come in two possible spline fittings:

3 spline / ISO sprockets - as shown here, are used on the SRAM 3 and SRAM 6 speed rear wheels, and on the Sturmey Archer 3 speed rear wheels.

They are available available with 13 teeth (13T) -  (standard on the 3 speed BSR - Brompton Standard Ratio rear wheel, and used on the Sachs/SRAM 3 and 6 speeds).

The 14T sprocket was a minor gearing option change for the Sturmey Archer rear wheels - but only in conjunction with a 1/8 inch chain - which is pretty much unused any longer.

The 15T sprocket was used on the Sachs/SRAM 6 speed rear wheels along side the 13T.  


Shimano style splines, as shown here use 9 splines spaced so that the sprocket can not be put onto the hub the wrong way around.

12T - used on single speed Bromptons and in conjunction with the 16T on the two speed Brompton.

13T - used in conjunction with the 16T sprocket on the 6 speed BWR - Brompton Wide Ratio - equipped Brompton Sturmey Archer rear wheel.

16T - used in conjunction with the 12T on the 2 speed and the 13T on the BWR 6 speed rear wheel.

Which width Sprocket?

Sprocket size	Sprocket	Sprocket stack	Splines	Note
12t	QRSPR12	QRSPRSTACK12	ISO 3 Spline	Single speed
13t	QRSPR13	QRSPRSTACK13	ISO 3 Spline	3 speed BSR
14t	QRSPR14	QRSPRSTACK14-SA	ISO 3 Spline	3 speed BSR
15t	QRSPR15	QRSPRSTACK15	ISO 3 Spline	3 speed SRAM

 

 To be continued ......

Brompton 2016 Black edition

Following the success of the BLACK Edition last year, Brompton have released another limited run of the Brompton BLACK Edition folding bike. They are the first 2017 specification Bromptons available.

 

Black edition features

The BLACK edition special features include*:

• Black Wheel Rims, spokes and hubs (braking surface is still silver)
• Black Pedals (both the folding left hand and fixed right)
• Black rear reflector bracket
• Black mudguards
• Black brake levers (the standard ones have black levers - but the body is also black on these ones)
• Black saddle rails and pentaclip (fixes the saddle to the seatpost)
• Black seatpost
• Black chainring and cranks
• Black handlebars
• Black hinge clamps 
• Black mudguard roller wheel

* We could have missed some!

 

Brompton BLACK edition colours

They are available in a limited choice of colours - to highlight the black features

• Black
• Orange
• Lime Green
• Lagoon Blue

Brompton Black Edition - Orange

And unlike most Brompton where the main frame is one colour and the extremities are another, these have the main frame and handlebar stem as one of the four colours above, and the front forks and rear triangle in black.

The black colour bikes (so all-black) have an almost black decal not used on any of the other bikes in the Brompton range

Unfortunately the photo to to the right doesn't do it justice - we'll try again soon!

 

Brompton 2017 new features

The BLACK edition Bromptons are the first of the 2017 models produced.

New features for 2017 are*:

2017 model lock on Brompton grips and gear changer

• Lock on grips. It seems that the lock on Brompton grips have finally been released by Brompton. They are still foam, but fixed on with a lock on clip at the inside end.
•  New gear triggers. Both the 3 speed (for the hub gear) and 2 speed (for derailleur system) have new gear triggers. They are similar to the Shimano trigger style changers. 
• New brake levers? The gear triggers / shifters (whatever you would prefer to call them) integrate with the brake lever. We haven't taken them apart to see, but the existing levers don't seem to have the mounting holes.
• New gear cables. The new gear shifters use new gear cables - so you will have to select the correct one - for the Brompton 2016 BLACK edition it is the 2017 model cables!

*Again - we could have missed some

You can see our range of Brompton BLACK edition bikes here.