Taking my P Line to 6 gears

[TC99]

I have four gears. Its not enough. I want more with closer ratios.

Is this feasible?

 

[Kell]

I'm not sure you'd ever be able to take it to a 6-speed. But maybe a 12-speed is possible.

I asked the question a while back after a mate of mine got his 4-speed.

This is the thread: https://www.cyclechat.net/threads/adding-an-extra-gear-to-a-4-speed.290120/

But in the meantime, the 12-speed bike has launched which is a 4-speed derailleur and a 3-speed hub.

I don't know enough about them to know if it's a simple wheel swap and additional cabling. Something in the back of my mind has me thinking the 12-speed has a wider triangle, but not sure.

Weirdly, the 3-speed bike has a wider range - which would cure one of your problems - but make the other problem worse (the gaps between the gears). In fact I think one of the selling points of the 4-speed is the fact that the ratios are quite close.

Here's how the various bikes stack up.

Also, from another forum, someone emailed Brompton and got the following reply:

Thank you for contacting us here at the Brompton factory and for your interest in our bicycles.

Yes, you may upgrade your current 4-speed gear P line to 12-speed. However, the upgrade might be costly. Below there is the list of what parts customers will need to perform the upgrade based on the model they own:

• 12 Speed Hub Gear Indicator Chain
• Hub Gear Cbl Pulley Ass Rr
• Hub Gear Cbl Anchorage Sturmey
• Hub Gear Shift Set with LH Brake
• Superlight 12 Spd Brom Rear Wheel - Ryde
• Rear wheel hub guide nut

Gear cable depending on HB type

• H Type hub gear cable
• M Type hub gear cable
• S Type hub gear cable

 

[TC99]

This looks interesting. I have seem similar on ebay for £160
https://bromptonkitchen.com/en-gb/products/5-speed-stock-upgrade