-Choosing Handlebars
There are a few things to keep in mind when choosing your handlebar.
A, C, P Line and legacy Bromptons have a non-removable faceplate stem so the bars can not have a crossbar or a loop, the stem clamp is 25.4mm so no oversized handlebars can be fitted.
The T Line has a 31.8mm clamp with a removable faceplate.
Older MTB-style handlebars, Easton, Raceface, and Nitto generally work well. Some city-style bars can also be fitted as long as the sweep is not too great.
https://whatbars.com/ is a good resource for checking handlebar size before purchasing.
-Parts list
You will need the following parts
-2 Brake cable inners, the Brompton uses MTB brake cables. I like Shimano.
-Brake housing. Again I like Shimano. Use the road style if you have the option, Shimano's SLR is good.
-Shift cable inner. If you are using the stock Brompton shifters I recommend getting the High handlebar gear cables and using just the inners. Get whatever matches your gearing system (eg, one derailleur and one hub gear). If you are using an aftermarket shifter, get whatever cable inner matches your shifter.
-Shift cable outer. Shimano shift casing is what I used but any shift casing should work.
-Cable end caps for everything.
-Brake noodles or flexi noodles if you are using non-standard levers.
-New handlebars (obviously).
That should cover everything basic. When you are doing this it is also a good time to replace any worn parts (grips etc).
-Tool list
-Allen keys, a standard 2-2.5-3-4-5-6mm set should do the job.
-Cable cutters, something that works for braided cables is a must.
-Measuring tools, rule, tape etc.
-A bike repair stand, is not strictly required but it makes life easier.
-Process
-First, make sure the bars will work. Make some basic measurements with the bike folded to check fitment with the bike folded. You could even make a cardboard template of the bar you would like to fit and make sure it clears everything.
-Remove all cables, brake levers, grips, and shifters.
-Remove the original handlebars.
-Fit the new handlebars.
-Refit the brake levers, shifters, and grips. Once those are fitted it is a good idea to, carefully, check the folding action of the bike and adjust brake lever angles as needed. The handlebar latch can also be adjusted at this point.
-Fit the front brake cable. Start with the lower section. You can reuse the original section or cut a new one. Once the lower section is fitted, you can cut the upper section to fit. Pay close attention to the routing and where the cable gatherer fits. Once all the lengths are OK you can fit the inner and tighten down the cable.
-Size and fit the rear brake brake casing. Make sure the carefully follow the original routing. The cable should be almost lever with the ground when it comes out in front of the bottom bracket. Fitting the inner cable and tighten everything down.
-Fit the shift cables. As long as you follow the correct routing and the cables follow the brake nicely this is the easiest part.
-Once the cables are all fitted, check that the bike folds correctly. Adjust lever position, bar angle, etc, as needed.
-Do a final brake and gear adjustment, fit cable ends and the bike is finished.
-FAQ
This will be updated as questions come in.