Cycling UK Forum

Hi, Brompton say that the chain lengths on their bikes are extremely critical for proper functioning of the rear changer, which is not a true derailleur and the tension arm has a much more limited range than the proper derailleur type changers you find on many other types of folding bikes. If you change the size of the chainwheel, say from the standard, to the low gear Brompton chainwheel, you have to actually trim the chain, even though this is only a matter of a few teeth. I have heard of people making this kind of modification to other folding bikes which have a more conventional rear derailleur set up, but I've never heard of anyone doing it on a Brompton. I f you know of anyone who has done this, I'd be interested to hear about it. Hope this helps.

Hi, I use a Garmin etrex 10, one of their cheapest offerings, around £75. I use it in conjunction with .gpx files from either cycle.trsvel or better, Memory Map software. The 1:50000 stuff is more than adequate for cycling, around £80 for all GB coverage (the OS are charging £7 for a single 1:50000 sheet.) I download the route on the GPS, which is clipped on the bars, mounts cost under £3 on eBay, so you can afford one on all your bikes. You can use the GPS simply as a cycle computer then download your track on to your PC to review it, or you use the routes downloaded onto the GPS for navigation, if you need to actually refer to a map, then I have the memory map on my smartphone, you get 5 licences for different devices. The GPS runs for 20 or more hours on a pair of penlight batteries. Any map display screen device, phone or GPS will have a shorter battery life. And, you'll need to carry a charger or power pack.

I regularly use a Brompton P6 for commuting, I fitted a telescopic seat post, as I am 190cm tall. However, the top section of the post is easily removed via the quick release clamp. Which could be a temptation to thieves if you lock the bike up outdoors, particularly in town. I know some people use a thin lock cable which they thread through the saddle then through the shackle lock. I secured mine with a piece of standard inner brake cable, threaded through the rubber bung at the base of the seat post then secured at the top by one of the nuts which holds the saddle. If you set the length of the cable to the height you have the saddle, you simply pull the top section up as far as it goes, then it's automatically at the right height. Just an idea.