She has started a new job recently which will involve a longer commute, and wanted to sort out many little niggles with the bike that had developed over the past few years. Initially she felt that pedalling it was very draggy and inefficient, possibly due to a worn bottom bracket or something in the drivetrain. So she made the decision to overhaul the entire drivetrain, in the process lowering the gearing as the lowest gear (38 x 28t) was not enough for some hills in south London.
Cranks and bottom bracketSo the first port of call was to take off the cranks to put on lower geared chainrings and overhaul the bottom bracket. This was not so easy as all old Stronglight cranks require a crank extractor which is specific to their brand pre-1980. I already have the Spécialités T.A. 23mm extractor so why not get a the Stronglight one which is 23.35mm... Yes the measurement is very close however if you use one in the other you will ruin the threads and never be able to remove the cranks!
We removed the cranks with the correct tool and took apart the bottom bracket, it was in very good condition, with only some minor nicks on one cup. However we decided to replace it with a sealed unit to cut down on maintenance. We settled on a Velo Orange French threaded sealed BB, the other option would have been a threadless BB however I'm not too sure how secure they fit in the BB and the price difference wasn't much anyway. It's quite a nice unit, spins very smoothly and is very light partly due to the hollow spindle.
The other minor thing we needed to do to the cranks was tapping the pedal threads from French to English (standard) threading. I already had the taps for this, it was the first time I'd ever done it and it turned out to be quite straightforward. You just have to make sure that the tap is started straight and the rest is just like any other thread tapping.
The brakes that came on the bike were Mafac Racers which are at best speed modulators. They do slow the bike somewhat but don't really bring it to a stop in any reasonably hasty manner, also their setup is a little fiddly. I've played around with these brakes on many bikes, and to be honest I'm not a big fan, the arms are much too flexy and actually deform if you brake very hard which ruins any brake pad alignment. I've only ever used the centre bolt mounted versions with a connecting bridge, you can however fit the swingarms directly to the frame with braze on studs but these are uncommon.
We decided to just replace these with modern Tektro dual pivot calipers with cartridge pads. This simplifies the setup and upgrades the brakes to modern standards. The model used was the Tektro R559 which has a reach of up to 75mm which was just enough for the longer reach rear.
Setup of brake pads alignment is drastically simpler and more precise only requiring an allen key, adjusting pads on the Mafac usually involves an adjustable wrench for bending the arms to achieve sufficient toe-in to prevent squealing. The calipers also have a quick release which means removing wheels is much quicker than with the Mafacs, which have a sort of quick release but isn't too user friendly.
Now the crankset and brakes are sorted... all that is left is the gearing. Originally we set out to merely upgrade it but we eventually went in a different direction completely.