At 23:31 I glanced at my page views to discover I had passed the 160,000 page views. The last 10,000 have come in 9x days!
I wanted to post someone about this last night but I was half asleep and needed the rest.
As always thank you for reading, wherever you come from and whether or not your own a Brompton.
Keep coming back and commenting on anything you find of interest. I have lots of adventures coming up on both my Original and Titanium Brompton so here will be plenty more to read about.
If I lived anywhere close to London I would show you how to do this. Sadly I don't. This is a straightforward job and the tools are cheap to buy and a worthwhile investment. I think you will have no problem undertaking this!ReplyDelete
You will need:
1) FAG/Campag Square taper BB Tool
2) A square taper Crank Extractor
3) Copper Grease (not the spray stuff)
4) Isopropyl Alcohol or Brake Cleaner
First remove the pedals and unhook the chain. To remove the old chainset you will need the Crank Extractor:
Tips - crank extractor should be firmly (not super tight) screwed in to crank to be removed. It needs to locate with as much of the fragile alloy crank threading as possible. The original Brompton swaged chainset is very lightweight (too light IMO). It would be interesting to compare weights of your old and new chainsets!
And to remove the Bottom-Bracket a FAG/Campag BB removal tool:
Tip - Be careful these FAG BB units are plastic /fragile. Ensure the tool lobes are engaged with the BB and slowly turn whilst applying hand-pressure against the tool which ensures it won't slip. Work on both cups undoing each a little at a time. IMPORTANT: the drive-side BB unscrews clockwise and the non-drive side anti-clockwise.
New BB Installation:
Use Copper Grease on the BB and Brompton BB shell threads. This will stop corrosion & ensure that the BB is easier to remove next time!
Using the FAG BB tool Install the new BB (make sure it has the non-removable fixed cup on the drive side!)
IMPORTANT: Hand screw (don't force!) the non drive side cup in for 3 or 4 turns and then the sprocket side (anticlockwise to tighten) for about the same. Continue to tighten each side so that it is firmly tight (tighten down and then a bit more - like a wheel nut).
Install the cranks:
Using a clean rag or cotton bud wetted with cleaner ensure sure the tapers on both the BB crank and BB are clean and free from dirt and grease. I use Isopropyl Alcohol (from a chemist) for this, you can use thinners or brake cleaner as well.
Locate the Drive side crank on the taper, use a soft-headed mallet and give the crank a firm tap to locate onto the axle. A heavy book would do just as well. Apply some Copper Grease to the BB axle bolts and then tighten firmly (tight and then a little more). Repeat for the other crank. Check crank bolt tightness after 20 miles, then again at 50 miles.
Chain on, pedals refitted (use Copper Grease on the pedal threads). Go ride!
Many thanks Simon. This will be as much help to me as it could be for those thinking of carrying out this task. I think I just might take your advice and have a go.Delete
It is a straightforward job. I started bike fettling when I was 15 after a bike shop messed up my bike big time by forcing an Italian BB cup into a BS shell thread - it was very out of line and obviously wrong! At least you know it is done right if you DIY. You need a few key tools which can be built up as required. A workstand is useful but hardly essential. Bikes are/should be pretty simple really (I'm not mentioning air forks or electronic shifting at this point)! One point missed from the above is to work on the Brompton in its unfolded state with both wheels on the ground. This is nice and stable and is best for when tightening the BB/cranks as any stresses are absorbed by the tyres. You will notice when stripping down that Brompton (well at least on my bike) grease their crank tapers - there is some debate about the merits of this. It does mean that the crank is easier to remove in the future, it also introduces the possibility of the crank being forced too far up the axle taper which could stress/crack the crank itself. I've been fettling bikes for 30 years and have never greased or encountered a problem with dry tapers.ReplyDelete