What's non-standard about the Brompton?
 

My current folder is an R20 (Made in New Zealand). It's my first folder and I love it the way you do a first love. :)

Now I'm in the market for a new folder, one that folds as compactly as possible and can accompany me on my plane trips.

From my research, it looks like the Brompton takes the prize for the most compact fold. But I've also read the Brompton is fitted with "non-standard' parts. So I'm curious which of the parts on a Brompton are non-standard? For instance, is the 16" tire/wheel is of a strange size that can't be found easily?

Thanks!

Brompton is a nightmare for bike modders. I used to own one and tried hard to upgrade it, but I gave up.
Almost every part of brompton is 'non-standard' or more exactly, seriously outdated.
Brompton parts are comparable to those of 50-years-old classic english 3-speeder :[

Here I list some:
-Brake dimension is non-standard (Brompton requires very rare, extra long reach caliper brakes)
-Rear wheel spacing is non-standard (around 120mm... now the standard is 130/135mm)
-Seatpost diameter is non-standard (Almost impossible-to-find 31.8mm size)
-Saddle clamp is non-standard (You need pentaclip to fit modern saddles)
-Chain tensioner is non-standard (And it breaks often :[)
-Chainring BCD is non-standard (You cannot fit typical 130BCD road chainrings)
-BB size is non-standard (I've heard that standard BB spindle length is >120mm)

However, if you don't think about upgrading your folder, brompton is just fine.
Still it is quite expensive, considering its very low quality components.

To be fair, ALL folders that are handmade in western countries are expensive too. (BFs, moultons, etc.)
In fact most folders are much more expensive than conventional bikes with similiar components.

The front hub is also narrow ... 74 mm ?

74mm front hub width is becoming a norm among folders.
Dahons, Tikit, Birdy, New series moulton uses 74mm front hub.

Perhaps among folders; but not a standard part you can easily find.

Both fair and unfair comments there. Yes a nightmare to modify unless you have engineering leve experience or as genius ability mechanically speaking. However Bromptons are reliable and I'd hardly call them 'very low quality components'.

My own Brompton was somewhat customized by my LBS with non Brompton parts (see my Flickr Web site for photos and captions). I strived to make my Brompton into the bike I wanted and got exactly what I wanted. In the future though, I do plan on adding some Brompton parts that fit what I want in that bike.

Brompton is reliable indeed. However, if you disassemble it and inspect parts (and weigh them), you'll be surprised that its components are actually inferior to $120 e-mart bike!

If you compare brompton to dahon curve SL component-wise, you'll know what I have meant.

Hi,
its true that measures are different - mostly smaller which leads to the small fold. But a nightmare? Hmhm I have a different opinion: to modify a brompton can be an adventure and great fun - it needs a little more research maybe. There are existing a lot of modified bromptons in the this world.
Tires: there are quite some rims and tires in the ETRO 349 size on the market. In rims you can get Velocity, Alex, Sun and others. Its also possible under special conditions (no mudguards, slim tyres) to fit the old moulton standard (ETRO 369) size or the birdy rims (ERTO 355).

The brakes are difficult to change, but one can change brake cables and brakepads to improve them. Or one can mount MaguraHS33. Or if using the birdy or moulton rims one can use short reach calipers. Some have welded on brake bosses for mounting v-brakes.

Of course one can put a different BB. Many Bromptoneers have put Ti-BB to save weigth. I haven't heard of often broken chain tensioner with brompton - what I have heard is that it brakes in merc - but there can be changes to alu and then be ok.

You might like to look at flicr the brompton group to see modified bromptons.

Seatpost diameter isn't too much of a problem ; there are other solutions for getting a normal seatpost in this. Calhoun shows this by offering one that cuts down a stock brompton one and inserts a shim to insert a standard 27.2 seatpost inside. Which then gets rid of the saddle clamp/saddle. You can do that mod yourself with stock post. Buying a post to cut is not that expensive.

Chainring/bottom bracket can both be swapped for ~$50 (nashbar parts). I used a compact and an ISIS crankset with no problems, now 6 speed if front-deraill'ing by hand. No folding/clearance/derailleur issues.