How do you feel about wheel diameter?
 

So I've been riding folders for a number of years now and I've basically come to the following bimodal conclusion:
1. Purchasing quality non-standard spokes, tires, tubes, wheels, etc is a pain in the arse. So for that reason it's really nice to stick with 700c, 26", or at least 20" wheels.
2. There's nothing inherently wrong with small wheels so if you're gonna go nonstandard then you might as well go as small as possible (ISO305 or smaller like 8" or polyurethane skate wheels).

How do you feel about it? I'm toying with the notion of replacing my downtube with a montague so I can buy tires and spokes at any LBS.

I wouldn't easily go smaller than 16" for your point 1), and also in opposition to 2), small wheels limit the possibilities where I can ride it, eg definitely not on gravel and soft surfaces where I ride a lot, as in every day on my commute and many times on weekends. Roads may be OK but I am not sure about rolling resistance. Getting high gears is also very hard, with makers resorting to double-step drivetrains or the expensive Schlumpf.

Well I ride exclusively for transportation (and transport myself exclusively by riding) so I almost always ride on (sometimes badly) paved roads because that's almost always the fastest way (even if it's longer). So in that context, differences in rolling resistance are, as far as I can tell, pretty much undetectable (due to tire diameter itself...tire quality, inflation pressure, etc makes a big difference so that I've found riding good quality small diameter tires is much easier than poor quality 700c ones).

As to high gears, yeah they're harder to get if you go below 16", but with nonstandard rear and front cogs (and micropitch chains) you can basically get them as high as they need to be to keep up with motorized traffic on roads with traffic signals (IME)...which brings me back to #1: that the real issue is how much nonstandardization you're really willing to put up with because it makes every maintenance task that much harder.

For example, I just fixed a rash of 11 flats in a row and the problem turned out to be....poorly specified (or manufactured) 20" tubes. So yeah, I'm feeling like when you're the only person within 100 miles riding 20x2" wheels at 100 psi then you have the privilege of being the guinea pig for all the parts you get...even if you'd rather be spending your time on other things.

As a general rule I prefer riding my 20" (406) folders out of any of my big wheeled bikes. IMHO my folders are easier to handle and more tractable in mud, sleet, snow and rain... the smaller wheels sling less of those three around... small wheeled bikes allow me to pack more 'gear' yet maintain a lower center of gravity and normally they are a smaller overall package to transport when traveling. When it comes to touring/commuting/'pootling', small wheeled bikes can't be beat... but of course they can't beat a good old 29er for bombing down a mountain.

Well I got a 26" wheel Trekking bike, then the Brommy,
then a Bike Friday, in the last 12 years..
the Rohloff hub works better in the 20" wheel
because the 53/16, is well within design criteria ,
whereas the 38/16 in the 26" wheel,
is at the low end of the accepted range .
..
but the hub spokes up in the 26" wheel a little better ..
the hub was made to improve MTB drivetrains in a country
has some rather wet summers, sometimes..

Ride the Bike Friday more these days..
the step thru dismounts are good,
the trekking bar setup is pretty dialed in. hub dynamo lights
and disc brakes , just the thing this past winter..

the Brommy [M3L with a 54t mountain drive, 15t on BSR]
got a trip to Ft Stevens & the south jetty road
ridden by a friend I had to drag out of town
loaning a bike to go see stuff.. good to have a nice guest bike
then folding up to store at home..

I`m with Jur as far as rough conditions go. I`m realy impressed by how well 406 wheels do on pavement, off pavement, not so much. With 20 x 2.0 Big Apples, hardpacked and smooth-ish unpaved roads aren`t too bad, but they`re terrible when I "transport" myself over rutted or rocky roads. I haven`t ridden any washboard on the 20s yet, but I suspect I`ll find my self cursing the little boogers when that condition does arrise. 406 is the smallest I`ve used on an upright bike and the smallest drive wheel I`ve used, period. Gearing hasn`t been a huge issue for me.

I'm hoping that rim, spoke and tyre choices improve quickly as folding bikes grow more popular. I don't want to be locked into buying Brompton parts as they're overpriced, sometimes laughably so.
It would be easier if there were more cross-compatibility, e.g. if I could find a cheap 20H 349 rim so that I could run a Dahon / Tern front hub on my Brompton. I imagine the market will evolve quite quickly and there will be more options soon.

Is there a not- cheap option for this? Thinking about the same.

I rely on buying on the web for my small wheel bikes, only tubes could maybe be bought locally. Sometimes I butcher a free childrens bike if quality is ok.

To the OP: What about 24" wheels if you want to keep it small but buy locally?

Perhaps a very expensive rim is available in 20H, but with small wheels fancy rims aren't necessary as they're inherently so strong. 28 spokes is too much for a front wheel and unnecessarily heavy, plus the Dahon sealed hub is cheaper than the Brompton sealed hub and probably lighter. However, some modification would be necessary to make the axle diameters compatible, Dahon being larger. It all gets a bit complicated.

There were 349 20 spoke fronts, my Mk2 Brommy had one..
BiFri uses a 24 hole in their Tikit Builds.. another 349

Oh yeah I forgot about that...small wheels are so much better for carrying stuff. I guess that's something to think about if I decide to get a Montague.

Yeah, and speaking of which, when is Bike Friday going to make a ISO406 wheeled version of the tikit? I'd buy it in a second cause it's the only bike they make with a unified rear triangle. It's amazing the kind of punishment you can force a drivetrain (either traditional chain or belt drive) to take with a nice stiff chainstay and a rigid tensioner.

It'd be really nice to get some third party service on my bikes, but the only folder manufacturers that seem to have a URT, standardish rims, and standard hubs are:
-Downtube
-Xootr Swift
-Montague
And you can't really get good manufacturer or dealer support from any of them (well maybe Montague, but it's a bit of a different animal).

Tikit has good manufacturer support and a URT, but non-standard rims
Dahon/Tern has good dealer support and a URT, but non-standard hubs
Brompton has good manufacturer support, but a non-URT, non-standard rims, and non-standard hubs

I do not discriminate based on wheel size... :)

http://www.ravingbikefiend.com/bikep...orrestpug1.JPG

Good ERTO 406 tires are getting easier to find at the LBS in my experience; but still more difficult than 26" or 700c. Going smaller than ERTO 406 is a pain for other reasons too. For instance, if you like internal hubs which tend to have bigger flanges, not only is finding spokes harder but using a tensionometer can be impossible for a 305 wheel ... at least it was impossible with my Park Tool tensionometer. Overall, I think that the availability of 406 stuff is much better than 305/349 such that extra compactness comes at a bigger price for #1.

How often do you go through tires or wheels? You might be able to address 90% of the problem by replacing stuff a bit sooner than later.

There was a time that if you ran a 406 wheel the options for higher performance tyres was nearly non-existent and this got worse as tyre sized got smaller but this is no longer the case.

When you get below 20 inch wheels with higher volume tyres you start to run into ride quality issues and Moulton solved this by adding suspension / damping to his bicycles although gearing becomes an issue unless you use an IGH and perhaps a dual drive. I have a 60 tooth chain ring for my Moulton to be run with a 12 tooth driver on an SA 4 speed just to give it a proper top gear.

With a 20 inch wheel and a modern cassette hub with an 11 - x cassette and a standard sized chain wheel gives one all the gearing they might ever want.

Unless one is looking for a super compact fold there is not much reason to drop below the 406 wheel / tyre size.

width matters
 

When got my folder I did not like how bumpy my ride was. I fixed that quite successfully with a (much) wider 406 rim.

Wide rim made such a difference that I decided to keep my old tire in the rear and I see it as one of the better upgrades one can do to a small wheeled bike (if you're riding on uneven pavement).

The negative about small diameter wheel is that cassettes and most IGHs are configured for larger wheels and their gear ratios are too close to eachother