shipwreck

Reading customer reviews on folding bikes, one thing I have noticed is some people saying that they could not climb a bridge or a hill "because of the small wheel size".
As a cyclist and someone who can reason out the principles of gearing and leverage this makes little sense to me. So are they just goofy, or is there something else that explains some peoples difficulty? Most claim that they can get over the hill on a full sized bike because of the higher speeds the bigger wheels get. This also sounds goofy to a "spinner" like me.

But as I have never ridden a 20 inch bike, I try not to assume I know anything.

The other thing I am looking at is weight limits. the Downtube claims a limit around 200 pounds, and I am capable of getting down to that, but would still be close. The Tern is at 240 I think, and i am looking at their midrange eight speed.

Thing is, I am also still looking at the Citizen Gotham II. It has a 220 weight limit, so I am a bit below that, and of course the price is right, especialy considering that I would be customizing it almost at once with different front crank, modified alloy north road bars, and lose the grip style index shifter for a decent vintage suntour friction thumby. I have lots of parts on hand, so further outlay won't be high.

I know that this bike gets sneered at a bit, but in the "folders, read this first thread" it is listed as a viable low cost first folder.

Sorry for the questions/angst, but I have not purchased a new bike in over 15 years, since the mountain bike craze. All 23 of my regular bikes are vintage, or failing that, just old and loved.

bargainguy

Shipwreck, they're just goofy. The opposite tends to be true: Smaller wheels need larger corresponding gearing to be comparable to "normal" size bikes. Not unusual to see Bike Fridays, for ex., with insanely large chainrings to compensate for the smaller wheel size.

Now with rider weight, we're getting into a different issue. With standard non-folding bikes, rider weight tends to be harder on wheels much more than the frame. The wheels flex more under load and so very close attention needs to be paid to proper spoke tension, dishing, etc. Some believe that double-wall rims reduce flex and therefore prolong wheel life.

With folding bikes and increased rider weight, I'm going to say something a lot of folks here may not agree with. Stay away from cheap folding bikes. I lump the downtube and the citizen in that category.

Cheap folding bikes tend to have more issues with hinge clamps etc. so in my mind, not worth it to trust those parts to hold up to repeated stresses. Any of the better dahons, bike fridays, bromptons etc would be fine. Heck, I just bought a 90's Fuji folding mountain bike that would probably work in your situation, although it is certainly not as elegant as today's models. Pic attached.

Don

Ozonation

I've climbed a number of hills and inclines with my Brompton and its 16" wheels. The engine gives out before the bike...

shipwreck

Thats absolutely what I figured about smaller wheels... An idea I have is to replace the crank with a 54/48 half step, and shift the front manualy as needed, making sure that the rear meck can handle it. If it does not work, then it can always go back to stock or try something else. Some of the low gear ratios have me thinking about this, sort of a cart before the horse thing

one of my criteria is that I have to be able to fly with this, preferabaly broken down to suitcase size. I got a lot of good feedback on that on my last post.

To that end, I was thinking about using self extracting bolts, and taking the crank off to pack it. I have a lot of old deore cranks so if one starts to wear from repeated instalations, I can replace it! The 54/48 rings fit them all, so those would be moved to the new crank. I like working on things like that anyway, its meditative.

I agree about a cheaper folder, and its why I am asking things here.( I have read lots of threads, so a lot of my questions have been somewhat answered) My only reason for thinking about a cheaper one is that I would be using this bike in various citys, and as I am from a town where I typicaly forget my lock when going to the library, post office, grocery store and what not with no problems yet, I am not theft savy. I have tons of locks because I have to buy one everytime I travel with a bike cause I forget to bring one!

But, as I have several months to find something, I will be looking for a good second hand bike. Seems there is generaly a lot of love for the downtube, and other than the weight issue, was thinking about it because of its upgrade potential(front meck mounts). Interesting to hear it lumped with the cheaper options. Wish I could see some of these in person.

On another note, I have a set of 20 inch wheels from an older bike, medium/good quality rims and hubs, seven speed cassette with a outboard drum brake on the rear. Problem is the rear is 125mm. If I could find a wheelless frame, I would love to play with those.(up to now they have been slated for a home built recumbent, if I ever found the time).

JimBeans83

Typically you won't see the best gearing on a folder (standard 586% range on a mountain bike (22/32/42->11/34 casette), but that's also mitigated because many folders aren't gear to let you go as fast.

You can choose the gearing as low as you want, you just cut your top end. If you want to spin at 4 mph, your top end is at 12mph. I think most folders have around a 300% gear range, whether that's obtained with an internal gear hub, or a more limited cassette/double chainring. A 34tooth cog in the rear on a 16" wheel is too big, it's almost too big on a 20" wheel, leaving about 1-2" (if I remember) between the derailleur and the ground under normal range tensioning.

I think what you've seen is from folders that are normally spec'ed to let you pedal at 90rpms around 15mph, which gives you a low end (typical 300% range) at 5mph or more. Bromptons have a gear range around 186%, which would drop that to 8mph. Some hills could make that a challenge for the gearing, as normally your not outfit as well for hills as you would be on a road bike, and there are some other inefficiencies that don't make it as easy to equate the speed difference - meaning if you don't struggle at 8mph up a certain hill on a road bike, that doesn't mean the same would be true on a folder.

You can always drop your front ring to be lower, you'll just lose top end.

bhkyte

Some fast 20" folders will keep up with good road bike.
My ultergra equiped upgraded Downtube with drops was great. I sold my Renulds 653 tubing road bike, as there was not enough difference in performance to bother keeping it over that folder. I then sold my Downtube 20" wheeled folder as it seemed excessive as I had a simularlly upgraded 16" mezzo.

Try a good folder like a Speed TT, or an animal or most with addded drops.
The idea of vastly inferior preforamnce is incorrect.

Many folders are not fast in standard form as they are under geared or lack gear options.

SJX426 

I recently picked up a BF NWT for less than $175. It came with a 44 ring and a guard ring on the outside. The PO included a FD but not the controls. What was interesting to me was the Caprio hub and cassette. Smallest cog is 9 teeth! I don't know much about folders, but BF may be one of the only ones selling with the Caprio(Shimano) hub. A 46 tooth ring will take it to slightly over 100 inch ratio. The crank is set up as a triple but I would need to change the BB to 118 and check the range of the FD.
As you may know, this folder is designed for travel via airplane in a suitcase that can double as a trailer.

shipwreck

One of the first things I will do is get the gearing suitable for actual riding. Top gear inches of 60 to 70 actualy might not be that bad, but yeah, I am used to more. One thing I like is a tall gear, my touring bikes have a 52 tooth big ring, Even the off road gravel grinder tourer. Getting spun out is very frustrating to me, unless its a mountain that I can hit 50 on going down.


Most of my riding on a folder will be in places like Chicago, Denver, San Diego, St Louis, various places in Florida, KC. So There is the possibility of needing different gears on different trips. Unless I can get that broad a range with a double, and wide range gears in the back, I would think about customizing the gears for each trip. And either some sort of drop bar, or cow horns. I ride in the drops a lot, so might like those set a little lower.

Thanks everyone for the responses, I know more about french BB threading than I do folders, and the glut of info on the net is so contradictory. One guy likes one bike another thinks is crap...

shipwreck

Thats a great deal. I would gladly pay that for a basket case if the frame was strait. Thing is, craigslist in my area of Arkansas is stuffed with "super rare Magna girls bike, super nice, never ridden, needs tires chain and seat". That and triathalon bikes for more than they list for. No folders in a year or so of looking.