gmcjetpilot

Hi Forum. Newbie here. I just bought my 2nd Folding Bike. I landed on Green Zone alloy 20". I have about 10 miles on it and impressed with the ride and quality, but folded dimension SPECS were an inch or two larger than the SPEC and weight 1 lb heavier.. So it is advertised as 28" x 21" x 11" @ 28lbs. That is pretty good considering a Brompton A-line 25.3" x 23" x 10.6". @ 23.1 lbs.

Measuring a folding bikes L x H x W is not easy. They are approximate. I looked at 14 folding bikes under Approx $1000, a Brompton (A-line $1050), the Green Zone, Dahon, and several Citizen's, Tern's, Zizzo's and a Amazon Cheapest reasonable folding bike, Goplus $220: All are 20" except one of the Citizens. Some came with fenders and or rack. Green zone has both fenders and rack, alloy and 7 speeds: These numbers are based on REPORTED SPECS not actually measured.
Average Weight 28.4 lbs
Average Price $537 (threw out most expensive Brompton and cheapest Goplus)
Average Dimensions
L 31.25"
H 25.7"
W 13.75"

The Green Zone is rocking on paper but the actual dimensions were more like
31" x 23" x 12.5 @ 29 lbs. (better than Avg but not near Brompton)

I had to ignore a few lumps and bumps, like a latch still sticking out. The H of 23" required the seat post to be removed, otherwise it would be 24" not 23. Green Zone is better across the board, even with higher actual numbers (as measured by me). Not a big deal for most people, especially since the bike is a great value (comes with carry bag and other goodies), and it rides very nice with good quality materials, fit and finish. However I am super picky and cheap. My mission of fitting this bike in a tiny 2 seat experimental kit built airplane baggage compartment (easily) requires Brompton SPECS, assuming Brompton is accurate. The Green Zone will work but not ideal, but the advertised SPEC numbers would be better. The bike is great and a keeper, perfect for car, small Apartment and commuting on train and bus. It is under 29 lb's with rack and fenders. Best of all I paid $399. This is one of the least expensive in this price range with as good or better spec (as measured) than the advertised Specs for other brands in same price rang (under $1000), mqny cost 2 or more times as much. Great bike, just that I have the airplane requirement. It seems like Brompton is the only way? I really did not want to spend that much. The ride of Green Zone I bet is better than the Brompton (16" tires, reported flex of handlebars). The Green Zone is very solid. It feels like a full sized bike. However the folded size and weight is everything to my mission. I suspect all folding bike SPECS have some fudging and exceptions.

THE QUESTION? How accurate are these specs?

Pinigis 

When you measured the width, do you measure the total including the quick-release or nuts? Some manufacturers are a bit dishonest there and measure only the frame (like the opening you are trying to put it through won't notice the other bits sticking out).

gmcjetpilot

Yes, First time I measured it, I gave no allowance and no liberties or discounts for any bit or piece.. I had posted that originally. However I went back and edited it with new numbers.
SEE NEW NUMBERS BELOW

I went back and did not measure latches and removed seat post (read on). The seat and seat post off the bike is 25" total, When measuring folded measures 24" even retracted into frame, as it comes out bottom of frame, .The seat post is for +6' riders. I could cut an inch or two off that post and have plenty of insertion into frame and height for all but the tallest riders. Then the headstock of the frame where handlebars fold down would be the limit. There is also a nice rear rack (but heavy), Taking that off rack does not change overall folded dimensions but reduces volume. I'm sure some fudge the numbers. However Brompton has an travel case for their bikes that is very compact. Can't fudge that. I believe Brompton is the only bike you can carry on or check as regular luggage.

Green Zone
Folded 30.25″ x 23″ x 12.25″
Listed Spec 28" x 21″ x 11″
That is close but again I had to discount and ignore some bits and pieces and remove seat/post or will have to cut an inch off the post.

Weight Measured 29 lbs
Weight Spec 28 lbs
Weight (no accessories) 25,8 lbs -
Removing rear cargo rack (steel), front fender (plastic/steel), rear fender (plastic steel), water bottle holder (plastic), aluminum kick stand. saved 3.2 lbs.

To get super tiny 16" or even 14" tires you are getting into clown bike territory. Even brompton has found a limit. THE MAIN THING is I don't want a clown bike, The Green Zone is a very nice riding bike, very solid, sable no flex. Some report Brompton's have handlebar flex. The GZ has 7 speeds 20" wheels, fairly light, low rolling resistance. I would put the Green Zone's ride up against Bromption 16" and known handlebar flex. Mind you never road a Brompton and going on YT videos.

There are limits and compromises in all bikes. Do I think Green Zone was fudging? No. They have been great; Alan top notch customer service. With that said they changed the specs (long seat post and frame) over the years. The longer frame no doubt makes the geometry better. Unfolded it looks sleek. I can say it is super sold and comfortable to ride. Would I do 100 mile day? May be, may be not, but 50 miles no problem, stable, low rolling resistance and 7 gears. Brampton may be only 2 or 3 speeds, but that is fine for flats and commuters riding to and from the train station.

Average Dimensions - Green zone actual measurements beat the average and cost $399. Recommend it.
L 31.25
H 25.7
W 13.75
Weight 28.4

Jipe

You should avoid to use wheel dimensions in inches because they are misleading.

For 16" for instance, the Brompton 16" is ETRTO349 not ETRTO305 (both are called 16") so the Brompton wheel is only 57mm smaller than the most common 20" = ETRTO406 (the one you have on your Green Zone, there is a second 20" = ETRTO451) and not 101mm smaller.

There is no real difference in behavior and rolling resistance between ETRTO349 and ETRTO406 with the same tires. What really make the difference is the type of tire and the tire width and of course the whole bike design.

For small wheel bikes, wide tires is a major advantage.

For the Brompton (and many other folding bikes), the adjustment of some components (mainly the saddle and seatpost) has an influence on the folded size. This explain why announced folded size may not match what you measured on a real bike (and of course the fact that some bike manufacturers cheat on the advertised folded size of their bikes just like they also cheat about the weight of their bikes, cheating on the bicycles weight is almost systematic in the world of cycling).

For the number of speed, you should look at the gear inch range and not the number of speed. The 6s Brompton has a gear inch range of 306% similar to a 11-34 cassette (whatever the number of speed of the derailleur)

gmcjetpilot

Interesting. Thanks. My "20 in" tires say 40-406 20 x 1.5. It measures to outside of tire 19.25" approx. I am just going to use 16" and 20 " for this discussion, but appreciate your comment. Learning. The 20" is a large diameter and does have some advantages over 16", albeit small (no pun intended). They play with width and compound. Cool. I have no doubt the 16" Brompton's ride nice. However when a really big dude is on one they do look like clown bikes (even 20" bikes). There is NOT a big difference in folded size and weight between 16" and 20". However to get ultra small Brompton carry on airliner folded size 16" is a must. I am in that camp, I need (want) carry on airliner size folded bike.

I concur the seat post on my bike is LONG for tall riders, It makes a big difference in folded size in that direction, so when retracted into frame, the seat post is hitting the ground a bit before seat hits frame. I could cut the seat post down one inch or just remove for tight quarters, saving about an inch before part of frame is extremity. I know Brompton has optional telescopic seat post. The gear ratio on my Green Zone 7 Speed is perfect for me. I am very pleased with the low rolling resistance. Just the slightest down grade I can coast forever, quickly. I went on a 10 mile ride with some short moderate hills, up and down. Gears were perfect (for me). My theory is I don't need to do 60 mph down hill or if hill is so steep I need to pedal 120 rpm to do 3 mph, I am going to walk it. Ha ha.

Jipe

The Brompton is a very user friendly bike, the folded bike is not only the smallest but has also a very good shape that make it easy to carry folded much easier than Dahon middle frame folding bikes.

The front bag carrier system is a also very easy to use and allow to carry up to 10kg loads without influencing the bike behavior.

For the difference in folded size between a typical 20" folding bike with center frame folding and the Brompton, see below:




For the difference between ETRTO406 and ETRTO349 or ETRTO355, I ave also a Birdy on which its easy to change the wheel size, I compared ETRTO349 and ETRTO406 on the Birdy with the same type of tires that exists in both sizes with the same width (Continental Contact Urban 35x349 and 32x406 that on my wide rims are 35mm wide) and ETRTO406 doesn't bring any advantage.
What makes a difference is moving to very fast tires like the Greenspeed Scorcher for top speed or wider 50mm tires like the Big Apple for overall performances.