Majority folding bikes I’ve seen around use 20” wheels. I’ve ridden the Brompton and one other (a Chinese knock-off, forgot the brand) They all have 20” wheels.

While in theory the 24” wheel would roll more efficiently and go over bumps and cracks more smoothly. Has anyone ridden one with 24” wheels and can compare to 20” wheels to share your experience?

I have the option to get one with 24” wheels, or one with 20” wheels for the same cost. I’m not sure which one to get. The 24” one could potentially have better ride quality and faster, but it’s quite a bit heavier and bulkier, which will be harder to carry around once folded.

No shop around me has any 24” wheel folding bike to test ride on.

The wheel size doesn't define how a bike rides.

24" wheels (BTW., which 24" size, ETRTO507, ETRTO520, ETRTO540...?) do not necessarily ride better nor are necessarily more comfortable than 20" on bad roads, bumps... the most important is the tires and especially the tires width, wide tires (50mm or wider) with 20" wheels are better than 24" wheels with narrow tires.

For the riding behavior and bike efficiency, its the bike geometry and frame design that define them, not the wheel size.

For your test of a Brompton, unless it was the recent G-line with 54x406 wheels, its not a 20" wheels size bike, its a 16"-ETRTO349 wheels bike and the 16" Brompton is known to be very uncomfortable and very inefficient on bad roads.

As Jipe noted, there are several 24 inch tire sizes. Mine uses 507X40 tires. The 507 is a dimension specific to the wheel rim, 40 is the tire width in mm. In my case 507X40 is a very rare tire size, I keep a few spares on hand in case I need them. But that is not likely an issue for you. Most bikes that take 507 will use a wider tire which is very common.

I am guessing that you are new to folding bikes. If not, sorry I misjudged you from your post.

If you are new to folding bikes, they are compromise. Some folding bikes prioritize portability and others prioritize how well it rides. If you want to fold the bike and carry it into your apartment every day, or when you get to work after you rode it a few miles, you fold it up and put it into your cubicle. For that you want to prioritize portability, thus smaller wheels. If you only occasionally plan to fold it and when you ride it you ride tens of miles (or tens of kms), then perhaps you want a folder that has larger wheels.

If you might want to pack it up and bring it onto an airplane in a standard sized piece of luggage, you most certainly would be happier with a smaller wheel folder.

My folder below, an Airnimal Joey that I built up about 19 years ago. With 24 inch wheels, it rides very nice. Not very compact when folded compared to the smaller wheel bikes.



Some folding bikes have a range of "folds", first fold might take less than a minute, and it is not as compact as it could be, but good enough to carry into a building. But a much more complicated fold to pack it into a piece of luggage. My Joey first fold below.



But it takes over an hour to disassemble my bike to fit into a case that meets airline specifications for non-oversize.



So, think about how you want to use the bike and why you want a folding bike.

I’ve never own one. So yes, new to it.

I’ve ridden a couple though, for a few hundred miles and over a few days. So not entirely unfamiliar with folder either. You can even call me a new convert.

Since both are from the same family. I’m guessing would be similar in other aspects. Unfortunately I’m only able to test ride the 20” wheel one.

ETRTO507 wheels (which originally was a BMX wheel size) are often used on long tail cargo bike and for these bikes the tires are usually wide, 50mm or more.

But for folding bikes with ETRTO507 wheels, not all frames are designed to accept wide tires because wide tires increase also the overall wheel diameter what increases the folded size of the bike. Helix is for this reason also limited to 40mm wide tires.

I think the old Tern Eclipse with 24" wheels where also limited in tire width (Tern switched to 26" wheels for the Eclipse due to the problems of availability of relatively narrow 24" tires)?

I got to borrow a Tern "Eclipse S11i" for a month to see how it would perform compared to a "Verge S11i", which was the bike I planned to get.
The ride is a bit smoother on the 24" wheels, but not a huge improvement in my opinion. The hydraulic disk brakes were amazing. Unfortunately, the larger bike was a bit unwieldy on the train portion of my commute. So I went with the Verge and have been very pleased with it. The V-brakes are more than adequate. HTH.


Here's the Eclipse on the METRA. It is workable, but noticeably more trouble to move around and store than the smaller Verge.

You just described my Airnimal Joey, soon after I bought mine they modified the design to take a more common wider tire. Unfortunately I bought one of the first ones.

You have not given us much info on why you want a folder, how you plan to use it, just that you want one.

Based on what you have said, I would say if you liked the ride on the 20 inch wheel folder, then get it. If you did not like the ride on it, keep looking.

If you said what the models you were looking at were, others that own them here could offer their opinions.

Long time ago, I had a bike with 24" - ETRTO520 wheels, technically this wheel size was a good choice but finding tires was a nightmare, there were only two types, the Schwalbe Durano 23x520 and the Panaracer Pasela 25x520, really available both narrow road tires what was a limiting factor for the use of the bike.

The tire is one of the most important component of bike that influence a lot its behavior and performances and only tires manufacturers can make high performances tires, bike companies are not able to do that themselves, they totally rely on tire manufacturers to provide tires for their bikes.

I didn’t given much information because I wasn’t sure what else I want to use it for.

But the primary reason is to use it for commuting. So I’ll be folding it daily to bring into the building, which involves going up and down stair too. The rides will be short (<30min) but on busy streets.

Thanks for those who responded. I think I’ve concluded I want the 20” wheels. It’s lighter and easier to carry once fold up. Even if the ride is better, the bulk and weight of the the 24” version is a bit much for my primary use.

Dahon was running a sale on their 24” model Brieza.

Personally, I'd stay away from a 24". Compared to 20", it does not pack away as well and I find the tyre choice is poor. A 20" bike with good tyres will ride better than a 24" with poor tyres.
I looked into 24" bike when the kids grew out of their 20" and I went of 650b/27.5" and 26" because of tyres, wheel choice, tubeless etc.

If you are after bigger wheel to roll over uneven terrain better, may be look into 26" folder that won't fold much worse than 24" but will come with many more Pros than the 24"

+1: high performances tires make the difference, they are more important than a relatively small overall wheel diameter difference..

Yup. When I ordered the frame and fork 19 years ago, I ordered three Schwalbe tires for it at the same time.

I was considering doing a bike tour on that bike a few years back. Looked for some folding tires, that was when I discovered that the tires in that size are almost impossible to find. But I found one manufacturer that made an expensive tire, I ordered several, probably have a lifetime supply. Did not do that bike tour, instead Covid occured and related travel shutdowns.

I ride that bike very little, I probably have less than 3k to 5k total miles on it, the original Schwalbe tires are still on it. So, for now I am set.

I used to travel a LOT for work, wanted a folding bike I could bring on trips for my off time. Built it up at about the same time I changed jobs, the new job did not involve any air travel. So, my reason for having the bike evaporated. Most years I do not even ride the bike. Retired 15 years ago.

Good call, folding and carrying up stairs every day, a 20 inch wheel makes much more sense.

Busy streets, be careful.

If you do not have a rear view mirror, get one. I prefer one on my helmet. A friend that I have done bike tours with prefers one mounted on his sunglasses.

A high visibility vest is a really good idea too. Preferably mesh so it is cool to wear when you are exerting yourself.

I used to commute on a motorcycle. After years of doing that I came to the conclusion that on overcast days, if I could not see my shadow, I was invisible. Meaning car drivers could not see me. And I drove that way, very defensively. But on bright sunny days, I was much safer, everyone could see me unless they were on their cell phone.

24" wheels (BTW., which 24" size, ETRTO507, ETRTO520, ETRTO540...?) do not necessarily ride better nor are necessarily more comfortable than 20" on bad roads, bumps... the most important is the tires and especially the tires width, wide tires (50mm or wider) with 20" wheels are better than 24" wheels with narrow tires.

For the riding behavior and bike efficiency, its the bike geometry and frame design that define them, not the wheel size.
[/QUOTE]

False. Tire diameter is one factor in how smoothly a bike rides. The larger the diameter, the lower down on the circle the tire hits bumps. Or, looked at another way, it doesn't fall as deeply into a hole or crack in the road as a smaller tire will.

Tire width and bike geometry are also factors, but so is tire diameter.

With all else being equal, the larger diameter tire will ride smoother; that's why "normal" bikes have bigger diameter tires and wheels. If there was not a reason to do this, they would be kept smaller for cost reasons, if nothing else.

True for the Eclipse, but their Node series still has 24" wheels:
https://www.ternbicycles.com/en/bikes/473/node

It's not that important to have a large selection of tires, as long as one is available and not too expensive that meets one's needs. In the case of the Node, Schwalbe Big Apple are supplied and I assume available. They're great tires; I have them on my Vektron and had them previously on a 16" Dahon.

False. Tire diameter is one factor in how smoothly a bike rides. The larger the diameter, the lower down on the circle the tire hits bumps. Or, looked at another way, it doesn't fall as deeply into a hole or crack in the road as a smaller tire will.

Tire width and bike geometry are also factors, but so is tire diameter.

With all else being equal, the larger diameter tire will ride smoother; that's why "normal" bikes have bigger diameter tires and wheels. If there was not a reason to do this, they would be kept smaller for cost reasons, if nothing else.[/QUOTE]

The Moulton experience demonstrated that it was possible to make a fast small wheel race bike till small wheels were banned.

And 20" wheels are only about 17% smaller than 24" wheels, its a minor difference that can easily be compensated by the higher performance tires available in 20".

Tire performances and frame performances have much more influence on the bike performances than the small diameter difference between 20" and 24".

This ^^. On my folding commuter bike, I find a bar-end mounted mirror is effective, and always there. I use a glasses-mounted mirror on my road bike and mountain (trail) bike. All these mirrors are from Third Eye Mirrors and I've been very pleased with their performance over many years.
But the most important thing is to use a mirror.

While I mostly agree with your post, I disagree with you on Moulton. I would say the Moulton experience demonstrated that it was possible to make a comfortable riding bike with small tires but not a fast one. Moulton bikes are not fast. The small wheels were banned not because they were fast but because they thought it gave the riders an advantage in drafting behind larger bikes. Again I would refer you to Bike Quarterly's review of the Moulton speed. The only legitimate record the Moulton holds is with the fairing and that is because the shape of the frame and small wheels gives allows for a lower profile fairing to be used.

Well... 24's are faster. This is true Better with bumps... generally, yes

You WILL sacrifice the size of your fold. No getting around that with current designs, so if your clearances are even REMOTELY close with storage space in your home, on a train, in your car, then a 24" folder is likely a bad choice.

All things are compromise.
Need the small fold AND a smooth ride, you can do it with 20" thicker tires..... but it'll be slower
Speed is everything? 24' or 26" or even a non folder

Bromptons fold REALLY small, and have rudimentary rear suspension.
(been a while since since I've ridden one so I don't know if you can tune them to be smooth and fast)

I'm on a 20" bi-fold with armored tires because puncture protection is my primary concern, fold size is a close second.
I added a custom suspension seat post and suck up the 2-5mph speed loss (schwalbe marathons)
((tried 1.25" at 100+ PSI and got the speed back but the ride was violent))

At the same pressure and with a similar structure, wider tires have a lower rolling resistance and are faster.

This is the reason why road race bikes use wider and wider tires, moving from (long time ago) 19mm wide tires to 21, 23, 25 and nowadays 28 or 30 or even 32mm wide tires. The reason why they were previously using narrow tires was aerodynamics but bike manufacturers discovered that aerodynamics was not mainly defined by width but more by tire+rim shape and that it was possible to have as efficient wheels with wide tires and well shaped rim than with narrow tires and therefore having both a low rolling resistance an an excellent aerodynamics with wide tires and rims designed for wide tires.

So, due to the very limited availability of 24" tires up to 40mm wide, a 20" wheels with a wider high performance tire will be faster than a 24" wheel with the few available narrow tires.

Note also that the use of wider tire on a 20" wheel reduces even further the overall wheel diameter difference, for instance Helix with max 40x507 vs. Brompton G-line or Bike Friday with max 55x406: the overall wheel diameter difference drop to only about 12%!

Tire/wheel availability for 24" is also much more limited. I certainly agree
I also agree with the tire size and wheel design.

My comments are general.
With enough engineering, you can overcome any limitation, but it always costs something.

Folding bikes are an additional and substantial compromise to cost, weight, speed, rigidity, strength, and ride.

If storage space or enclosed transportation are NOT a factor, I make best efforts to avoid folding bikes all together.
24" bikes border on the edge of not needing to fold in the first place.

That said, there seems to be in theory a lot of the BMX tyres discussed in the Trail Tires thread available in 507 size. A quick glance at the Maxxis website shows a fair few options for wider grippier treads.

Yes, true and there are also several touring tires (meant for cargo bikes with ETRTO507 wheels) but all 50mm wide or more.

What is missing is 40mm wide or less high performances tires (there was a Schwalbe Kojak with decent performances when the Helix project was started in 2015, but that size was discontinued by Schwalbe), its the reason why Helix asked a small company to make a special narrow lightweight tire for Helix but, as far as I know, its only available from Helix?

Note also that most BMX tires since they are not meant to be used on open roads have a limited puncture resistance.

Jipe, your analysis of 24" vs. 20" seems to focus on rolling resistance of the tires, but ignores that the greater leverage from the larger radius has makes the hubs work better.

I would argue that the ride can be BETTER on a folder for a given wheel/tire BECAUSE of the lower rigidity.
I think it's one of the reasons Bromptons ride pretty well, despite going on 16" wheels and 100 psi tires. There's all that frame flex, plus seat post and handle post flex absorbing energy.