Sentinel1

I've owned the Tern Verge X11 for 7 years. It was expensive yes. £2,400 when I bought it.But it is an incredible bike. And in the last 7 years its made my money back over 8 times over in the money I've saved on public transport. As someone who never owned a car. I wanted a bike that could take me from one side of London to the other. Could handle any hill.

As fast as a full sized bike of the same weight. Reliable and easy on the eye. And could fold up in emergencies for other transport. The Tern Verge X11 answered all the questions.

If you want the best it's gonna cost more. But when you have a bike of this quality. You will want no more. And it delivers on performance and reliability.

Derailed

Sweet! Around the same time I was very tempted by this bike. At the time, I couldn't decide between it and a Bike Friday, but was very impressed by X11. I recall wishing that there were more reviews of it. I'm sure at some point I'll feel feel a renewed desire to get a do-everything folder, and I'll be sure to keep your comments in mind

Duragrouch

I went permanently 20" wheel folder ten years ago, however it was only two years ago that I expanded the gearing on it to get the lows it missed from the factory. I don't fold it often, but when I need to, it's great. Have taken a train trip with it. Not flown yet, would be a lot more hassle, trying to squeeze it down to checked bag size, I'd probably need to split it into two checked bags, if checked bags were free. A Brompton would be easier to travel with, but considerably more difficult to fit racks that could hold conventional panniers without scraping the ground or interfering with pedaling, and they would also impede the fold; Most Brompton travelers put things in a backpack sitting on the rear rack and strapped to the seatpost, and a big handlebar bag. My folder is my townie, used for shopping, I need the panniers. Even with upgraded gearing, it was a small fraction of the price of the Verge, but at the time, I had to grow my own to get it how I wanted. I also want 406 wheels and not 451, for the greater tire size selection and lower price. But the Verge packs a lot for someone that wants a turn-key ready bike with the capabilities they need.

Sentinel1

I have a Dahon Helios XX too. Only 300 were ever made to celebrate Dahons 20th anniversary in 2002. And its the lightest 20 inch folder ever made. Weighing about the same as the new Brompton T line 7.7KG.

But the ride experience on the X11 is very different. With the X11 uou truly forge you're on a folder. It's so solid and handles like a full sized bike. At the same time you get that small wheel acceleration. From a stop. It really is the best of both worlds. And although the tire selection is more limited for a 451 wheelset. There is a tire called VEE SPEEDSTERS. And they are awesome. They come in 1 3/8 width. And they are a great alrounder. Fast low rolling resistance. And super grippy. I've ever gone off road with the X11. And it can handle it. The bike is amazing. After you ride an X11 you never look back I'm telling you. And it's addictive. You cannot wait until your next ride.

You can take curbs. Potholes and rough roads are handled much better than 406 wheels. And you power transfer from foot to road is amazing. I've had guys on road bikes flag me down. To ask me about this bike. When you tail a road bike for several miles or even overtake them. They get curious. The X11 Can break 28mph on the flat. It's an awesome bike.

Duragrouch

(above) Glad the bike is fast. 451 wheels help for that. But, respectfully, there is no way 451x1-3/8" can handle potholes as well as 406x1.75" and most especially 2.0". There is marginal difference in outside diameter but a much larger percent difference in section height. This is why I don't run low-profile tires on my car, they bend rims on potholes. This is also why someone on the forum runs 16"/305 with FAT tires instead of 16"/349 with skinnier tires; About the same outside diameter but a lot more cushion with 305 fat. That example is within ***1mm*** of the difference between 451 and 406.

Speed is nice, I rode a road-race bike for many years on 700Cx23, then 700Cx28 because it made a big difference in ride and rim durability. My folder now matters less for speed, than for cargo ability for shopping as a townie, and trips. Pic below is before I put larger tires on it:

Ron Damon

That's right, Grouch.


58-305


58-406

​​​​​​

Jipe

I fully agree: ETRTO406 + 50mm wider (or even wider) fast tires is better than ETRTO451 + 1 3/8 tires.

The overall wheel diameter is almost the same (less than 3% difference) and wide tires are much better, the whole bicycle industry, for all types of bicycles, is moving to wider tires!

Sentinel1

Not on hills. The whole reason I bought the X11 was where I live there's a tonne of hills to navigate. I had a folder with 406 wheels and two inch wide tires. It was like trying to ride a tank uphill. What alot of people don't realize is the rotational weight of the wheels make a helluva lot of difference. To how much the ride takes out of your legs. This is why the 451 wheelset with vee speedster 35mm wide tires is perfection. And the rolling resistance is still very low. And I can fly up hills at 8--10mph that once would have killed me to get up at even 6 mph.

And while yes the industry is moving towards wider tires there are diminishing returns at both ends of the spectrum. Too narrow 19 to 25MM and the ride is uncomfortable and the wheelset prone to easy damage. Too big and the wheels are too heavy and the speed is compromised. The SWEET SPOT really is the mid 30s. 32 to 37mm is absolute perfection. From a road bike to a touring bike

Jipe

It depends of course of the tires!

If you put heavy wide ETRTO406 tires, it won't do the job.

Even on hills, if you mount a lightweight fast wide tire on a ETRTO406, it will be faster than ETRTO451.

A small overall wheel diameter won't change anything, try ETRTO406 with Greenspeed Scorcher 40x406 (the fastest ETRTO406 tire, much lower rolling resistance than any ETRTO451 tire), you will fly on your hills!

noglider 

@Sentinel1, each person has their own sweet spot. I happen to agree with you on where it is, but it's a function of the kind of riding you do and your conditioning.

Sentinel1

I've tried them all and nothing beats VEE Speedsters. And I've off roaded with them too. The 451 wheelset has superior handling to the 406. Especially on rougher roads. And off road. There no getting away from that. You have to experience it to understand. I've got both sized wheelsets.

The Dahon helios XX runs 406 wheels with Vee Speedster 40mm tires. The bike weighs 8.4KG with those tires.

The Tern Verge X11 run 451 wheels with Vee Speedster 35mm tires. The bike weighs 11kg with those tires.

The X11 has superior speed and handling on all terrains. Those 451 wheels eat up the miles better. That's why it's able to live with most non professional roadies. The Helios is a fast bike too. But not as fast as the X11. And if I have to ride across London (21 MILES) to see family..Its a no brainer which bike I'm going on. If I am doing short journeys or going shopping. I will jump on the Helios.

Fentuz

this is the same discussion as 650b or 700c. The bigger the total outer diameter is the less susceptible to road bumps it is. At equal weight, the small wheel will accelerate faster, on hill climb, a fast rolling tyre on a small wheel will be faster and if that tyre is a larger volume, you can put less air, get better deformation and therefore smoother ride.
Having said that, a equal weight, on flat, the larger wheel may be faster than the smaller one as it will store more potential energy and will require less input to keep going. The perceived required effort to and small climb from rolling start will be less on bigger wheel too. From a stationary start, smaller will win.

All in all, it is about momentum conservation, the system that requires the less energy to increase/keep the speed is the winner of the given situation.

for example, my 20" minivelo has the same gearing as my gravel bike and tyres with similar rolling resistance yet, I ride much faster on the gravel than the minivelo.
Tyre wide, I tested panaracer gravel king slick 35mm 700c vs Continental speed king 50mm 650b; despite being 15mm wider on 650b and a over diameter and little smaller, the speed king is much much faster and has a lower RR @ 20-22psi than the gravel king @ 35psi. The result is faster and more comfortable...

Note that the german and dutch pedal car racing organiser have done back to back test and the best tyre was conti contact Urban; it was also better that the conti contact speed
https://wimschermer.blogspot.com/202...ental.html?m=1

Jipe

Wim Schermer is dutch guy and is a velomobile user (he has a Quest).

Its tire tests are dedicated for tires used on velomobiles who have small wheels on the font (most have ETRTO406).

The fastest tires are the Greenspeed Scorcher 120, I tested them myself compared to the excellent Continental Contact Urban and indeed they are faster.

The comparison was done with my Moulton Speed small wheels race bike (high performance stainless steel frame, weight is under 9kg depending on the tires) with aero wheels that uses ETRTO406 wheels.

Fentuz

yes, but I don't seem to be able to get them easily in the UK (at reasonable price) and my wheels take 35c max

Fentuz

Oh yes and I forgot to mention that if you want to go faster, TPU inner tubes like tubolitos reduce RR and the gain is noticeable however, if you get a puncture, make sure you have spare tubes because you cannot repair/patch quickly these inner tube at road side (they are the reason I moved to tubeless for CX/XC and gravel)

Schwinnsta

To my recollection, Primo Comets on the Brompton is a better ride than the Conti Contacts I have on it now. They are plush and fast. If you get them at a cheap price and if you're not flat tire averse, then they sense. They do wear fast, and they are more prone to flats, particularly as they wear. I should get a set again, but I am happy with the Contacts. I think I may be talking myself into a set.

Fentuz

i like the contact urban (well I did nt like the reflective strip but that s cosmetic). The side wall perished with all the winter salt so put back a set of kojak because i couldn t be bother to order new tyres and i could nt see to point as i ise the minivelo as training bike ( don t clean much and ride it anywhere!despite weather).

Jipe

I had a very bad experience with ETRTO406 Tubolito for narrow tires (28x406): 3 leaked slowly without possibility to locate the place where they were leaking because its not possible to put pressure on them if they aren't in a tire (if you try to put some pressure, they explode like a bubblegum).

Tubolito exchanged the two first ones.

The fourth I had died with a real puncture in a type of tires I never had punctures with butyl inner tires previously !? The special patches didn't last long (it was the first type of self adhesive patches, Tubolito has now a new type with glue).

Sentinel1

Never skimp on inner tubes. For the sake of a bit of weight saving unless you are a pro cyclist its not worth it on rough uneven roads. I stick with schwalbe tubes and still get plenty of speed. Some things are taken too far by ordinary everyday cyclists. It's like these weight weenies using fragile carbon brakes to save a few grams. Imagine they snap when you are going 30 plus miles an hour down a steep hill. I know someone paralysed from crashing their bike into a wall. When their brakes snapped at high speed.

Nobodies life or health is worth it.

Duragrouch

Yes, I was talking about you, and thought of giving attribution, but thought I should not mention your name without permission. Some on the forum are sensitive to being quoted or perhaps mentioned.

Duragrouch

Maybe yes and maybe no. As someone with extensive experience in vehicle dynamics, I know that you need to consider independently, tire performance versus chassis performance. Sometimes this can be tricky because, in all new designs, tires are chosen first, and the chassis designed around that tire characteristics.

Given the same bike chassis, you will feel a difference between skinny 451 and fatter 406, simply because of the difference in rotating mass. But it gets especially weird in comparisons unless both forks were designed for their given tires, because in 20" especially, even a small difference in outside radius will change the fork trial/caster significantly, larger diameter tires yielding greater trail, smaller diameter yielding less trail, given the same fork geometry. And in terms of geometry, fork trail has the greatest effect on steering stability versus agility, or "handling feel". For some, "good handling" means stable steering and the ability to ride no-handed and inspiring confidence on fast descents and turns, others it means agility in traffic, even at the expense of stability. Usually, on bicycles, it rarely means lateral traction and the ability to corner at high speeds near the traction limit, because unlike 4 wheel vehicles which can "drift" with stability with expertise, this is extremely difficult to do with 2 wheel vehicles, to operate at the limit of adhesion, and I have only seen top road-race motorcyclists do this with the bike not fully leaned, but more upright, with the rider hung far out near the pavement, to allow the tire to be more upright to have more rubber on the ground, operating very near the limit of adhesion, and that is an extremely rare skill. I don't see this even with top racing bicyclists. Plus it puts a heck of a lot of lateral force on the wheel, and introduces "slip angle" as a steering component, where sidewall stiffness has a great effect on steering geometry and not just ride, whereas 2-wheel bike tires typically operate more as "camber thrust" in steering. Which is why, putting a "bike" tire on a low trike that can do hard turns, is loading the tire in a way that was not designed.

So... when you say 451 handles better... in what way?

Sentinel1

In every wev. They barrel up to speed easier. And staying over 20mph is easier. More efficient. The routes that used to feel rough on my 20 inch Dahon. I glide over on the X11. The ride is more stable. I Corner at Greater speed. I can go off road and run over uneven paths alot better. Jump on and off deep curbs.

You feel like you can do anything on an X11. On a smaller wheel folder. You feel the limitations.

Duragrouch

Most of what you are saying equates to better rolling efficiency. Which a skinnier 451 should be superior to a wider/deeper 406, though not necessarily; Bicycle Quarterly and GCN have both tested wider road tires and gotten equal rolling resistance, sometimes even better, if they are supple enough to absorb the small vibrations present in typical pavement, not an indoor bike track, but can have higher aero drag. If the 451s feel "smoother", it is not due to the size per se, the outside diameter is nearly identical, it's that the specific 451 tires probably have a thinner, more supple tread area, in comparison to the 406s. I think a 406 with similar design and quality tires in the same section height would roll just as smooth, and in a higher section height, even smoother, provided the tread area is not too thick and stiff.

The (leaned) cornering ability you speak of is very dependent on the tire shape, in terms of a smooth blend of tread to sidewall, and again, your *specific* 451 tire is probably good in that respect. A 406 tire where that area is a bit more "squared off", will not corner hard well, and most especially if treaded there and not smooth.

So my point is, it's not the 451 size, but the quality of tire. Put the same quality tire on 406, and have fork geometry tuned to each size, and you get extremely close results, because they are extremely close in size.

Until now at least, 406 is a more versatile size, where you can get smooth and racy tires as well as treaded for off-road. I think 451 tires are more narrow selection to sporty road tires, although that could have changed.

Used to be the same with 26" vs 700c, you could find any tire in 26" including smooth/baldy/kojak road tires, whereas 700c was generally more limited, a store might stock a cyclocross tire in 700c. But now we have 29er tires, very deep section on 700c rims, in aggressive treads, if your frame has the clearance for them.

In automotive road tests, with sporty cars coming with different tires, it's extremely important to know how much handling is due to the vehicle and suspension design, and how much due to tires, as the tires can be changed.

Jipe

The tire structure is a key element for the tire behavior.

To make a fair comparison between a wider and narrower tire, the tire structure should be the same.

The second element is pressure. On perfect surface; higher pressure reduces the rolling resistance. But on bad surface like off-road its the opposite. A real average road is somewhere in between. To make a fair comparison, the pressure should be the same.

With the same structure and pressure, it has been demonstrated that a wider tire has lower rolling resistance.

The overall diameter has also an influence, a higher diameter reduces the rolling resistance but, as already explained, between ETRTO406 with a wider tire and ETRTO451 with a narrower tire, the difference in overall diameter is very small, too small to have a real influence.

The inner tire has also an influence on rolling resistance, not only for its weight, but also because it influences the deformation of the tire. Latex and TPU inner tubes give a lower rolling resistance than Butyl inner tubes.

Besides rolling resistance, there is also air resistance: long time ago, it was considered that narrower tire were better, less resistance. But nowadays, things changed, and we know that its a combination of the tire and rim: with matching tire and rim, its possible to have as low air resistance with a wider tire. The shape of the wheel side where tire and rim joint is a key element for the wheel aerodynamics, a good shape will reduce turbulence's. Its the reason why bicycle rim width is also increasing.

Of course, to make any valid comparison between tires and wheels, the same bike should be used.

Schwalbe has a short but clear explanation about tire rolling resistance: https://www.schwalbe.com/en/technolo...ng-resistance/

I also made some own comparison af several wheel sizes, tire width and tire types on my Birdy Titanium that allow several wheel size because it has disc brakes. I tested 3 wheel sizes and 3 types of tires:
- ETRTO349 with Continental Contact Urban 35x349 and Greenspeed Scorcher 40x349.
- ETRTO355 with Big Apple 50x355 (because there are no Big Apple nor any other 50mm wide tire in ETRTO349).
- ETRTO406 with Continental Contact Urban 32x406 (there are also wider tires in ETRTO406 including Scorcher 40x406 but the Birdy frame does not accept tires wider than about 35mm in ETRTO406).

The faster configuration was the 40x349 with Greenspeed Scorcher. The 32x406 maybe rolls better than the 35x349 Conti Contact Urban but the bigger wheels had more inertia and this was more noticeable than the lower rolling resistance.

Between the 35x349, 50x355 and 32x406, the faster and most pleasant to ride on average to bad surface was the 50x355 due to the wider tire and lower pressure. The two Conti's were much less comfortable than the Big Apple.
I am now using mainly the Big Apple wheelset because the Greenspeed Scorcher are slick pure road tires and are not usable on trails, too fragile for trails with stones, slippery on wet trails.
The ETRTO406 wheels were the less pleasant to ride due to the higher inertia that changes the Birdy behavior (I must also say that I do not fully understand why the Birdy behavior is so different between the 32x406 and 50x355 since both have almost the same overall diameter and the Big Apple are heavier than the Conti's ???).

The 3 wheelsets for the tests were very similar, same hubs (Hubsmith front, Hope rear with SRAM XDR freewheel), same type of spokes (Sapim CX-ray), similar rims (I could not find the same type of rims in the three rim sizes, of course, the ETRTO406 rim was slightly heavier and spokes longer so also slightly heavier), same cassette (Ethirtheen).

Ron Damon

Unless you hand over the dataset and we can verify the differences you cite via, say, an ANOVA, it's all rather subjective and uncontrolled, with confounding factors aplenty. Are the differences statistically significant? Data or it doesn't mean anything.