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review

BTwin Ultra Compact 1 Second Light

7
£849.99

VERDICT:

7
10
Compact folder with some very clever details and welcome extras
Low weight
Easy & quick to fold & unfold
Easy to carry
Very compact fold
Mudguards, lights & folding pedals included
Harsh ride
Twitchy handling
88kg effective total load limit
Weight: 
12,300g

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The Btwin Ultra Compact 1 Second Light packs small, is easy to carry and includes a range of features that make it excellent value for money. Reservations about the handling limit its versatility, but if your ride to the station is more or less flat, it's a viable alternative to a Brompton.

If you're interested in the BTwin Ultra Compact 1 Second Light, check out our guide to the best folding bikes for more options.

2023 BTwin Ultra compact 1 second light folding bike - folded 1.jpg

The Ultra Compact 1 Second Light (which I'm mostly going to just call Ultra Compact from now on) folds into a very compact package, and presents nimble handling that's good for nipping around town and dodging potholes, but you might find it's a bit TOO nimble.

The unique feature and best thing about the Ultra Compact is the brilliantly engineered One Second hinges in the main frame and handlebar stem.

2023 BTwin Ultra compact 1 second light folding bike - frame hinge.jpg
2023 BTwin Ultra compact 1 second light folding bike - frame lever.jpg

When you unfold the bike, these snap into place with a very solid click as internal springs pull them closed and their latches lock them into place. You don't have to do anything else. There's no twiddling wingnuts or manually closing quick-release levers. This makes for an incredibly quick transition from portable to rideable.

The ride

The Ultra Compact has a very upright riding position; the handlebar is high and close to the saddle. It's a good position for threading your way through traffic, but it's a bit too upright for my taste. Fortunately the handlebar has a couple of inches of rise, so rotating it forward adds enough reach for me to get comfy.

Decathlon recommends you run the tyres of the Ultra Compact at a pressure of 6 bar (90psi). That's really high for 1.5in/38mm tyres, and as you'd expect it produces a very firm ride. It's buzzy and harsh over anything but perfectly smooth tarmac, and you really feel the impact of potholes and other road imperfections.

However, that high pressure does help compensate for the inherently high rolling resistance of a 16-inch tyre so with the tyres cranked up like this, the Ultra Compact zips along very nicely, if you can put up with the harsh ride. Messing around with the tyre pressures, I ended up at 40-50psi as an acceptable compromise.

2023 BTwin Ultra compact 1 second light folding bike - riding 4.jpg

Speaking of 16-inch tyres, the Ultra Compact's 16-inch tyres are not the same as Brompton's 16-inch tyres. These 1.5in tyres have an ETRTO designation of 38-305; Brompton uses 16 x 1 3/8in tyres, which are 35-349. If you want to go down the rabbit hole of why bike tyre sizing is a stupendous fustercluck, the late great Sheldon Brown covered it extensively in all its mind-mangling stupidity. 

2023 BTwin Ultra compact 1 second light folding bike - tyre.jpg

The practical upshot is that the Ultra Compact's wheels are smaller than a Brompton's by about 4cm and the Brompton has a slightly smoother ride as a result. On paper 38-305 tyres should be 381mm from tread to tread, which is 15 inches in old money, but these are more like 15 1/2 inches because the Schwalbe Marathon Racer tyres are taller than they are wide.

2023 BTwin Ultra compact 1 second light folding bike - riding 3.jpg

I asked François Poupart, the project engineer for Decathlon's folding bikes, why they'd gone for that wheel size rather than the Brompton-style 35-349 and he told me that Decathlon's customers had 'expressed to us a greater need for compactness, ease of folding and unfolding and more lightness. We therefore opted for a folding mechanism with 2 hinges for [better] ergonomics with 38-305 tires. It seems to us to be the best compromise to achieve these objectives'.

Like many small-wheeled bikes, the Ultra Compact's handling is very immediate, verging on twitchy; the slightest turn of the handlebar yields a very rapid change of direction, and above about 30km/h (20mph) it's downright scary.

That's almost certainly a function of the steering geometry, which, according to François Poupart, comprises a 74-degree head angle and 35mm fork offset.

2023 BTwin Ultra compact 1 second light folding bike - riding 2.jpg

A bike's handling is largely determined by its trail, the distance between the point where the front wheel touches the ground and the intersection of the ground and a line drawn down the steering axis. On the whole, more trail gives increased stability. The combination of head angle, fork offset and overall wheel size determines the trail. Trail decreases if you make the wheels smaller, the head angle steeper or the fork offset greater.

Steering geometry (public domain image via Wikimedia Commons)

Bikes that exhibit stable handling typically have about 50-60mm of trail; the Ultra Compact has 18mm of trail, which accounts for its flighty manners.

Weighty matters

The Ultra Compact has a 100kg weight limit including the bike, above which you void the warranty. If you weigh more than 85kg or so and you're carrying, say, a backpack with laptop, various spares and a jacket, and wearing anything but the lightest clothes, you could easily exceed that.

The load limit for a Brompton is 110kg, and that doesn't include the bike.

The frame

The Ultra Compact is welded from good old 6061 aluminium, but that's where the resemblance to a run-of-the-mill bike ends. Like many folders it has a single hinged main beam, but out back there's just one seatstay and one chainstay, while up front the wheel is supported by a single leg (so technically it's not a 'fork').

2023 BTwin Ultra compact 1 second light folding bike - frame shape.jpg

Losing a fork leg and a seatstay and chainstay makes for a more compact fold than most because it gets the wheels closer together. It also allows Decathlon's designers to put a magnet on the front wheel and a steel piece on the rear to hold the two together when the bike's folded.

2023 BTwin Ultra compact 1 second light folding bike - front mudguard.jpg

Rather than paint the frame, Decathlon has chosen to coat the brushed aluminium with smoky varnish so that no two bikes are identical.

2023 BTwin Ultra compact 1 second light folding bike - rear.jpg

The fold

Rather than just putting bog-standard hinges in the frame and handlebar stem like almost every other folder ever, Decathlon has used hinges with sprung articulations to pull the hinge shut when it gets near to the closed position. The latches then close to hold the hinge together, so, as already mentioned, you don't have to do anything else.

2023 BTwin Ultra compact 1 second light folding bike - seat post lever.jpg

There's one hinge in the main body of the frame and one in the handlebar stem. The seatpost slides down into the frame to make everything smaller, or stays up so you can wheel the bike around while holding the saddle.

2023 BTwin Ultra compact 1 second light folding bike - folded push along mode.jpg

To fold the Ultra Compact, you break it in the middle first and swing the front wheel round to the back wheel, where magnets grab each other to hold the folded bike together. As I said above, to make the folded bike narrower, there's no seatstay or fork leg on the sides where the two meet; both fork and rear triangle are single-sided. Clever stuff.

2023 BTwin Ultra compact 1 second light folding bike - folded 3.jpg

When you slide the seatpost down into the frame it rotates so that the handle under the saddle faces backwards and is in a better place to lift the bike. When the post gets right to the bottom of its movement, a pair of little feet pop out of the bottom to provide a stand to support the folded bike. More clever stuff.

2023 BTwin Ultra compact 1 second light folding bike - folded 2.jpg

Decathlon claims it folds down to 71 x 69.5 x 35cm; I made it 71 x 71 x 35.5cm. Brompton is claimed to be 58.5 x 56.5 x 27cm but the Brompton I've just measured came in at 63 x 61 x 29cm. The Ultra Compact doesn't fold quite as small as a Brompton, then, but it's still pretty good. It's certainly small enough to fit easily in the kinds of places you'll want to stow a folder: train luggage areas, under your desk and the like. And at 12.3kg, lifting it's not too onerous.

Lights

The bike comes with a pair of LED lights that clip into a mount on the handlebar and onto the saddle rails. In the top of the box there's a double-ended micro USB cable to charge them. Plug them in and they flash red to let you know they're charging, then small green LEDs light up to tell you they're fully charged.

2023 BTwin Ultra compact 1 second light folding bike - front light.jpg

These are basic units for being seen rather than seeing, but it's nice to get them included in the package.

2023 BTwin Ultra compact 1 second light folding bike - saddle and light.jpg

Components

It's unusual to see off-the-peg derailleur gears on a bike with 16-inch wheels because the bottom of the derailleur ends up perilously close to the ground. Decathlon has used the short-cage version of the Shimano Sora rear derailleur which clears by just a couple of centimetres. It's gone with an 11-28 cassette for a 254% gear range, even though the derailleur is theoretically capable of handling 11-32 for a 290% range that's closer to the 300% range of some Bromptons.

2023 BTwin Ultra compact 1 second light folding bike - rear mech.jpg

The gear range is pitched low, with a top of 73 inches and a low of 29 inches, so you're not going to be winning any sprints, but it's practical around town and for most urban and suburban hills in the UK. The lower gear provided by an 11-32 cassette wouldn't hurt, though.

2023 BTwin Ultra compact 1 second light folding bike - crank.jpg

Decathlon feels the gear range is adequate. François Poupart told me: 'This is a bike made for riding in town with 16in wheels which therefore turn very quickly when riding at 25km/h. In addition, we have done a lot of tests to validate our product.'

From those tests, Poupart and his team concluded that they'd actually like to have a higher top gear, but there's no straightforward way of doing this at the moment. Shimano used to offer a groupset specifically for small-wheeled bikes called Capreo, with a nine-tooth small sprocket. 'The Capreo System would have been a great choice for this bike,' Poupart told me. 'Unfortunately, it's no longer available for OEM products.'

If you were slightly mad you could probably do something with a SRAM AXS system, fitting a 10-33 cassette, a compact rear derailleur like a Rival road mech, and a mountain bike shifter.

Stopping is by a pair of anonymous V-brakes. They're adequate, but they end up feeling spongy because of the unsupported brake pads and long runs of fully-enclosed cable needed to make the fold work. Hydraulic discs as on the Carrera Intercity Disc 9 that Matt reviewed would be better, but implementing them with the single-sided aspects of the design would be tricky.

2023 BTwin Ultra compact 1 second light folding bike - rear brake.jpg

The plastic-bodied folding pedals are easy to use and surprisingly grippy. Brompton's metal folding pedal is a more elegant design that takes up less space, but both do a good job of taking up less precious hallway space.

2023 BTwin Ultra compact 1 second light folding bike - folding pedal.jpg

At the top of the lengthy seatpost, the Btwin own-brand saddle is well padded and comfortable. And it incorporates that handle to make carrying the bike easier.

2023 BTwin Ultra compact 1 second light folding bike - saddle.jpg

The custom mudguards each have a single steel stay with a plastic cover to make them look tidier. In another of the bike's many clever touches, the front mudguard stay provides routing for the brake cable so it's out of the way when you fold the bike. However, if you wanted to fit fatter tyres to the Ultra Compact, the mudguards are almost certainly going to be the limiting factor. You might get a 1.75in/44mm Schwalbe Marathon or Road Cruiser under them, but it doesn't look like a 2.0in/50mm Big Apple would fit.

2023 BTwin Ultra compact 1 second light folding bike - front mudguard 2.jpg

Optional extras

Decathlon offers a small range of accessories tailored to the UltraCompact. There's a £27.99 protective cover, a OneSecondClip messenger bag that mounts on the front of the frame, and a phone case that clips into a quarter-turn mount on the top of the handlebar stem. The mount looks like a Garmin or Bryton mount, but while Garmin and Bryton devices will both go into it, they both end up a bit loose.

Rivals

For several decades the folder of choice among British multi-modal travellers has been the Brompton, with its low weight and incredibly clever fold. But Bromptons have got steadily more expensive over the years: the base model is now £925 from Halfords for a bare bike with a three-speed hub and without folding pedals.

For £75 less, the Btwin Ultra Compact comes with lights and mudguards, 9-speed gearing, folding pedals and a kickstand (though the ability to fold a Brompton's rear triangle under the bike makes a kickstand unnecessary).

The Btwin Ultra Compact therefore bears comparison with more expensive Bromptons like the C Line Explore that we tested in February 2023. 

Tern is one of very few other folder makers in this price bracket. The well-regarded Tern Link C8 costs £850 and while its 20-inch wheels mean it doesn't fold as small as the Ultra Compact, they do offer a smoother ride.

Conclusions

I've made a lot of comparisons with Bromptons in this review and I think that's unavoidable considering the Ultra Compact's price and 16-inch wheels. The Ultra Compact isn't quite a Brompton killer but, setting aside my reservations about the handling, it's a very good value folder that boasts lots of clever engineering.

Even more so than the Brompton, this is a bike with a very tight focus on getting you from your door to a train station or bus stop. While people can and do tour on Bromptons, the Ultra Compact's twitchy handling and firm ride make longer rides rather wearying, and it doesn't have the Brompton's basic but effective rear suspension to cosset your bum.

But what it does have is brilliant hinges that unfold incredibly quickly; clever details like the swivelling seatpost and its internal foot; and lots of welcome extras you often don't find on a folder at this price like lights and mudguards.

The Ultra Compact is a short-journey, multi-mode specialist, and a very good one.

As for the handling, well, to a certain extent bike handling and stability is a matter of taste, but the Ultra Compact's short trail is so far out of the bike geometry mainstream that you should certainly test ride before buying.

Who should buy the BTwin Ultra Compact 1 Second Light?

This is the right bike for you if you weigh less than 85kg and have a short, flat journey to catch a train or bus, say less than about five miles. In that use-case, you probably won't be on the bike long enough to find the handling annoying, and the Ultra Compact's quick fold to a small package really comes into its own.

Verdict

Compact folder with some very clever details and welcome extras

If you're thinking of buying this product using a cashback deal why not use the road.cc Top Cashback page and get some top cashback while helping to support your favourite independent cycling website

road.cc test report

Make and model: BTwin Ultra compact 1 second light folding bike

Size tested: n/a

About the bike

List the components used to build up the bike.

Frame: 6061 T6 aluminium, brushed with smoky varnish

Fork: Single-arm, 6061-T6 aluminium

Folding & fastening system: articulated hinges with chunky quick-release levers. Magnets to hold frame together when folded

Claimed dimensions

Folded (L/H/W): 71 x 69.5 x 35 cm

Unfolded (L/H/W): 129 x 107 x 57 cm

Total load limit (bike + user + luggage):

Brakes: V-brakes

Wheels: 16-inch, single-walled, machined rims. Reinforced single-sided hubs with sealed ball bearings (the same technology that we use on our road bikes).

Tyres: Schwalbe Marathon Racer 16 x 1.50 with reflective sidewalls; Schrader valves

Rear derailleur: Shimano Sora 9-speed

Shifter: Shimano Sora trigger

Cassette: 11-28

Chainset: 170mm square taper cranks, 52-tooth chainring

Gear range: 30 to 76 inches

Pedals: plastic-bodied folding

Seatpost: BTwin aluminium 34.9mm with built-in stand

Saddle: BTwin ergonomic with handle & height markings

Stem: aluminium, folding, not height adjustable

Handlebar: aluminium, 22.2 mm centre diameter, 560 mm wide

Extras: LED front and rear lights, USB chargeable; mudguards; kickstand; USB charge cable

Tell us what the bike is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?

It's a light folding bike with a very compact fold and several unique and very clever features.

Decathlon says:

What makes us special

Our dream was to give you a superpower:

the power to instantly transform your bike!

After all, who hasn't ever wished they could switch from cyclist to pedestrian to passenger in just 1 second?

It's now totally possible thanks to the patented automatic locking hinges developed by our design team in Lille, France.

Your Fold Light 1 Second will adapt to your needs in an instant.

So your transitions will become a real pleasure!

Designed for commuters who want an ultra-compact bike that they can take anywhere. It lets you switch from walking to cycling in 1 motion and 1 second!

With its 16" wheels and its single-arm aluminium frame and fork, this bike is the most compact in our range. This makes it the perfect partner for tight spaces like trains, the underground and lifts!

Easy opening / closing

It's so easy to fold up. And it takes just 1 motion, and 1 SECOND, to unfold!

Compact design

16'' wheels. Single-arm frame and fork. Take it anywhere! (underground, office)

Efficiency

Go further and faster with its 9 gears. It adapts to suit your journeys.

Lightweight

Weighs just 12 kg. Very balanced when you carry it folded up. No need to worry about steps.

Cycling comfort

Ergonomic grips. Comfortable, seamless foam saddle. 70° back position

Easy to move

This bike rolls along brilliantly when folded up! Push and steer it with just 1 hand!

Ease of use

Designed to be comfortable to hold and steer. Automatically locking hinges.

Easy transport

The handle under the saddle makes it easy to carry.

The story behind the design

To help them tackle this technical challenge, our design team turned to the experts at the Decathlon Sports Lab R&D centre in Lille, France.

This network of ergonomists, human science engineers and human body specialists helped us to find the best possible ergonomic set-up for:

- carrying

- steering

- posture

We carried out numerous tests (perception, use, fatigue) in the lab and in real-life conditions.

Incredible: unfolds in just 1 motion and 1 SECOND! And easy to fold too!

We want to make your transitions quick, smooth and easy with a simple folding and unfolding system.

UNFOLDING:

Incredible, in just 1 motion and 1 SECOND!

There's no need to touch the hinges at this stage thanks to the patented automatic locking system that's exclusive to Decathlon.

FOLDING:

The easy-to-locate levers make the hinges simple to operate.

The chunky levers have rounded edges so that they're comfortable to grasp.

Frame

6061 T6 aluminium frame that's lightweight, dynamic and sturdy.

The single-arm frame design makes the bike narrow when folded.

In fact, it's only 35 cm wide. That's 20% more compact than our 20" folding bikes.

Fork

Single-arm, 6061-T6 aluminium frame for less weight and more strength.

The single-arm fork design makes the bike incredibly narrow when folded.

In fact, it's only 35 cm wide. That's 20% more compact than our 20" folding bikes.

We've also used topology optimisation to develop a more "open" frame.

This technology ensures that we use just the right amount of material while retaining the necessary rigidity.

Fastening system

The Fold Light 1" is held in its folded position by a brand-new system.

Magnets located on the front and rear hubs hold the bike's wheels parallel.

Once folded, the stem is held against the frame by a clip system.

This clever system allows you to push your bike when it's folded, and to carry it without a second thought.

The bike rolls when folded

YES, the Fold Light 1" rolls along nicely when folded!

You only need to carry it when absolutely necessary. In other words, when you come across a staircase or need to put it in a train luggage rack or car boot.

The rest of the time, you can easily move it by simply pushing it along, even when folded.

Leave the seatpost in its raised position and use one hand to steer it anywhere, even in busy pedestrian zones (e.g. stations and shops).

Brakes

This bike has V-brakes with aluminium levers and calipers for powerful, progressive braking.

Recommendation:

your brakes will gradually wear out over time. How quickly they wear out will depend on how much you ride and how you ride.

If your brakes become too soft, and your levers end up touching the grips when you squeeze them, we recommend adjusting your brakes yourself or getting a workshop to do this for you.

Wheels

16 inches.

Single-walled, machined rims. Reinforced single-sided hubs with sealed ball bearings (the same technology that we use on our road bikes).

Tyres and inner tubes

Tyres- Schwalbe Marathon Racer.

Size: 16 x 1.50. - Light and precise, with good puncture protection to suit intensive users.

- Reflective bands on the sidewalls to make you more visible from the sides at night.

Inner tube:

- Schwalbe for excellent durability.

- Large Schrader valve.

Tips:

We recommend inflating your tyres to 6 bar to reduce the risk of punctures and to make your pedalling more efficient.

Drivetrain

You'll be amazed by the Fold Light 1"!

Its Shimano Sora 9-speed drivetrain (the same one we use on road bikes) makes it incredibly efficient, especially for an ultra-compact bike.

The trigger system makes gear changes precise and reliable.

This bike is great on both flats and downhills. It adapts to whatever happens on your ride and helps you manage your effort.

Cassette

9 speeds

Gearing: 11 / 28 teeth

- 11 teeth on the smallest cog. For riding faster.

- 28 teeth: on the biggest cog. You won't have to push the pedals too hard.

Crankset / Pedals

52t aluminium chainring with 170 mm cranks.

Folding pedals so that the bike is even more compact when folded.

Saddle

When you're cycling:

The seamless foam saddle keeps you comfortable.

When you're walking / on public transport:

The ergonomic saddle under the saddle has two functions.

- It makes the bike easier to carry when completely folded. The saddle swivels to face backwards to keep the bike evenly balanced when you're carrying it.

- You can use the handle to hold the bike and push it along when folded. Simply leave the seat post raised.

Seat post

- Made from aluminium, with a diameter of 34.9 mm.

- Marked so that you instantly know exactly where to set it to each time for the most efficient ride.

- Automatically rotates as you lower it. It's guided by 1 brass screw and 1 groove. The saddle swivels to face backwards to keep the bike evenly balanced when you're carrying it.

- Turns into a stand when you lower it fully so that the bike remains stable once folded.

Bike stability: 3 stands

- Adjustable stand with a button to adjust the length. The stand keeps the bike stable when it's unfolded (whether or not you have bags on it).

- Frame support stand that the bike rests on as you fold it and that protects the chainset.

- The bottom of the seat post turns into a stand if you lower it all the way when folding the bike. This keeps the bike incredibly stable when it's folded so that you can put it away or take it on public transport.

Bike weight

The Fold Light 1" weighs in at just 12 kg!

It's very light and incredibly easy to transport thanks to:

- its 6061 T6 aluminium frame and fork.

- its single-arm frame and fork design, making it very narrow.

- its good balance when folded.

Simply hold your bike by the handle under the saddle.

Climbing up stairs or onto the train will be an absolute breeze.

User height and maximum load

One frame size only.

This bike's geometry is comfortable for cyclists between 1.45 and 1.95 m tall.

This bike complies with the requirements of standard ISO 4210.

The maximum load it can take is 100 kg (bike + user + luggage). Above this weight, the warranty no longer applies.

Special accessories that are compatible with the Fold Light 1"

- The 16" protective cover (ref: 8610451):

can be used to cover your bike when transporting it (Eurostar, car, train, etc.). The cover comes in a zip-up pouch that you can attach to the underside of your bike's frame.

- 25L front bag for folding bikes (ref: 8735484):

for carrying all of your belongings. Clips onto the front of the bike's frame in 1 second.

- smartphone holder (ref: 8595221):

clips onto the bracket on the handlebar.

How can you carry your bags?

The bike comes with mounting points on the frame (above the front wheel).

These mounting points can be used for an exclusive bag designed by the B'Twin teams:

our 25L front bag (ref: 8735484). It can be clipped on and taken off with 1 hand in 1 second.

As it sits on the frame, you won't notice its weight and the bike will remain stable.

You'll be able to control your bike as normal.

/! When your bag is full, you won't be able to lift up the front wheel to mount pavements.

Accessories that AREN'T compatible

- This bike is not compatible with a rear pannier rack. This is because it only has a single chainstay at the back.

- Pannier racks that attach to the seat post are not compatible either.

- Child seats are not compatible

- Child trailers are not compatible

Stem / Handlebar

Stem:

- aluminium

- folding thanks to a patented system of hinges that automatically lock in 1 second

- height can't be adjusted

Handlebar:

- aluminium

- 22.2 mm diameter

- 560 mm wide

USB rechargeable front and rear lights

USB front light:

- 5-hour battery life.

- 10 lux for seeing and being seen.

- Clips onto a special bracket in the centre of the handlebar.

USB rear light:

- 6-hour battery life.

- 5.4 lumens.

- Clips onto the seat clamp. It's positioned nice and high so that you're really visible.

These lights comply with the French highway code and with German standards.

The dual port micro USB cable is supplied with the bike

Bike dimensions

Folded (L/H/W):

71 x 69.5 x 35 cm

Perfect for switching between transport modes!

You can take it absolutely anywhere, including in the tightest of spaces, such as trains, the underground, lifts, turnstiles, security gates and car boots.

Unfolded (L/H/W):

129 x 107 x 57 cm

Frame colour

You might notice "imperfections" in the colour of the green frame. This is not a quality defect, but rather the result of our design choice to use brushed aluminium and a smoky varnish. Your bike will therefore look like no other!

Maintenance / repair advice

Scan the QR code on your bike's frame or visit Decathlon's support website to find all our tips and tutorials on looking after and repairing your bike.

What is the QR code on the bike's frame for?

The QR code opens the door to a comprehensive user experience.

Scan it to access all of the information you could possibly need about your bike and how to use it.

- 1 video tutorial on folding/unfolding the bike.

- the support website with maintenance and repair advice.

- the spare parts website.

- the shop selling compatible accessories.

- the link to our services and insurance offering.

- latest news and design stories

RESTRICTIONS

/! It's important to always look to make sure the hinges on your frame and stem are locked in place before you ride.

This bike should not be used for stunts, mountain biking or BMXing.

Warranty

Lifetime warranty on the frame and stem (excl. hinge), rigid fork and handlebar.

Where does this model sit in the range? Tell us briefly about the cheaper options and the more expensive options

Decathlon/BTwin offers five models of folding bike, plus one with electrical assist. This is the top model, and the only one with 16-inch wheels to make for a compact fold. The next model down in the acoustic range is the £500 BTwin 900 folding bike, with a more conventional folding mechanism and the same Sora nine-speed gears and V-brakes.

Frame and fork

Overall rating for frame and fork
 
8/10

Tell us about the build quality and finish of the frame and fork?

The chunky welds are tidily done and the varnish-over-brushed-aluminium finish is distinctive and unusual.

Tell us about the materials used in the frame and fork?

Good old 6061 aluminium that looks to have been subjected to various forming processes to shape the tubes. Very standard stuff (the 6061 formulation is only a few years off its centenary) but well executed.

Tell us about the geometry of the frame and fork?

It's short, and the trail being short too really dominates the handling.

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

One size fits all, but the reach is very short compared even to other folders.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

With the tyres at the recommended 90psi it's distinctly buzzy and the upright position and short wheelbase really don't help. The upshot is that this isn't a bike you'll want to ride for hours on end, but it's tolerable for short rides, and considerably improved by running the tyres at 40-50psi.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

Fine overall, but the extended handlebar stem is noticeably flexible if you haul on it at all.

How did the bike transfer power? Did it feel efficient?

It's not race-bike eager but it's decently efficient.

Was there any toe-clip overlap with the front wheel? If so was it a problem?

No.

How would you describe the steering? Was it lively neutral or unresponsive? It's lively as. In fact it's twitchy to the point of being unnerving at speed.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

It's twitchy. That's good for swerving potholes round town, but at speed it's quite disconcerting.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

The saddle and grips are good and help to alleviate the bike's buzziness.

Rate the bike for efficiency of power transfer:
 
7/10
Rate the bike for acceleration:
 
6/10
Rate the bike for high speed stability:
 
2/10

It's almost scary on fast descents.

Rate the bike for cruising speed stability:
 
6/10
Rate the bike for low speed stability:
 
6/10
Rate the bike for flat cornering:
 
7/10

The highly responsive handling makes for a bike that's quick into turns.

Rate the bike for cornering on descents:
 
2/10

At speed the twitchiness dominates, whether you're cornering or riding in a straight line.

Rate the bike for climbing:
 
7/10

A lower bottom gear would be nice, but it basically goes uphill just fine.

The drivetrain

Rate the drivetrain for performance:
 
8/10
Rate the drivetrain for durability:
 
8/10
Rate the drivetrain for weight:
 
7/10
Rate the drivetrain for value:
 
8/10

Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?

Shimano Sora 9-speed with a KMC chain and anonymous cassette, but it all works fine together.

Wheels and tyres

Rate the wheels for performance:
 
7/10
Rate the wheels for durability:
 
8/10

It's pretty hard to make a small wheel that's not tough as old boots.

Rate the tyres for performance:
 
8/10

Great little tyres, with decent puncture resistance.

Rate the tyres for durability:
 
8/10
Rate the tyres for comfort:
 
7/10

Ignore Decathlon's 90psi recommendation and run them at something sensible like 50psi and they're okay.

Rate the tyres for value:
 
7/10

Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so what for?

I'd be tempted to try something fatter, like a 1.75in Schwalbe Marathon or 2.0 Schwalbe Big Apple, though the latter would be a tight fit.

Controls

Rate the controls for performance:
 
9/10

Your summary

Did you enjoy riding the bike? On the whole, yes.

Would you consider buying the bike? Yes, if I had a budget of less than £1,000 and needed a well-equipped folder for multi-mode commuting, but if I had Cycle To Work scheme access it'd be hard to resist going the whole hog and getting a Brompton.

Would you recommend the bike to a friend? Yes

How does the price compare to that of similar bikes in the market, including ones recently tested on road.cc?

For several decades the folder of choice among British multi-modal travellers has been the Brompton, with its low weight and incredibly clever fold. But Bromptons have got steadily more expensive over the years: the base model is now £925 from Halfords for a bare bike with a three-speed hub and without folding pedals.

For £75 less, the Btwin Ultra Compact comes with lights and mudguards, 9-speed gearing, folding pedals and a kickstand (though the ability to fold a Brompton's rear triangle under the bike makes a kickstand unnecessary).

The Btwin Ultra Compact therefore bears comparison with more expensive Bromptons like the C Line Explore we tested in February 2023.

Tern is one of very few other folder makers in this price bracket. The well-regarded Tern Link C8 costs £850 and while its 20-inch wheels mean it doesn't fold as small as the Ultra Compact, they do offer a smoother ride.

Rate the bike overall for performance:
 
7/10
Rate the bike overall for value:
 
9/10

Use this box to explain your overall score

Overall, I'm rating the Ultra Compact as Good because much about it is excellent, and it's great value for money, but the handling takes the shine off for me, and it has the lowest weight limit that still meets the requirements of the ISO 4210 standard for bikes.

Overall rating: 7/10

About the tester

Age: 56  Height: 5ft 11in  Weight: 100kg

I usually ride: Scapin Style  My best bike is:

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, mtb,

John has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.

He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.

Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc founder Tony Farrelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.

John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.

He joined road.cc in 2013. He lives in Cambridge where the lack of hills is more than made up for by the headwinds.

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1 comments

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Secret_squirrel | 11 months ago
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Quote:

"From those tests, Poupart and his team concluded that they'd actually like to have a higher top gear, but there's no straightforward way of doing this at the moment. Shimano used to offer a groupset specifically for small-wheeled bikes called Capreo, with a nine-tooth small sprocket. 'The Capreo System would have been a great choice for this bike,' Poupart told me. 'Unfortunately, it's no longer available for OEM products.'"

Poupart didnt do enough research.  The Capreo spec cassette was licensed out to Sunrace who produced (not sure if they still do) 10 and 11 speed versions of it.

(Edit: the Birdy Touring still has a 9-32 10 speed cassette)

Birdy and Airnimal folders fitted the 10sp version for a while.  

I actually did the mad upgrade noted above using the 11 speed Sunrace stuff on my Birdy. 9-32 Cassette  3 and an 11 speed Shimano Deore rear mech & shifter.

Besides all that looks like there is plenty of room for a bigger chainring, again Birdy offered a 52 as standard and a 56 as free upgrade.

 

 

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