Tern BYB S11 review

Tern's tri-fold BYB S11 is its most compact folder to date

Our rating 
4.0 out of 5 star rating 4.0
GBP £2,300

Our review

One of the best handling folders around, if you want ride quality over everything else get this
Pros: Solid handling, stable ride, great gear range
Cons: Pricey, heavy, folding is more time consuming than simpler designs
I’ve had the Tern BYB for a couple of weeks now, which has given me the chance to use it by train, on the road, towpath and trail, and store it in the boot of a car. Here’s my take on this unique addition to the weird world of folding bikes.

The folding bike market is still pretty much dominated by the humble Brompton. Yes, there are plenty of options around for simple, single-fold bikes for all budgets, but nothing that comes close to the minimal packaging of the Brompton.

If you were expecting Tern’s ‘smallest’ folding bike ever to take on Brompton’s compact crown then you may well be disappointed, because although the new BYB does indeed pack down small and slim, it’s not Brompton small.

At 81cm tall, 35cm wide and 52cm deep it’s a reasonably small package, and because of the clever Metro Transit rear rack with its integrated trolley wheels the BYB is easy to move around, despite its 13.3kg weight (Tern claims 12.7kg).

You can completely fold the bike down, including the long stem cum steerer, which it calls the Physis handlepost, or leave the bar extended and then it becomes a handle to help you manoeuvre the bike when trolleying.

Tern BYB folding road bike rear rack
The ‘Metro-transit’ rear rack has integrated spinner trolley wheels to make it easy to move when folded
Warren Rossiter/Immediate Media

That means as a ‘folded’ bike it’s neither as compact or as light as a Brompton, and the tri-fold with its three ‘TFL’ joints does take a bit of practice to get the routine mastered. Once you’ve unclipped the joints and removed one of the quick release MKS pedals (and holstered the pedal in to the welded frame holster) you then fold the bike up and press the anchor bolt mounted onto the fork into the rear dropout.

This is a much more secure setup than Tern’s old magnetic clasp, but it does mean that to unlock it you have to activate a lever mounted on the rear stay, which can be a little messy to reach especially if the bike’s dirty.

Tern BYB folding road bike folded
The tall-yet-slim folded BYB
Warren Rossiter/Immediate Media

The folded bike does however have a neat accessory in the form of the ‘PopCover’. This disc-shaped package mounts securely onto the rear rack, and when you unzip the case and take out the cover it pops open like a pop-up tent, creating a full cover for the folded bike.

A neat zip opening on its top means you can access the frame as a grab handle to manoeuvre it, or use the full length side zip to wrap it around the extended bar to do the same. I like this accessory because it means I won’t be brushing a damp, dirty bike against fellow commuters on a busy train or marking the furniture in the office when storing it by my desk.

Tern BYB S11 ride impressions

folding road bike
The Andros stem design allows for quick adjustment so you can get the right fit for a wide range of riders
Warren Rossiter/Immediate Media

Where the BYB does score is in its ride. The long wheelbase, 1,028mm, and 20-inch wheels, combined with the twin-spar frame design, mean the BYB feels solid and doesn’t suffer from the noodley feeling of smaller wheeled folders.

The BYB is one of the very few folding bikes I’ve been more than happy to get out of the saddle and sprint on. Up front the Physis steerer and Andros stem combo is suitably stiff and at first I thought the dual quick-release bar clamp/stem angle adjustment on the Andros was a bit of a hassle, but in use it means you can tune the reach, bar angle and stack easily.

I’m 6 foot 2 inches, yet I  could find a position that I was more than happy with and so could my wife despite her smaller 5 foot height. Combined with the telescopic seatpost, this meant we could both set our ideal saddle height too.

Tern BYB folding road bike Ultegra gears
It’s rare to see something as swish as Ultegra on a folder
Warren Rossiter/Immediate Media

The BYB’s 20-inch wheels with slick 1.5in tyres feel pretty rapid to accelerate and their width allows for a few excursions off-road onto towpaths, trails and even a bit of GPS-induced singletrack through the woods.

The gear range is a big bonus having an 11 speed, 11-32 cassette driven by an Ultegra mech and a 54-tooth chainring. This provide a decent range with a low climbing gear and a top end that’s enough to keep up a fair lick and stay ahead of urban traffic.

That range of gears is something you certainly don’t get from many of the BYB’s rivals and goes a long way to giving the BYB its feeling of being a proper bike that’s not compromised by its compact folding design.

Good contact points in the form of Ergon grips and the excellent Ergon saddle all reinforce the riding nature of the BYB and add to the impressive overall ride quality.

folding road bike
The £1300 P8 is the cheaper model in the BYB range

The Tern handles quickly without being twitchy (which small wheeled machines can often be plagued with) and the aforementioned solidity of its chassis all make this a bike I’d recommend to riders looking for a decent mixed-mode commuter bike that you can ride anywhere — just build in some time to master the folding process or allow a bit more time at the train station to get it packed up.

The S11 is an expensive machine, even Brompton’s range-topping Superlight M6L comes in cheaper at £1,720, but the S11 does have the advantage of its broader gearing and superior handling. I’d be happier riding the S11 longer distances, but this is going to find its place among commuters rather than tourers or general riders, so it may be a tougher sell. The P8 is more competitively priced against the higher-grade Brompton’s but it’s still going to be a pricier proposal.

Personally, I’d choose the ride quality of the BYB over its rivals every time, but if your commute is a few short miles rather than my 60-mile round trip, 12 miles if I mix it with my car or 18 miles if mixed with the train, then something cheaper such as a Brompton is probably your more fiscally-responsible option.

Tern BYB S11 specifications

folding road bike
The £2300 S11 is Tern’s flagship model for their tri-fold design
  • Weight: 13.3kg (including pedals)
  • Frame: Aluminium
  • Fork: Aluminium
  • Rear mech: Shimano Ultegra
  • Shifter: Shimano RS700 shifter pod
  • Cassette: 11/32
  • Chainset: FSA Gossamer Pro with 54t Megatooth chainring
  • Brakes: Tektro V brakes/Shimano R780 levers
  • Wheels: Kinetix Pro
  • Tyres: Schwalbe Marathon Racer 20in x 1.5in
  • Seatpost: Tern telescopic alloy
  • Saddle: Ergon SMC30 saddle
  • Bar: Kinetix
  • Handlepost: Tern Physis
  • Stem: Andros
  • Pedals: MKS QR
  • Mudguards: Tern
  • Extras: Tern Metro Transit rear rack with trolley wheels, bell