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Just in: B'Twin Ultra 700 AF

Smart-looking £750 alloy road/endurance bike with a Shimano 105 transmission

Fresh in the door at road.cc towers is this £750 Ultra 700 AF road bike with a Shimano 105 transmission. It's the world's first autofocus bike.

Kidding! AF stands for alloy frame (of course) and the bike is based around a new B'Twin Ultra alloy frame that's UCI-approved and has a claimed weight of 1,400g. You get variable-thickness tubing that's designed to both reduce the weight and give the bike a bit more comfort over the sorts of surfaces we're used to in the UK. Cable routing is internal, and the rear brake positioning is under the bottom bracket. The geometry is fairly sporty, with our medium-sized test bike featuring a 147.5mm head tube and a wheelbase of 984.4mm. B'Twin don't publish stack and reach measurements for the bike but by our calculation the stack-to-reach ratio of the medium bike is about 1.45, which plants it firmly in fast-endurance kind of territory.

The alloy frame is complemented by a carbon-bladed fork that has a claimed weight of 550g. It uses an alloy steerer which you'd expect at this price point; B'Twin say that they have "achieved a damping effect on very uneven and bumpy terrain such as paving or cobblestones", which sounds promising. We'll wait to see on that one.

Transmission is mostly Shimano 105. Given that getting high-quality braking is trickier when you're using the under-bb brake position at the rear it's good to see that B'Twin have specced the 105 direct-mount callipers at the front and the rear, rather than opting to save money there. They have saved on the chainset, which is the dependable RS-500 five-arm unit you see on bikes over a wide range of prices. It's not as sexy as the 105 groupset but it doesn't give away much in terms of performance. B'Twin spec the Ultra 700 AF with a 50/34 compact chainset (crank length depends on the frame size) and an 11-28 cassette, so you shouldn't ever want for gears.

The wheels have been developed in-house by B'Twin: they're a 28mm alloy rim with catridge-bearing hubs, laced with 24 spokes at the rear and 20 at the front. Claimed weight is 1,790g which is decent training wheel weight, and they came true with nice even spoke tension. You get Hutchinson Equinox 25mm tyres as standard, and there looks like there's plenty of room to size up to 28mm if that's your thing.

B'Twin supply all the finishing kit too. You get an alloy stem and bar that are well-finished and scaled to the size of the bike, a matching alloy seatpost and B'Twin's own saddle with Cromoly rails. You even get a set of Look-Kéo-compatible B'Twin pedals, and cleats. And some (basic) lights. And a bell.

The bike tips the road.cc scales of truth at 9.17kg and it's off out now to be thrashed around the lanes of Wiltshire and surrounding counties by Stu Kerton. Stay tuned for a full review.

See more at the Decathlon website

 

Dave is a founding father of road.cc, having previously worked on Cycling Plus and What Mountain Bike magazines back in the day. He also writes about e-bikes for our sister publication ebiketips. He's won three mountain bike bog snorkelling World Championships, and races at the back of the third cats.

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