A great package of wheels and components makes this starter road bike from French sport supermarket Decathlon look like a winner.
Ride & handling: stiff & stable
Heavy riders will warm to the stiff and stable ride and the long and low riding position suits racing or sportive riders who’ll trade comfort for speed.
The effect of combining a low riding position with a long stem creates a race-orientated feel and the relatively short wheelbase (for a 57cm frame) makes for sharp and responsive steering.
We found that the B’Twin Sport 4 was a little easier to lay into turns than the similarly sized Specialized Allez.
Frame/Chassis: controversial looks & too few sizes
The frame is based on 6061 aluminium tubing, and the seatstays are carbon ﬁbre moulded into a wishbone pattern.
Decathlon has omitted a frame sizing guide on its website, but there are five sizes on offer. The 57cm version on test has a top-tube dimension that aims to cover riders from 5ft 10in to 6ft 2in and the smaller (53) size will be ﬁne for those from around the 5ft 4in mark. There are also 51cm, 60cm and 63cm models available.
The use of carbon wishbone seatstays in place of a pair of welded aluminium tubes here speeds up large production runs and saves a few grams, but the notion that they help absorb shock is misguided as this part of the frame cannot be easily compressed by vertical forces.
Our test riders were divided on the very angular multi-shape tubing and bold metallic graphics, and while there’s a ﬁve-year warranty on the frame, that’s about par for the course with this level of bike.
Equipment: 105 & Truvativ mix great for the money
The Sport 4 is well appointed in the gearing department with Shimano 105 levers and derailleurs and a Truvativ Elita triple chainset.
The 10-speed 12-25 cassette provides close steps between gear changes and a range of extremes that satisfy the needs of both beginner and more experienced rider.
Cassette changes were also curiously smoother than the other bikes on test with the same Shimano 105 kit.
Opinion was divided on the ITM 300 handlebar that felt rather short with your hands rested on the drops.
The round black chainguards are intended to prevent the mech from going into the spokes in the event of a side impact, but they have the unfortunate effect of making the bike look like it was plucked from the pages of a mail order catalogue, while the seatpost looks agricultural.
The Selle Royal Xsenium saddle squashes a bit too much for our liking. The matt chrome plated chain is a small detail that’s worth having.
Wheels: light & fast
Mavic Aksium Race wheels have a knack of feeling faster than they have a right to for their budget price and the Hutchinson Top Speed Kevlar tyres would do justice to a bike costing four times the price.
The combination is unusually light for a bike at this price.
Verdict: impressively light
The B’Twin has understated looks, but the workshop report tells us the all-up weight is very impressive for a large size. The stretched riding position and sharp handling make it a great option if you are won over by sophisticated looking carbon wishbone stays.
|Brakes||forged alloy dual pivot|
|Rear Tyre||Top Speed|
|Front Tyre||Top Speed|
|Available Sizes||51cm 53cm 57cm 61cm|
|Top Tube (cm)||56.5|
|Standover Height (cm)||77|
|Seat Tube (cm)||47|
|Bottom Bracket Height (cm)||27.5|
|Stem||B'Twin forged alloy|
|Cassette||Shimano 105 10spd|
|Shifters||105 STI triple|
|Seatpost||Alloy with single bolt clamp|
|Rear Derailleur||105 long cage rear|
|Handlebar||300 alloy anatomic deep|
|Front Derailleur||105 triple front|
|Fork||Carbon blades. alloy crown and dropouts|
|Cranks||Truvativ Elita triple|
|Chainring Size (No of Teeth)||30 39 50|