Lapierre Pulsium 700
Can the Dijon company’s new endurance bike cut the mustard?
In the old days, you just sat on a log. Then came the Egyptians with their chairs, and suddenly logs just weren’t good enough any more. As the years passed the Chinese whittled, the Mayans carved and the Parisians stuffed, and by the age of the Ikeans, hard chairs were only considered fit for the most utilitarian of dinner tables. The number and style of chairs had diversified beyond recognition, but there was always one notable goal: comfort.
Lapierre, and the bike industry at large, seems to have similar ideas. Years ago you just had a road bike. You rode it on the road and that made it a road bike. But now there are as many subtly different road bikes as there are subtly different road conditions. Want to ride slightly faster than usual? You’ll be needing an aero bike. Want to ride on a loosely determined surface somewhere between forest floor and towpath? You’ll be needing a gravel bike. Want to ride a bit further than last Sunday? You’ll be wanting an endurance bike because you need more comfort. In which case, perhaps this Lapierre Pulsium 700 might tickle your fancy.
Minute differences, maximal changes
What makes an endurance bike? The key concept is extra comfort for longer miles. Depending on the manufacturer, that comfort might arrive in a variety of guises. Taller, slacker head tubes for a more upright riding position; longer wheelbases and increased fork rakes to add stability; or some form of extra damping built into the frameset to reduce road vibration. In the case of the Pulsium, it’s all of the above.
‘On the size large [tested here] we use a 72°, 185mm head tube and instead of a 43mm or 45mm fork rake, it is 50mm. This provides more leverage for shock absorption and a longer wheelbase for better stability,’ says Lapierre’s R&D project manager Rémi Gribaudo. ‘But the standout feature is the elastomer in the top tube, which gives us 25% more vertical flex when
measured at the saddle than the first generation of the Sensium [Lapierre’s other endurance offering].’
To put that in context, Lapierre’s raciest bike, the Aircode, has a 73°, 170mm head tube and 4mm shorter chainstays, resulting in a wheelbase of 993mm compared to the Pulsium’s 1,011mm. While the elastomer is undoubtedly the thing that sets the Pulsium apart from the crowd – not least in terms of looks – it’s this geometry, or rather the ride it creates, that I found most arresting. So I’ll come back to the elastomer later.
A degree here or a few millimetres there might not sound a lot, but it gives the Pulsium a ‘unique’ feel. From the first pedal stroke I noticed a gulf between this and a road bike with more aggressive geometry.
The front wheel wanted to ‘tuck in’ below the frame, like a caster wheel changing direction
Having a tall head tube doesn’t necessarily translate to much more than a more upright riding position as the drop between saddle and bars is lessened. However, make that head tube slacker in angle, put on a fork with a more pronounced rake and it’s like going from a Motogp superbike to a Harley Davidson chopper. That is to say at lower speeds – ie negotiating traffic or turning through tight corners – I found the handling rather unnerving, with the Pulsium exhibiting a disjointed feel, like it was flopping unduly about its steering axis, the front wheel wanting to ‘tuck in’ below the frame more than a normal bike would, a bit like a caster wheel changing direction.
I’d put money on this being down to the fork/frame combo. If you turn the bars from side to side when the bike is stationary the top tube moves up and down, indicating the front centre contact patch of the tyre is changing, moving backwards towards the frame (thus raising the top tube) when the bars are turned.
Conversely, this actually made the Pulsium a heap of fun to ride fast and descend on. Slack head tubes and long fork rakes and wheelbases have been used on downhill mountain bikes for years, providing greater stability and more predictable handling at speed, and so it is with the Pulsium. Get it past 32kmh and it holds its line assuredly, yet reacts to the deftest of steering inputs, presenting that exhilarating suck-it-and-see attitude of a downhill mountain bike. But below that speed? Well, it’s a mixed bag that takes a great deal of getting used to.
As right of reply I put these issues to Gribaudo, who conceded that he could ‘understand my point of view’, however he assured me he hadn’t received such feedback from sponsored team FDJ or the Pulsium’s testers.
Proving ground
As per the steering, the Pulsium is a bike of two halves – almost literally. The top tube has a gap in the carbon, where Lapierre’s engineers have inserted a rubber elastomer that acts like a little damper. Because of this disconnect, a gusset tube runs over the top of the elastomer assembly, connecting the top tube to the seat tube such that the frame is at once rigid laterally and able to flex vertically. It’s a clever piece of engineering, but
attempting to add damping to a bike is by no means a new idea, and neither has it always been that successful.
The Pulsium was officially launched at ParisRoubaix last year, a race that has traditionally been a showcase for leftfield bike designs. As far back as 1992 Greg Lemond and team-mate Gilbert Duclos-laselle debuted a pair of Rockshox Roubaix suspension forks at the Hell of the North. Two years later Johan Museeuw rode a full-suspension Bianchi that was claimed to cost around £16,000 to build, and in the mid-2000s Trek took a hacksaw to its 5000 OCLV series carbon frame and installed an elastomer above the wishbone seatstays. Although Duclos-laselle won Paris-roubaix on his Rockshox, the forks failed to catch on (Museeuw punctured and finished 13th, while George Hincapie aboard his Trek was outsprinted by Tom Boonen in 2005).
Trek at least did not give up, and in 2012 the Domane entered the fray with its Isospeed Decoupler damping system (see Cyclist issue 7), of which the Pulsium’s SAT (Shock Absorption Technology) bears striking resemblance on paper, allowing as it does the seat tube to bow significantly more under load than a regular bike’s. The question is, does it work? The answer is yes. And no.
The Pulsium’s rear end definitely feels different to a non-elastomer damped bike. The sting is taken out of big hits, while allowing the rear end to perform normally, as it were, over smoother surfaces. In this respect it’s a winning design, palpably more forgiving than other road bikes, and up there with the Domane. But it seems to me to lack positivity in the rebound. That is, as much as it absorbs shocks it doesn’t have the feeling of pinging back down again to reattach the bike to the road. For some riders this will be fine – they’ll like the fact the Pulsium
The sting is taken out of big hits, while allowing the rear end to perform normally over smoother surfaces
irons out the bumps rather than tracks their undulations – and on longer rides I was glad of the fact. But where it really mattered, on more technical sections of road, I felt the insert gave the Pulsium a slightly dead-feeling rear, which left me struggling to feel connected to the road.
This, together with the handling, means the Pulsium isn’t a bike for me, which isn’t something I often find myself saying. I’m all for comfort, but not at the expense of handling and ride feel. I guess I’m just the type of person that would rather perch on a bar stool in a busy pub than put my feet up in a reclining armchair. Even if that armchair is a blast down the hills.