When disc brakes first appeared on road bikes, a number of brands rushed out a redesigned frame in order to be quick to market.
As a consequence, many of these frames changed the character of their rim-brake predecessors, and not always in a good way.
The resulting frames were usually heavier and often less forgiving than before, owing to the extra reinforcement at the fork and rear triangle to account for the more powerful forces that disc brakes exert on a frame.
Carbon fibre wheel specialist Lightweight has taken a comparatively long time to come to market with a disc brake version of its Urgestalt road frame but as product manager David Bergmann explains, the company doesn’t see that as a disadvantage.
‘For us it’s always a little bit difficult to be quick to respond to trends,’ he says. ‘We’re different to other manufacturers because so many of our products are handmade, so the R&D takes a huge amount of time and expense.
‘It necessitates us waiting to see whether changes are fashion or a definite new direction, so we monitor the market and can learn from others’ mistakes.’
According to Bergmann, that hindsight allowed Lightweight to create a disc-specific frame that weighs a claimed 800g, with the total build as shown coming in at just 6.96kg.
To put that in perspective, the top-spec BMC Roadmachine (a disc brake bike costing nearly £9k) weighs 7.8kg.
‘Relative to our competitors, the increase in weight from our rim brake Urgestalt to the Urgestalt Disc is very small – just 10g.
Completely new
‘That being said, the Urgestalt Disc frame isn’t just the regular Urgestalt with discs bolted on – it’s a completely new frame.’
According to Bergmann, the feedback regarding the handling of the original Urgestalt was so universally positive that its geometry has been closely replicated on the Urgestalt Disc, but there are other marked changes too.
Lightweight has dropped the obsolete brake bridge over the rear wheel and slimmed down the seatstays in a bid to improve comfort – a feature Lightweight nurtures further with more generous tyre clearances.
‘We have two types of customer buying the original Urgestalt,’ says Bergmann. ‘We have the serious, very skilful rider who likes the frame because it amplifies the characteristics of our wheels – it’s quick to accelerate and very stiff.
‘But it’s also a demanding frame that needs to be controlled, so we have another customer: the enthusiast of the brand who is not so athletic, and is asking for a little more comfort.
‘Redesigning for disc brakes gave us the option to cater more for comfort in the Urgestalt Disc.’
It’s a theme that continues at the front of the bike. For additional comfort as well as sufficient stiffness, the fork has what Bergmann calls an ‘asymmetrical lay-up schedule’.
‘It’s far different to the one in the original Urgestalt,’ he says. ‘Asymmetrical in this instance means that the torsional forces of the disc brakes are braced for, but the vertical forces caused by bumps in the roads are allowed for, which adds a little dampening.’
System superiority
Something that’s unsurprising considering the brand’s heritage in wheels is that the new frame was designed to work specifically as a system with Lightweight’s Meilenstein Disc wheelset.
‘This was one of the few things that’s no different from the original Urgestalt. That frame was designed around the Meilenstein clinchers, and I think it’s crucial to the performance of both bikes,’ says Bergmann.
‘It allowed the rim brake Urgestalt’s stiffness-to-weight values just as it allows the Urgestalt Disc’s comfort and controllability.’
Key to this element of control is the Meilenstein Disc’s pentagon-shaped hubs. Bergmann explains that the heat build-up of prolonged braking on disc wheels with carbon hub shells can cause the bond between disc mount and hubshell to soften, allowing the two components to move relative to each other.
This is catastrophic to a bike’s braking performance, so Lightweight moved to the pentagon shape so that the disc mount physically cannot move inside the hubshell.
The design also weighs less, which obviously for a brand named Lightweight is a bonus.
‘Despite our name, we would rather make things 50g heavier than 50g lighter if that brings with it any compromises,’ cautions Bergmann. ‘That said, as long it’s safe we will continue to get even lighter with our products.’
Verdict: Lightweight has taken a while in getting the Urgestalt Disc to market, but with the additions of discs having added only 10g to the total frame weight, the time looks to have been well spent.
£3,989 frameset, approx. £12,899 as built, vielosports.co.uk
