Eurobike 2017: The World’s Lightest Hardtail Frame?

by
September 3, 2017

Last year at Eurobike, we were introduced to Bike Ahead’s incredible, German manufactured, sub-300 gram carbon fibre rims. At this year’s show, Bike Ahead was back to again show off its lightweight carbon rims, and six-spoke carbon wheelsets, but it also had a couple of complete bikes on display as well.

Branded as ‘Stoll’, these two exotic-looking carbon fibre bikes are designed in Switzerland by a two-man team that includes owner Thomas Stoll, and Jan Bahalla. The frames themselves are manufactured in Germany by Bike Ahead, and hence why they were sharing the same booth at Eurobike.

stoll german carbon hardtail r1 eurobike
The Stoll R1 frame is claimed to weigh 780g bare.

Both bikes were showstoppers, but it was the R1 hardtail that blow us away with its 780 gram claimed weight. Let us repeat: 780 grams.

Just to confirm, that’s 780 grams for the bare carbon frame, and doesn’t include the 21.5g thru-axle, the 18.5g hanger, 9g seatpost clamp, and 4.5 grams worth of cable ports. With those parts included, you’re looking at a portly 833.5g for the R1 frame before it’s ready for all the other bits to be bolted on. Compare that to the new Specialized Epic HT World Cup frame, which is claimed to weigh 845g including hardware, and the Canyon Exceed SLX that weighs in at 870g.

If Stoll’s claim is correct, that makes this one of, if not the lightest hardtail frame on the market. As far as the complete bike? Well this showstopper here apparently comes in at 6.9kg (sans pedals). In other words, lighter than most road bikes.

stoll german carbon hardtail r1 eurobike
Ram headtube badge must surely add a few grams.

According to Stoll and Bike Ahead, the R1 frame is unique in that the frame is made from one mould. Most frames are made in two pieces, or sometimes several different tube assemblies that are then bonded together and wrapped with additional carbon. To achieve the incredibly low weight, the R1 frame is made as a single piece, which aside from reducing additional material and weight, also means that continuous carbon fibres can be routed from the head tube, down to the bottom bracket and all the way through to the dropouts. In theory, this should actually lead to a stronger structure overall.

stoll german carbon hardtail r1 eurobike
Stoll is a new brand with Swiss design and German manufacturing.

There are some dead-lovely lines to the R1 frame, and the geometry looks promising too. There’ll be three sizes available – Small, Medium & Large – and each frame features a 68.8° head angle, 432mm chainstays, and a sizeable 70mm bottom bracket drop. Reach measurements are solid, with the Medium getting a 428mm reach, and the Large getting a 455mm reach that should lessen the need for enormously long stems.

While the geometry is pre-set for the stock frame sizes, Stoll states that each frame is tailor made to each rider, so that the carbon layup is specific to the rider weight. That means heavier riders may end up with a slightly heavier frame, but ideally one that’ll be stiffer and stronger where required to handle the additional forces.

stoll german carbon hardtail r1 eurobike
Huge, boxy downtube meets the full width of the PF92 bottom bracket.
stoll german carbon hardtail r1 eurobike
Because the frame is made in one mould, there are continuous carbon fibres running throughout the entire length of the frame structure.
stoll german carbon hardtail r1 eurobike
The 12mm diameter thru-axle is claimed to weigh just 21.5 grams.
stoll german carbon hardtail r1 eurobike
Curved seatstays are designed to encourage vertical flex for added rear wheel traction and comfort.
stoll german carbon hardtail r1 eurobike
Carbon-Ti seatpost clamp and scary Schwalbe tyres for the riders that have only read about mud on the internet.
stoll german carbon hardtail r1 eurobike
Seatstays wrap around the seat tube to help transfer impacts into the top tube, rather than upwards through the seatpost.
stoll german carbon hardtail r1 eurobike
Loads of tube shaping going on between the rear wheel dropouts and the bottom bracket.
stoll german carbon hardtail r1 eurobike
Chunky in all the right places.
stoll german carbon hardtail r1 eurobike
This complete bike was decked out with Trickstuff Piccola brakes and Bike Ahead’s 119g carbon handlebar. Wowsers.
stoll german carbon hardtail r1 eurobike
The Stoll R1 frame is designed around a 100mm travel fork with a 68.8° head angle and a longer front centre for use with shorter stems.
stoll german carbon hardtail r1 eurobike
For trail riders, the Stoll T1 comes with 29in wheels and 135/140mm of suspension travel.

The second bike that Stoll and Bike Ahead on display was the T1 – a full carbon fibre dual suspension trail bike with 29in wheels, 135mm of rear travel and a 140mm travel fork. The T1 was fitted with Bike Ahead’s biturboRS wheelset, which is made entirely of carbon fibre (save for the hub internals) and features a 27mm internal rim width and a claimed weight of 1189g. Exotic is putting it lightly.

stoll german carbon hardtail r1 eurobike
Like the R1, the T1 is also made in Germany.

The Stoll T1 frame can be run with 130-140mm of fork travel. With the longer 140mm travel fork the head angle sits at 67.25°, while the seat angle is 74.5°. The rear centre measures 438mm long, bottom bracket drop is 35mm, and the reach measurement is almost identical to the R1 frame, with the Medium coming in at 428mm.

stoll german carbon hardtail r1 eurobike
The 135mm of rear travel is controlled by a RockShox Deluxe RT3 shock.
stoll german carbon hardtail r1 eurobike
A smooth bearing mount sits at the lower shock eyelet to help reduce friction.
stoll german carbon hardtail r1 eurobike
Love this detail – the seat tube is moulded with a curved profile that makes room for the water bottle.
stoll german carbon hardtail r1 eurobike
Hockey-stick downtube leads to a PF92 bottom bracket shell.
stoll german carbon hardtail r1 eurobike
Note the reinforcing carbon weave underneath the downtube that’s there to armour the frame against rock strikes.
stoll german carbon hardtail r1 eurobike
The rear swingarm is a one-piece carbon fibre monocoque assembly that saves weight and keeps it strong.
stoll german carbon hardtail r1 eurobike
Post mount brake tabs are crafted from machined alloy rather than carbon.
stoll german carbon hardtail r1 eurobike
The carbon frame is otherwise left raw, save for some detailing on the inside face of the swingarm.
stoll german carbon hardtail r1 eurobike
A closer look at the six-spoke carbon wheels on the Bike Ahead biturboRS wheels.
 stoll german carbon hardtail r1 eurobike
Even the internal routing ports are moulded into the frame shape.

If you’d like more information on these trick German machines, head to the Stoll Bikes website and Bike Ahead’s website for further details.

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