July 31, 2021

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Prime Bicycles Launches with New Downhill & Enduro Bikes

Prime Bicycles is a new European bike brand with offices in both Poland and Austria. It’s a brand that you may have seen on Instagram or even on Pinkbike, as we covered its initial launch last year.

A lot of what is true then is true now. The brand is the brainchild of Peter Siulczynski, a former downhill World Cup team manager who worked with riders such as Nathan Rennie and Sam Blenkinsop. In 2008, the Gravity Group disbanded but Peter wished to develop his ideas further. Peter explains that he had plans to return to the World Cup circuit with a team that included a top-5 ranked rider. However, although he had no problem finding component and technical partners, he struggled to find a frame manufacturer that truly aligned with his vision. Whilst speaking to Peter via Zoom before the launch of Prime, he went on to say that he would liked to have made a team that occupied the same place as some F1 teams. They’re not there to make a road-ready consumer car but rather a testing ground to prove and develop concepts that, sooner or later, would come to benefit the end consumer.

After years of work and refinement, Prime Bicycles is ready to make its first foray into the industry with the launch of two new bikes: the Rocket downhill bike and the Thunderflash enduro bike.

The bikes are aimed to offer similar quality and desirability as the high-flying, and often extremely high cost, boutique brands but with prices that should be more accessible. They’re not meant to be cheap and cheerful, mind you, and I don’t think they would level themselves as that. They position themselves to be good value for what they are and affordable considering the frame and build kit you get.

The bikes were initially designed with technical support from Cero Design Studios, who many of you will know via their association with Cesar Rojo. After the initial concepts were achieved they then went through a process of refinement involving both Cero and the in-house team at Prime Bicycles. The result is two bikes that were years in the making.

The first concept of geometry and kinematics was developed in 2016. However, as the rumour circulated of a Fox 40 that was compatible with 29-inch wheels, Prime decided to put their process on hold until they could receive both official confirmation as well as technical information about the new fork. They subsequently tested both main wheel sizes over a variety of test mules and found that 29-inch wheels offer the ride characteristics they prefer. Mules were tested in multiple sizes by multiple riders over the course of a year. After an additional extended period of refinement, including a carbon prototype, they began production of all sizes in carbon. Both the Rocket and the Thunderflash are manufactured by VIP Composites and are truly full-carbon, with not only the frame but also the rocker links made of carbon. They are manufactured in Asia before being assembled in Germany.

Test mules of both bikes during a camp in Madeira.

During this period of testing, they tweaked both rear travel and bottom bracket height. This was not only to achieve the feel they wanted but also to consider rear-wheel clearance for riders of different statures, and the role these dimensions play in this. While talking to Peter, he explained that it wasn’t that they didn’t consider a mixed wheeled platform, far from it, but rather upon further consideration Prime’s team feel that for the majority of riders a well designed 29er will offer a better ride.

Throughout the range, you won’t find any flip-chips. This is an approach I personally like, especially with a bike that will be pedalled. To change a bike’s geometry with a flip-chip can never solely affect a singular dimension and will often compromise another. You might find yourself wishing to have the head angle of one setting combined with the seat tube angle of another and it can be frustrating. Prime decided to stay away from this entirely by building the bike they want and they feel rides best even if it forgoes what some people might perceive to be a useful adjustment. In fact, speaking of useful adjustments, the test mules that Prime made enabled them to test a massive 80 different geometry variations.

Both bikes use Prime’s S.H.R.E.D Dynamics suspension and geometry concept. The suspension layout consists of two links that co-rotate in the same direction. The lower link pierces the seat tube just above the bottom bracket junction and, to look at it, shares visual similarities with other platforms. You will find six bearings in the lower link, two on the non-drive side with four on the drive. This is to offer better lateral stiffness, and although they don’t explicitly state it, I would imagine it would help increase bearing longevity. All the hardware consists of additional sealing to keep moisture and grit out.

The bikes both come with fenders to keep dirt away from the shock and take advantage of a degree of customizability in the build process. For instance, if you wish to buy the base model of the Thunderflash but with the ENVE wheels then Prime are happy to accommodate.

The Rocket is a 29″ downhill bike and has 195mm of rear travel. It has full internal cable routing, a 203 post mount brake, ample frame protection and a threaded bottom bracket. It will come in four build options – the RS, R, S and C. Full builds start at €5299 for the C. All bikes come with a mixture of Fox, SRAM, Maxxis and Renthal. Framesets will be available for €3499.

The Rocket also uses an aero seat post but its reasoning might not be what you expect and its execution is reassuringly sensible.

Prime Bicycles Rocket

• Wheelsize: 29″
• Travel: 195mm (r) / 200mm (f)
• Carbon Frame & Linkage
• 63.5° head angle
• Chainstay length: 450mm
• Reach: 455, 475, 500mm
• Full builds from: €5299

The design team feel that a non-circular seatpost stops the needless complication of twisting your saddle should you crash during a run. They’re very confident you won’t have any issues but, should you do so, they will replace it for free. They are also currently awaiting a shipment of shims that will plug the leading edge of the seat tube to make the frame compatible with 27.2 posts, in case you need a replacement at short notice. If you order a bike and these shims have not arrived yet then they will forward one to you free of charge as soon as they take delivery.
The suspension starts out with a relatively high levarge rate of nearly 3.6. This will give the rear wheel a very solid mechanical advantage over the shock and should ensure decent small bump sensitivity. The curve is both progressive and consistent. At 30{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a} the ratio is down to 2.9 and that reduces further to 2.1 at the end of the stroke. This reduction in the leverage ratio should give good bottom-out resistance and provide the rider with good performance irrespective of spring type.
The anti-squat values tell a similar story of quite a high value at the beginning of the stroke, a not inconsiderable 200{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a}. This is reduced to 116{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a} at 30{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a} sag and reduces further to under 50{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a} at the end of the stroke. This should make for a downhill race bike that is very efficient should you ever stamp on the pedals either in a race run or just to get over a “must clear” gap.

The bike is available in any build kit in the choice of midnight blue or anthracite. Each bike will be unique in regards to its own splatter effect which is quite a nice touch.

The Thunderflash benefits from many of the same characteristics as the Rocket. Again, it has 29″ wheels, is truly full carbon and benefits from clean lines that are particularly easy-on-the-eye. Its build kits are also available with the same brands, albeit with the inclusion of either a BikeYoke or Reverb AXS seatpost. It has 165mm of rear travel which is coupled with a 170mm fork.

There will be five build options the RSX, RS, R, S and C. Full builds will start at €4999 with frames for €3499. Much like its downhill counterpart, the base model comes with an air shock as opposed to a coil one. Prime feel that this will give more adjustment to a potentially less experienced rider.

Prime Bicycles Thunderflash

• Wheelsize: 29″
• Travel: 165mm (r) / 170mm (f)
• Carbon Frame & Linkage
• 64° head angle
• 77° Estimated seat tube angle
• Chainstay length: 445mm
• Reach: 460, 480, 505mm
• Full builds from: €4999

The Thunderflash also does away with flip-chips and is in “shred position only.” You may also note that both the enduro and the downhill bike don’t have increasing chainstay length depending upon frame size. Prime feel that although some riders may well be sensitive to an additional 5mm or so in rear-centre, it isn’t worth compromising the exact suspension feel that they spent so long agonising over. This will in no doubt not be to everyone’s liking but I thought it was an interesting take.

It has a 180mm post-mount brake, full internal cable routing and a rubber grommet near the headtube that not only works as an entry port but is also there to stop the fork from damaging the frame. Like the Rocket, it also benefits from the fully sealed bearings, including the six-bearing arrangement in the lower link and a generous amount of frame protection.

The leverage ratio of the Thunderflash, whilst not quite as high as the Rocket, is still reasonably large at 3.1 at the beginning of the stroke. The curve is progressive and, like its downhill counterpart, it will happily accept a coil or air shock.
The value of anti-squat at sag in the middle of the cassette is 112{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a}. This will mean that where you do your pedalling will offer a good platform. Although we think of 100{184722e0e226bcc33313b73fd463388417f454aa3a20797559fe2c0007fff18a} as being neutral to pedalling force, when you consider the varying loads we put through our bikes and how the rider’s centre of gravity moves around, something a little over that number will result in a consistent pedalling platform that grips well.

The bike is available in midnight blue or gunmetal.

Post-covid, Prime Bicycles will be able to welcome customers and potential buyers in Innsbruck and show them some of the technical aspects of their bikes in person at their test centre. All bikes are available from Prime directly. We look forward to receiving a Thunderflash in the coming weeks for review.