While tyre dimensions have been cemented for years, the tyre and wheel industry has now awoken from its slumber. It is developing new standards at breakneck speed. After initially expanding the diameter to include twentyniners and 27.5", the focus is currently on tyre width: the fat bike trend is now being followed by the plus format. If you compare the wheel sizes with musical notes, it seems that the right tone has not yet been found. But with every new tyre and wheel standard, the uncertainty of the biker customer also increases: Which tyre size is best for me?
Spoilt for choice with the Scott Genius
To get to the bottom of this question, we carried out the reader test with the Scott Genius. This is available to the customer in three wheel variants: 29 inch (Genius 900), 27.5 inch (Genius 700) and 27.5+ (Genius 700 Plus). To ensure better comparability, all three all-mountain models rolled into the editorial office in the respective top-of-the-range Premium (Genius 700) or Tuned (900 and Plus) configuration. All were converted to tubeless. Small differences in the equipment can still be seen in the details: The carbon frame forms the basis for all three models, only the Plus model has to make do with an aluminium rear swingarm. When it comes to the gearing, Scott fits Sram's 1x11 drivetrain on the Tuned models and Shimano's XTR 2x11 groupset on the Premium version. In practice, the latter offers a noticeably wider gear range and belongs on all-mountain bikes like the mouthpiece on a trumpet. Otherwise, all three play in harmony: Shimano XTR trail brakes, Fox suspension with stiff 34 mm forks and three selectable modes (Lockout, Traction Control, Descend) via Twinlock levers. RockShox Reverb dropper posts and 740 millimetre wide carbon handlebars, whose steering impulses are directly transferred thanks to 60 millimetre short stems, are also standard in this price range. All three are absolute dream bikes on paper. With 130 to 150 millimetres of suspension travel, the Genius models tested fall into the all-mountain category - bikes for demanding off-road use.
The bike park on the Geißkopf provided the perfect test environment: instead of taking the lift, we headed up to the mountain station via long gravel climbs and crisp trail passages and then back down again via flowing and rough trails. For our two reader testers Dominik and Tobi, who are usually hobby bikers on sporty race bikes, this was a new but also unbiased experience. We wanted to clarify the question with them: Which wheel suits whom?
The air pressure makes the music
Tobi is already surprised when "tuning" the bike set-up on the Plus: "What, only 0.8 bar? I usually run at least two bar." But this is exactly where the advantages of the 2.8-inch half-fat tyres lie: less air pressure, but more comfort, traction and grip. Even on the first few metres uphill to the mountain station, Dominik is surprised by the harmonious rolling behaviour of the Plus tyres: "The fat bike goes uphill amazingly well! I wouldn't have thought that the difference to the other wheel sizes would be so small." Tobi also doesn't notice any major difference compared to the other two models. On the contrary: on the last 500 metres over wet roots and slippery stones, the Plus tyres clearly play first fiddle. While Dominik has to search for the ideal line on the 27.5 tyre, Tobias climbs relatively easily on the Plus. Thanks to the large contact area with the ground, the voluminous tyres blend like individual notes to a melody and therefore have significantly less slippage. In contrast, the smaller diameter of the 27.5 tyres is noticeable: "I'm more challenged by the bike, I have to counter-steer, correct and slide further forwards so that the front wheel doesn't lose contact with the ground," Tobi later describes the uphill handling. Dominik also criticises the more demanding climbing behaviour - subjectively, the smaller wheels always bump into the roots and edges instead of rolling over them smoothly like the 29er or Plus. All in all, however, the 29er is the most convincing in the Uphill classification with its mix of smooth and rough terrain. This is due to the excellent rollover behaviour, but also to the lightest wheels.
Once at the top, it's straight back down again. Here, all three bikes clearly benefit from the lowerable seat post and the increased riding safety it provides. On the first part of the descent, the flow country trail, the first differences between the models are immediately apparent. In the fast berms, the 29er and Plus ride "like on rails", they offer "a lot of smoothness, grip and traction" - according to the testers in unison. On the Genius 700, however, Tobias in particular had to be more sensitive to prevent the bike from becoming unstable. The geometry of the Plus bike, like that of the 27.5er, seems a little more manoeuvrable than that of the 29er, but due to the heavier wheels, quick changes of direction tend to happen in slow motion, i.e. quite slowly. When switching from the flow trail to the downhill piste, Tobi puts it in a nutshell: "On the rough descent, I find it much harder to ride precisely and hold a defined line with the plus bike. But that doesn't really matter, because the bike still gives you ultimate confidence!" While the Plus plays the quiet bass in the three-piece Genius band, the 27.5 is clearly the excitedly screeching electric guitar: agile, manoeuvrable, with plenty of reserves (more travel) and a significantly higher steering precision than its larger wheel counterparts in the test. "The handling of the Genius 700 simply feels much 'fuller'", both readers' testers agree. However, Tobias and Dominik are divided on the 29er: While Tobias navigates well through the rocks and over the steps, Dominik criticises the lower steering precision, which "is probably due to the large wheels". The 29er also offers the least puncture protection, which manifested itself twice during the test runs with a puncture on the rear wheel. Irrespective of this, lightweight tyres, such as the Schwalbe Rocket Ron fitted to the 29er and 27.5er at the rear, are unsuitable for all-mountain use. On the Plus bike, on the other hand, there is a "marshmallow feeling", as Dominik describes it, "which leads to technical indifference". The Plus is therefore subjectively more tolerant of mistakes. Subjectively, you can only guess how much the suspension elements on the Plus actually perform. This is because the feedback from the ground blurs with the thick tyres, which also provide enormous suspension.
Driving pleasure winner: The Plus format
During the "grand finale" in the bike park, the last metres of descent on the dual slalom track, the steering behaviour of the half-fat bike is sluggish and it has to be pushed more actively into the corners. It also requires more power when jumping over the tables compared to the 29er and especially the 27.5er, which even tempts Tobias to whip with its playful character. Nevertheless, the pure riding pleasure with the Plus feels the greatest. That sounds suitable for beginners. But: In order to utilise the plus advantages, you need a certain amount of experience, you have to meticulously control the air pressure and, in order to save weight, build the wheels as tubeless as possible. Plus bikes also weigh more. The cheaper the model, the more negative the effect. If you opt for the Genius Plus, you are theoretically buying two bikes in one. With matching 29er wheels (Boost standard), you can change the character in the direction of sporty. As a 29er for long distances, with Plus tyres for difficult terrain. Schwalbe Plus tyres cost seven euros more per tyre than "normal" tyres. They also show weaknesses in terms of puncture resistance. The thin carcass, trimmed for lightness, cannot withstand sharp-edged rocks.
Conclusion David Voll, BIKE test author
In the end, the three Genius models are like music: tastes differ. There is no clear-cut answer as to which wheel size is better. Rather, constitution (not every body size fits on a 29er), riding ability (the 27.5er in particular demands much more from the rider), personal pain threshold (if you want to go uphill dynamically) and, last but not least, the area of use all play a role. Although all Genius bikes belong to the all-mountain category, the choice of tyres, especially on the 29er, determines the range of use. Fitted with lightweight tyres, you can also ride a marathon. However, our two reader testers clearly found their favourite in the end: While the agile and playful Genius 700 emerged as Dominik's rock star, Tobias was won over by the poppy Genius 900 with its versatility and smooth ride. According to the testers, the plus bike is suitable for people who already have everything.
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ADVANTAGES AND DISADVANTAGES OF THE CONCEPTS
29 inch
PLUS Very good rollover behaviour, high traction, smooth and stable ride, easy to drive, low rolling resistance, wide range of applications
MINUS Wheels are more unstable/less rigid than smaller diameters, not suitable for all body sizes
27.5 inch
PLUS Agile and sprint-friendly, low weight, high wheel stiffness and stability, large selection of tyres
MINUS Weaker rollover behaviour, less comfort, more nervous and demanding handling in technical passages, less traction
27.5 Plus
PLUS Lots of grip and traction, subjectively high riding safety and comfort, very good rollover behaviour, Plus frame suitable for 29er Boost wheels
MINUS High weight (700-1000 g tyres), less agile handling, more effort required from the rider, limited choice of tyres
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THE TEST RESULTS
This is how we tested it: The bike park on the Geißkopf in Bischofsmais has a lot to offer for all-mountain bikers. From the valley station, it's four kilometres along a moderately steep forest path and a steep and very rough rock and root trail to the mountain station. We assessed the climbing characteristics during the 260 metres of ascent. From here, the command is to lower the seatpost and go full throttle into the flow country, a flowing trail with berms and small jumps. This is where the handling of the bikes became apparent on the downhill and when changing direction quickly. From the flow country trail, it was then over the blocked downhill section and over the dual slalom with steep bends and tables to the finish.
WHAT THE READER TESTERS SAY:
Prof Dr Tobias Huep:
For me, the Genius 900 is the all-rounder that, depending on the choice of tyres, can do everything - from bike park to marathon. I always felt safer with the Genius 700 Plus, but subjectively I wasn't any faster than with the other two concepts.
Dr Dominik Erhardt: The 27.5 mm Genius is agile on the climbs and surprisingly powerful on the descents. Although I'm a 29er advocate, I had the most fun with the Genius 700. The Plus format sets emotional accents. High ice-cream parlour factor and interesting for use on snow and sand.
THAT'S WHAT THE TEST LAB SAYS:
If you compare the three tyre dimensions using Schwalbe tyres (27.5+ in 2.8 inch width), the up to 200 gram heavier Plus tyres perform better than expected. The rolling resistance is good, the traction is better. The thin carcass is the problem when it comes to puncture resistance. With other tyre manufacturers and wider Plus models, the agility is worse, but the traction and riding safety is still higher than with 29 and 27.5 inch tyres. Interesting: For 2017, it is becoming apparent that plus tyres will tend to be narrower again. Insiders are talking about 2.6 inch wide, stable tyres. All the facts from our concept comparison in the lab can be found here->
VERSATILE GENIUS: TURN ONE INTO THREE
The comparison test shows just how variable the Scott Genius platform is. The Scott engineers have conjured up three different characters from the familiar all-mountain chassis. We were supplied with the most expensive, lightest Genius variants.
29 " | SCOTT GENIUS 900 TUNED: The bike with the widest range of use
The bike with the largest wheels weighs the least. This is mainly due to the carbon rims: The complete wheels with tyres, cassette and brake discs save almost a kilo compared to the Plus model. The advantages of the large wheels were particularly noticeable to the testers when rolling over root carpets and on steep uphill ramps. A clear case: the top model is a top-class all-mountain bike. Reader tester Tobias declared the bike to be his favourite - but with a double drivetrain, please.
Price8499 Euro
Weight (without pedals): 11.13 kilos
Suspension travel140/130 mm
Impeller weight complete: 3591 g
27.5 " | SCOTT GENIUS 700 PREMIUM: more agile, more playful, with reserves in the suspension
The smallest wheels and the largest suspension travel, with an excellent weight. The 27.5 Genius is aimed at people who want to let it rip downhill and have a playful riding style. The more agile handling is immediately noticeable on the downhill track. In the opinion of our testers, however, this bike requires more riding skill than the other two - both uphill and downhill. The testers rated the equipment and the double drivetrain as perfect. Quote: "This makes the bike the most versatile of all."
Price7599 Euro
Weight (without pedals): 11.59 kilos
Spring travel: 150 mm
Impeller weight complete: 3786 g
27.5 Plus | SCOTT GENIUS 700 TUNED PLUS: Plus format: for those who already have everything
The Plus model is the youngest bike in the Genius range. The thick tyres require the Boost standard for the rear triangle and fork, so the bike is technically more modern than its brothers. Advantage of the Plus chassis: 29er wheels also fit, provided the Boost standard is used. The reader testers were surprised by the traction. They found the Plus format the most fun to ride. The greater tolerance for riding errors comes at the price of less agility. Both readers therefore did not choose the Plus Genius as their favourite.
Price7999 Euro
Weight (without pedals): 12.29 kilos
Suspension travel140/130 mm
Impeller weight complete: 4439 g
