Rubena Kratos and Scylla Tubeless Supra Mountain Bike Tyre Review
- by John Hawkins
- Published: 29 November 2012
Rubena tyres have arrived on the Australian scene with a bang this year, appearing on the wheels of Australian Olympic mountain bikers Dan McConnell and Rebecca Henderson at the 2012 games. While unfamiliar to most regular Australian riders, Rubena is a brand with a long history. Originating in Czechoslovakia, the company began in 1924 as a manufacturer of soles for shoes, branching into tyres in 1934.
The subjects of this review, the Scylla and Kratos tubeless ready tyres, are aimed at the cross-country market and are intended to prioritise speed and low rolling resistance over outright glue-like traction. They are available in a long-wearing all-black single compound or SDX “Greyline” black and grey dual compound. This review deals with the single compound “Tubeless Supra 1 for 3” tubeless ready version. “1 for 3” refers to the fact the tyre has been designed to be used with tubes on normal rims, normal rims with tubeless conversion systems, and UST tubeless rims. Not all tyres will work satisfactorily with all systems, but Rubena has done its homework here.
Of the two tyres reviewed, the Kratos has the more aggressive open tread with slightly more raised and prominent edge blocks. The Scylla, on the other hand, has the lower and more closely spaced tread necessary for low rolling resistance. As most of my local trails vary widely in surface conditions, I opted to fit the Kratos to the front as the primary control tyre, with the Scylla on the rear where its low rolling resistance would be best utilised.
The quality of construction of both tyres was excellent, at least equal to any of the market leaders, such as the Maxxis Crossmark or Schwalbe Racing Ralph. The sidewalls have what looks like an embossed cross-hatch pattern and the moulding was sharp and uniform. They beaded up easily on my Mavic UST rims, and mounted evenly and straight.
Tubeless ready tyres use a UST compatible bead, but rely on the use of liquid latex sealant to maintain inflation. The leaking of small droplets of sealant through the sidewall initially is not uncommon but, contrary to expectation, these tyres sealed up very well and displayed none of the slow leaking over the first few days commonly reported with other brands of tubeless ready rubber. They continue to hold air well and just require topping up once a week or so, the same as the full UST or tubed tyres on my other bikes.
The Scylla and Kratos were both very light, though in my enthusiasm to try them out I neglected to weigh them before fitting them. They were, however, noticeably lighter than the Schwalbes UST Triple Evos I’ve been running, which are very light for tubeless tyres. Both Rubena tyres have a high thread count casing, 127 tpi, which accounts for the light weight and supple feel of the casing in the hand.
While these tyres were marked as 2.25″ wide, they came in at less than that, more like 2.1″. This isn’t a bad thing, it is just something to factor in when purchasing and, maybe, go a size up in width compared what you’d use with other brands.
Sydney’s sandstone trails are notoriously hard on sidewalls and, unless you’re using full UST tyres, with some brands you can expect the sidewalls to give up well before the tread wears out. After several months riding in these conditions, the Kratos and Scylla have both worn very well; the sidewalls showing none of the usual marking up I would have expected by now.
The tread is obviously directional, although on the Kratos the arrow showing recommended direction of rotation was a little hard to find. These tyres rolled extremely well thanks to the high thread count and they accelerate briskly, as you’d expect from their low weight.
In terms of feeling hooked up to the trail, I’ll admit it took a little while to warm up to them. Much of that was due to setup. The first few rides I ran my usual setup, 25psi on the front and 32 in the rear, and the front of the bike felt washy. Riding at Manly Dam, on the first lap, I burped the front tyre after striking the side of a rock. Clearly 25psi was not enough for the Kratos, so I upped the pressure to 30psi to get the bead to re-seat and left it at that to see how it would go. What a difference! The steering was much more positive and I was able to concentrate on the trail instead of worrying about understeer, although I felt there was still a little room for improvement.
A couple of weeks later, it struck me that I might get a better result if I changed the direction of rotation. All tyres slide to some degree, especially on dirt. On front tyres, it is the edge of the shoulder lugs facing the centre of the tread that you see get chewed out first, since they take most of the load when cornering forces are at their highest. Switching that around, so that the lugs look “toed in” at the top (see photo), sets the shoulder lugs so they are toed out when on the ground. This allows the broadest side of the shoulder block to face into the direction of slide when leaning on edge, giving more bite.
That change brought about an immediate improvement in cornering confidence and predictability, with no tram-lining and no loss of response when changing direction. A return visit to Terrey Hills and Cascades (Belrose) felt much better. Riding in dusty conditions at Taree’s Kiwarrak State Forest, the front felt dialed in.
During this time the rear performed faultlessly. Despite the closely packed low profile tread knobs, climbing performance was excellent. It would still spit out and slip on the occasional loose rock on the really steep sections, as most do, but instead of losing all drive it would bite again to keep you moving forward. Riding the buff single-track at Hornsby’s Old Man’s Valley mountain bike park (due to be open to the public mid-December 2012), they stuck to the track like glue.
One of my occasional riding buddies, Smilie, reported outstanding traction using the 29er version of the Scylla at both ends of his bike at the Scott 24hr at Mount Stromlo: “I had these on at Mt Stromlo at the Scott event; I wouldn’t ride there again with anything else. They were flawless on the red loop – from riding there in the past with other tyres, it was cornering the downhill and luge like I was on rails. But around my local single track they are a bit sketchy where leaf litter after back burning has gone thru there. 9.5/10 at Stromlo , 7/10 at local trails”
One of my WA contacts, Cotic Tony reports “I’ve got them on my HT bike right now and think they’re the best 29er combination that I’ve used so far. I’m running the Kratos front, Scylla rear, running tubeless on Stans crest’s in preparation for the Dusk till dawn… At around 650g each, they nicely bridge the gap for those who want to run tubeless but were previously limited to the delicate but light TLR/2Bliss offerings or the reliable but heavy (900g Ardent) Maxxis UST tyres… On the trails here in WA, I’ve been really impressed with them.”
As the range and availability of Rubena Tyres expands over the next 12 months, they should definitely be on your list when next shopping for rubber at your local bike shop. I would have liked to have tried the 2.4″ sizes in the dual compound versions but unfortunately they weren’t available at the time of review. I will definitely be fitting a set of these to my bike when the Mont 24 swings around again in 2013.
In January 2013, the road racing and commuter tyres, tubes and sealant arrive on Australian shores.
Light weight, high thread count
Impressive construction quality
Long wearing tread and surprisingly tough sidewalls
Ease of tubeless setup
Low rolling resistance
Kratos front and Scylla rear are an excellent combination across a wide variety of conditions from WA pea gravel to Sydney’s loose rocky sandstone trails and buff single track
Worth experimenting with direction of fitment to see what works for you
The Scylla is less suited to use as a front, except on buff single track, but it performed very well as a rear in a variety of dry conditions
Small for the marked size: buy the next width up from your current brand
Rubena Tyres are imported into Australia by PCI Imports and are available from all good bike shops. The front wheel Kratos retails for $75 and the rear wheel Scylla for $75 in the Tubeless Supra version.