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We first saw the German Bombtrack Hook EXT back in January and, as Dave Arthur said, 'we liked what we saw'. Having spent a month trying to find a trail it couldn't handle, I'm stumped. This is simply an awesome bike to take off-road.
After our initial intro, Dave got into more detail here. As he noted, the defining feature of the Hook EXT is the 650B (27.5in) wheel size. It's becoming popular in the category of do-anything bike – the ability to rock the toughest of mountain bike trails, then either fit really fat slicks for road riding/touring, or a set of 700C wheels on normal tyres makes for as close to one-bike-to-rule-them-all as you currently get.
At over 11kg in its SRAM Rival 1X 650B-fat-tyre guise, the Hook EXT is portly by road bike standards, and the 44T chainring as tested will spin out quickly – but let's not damn with faint praise here. Understand what you can do with the Hook EXT and your horizons widen. Literally.
Since bicycles were invented there have been hardy souls pushing the limits of where you can ride one. Fatter tubeless tyres have turned bikes that were previously roadbound into perfectly capable gravel bashers, particularly bikes better suited to endurance pursuits befitting slacker head angles and longer wheelbases. At 1020mm in a medium frame size, the Hook EXT is properly stretched out and stable at any speed, on any surface.
And it's on the rough stuff that this bike shines. With knobbly, wide, inner-tubed rubber underneath, any road riding will be a chore, but it makes the anticipation of hitting the trails ever-sweeter. I felt more confident on the Hook EXT than on my (admittedly ageing) full-suspension GT i-Drive, it's that good. And not even in the drops – the substantial SRAM Rival hoods provide ample grip for gloved hands, even on 20mph rocky descents, the one- or two-fingered hydraulic braking providing the reassurance that you can get out of trouble quickly.
Once back on the black stuff, those same hoods make for excellent aero handles, helping towards a not-too-shabby 20mph solo average back down the valley.
Chopping between flinty, rutted, branch-strewn chalk downhills and overgrown bridleways, the Hook EXT performed flawlessly, even on the tubed tyres running considerably harder than I'd go on a tubeless setup in order to avoid pinch flats.
The box-girder fork, 15mm thru-axle and tapered headset held everything together on warp-speed off-road descents, with the 160mm front rotor making scrubbing off speed a one-fingered affair, while the drop bar made dicing along narrow, foliage-lined tracks a blast, with far less swerving required compared with the usual 700mm-plus mountain bike flat bar.
The Hook EXT frame is defined at the chainstay bridge. Here you'll find obscene amounts of tyre clearance – Bombtrack says it's designed to take 2.2in tyres, but there's another half an inch of clearance here, a tiny bit less at the slightly narrower seatstay bridge. Looking down at the box-girder construction at either end of the chainstays welded to the massive 86mm-wide PF30 BB shell, this is clearly a bike built from the ground up to go full fat.
Should you be concerned about potential squeaks and creaks from the PF30 bottom bracket on a bike designed for serious off-road thrashing, Bombtrack claims 'great success' with PF30 in its steel frames, not suffering the possibility of creaking that carbon does.
The frame is Columbus double-butted chromoly steel, finished in a gorgeous grey with a clear topcoat. The relaxed 71-degree tapered head tube keeps things tracking nicely up front, and the well-proportioned, slightly overbuilt-looking (for steel) top and down tubes maintain the solid feel of the bike.
While the down tube is generous, it's half an inch narrower than the front tyre – meaning on my first ride out I was plastered within a few minutes of hitting waterlogged bridleways. Clearly a front mudguard is a must if you want to retain your vision and a sense of decorum.
Befitting a bike designed to get seriously muddy, the seat tube slot is forwards-facing – a nice detail. At the aforementioned PF30 bottom bracket, the driveside chainstay starts out as a 6.5 x 30mm tyre-swallowing steel bar that merges into the oval chainstay heading rearwards. On the non-driveside there's a rather odd dual-cowled platform for the rear flatmount calliper to bolt to, providing just enough heel clearance for size 45 mountain bike shoes in overboots. Those with larger feet might want to test clearance first.
The replaceable rear dropouts are large cowled affairs to facilitate welding, each with a single rack/mudguard mount matched by a drilled seatstay bridge, chainstay bridge and an upper rack mount below the seat tube junction. Setting this bike up as a deep winter or load-carrying machine would pose no problems. The rear end is held together by a large 12mm thru-axle.
Bombtrack has steered clear of internal cable routing on the frame, simplifying trailside repairs in the middle of nowhere. Its choice of cable stops strikes me as a bit odd though – the rear mech cable is exposed along the top tube then goes into a long run down the seatstay, passing through three loose-fitting metal hoops.
I can understand going for a solid cable lower down where mud and water are much more of an issue, but what this means is there's no chance to clear out the lower section when the inevitable happens and it becomes contaminated. The old trick of popping the whole cable free of the stops and sliding the outer sections away to then wipe down a sticking inner just won't work.
I suppose you could drill the stops out and put in a full outer cable run – it would be nice to see frame makers providing the option with wider diameter stops fitted with reducers for using naked inners.
The design has featured on previous Bombtrack bikes, and the company claims there's very little contamination gets down the cable. There's an unused cable stop on the right of the down tube for a front shift cable, and a tapped hole in the BB that would hold the plastic cable guide for a front mech. Bombtrack advises you can fit a double crankset up to 52/36, should you wish.
The muted paintjob and graphics are lovely, but you do need to keep an eye on the cables around the head tube, because they will scuff up the topcoat if left unguarded.
The cavernous carbon fork with its tidy internal routing, flat mount calliper and 15mm through-axle means serious off-road business – but you can fit mudguards too, courtesy of the drilled crown and dropout tabs. The steerer is alloy, as befits a bike where weight isn't the concern but crash survivability in remote areas is. As for the frame, the fork is defined by clearance – there's a whopping 3in of space at the crown, surely enough for pretty much any rubber you'd think of fitting.
Bolted to the top of the fork are the Bombtrack-branded stem and bar, the latter with a 10-degree flare at the drops to widen the grip when off-road and offer more varied hand positions. It's quite wide on the tops – not a full-on aero tabletop but certainly nice and broad to help spread the load and minimise pressure on rough roads. The flare does mean that the SRAM levers are the outermost part of the bike, so careful leaning on that coffee-stop wall...
Other items of note are the supplied 2.1in WTB Nano tyres, which, annoyingly, aren't tubeless-ready, unlike the matching WTB rims. With excellent off-road capability this is a bike crying out for tubeless, and would be the first upgrade I'd make. During the review process I fitted a set of tubeless Maxxis Re-Fuse 2in slick tyres to get a feel for how the Hook EXT handled on faster-rolling, more gravel-road mix orientated rubber, and found that, at the lower pressures possible, comfort and grip were almost on par with the WTB Nanos on Hampshire's varied chalk downland bridleways. Bombtrack says you can go up to a 45mm 700C size tyre, but I didn't have a matching set of 700C wheels to swap in to try.
I just couldn't get to be friends with the Selle San Marco Squadra Startup saddle, but hey – saddles are personal and after swapping to my beloved Charge Spoon I couldn't complain.
The rather excellent SRAM Rival 1X groupset was well liked by Dave on its release. Here in its 44T chainring, 11-36 cassette guise I feel it's a tad overgeared for off-road use in hilly areas, offering 33-108 gear-inches to be precise. This is akin to pushing a compact chainset, 700C-wheeled bike on 28mm road tyres up a hill in the small chainring and 29T sprocket. Once you get steeper than 7-8 per cent that's going to see many riders out of the saddle – not an ideal climbing position off-road where you want to keep weight as rearward as possible for the best traction.
It's fine for short bursts, but prolonged climbs with short, steep or technical pitches won't be welcomed towards the glycogen-depleted end of decent days out. There's nothing stopping you swapping out the 44T for a 38, or going for the SRAM 11-42 cassette to make things more enjoyable without compromising top-end speed.
As Dave noted in his review, the combination of alternating tooth profiles on the chainring/jockey wheels plus rear mech clutch meant in hundreds of miles of bouncy, rutted riding the chain never once skipped let alone came off, and chainslap was literally unheard of. I quickly re-learnt SRAM's Double Tap shifting, and after a tweak of the paddle position was happily shifting away through the mud and grime through double layers of glove.
I'd previously ridden up to 40mm tyres on gravel/cyclo-cross bikes and thought I was having 'fun'. The Bombtrack Hook EXT takes 'fun', adds ride-anything confidence and barrels you down bits of bridleway and rutted farm track at speeds that will see you leaving bemused and abashed mountain bikers in your wake.
If you aren't fussed about 11kg+, this is a great bike with all-round potential and the lifelong assurance of a steel frame
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road.cc test report
Make and model: Bombtrack Hook EXT
Size tested: 56cm
About the bike
State the frame and fork material and method of construction. List the components used to build up the bike.
TOPTUBE: (Effective Horiz.) Small – 541mm / Medium – 558mm / Large – 575mm / X-Large – 591mm
CHAINSTAY LENGTH: 425mm
HEADTUBE ANGLE: Small – 70.25° / Medium – 71° / Large – 72° / X-Large – 72.5°
SEATTUBE ANGLE: Small – 72.5° / Medium – 72.5° / Large – 72.5° / X-Large – 72.5°
BOTTOM BRACKET: 70mm drop
SEAT TUBE: (C-T) Small – 510mm / Medium – 540mm / Large – 570mm / X-Large – 600mm
WIDTH: Small – 420mm / Medium – 420mm / Large – 440mm / X-Large – 440mm
COLOR: metallic grey
FRAME: COLUMBUS Cromor double butted tubing,TA dropout, repl. hanger, rack & fender mount
FORK: BT BIKES CX-Plus carbon / alloy TA disc fork, 1 1/8-1 1/2in tapered steerer tube
BARS: BT BIKES CX-10 6061-T6 butted alloy, 10° flaired drop bar
GRIPS: BT BIKES PRO shock-proof bar tape
STEM: BT BIKES Origin forged alloy stem, -7°
HEADSET: FSA Orbit ITA sealed a-headset, tapered 1 1/8-1 1/2in
LEVER: SRAM Rival 1 hydraulic
SHIFTER: SRAM Rival 1 1–11 (integ. with lever)
BRAKES: SRAM Rival flat mount hydraulic with 160mm F / 140mm R rotors
CRANKSET: SRAM Rival 1
BB: FSA PF30 with 24mm adapter
PEDALS: not included
CHAIN: KMC X11-1
CHAINRING: SRAM X-SYNC alloy, 44t
CASSETTE: SRAM 11-speed cassette, 11-36
DERAILLEUR: SRAM Rival 1
FRONT HUB: BT BIKES Origin sealed, CL disc hub, 15x100mm Thru-axle
REAR HUB: BT BIKES Origin sealed, cassette CL disc hub, 12x142mm Thru-axle
FRONT RIM: WTB STS double wall sleeved, TLC, i19, 32h
REAR RIM: WTB STS double wall sleeved, TLC, i19, 32h
SADDLE: SELLE SAN MARCO Squadra-Startup saddle
SEAT POST: BT BIKES 612 alloy seat post
SEAT CLAMP: BT BIKES Origin forged alloy seat clamp
TIRES: WTB Nano 27.5 x 2.1
WEIGHT: 11.1kg (24.5lbs) – size M
Tell us what the bike is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?
So what does the EXT stand for? Well the truth is we can't even remember any more, extreme, extended, extraordinary...take your pick. The important thing, is what the Hook EXT is. Built on a 27.5' rim and using a wider tire produces a wheel with the same outer diameter as a typical 700x28c. This means it's possible to run bigger knobby mountain bike tires, with all the grip they offer, yet retain the geometry of a CX/gravel bike, something gravel racers have long dreamed of. This is made possible thanks to a specially designed frame that utilizes a wider bottom bracket and yoke to maintain a wide yet short rear end. The Columbus Cromor double-butted tubing has the perfect blend of being lightweight yet durable, perfect for gravel riding. The fork was then developed specifically for this bike, with a super wide crown offering massive tire clearance and a stiffer tapered steerer tube for more accurate handling.
The SRAM Rival 1 is ideally suited to the Hook EXT, thanks to its simplified 1x design with clutch derailleur, wide range cassette and X-sync chainring providing smooth shifting in any conditions. The hydraulic brakes bring a superior stopping power to the EXT, which is reassuring on steeper technical descents. The versatile build is designed to offer as much all-round use as possible, so if your journey is mainly on-road, swap out the wheels for a set of 700c's, with anything up to 45c tire.
Frame and fork
Tell us about the build quality and finish of the frame and fork?
The finish is excellent – it looks a million bucks, and the welds are – whilst not surgical – very tidy.
Tell us about the materials used in the frame and fork?
Columbus double-butted tubing is a solid choice, and the carbon fork is box-girder solid in construction.
Tell us about the geometry of the frame and fork?
Relaxed and long – that's about the summary. If you are worried about a degree either way, this isn't the bike for you.
Riding the bike
Was the bike comfortable to ride? Tell us how you felt about the ride quality.
Super-comfy for me – the combination of long wheelbase, fat tyres and flared bar made for über-confidence off-road.
Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?
Hard to be picky about frame stiffness with so much mass and squishy rubber underfoot, but it didn't feel inefficient.
How did the bike transfer power? Did it feel efficient?
It's an 11+kg bike on fat knobbly rubber – it's never going to feel snappy. That said, it didn't suck my will to live.
Was there any toe-clip overlap with the front wheel? If so, was it a problem?
How would you describe the steering? Was it lively, neutral or unresponsive? Forgiving, as a bike designed for loose off-road surfaces should be.
Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?
Confidence-inspiring and not surprising.
Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?
Loved the bar – perfect. Didn't like the saddle, but as noted that's the most personal of choices and easily remedied.
Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?
Tyres. Swap them out ASAP.
Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?
Again, look to tyres as the cheapest/easiest improvement and tuning to your ride.
The bar and steerer tube angle in the medium tested made for great manoeuvrability.
It's portly, but sticks to the ground.
Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?
Loved the clutch and narrow-wide tooth pattern on the chainring. No drops or skips, or chainslap.
Wheels and tyres
Tell us some more about the wheels.Did they work well in the conditions you encountered? Would you change the wheels? If so, what for?
A good choice, but maybe could benefit from a wider rim profile.
Grippy enough, but I'd want tubeless.
Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so, what for?
In my opinion, this bike needs tubeless.
Tell us some more about the controls. Any particularly good or bad components? How would the controls work for larger or smaller riders?
Can't fault DoubleTap.
Did you enjoy riding the bike? Yes
Would you consider buying the bike? Yes
Would you recommend the bike to a friend? Yes
Use this box to explain your score
If this bike were 2kg lighter it'd be 9 out of 10. But that's to miss the point – the overall combination looks beyond simple weight, to a place on the distant horizon you'll have a lot of fun getting to, and back.
About the tester
I usually ride: Merida Ride 5000 Disc My best bike is:
I've been riding for: Over 20 years I ride: A few times a week I would class myself as: Expert
I regularly do the following types of riding: cyclo-cross, club rides, general fitness riding, mountain biking, Dutch bike pootling.