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Mountain bike versus hybrid: Test lab

Mountain bike versus hybrid

Words: Matt Lamy

A few issues ago I had a First Ride on a Whistle Crow, which looked just like a typical hybrid bicycle: it had flat handlebars like a mountain bike but thin tyres like a road or touring cycle. However, contrary to our perhaps lazy view of a hybrid — a machine based on a mountain bike with a few changes made to encourage life on asphalt — the Whistle was actually a dedicated road bike, it just had the distinction of replacing its scary-for-some drop handlebars with more novice-friendly straight bars.

But it got us thinking about exactly what marks out a hybrid bike — which will probably spend the vast majority of its life on road or towpath — from a dedicated mountain bike that should spend its life glooping through mud and bouncing over ruts.

Is it really just a case of bike manufacturers sticking on bigger or smaller wheels and thinner or fatter tyres depending on the market? Could you — particularly the cycle commuter — turn your own mtb into a viable hybrid, and vice versa, with a simple switch of rubber? Or are there more fundamental design differences at work — and should you really make sure you have a bike ‘fit for purpose’?

Equipment
To understand this I’ve picked two comparable bikes from the same mainstream, well respected, bike manufacturer. The Scott Aspect 30 is a mountain bike that costs £549.99 while its cousin, the Scott Sub 30, is a hybrid that costs £20 more at £569.99. In terms of the spec sheet they share many components: each has Shimano Altus RapidFire Plus shifters allied to Acera front derailleurs, each has a selection of 27 gears, and each uses Tektro hydraulic disc brakes.

mtb vs hybridHowever, look in a little more detail and there are differences. The three chainrings on the Aspect 30 mtb (featuring 44, 32 and 22 teeth) are lower geared than those on the Sub 30 (48, 38 and 28 teeth). The Aspect is fitted with a Suntour suspension fork while the Sub has a rigid alloy offering.

The Sub gets a slightly better quality Shimano Acera rear derailleur against the Aspect’s Alivio version. And of course there are the tyres. Huge off-road specific, 2.1-inch wide Schwalbe Black Jacks make up part of the Aspect’s 26in diameter wheel and tyre combo. Meanwhile (slightly) more svelte and definitely less grippy 37c Schwalbe Citizen urban commuting tyres feature on the Sub’s 700c hoops.

It’s also at this point that it’s worth studying each bike’s frame and geometry. Both are constructed from double-butted 6061 alloy, and both feature an mtb-inspired sloping top tube. Again, like the spec sheet, a cursory glance would suggest a close relationship. But if you look closely you will see some important differences.

The head tube junction is perhaps the most obvious case in point: on the Sub hybrid the two joins are separated as on a typical road bike, giving the head tube a bit of breathing space and room to flex; whereas on the Aspect all three tubes converge in what looks an ultra-strong meeting of gussets. It’s the same with the profile of the tubes. On the Sub they seem a tad more rounded; on the Aspect mtb they are squarer-edged and potentially more rigid. And when it comes to geometry, angles and tube lengths also vary slightly (see page 58).

So these are two distinct bikes.

Theory
What do we expect? Well, the Aspect 30’s strong and compact front end should make it the more controllable bike over bumpy terrain, and its lower range of gears should make it more practical when tackling tough obstacles. It’ll also be interesting to see how effective the suspension fork is at aiding comfort.

Meanwhile, such is the construction of the Sub 30’s frame — as demonstrated by the more rounded tubes and the more open front end where the extra length of head tube should go some way to absorbing under-tread imperfections — I expect the hybrid to be the more efficient bike on the road and its higher gear ratios should also make it quicker, certainly over anything approaching a smooth surface.

Finally, I anticipate the effect of each bike’s sets of tyres will be crucial.

Method
I have devised a simple five-mile test route, split evenly into 2.5 miles of road riding and 2.5 miles of demanding off-road. Under the same conditions I will complete a timed ride over the course on each bike to see which is nominally faster. Then I will test the bikes on a straight, flat, four-mile road section.

More importantly, I will also record the sensations felt on each stretch of terrain with the different bikes. Because both the Aspect and the Sub run the same Tektro disc brakes and virtually identical rear cassettes, it should be possible — subject to tyre clearances and a bit of gear tweaking — to swap over wheels. Then I’ll find out how each bike performs with the other one’s hoops.

Conditions under tread: mainly dry with muddy patches off-road. Total climb on route: 500ft.

Results
Scott AspectScott Aspect 30 mountain bike (standard spec)
Despite its wide tyres, the Aspect is actually a pretty good road companion (for a mountain bike) and it rolled pleasantly enough on asphalt, especially with the front fork locked out. The high riding positioning also gives a commanding view of the road. However, when off-road the bike becomes far more responsive and satisfying. The chunky rubber keeps grip well through mud or over slippery surfaces and the suspension fork soaks up bumps well — it’s particularly effective when travelling at speed over loose fire road-type tracks.

Price £549.99
Frame 6061 alloy
Fork Suntour XCR 100mm
Crankset Shimano Acera
Gears Shimano Alivio/Acera
Shifters Shimano Altus
Brakes Tektro hydraulic disc 160mm
Wheel size 26in
Tyres 2.1in Schwalbe Black Jack
Weight 13.6kg
Size tested Medium (57cm)

Scott SubScott Sub 30 hybrid (standard spec)
The Sub instantly feels far quicker than the Aspect and despite the taller head tube I found myself naturally adopting a more aggressive riding position. On the road the riding experience was more rewarding than with the Aspect — I felt like my input was being harnessed efficiently. Off-road the difference was also significant, although not for the better. While the Aspect ploughed on, through or over difficult terrain, the Sub was left slipping and sliding — the back end being particularly keen to lose traction, particularly when under braking, to the point where I crashed heavily on one descent.

Price £569.99
Frame 6061 alloy
Fork 6061 alloy
Crankset Shimano Acera
Gears Shimano Acera
Shifters Shimano Altus
Brakes Tektro hydraulic disc 160mm
Wheel size 700c (28in)
Tyres Schwalbe Citizen 37mm
Weight 12.3kg
Size tested Medium (57cm)

Aspect 30 with 700x37c wheels and urban hybrid tyres
Fitting 700c hybrid wheels to a 26in-wheeled mountain bike frame isn’t something we’d recommend — you can get dedicated 26in semi-slick tyres if you want to introduce your mtb to the joys of asphalt — but for the purpose of this test it was just possible. With the Sub’s bigger wheels and less knobbly tyres the Aspect felt pretty quick on road but not particularly comfortable. There was a noticeable lifting of the rider’s centre of gravity, which did suggest slightly less stability, and the tight front end which had felt quick and direct with the grip of its normal tyres now became twitchy. Off-road the Aspect’s previous abilities all but vanished — its nippy handling was now rather at odds with an unpredictable rear.

Sub 30 with 26×2.1in wheels and off-road tyres
With high-grip rubber the Sub was a far more exciting and predictable performer through mud and over bumpy surfaces. However, due to a slightly more languid nature and relaxed geometry it still couldn’t quite match the fun of the Aspect. However, no amount of forgiving geometry can match the comfort provided by the Aspect’s suspension fork over quick trails. As expected, with big tyres the Sub’s former speedy performance on road became rather more turgid — the smaller-diameter wheels and lower centre of gravity made the bike feel like it was wallowing.

Conclusion
Considering the quite demanding off-road section of my test route I was surprised the Sub hybrid in its standard guise managed to keep up with the Aspect in the mixed terrain test. However, that isn’t the whole story, and while the Sub did well in terms of speed, the ride sensations off-road weren’t pleasant, and nowhere near as controllable as the Aspect (to the point where I ended up on my backside). When we switched wheels on the two bikes the reason for this was obvious — the grip with the Sub’s urban-specific hybrid tyres just weren’t anywhere near good enough for dedicated off-roading.

For its part, the Aspect mtb may have been the slower machine overall in standard spec — and on road the effort needed to getting it moving at pace was noticeably greater than that needed for the Sub — but it was massively enjoyable to ride on bumpy or slippy terrain. After swapping the wheels round the issue was clouded slightly with the mtb actually proving to be pretty speedy over asphalt, but it just didn’t feel quite right compared to Sub.

So can you just stick some slicker tyres on your mountain bike and turn it into a hybrid? Or can you put chunky rubber on your hybrid and it becomes an mtb? Certainly it helps, and it will broaden what your bike is capable of. But I do feel there is no value in second-guessing the engineers and designers that create these machines.

Whatever similarities the bike share, in action they are different beasts. Those small tweaks in geometry or construction have a huge bearing on the way each bike handles and, even at this relatively unassuming price point, each is specifically designed for a particular role.

mtb vs hybridFinally, even if you have no interest in ever riding a hybrid or mountain bike, there is another valuable lesson to be learnt: fitting the right tyres for your chosen bike in the prevalent conditions is supremely important. In our test both the Sub and the Aspect ran identical Tektro 160mm hydraulic disc brakes, yet in muddy conditions, with less knobbly rubber on, you’d be easily forgiven for thinking they were brakesets at different ends of the market. With no traction they just couldn’t perform. And it’s the same problem when you want to get the hammer down and move.

But just as you don’t want to be locking up brakes, or spinning your effort away, equally you don’t want to be having to overcome a massive friction coefficient if everything is smooth and dry under tread. So pick your rubber wisely.

It’s amazing how easily bike buyers can be swayed by a host of often unimportant considerations. The best advice is: choose the bike that fits your most common needs. If you’ve got a daily road or cycle path commute but you fancy heading off the beaten track from time to time, buy a hybrid. And if you like mountain biking but you might, very occasionally, have a go on asphalt, pick an mtb. With a change of rubber they’ll cope, but you can’t beat having the right tool for the job.