Sinnis Terrain 125 Review (2021)


The problem with most small bikes is that they tend to be too, er, small. Which was ok when learner riders were wispy teenagers, still waiting for life and beer to catch-up. But these days new riders are often older, more fully grown and needing a bike that is both big enough to be comfortable and light enough to not be threatening.

Adventure bikes are perfect for new riders. Plenty of room to look behind you, good visibility in traffic, comfortable at low speeds in town and enough presence that car drivers see you. But none of the Japanese manufacturers make a 125cc adventure bike and that left a gap for the smarter Chinese manufacturers to fill.


For and against
  • Full-sized learner bike
  • Very good value
  • Well-equipped
  • Brand snobbery
  • Feels a bit bulky in traffic
  • Resale values can be low
Sinnis Terrain 125 2021 Review Price Spec_06

A shade over £3k for a modern 125 with full luggage and crash protection


2021 Sinnis Terrain 125 price

List price is £2899 plus on-the-road costs (which amount to your road tax and the pre-delivery assembly and inspection) which comes to around £3100 depending on whether your dealer is paying London or Lincoln labour rates. That’s at least £1000 cheaper than any of the funky Japanese 125s for a bike with three-box luggage and serious crash protection, and at least £500 less than many commuter run-arounds.

The biggest challenge on Chinese bikes can be finding flexible finance. Most of the importers aren’t big enough to offer their own schemes so you’re reliant on the dealer’s provider. Mostly these are great, but interest rates can be higher than a subsidised manufacturer scheme.

The second biggest challenge can be depreciation. A lot of main dealers aren’t keen on taking them in part-exchange because they are nervous about parts supply and reliability. Which means sellers are left to the private market and that can negatively affect prices. Look after your bike, get it serviced regularly and write the greatest advert ever and you’ll sell it for good money. But there are plenty of shabby abused 125s out there and historically Chinese bikes degraded faster. Their reputation is getting better as the bikes get better, but somethings take time.


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Low seat is comfy, bars are high and wide, which means lots of room (and confidence) for riders of all sizes


2021 Sinnis Terrain 125 riding position and dimensions

Few people choose a particular 125cc bike because of its performance. Learner restrictions mean they all make roughly the same power and go as fast as each other. But the riding position, dimensions and comfort can make a huge difference to your confidence and enjoyment.

The riding position of an adventure bike is a lot more relaxed than a sports bike and roomier than a simple naked bike too. Plus, the screen and other bodywork helps keep much of the wind and rain off if you ride every day.

The usual downside to adventure bikes is that they can be very tall, which is un-nerving for new riders and makes the bike feel top-heavy and clumsy when pushing it around with the engine off.

The Terrain 125 strikes a good balance between a roomy and comfortable riding position, but still with a relatively low seat height. 


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All-new water-cooled engine makes the same power as the competition with enough torque to be flexible


2021 Sinnis Terrain 125 performance power, torque and economy

Sinnis has made huge improvements to things like build quality and suspension components in the last few years, but the one thing that held them back was an air-cooled engine loosely based on a 1980s Suzuki unit. The 2021 Terrain 125 gets an all-new liquid-cooled motor making the mandatory 12.7 (the .7 is important at this level) bhp and 7.7 lb-ft of torque. On the road that takes the Terrain up to an easy cruising speed of 55-60mph with another 5-10mph in reserve depending on the gradient of the hill you are descending. That’s not a bad speed considering that with all the luggage fitted the Terrain 125 has similar aerodynamics to an upright piano (with double candle holders)

The new six-speed gearbox allows sharp-enough acceleration to get you away from traffic lights ahead of the four-wheelers and is surprisingly flexible if you accidentally find yourself trying to pull away in third gear. Not that we’d do that as professional, experienced road testers, of course. It must have been someone else.

Our bike was brand new when tested, with just five miles on the clock. Most engines become more economical once they’ve loosened up a bit and done around 500 miles, so we’d expect the fuel consumption to be a little better than the 86mpg we achieved. 100mpg should be possible and that means up to 300 miles between refills of the 14 litre tank.


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Adventure bikes have their exhausts mounted high to clear rocks and streams when riding off-road


2021 Sinnis Terrain 125 Engine, gearbox and exhaust

Sinnis’ new engine is impressive. Water-cooled, fuel-injected and with a new six speed gearbox. The clutch action is light, gears click into place easily and finding neutral is always simple. The engine has enough pull in each gear for predictable, linear acceleration and there’s some flexibility that allows you to be in the ‘wrong’ gear and still find decent drive. Given that the bike has the added weight of the bodywork, crash bars and luggage, the performance is good, and the high-level exhaust gives the styling some off-road authenticity.


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Strong frame and competent suspension. Rear shock (it’s in there somewhere) is adjustable for preload for heavier riders or regular pillion use once you’ve passed your test. 


2021 Sinnis Terrain 125 chassis, suspension and handling

The chassis is simple, but substantial and fitted with suspension that allows the bike to soak up bumps and feel confident through corners too. One of the advantages of an adventure bike is that the wide handlebars give plenty of leverage through corners and the long-travel suspension makes light work of potholes.

Compared to a lot of 125cc bikes the Terrain does feel substantial and that brings a confidence to the handling where others feel a bit skittish. Wheel sizes are 17-inches at both ends which is what road bikes usually have. Proper off-road bikes tend to have a larger front wheel.

I didn’t take the Terrain 125 properly off-road, but I did do a bit of ‘grey-laning’ on the bumpy, gravel-strewn unclassified tracks and lanes of Sussex. Standing on the foot pegs feels natural and changing gear is possible if not exactly easy. Knowing that the bike has so much crash-protection adds confidence to try this stuff.


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Both brakes are strong good, rear brake pedal also operates the front


2021 Sinnis Terrain 125 brakes

There’s no ABS, but the brakes are linked so pressing the foot brake also adds a little front brake too. This linking helps settle the bike under hard braking and reduces the likelihood of locking a wheel.

The Terrain’s brakes are powerful enough in the dry to stop the bike sharply, but they also have plenty of feel for a rider to be confident braking more gently in the wet.


Clocks are simple and easy to use, the left side pannier is bigger than the right (which has to clear the exhaust) and the top box won’t hold a helmet


2021 Sinnis Terrain 125 clocks, equipment and controls

All the info you need on speed, engine revs, mileage and fuel remaining is available from the clocks including what gear you just accidentally set-off in instead of first. There’s a USB socket too so you can charge your phone (and Sinnis has uprated the electrics for this model including a more powerful battery)

All the controls are simple and straightforward to use, and the lights are powerful enough for the speed of a 125 on unlit roads.

The three luggage boxes are well made, use the same key as the ignition to unlock them and they hold a reasonable amount of kit. You can’t get a helmet in the top box, which is a shame, but there’s enough room for waterproofs, a lock and most of your shopping (unless you like enormous pizzas) on the way home. 

The rear luggage racks also double as crash bars in addition to the sturdy protection at the front. This protection is welcome on a learner bike because it’s all-too easy to take a tumble, but it does add some weight and makes the bike feel bulky when filtering through traffic.


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You can sneak up on it from any angle, but the Terrain is still a looker


2021 Sinnis Terrain 125 verdict

The Sinnis Terrain 125 is a great learner bike for full-size riders at any price. The engine is as quick and smooth as the opposition, it’s easy and confident to ride, has a lot of useful equipment as standard and is built to last.

Set your expectations accordingly and it’s as capable of doing longer rides in comfort as it is nipping around town. There are 125s that go (slightly) faster but they aren’t as comfy, practical or well-protected as this one. My biggest bugbear was that the width of the crashbars restricted agility through traffic. But I’ve been riding a long time and am less worried about crashing and more confident in traffic so maybe my thoughts are maybe not as relevant as someone more likely to topple and less confident at filtering through traffic.

It’s only when you remember that the price of this bike is a little over £3k ready to go that you realise what a good buy it is. Even without all that kit, it’s a very good price for what is a very good bike.


2021 Sinnis Terrain 125 spec

New price

£2899 (+otr)



Bore x Stroke

Not quoted

Engine layout

Water-cooled single-cylinder four-stroke

Engine details

Water-cooled 4v,OHC


12.7bhp @ 9500rpm


7.7lb-ft (10.5Nm) @ 7500rpm

Top speed

65mph (est)


6-speed, chain final drive

Average fuel consumption

86mpg tested

Tank size

14 litres

Max range to empty (theoretical)

260 miles

Reserve capacity

40 miles

Rider aids

Crash bars, linked brakes


Duplex steel cradle

Front suspension

upside down forks

Front suspension adjustment


Rear suspension

Single rear shock

Rear suspension adjustment


Front brake

Single disc, 2-piston caliper

Rear brake

Single disc, 1-piston caliper

Front tyre

100/80 x 17

Rear tyre

120/80 x 17


Not quoted


2090 x 865 x 1280mm (LxWxH)



Ground clearance


Seat height


Kerb weight



Unlimited miles / 2years

MCIA Secured rating

Not rated



Looking for motorcycle insurance? Get a quote for this motorbike with Bennetts bike insurance


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What is MCIA Secured?

MCIA Secured gives bike buyers the chance to see just how much work a manufacturer has put into making their new investment as resistant to theft as possible.

As we all know, the more security you use, the less chance there is of your bike being stolen. In fact, based on research by Bennetts, using a disc lock makes your machine three times less likely to be stolen, while heavy duty kit can make it less likely to be stolen than a car. For reviews of the best security products, click here.

MCIA Secured gives motorcycles a rating out of five stars, based on the following being fitted to a new bike as standard:

  • A steering lock that meets the UNECE 62 standard
  • An ignition immobiliser system
  • A vehicle marking system
  • An alarm system
  • A vehicle tracking system with subscription

The higher the star rating, the better the security, so always ask your dealer what rating your bike has, and compare it to other machines on your shortlist.