The Sinnis Terrain 125 or T125 if you prefer is no stranger to us at BikeMatters, back in 2019 the Euro 4 version got thoroughly tested by us for two weeks. Hit 2021 and the Terrain has been updated to include a new Euro 5-compliant liquid-cooled motor and 6-speed gearbox.

The Sinnis Terrain has been a popular 125 for a few years now as it offers something few else do in the 125cc market – an adventure-styled bike, good sized and well equipped at a rather budget-happy price. But will the new Euro 5 T125 maintain the Terrains' popularity?

As styling goes the 2021 Terrain looks, well, just like the previous Terrain. Bodywork, mudguards, crash bars, and luggage boxes are all pretty much the same. That isn’t necessarily a bad thing because the T125 is one nice-looking 125cc motorcycle, it looks very well-proportioned and more than kitted out for any rough journey you put its way.

Those crash bars and luggage boxes as standard help it look even more like a big bike, though with that large 14L fuel tank and 17” wheels most people would be excused for thinking this was far bigger than a 125.

So yes, not a lot has changed cosmetically with this new terrain. I think a few small bodywork updates and full LED lighting would be nice to have, but I dare say Sinnis want to keep the costs down and continue to have this available at a rather friendly price.

Looking around the T125 the general build quality looks good for the most part, though elements to me such as the side stand, centre stand and exhaust were already showing signs of wear.

Lastly, as colourway options go you have two choices: ‘Canyon Red’ or ‘Artic White’ – both look great, though I slightly favour the red myself.

Gone is the 11hp air-cooled motor of old, now the T125 sports a 125cc, single-cylinder, 4-valve, liquid-cooled engine that produces 12.7hp at 9500rpm (right close to that rev limit of 10,000rpm) and 10.5nm of torque at 7,500rpm. So, a modest increase in power by switching to that new engine, but then again that change is probably more focused on getting past Euro 5 rather than offering more power. A further addition to this engine is a balance shaft to help reduce those vibrations.

Starting my journey, you instantly become aware of the T125’s close gearing, rifling through the 6-speed gearbox as you build speed. Being a 125 and on the heftier side of things, you do have to really work it hard if you want decent acceleration. Red line is 9000rpm, you’ll hit the limit at 10,000rpm and once in the red, the vibrations do become rather apparent. The gearbox worked absolutely perfectly, easily finding gear and neutral without any problems whatsoever. The clutch is lovely and light too – it would be great for newbies that’s for sure!

Acceleration to 45mph is respectable, it just isn’t lightning-fast for a 125. Anything further than this and it’s sluggish.

As far as top speed is concerned, with favourable conditions and a rather long declining road, you should expect to hit 67-70mph on the speedo but that is giving it everything you’ve got, and you’d need plenty of time and road to get there. Therefore, your everyday realistic top speed will be around 60mph.

Sinnis put some pretty decent-sized discs on the Terrain 125, though their website neglects to tell you the exact sizes. With measuring tape to hand the front disc measures 270mm and the rear is 240mm. As you’d likely expect it comes with Combined Braking System (CBS) and not the preferred ABS, so put on that back brake and expect it to apply a slight bit of front brake too.

When testing, the braking was great and really does everything you’d expect, though feel for those brakes on a bend and you get slight pitching on that front USD fork as the front brake activates –  something to be aware of but you soon get used to this characteristic. I really have no complaints there, though obviously, ABS would have been nice that would have inevitably increased the price.

When it comes to suspension, we have some meaty-looking upside-down forks at the front, and hidden away at the rear is a monoshock.

Suspension is definitely set up on the soft side but dealt with the roads very well and, as I’ve said, that seat is rather comfortable along with that nice neutral upright riding position – it all feels jolly relaxed!

The dash and switchgear remain the same as the previous model so nothing should come as a shock. The dash itself is split.

The larger part to the right is the LCD panel which houses all the vital information nice and clearly, including clock, trip, odometer, speedometer and even a gear indicator. To the far left of this digital panel is the fuel gauge. Moving left of this and you are greeted with an analogue rev gauge. Above the display are your mode buttons for the display and also your neutral light. Further to the right of the digital display behind a small rubber cover is a USB charging port.

Onto the switchgear, and it is all pretty standard stuff, easy to use with no problems at all. Though the indicator feels a little flimsy it worked without any hassle during the whole test and no problems were encountered.

When it comes to the windscreen though small it does noticeably help reduce wind buffering. 

Seat height on adventure bikes can be very interesting, especially for short people like myself! With a seat height of only 780mm, the Terrain 125 keeps everything rather accessible so, even at 5’ 6” I can get both feet down absolutely fine, whilst still giving you great visibility of what’s up ahead.

The seat itself is relatively narrow, yet surprisingly comfortable. I was expecting to feel the comfort of a plank of wood, but I was pleasantly surprised by the padded and soft offerings the seat provided.

As standard, the Terrain 125 comes with three hard plastic storage boxes - the top box and two panniers. In total these three boxes give you 66.5-litres of storage space which isn’t exactly bad going and they all unlock using your standard ignition key.

That top box isn’t the biggest at 24-litres and will not fit a full-face helmet, though handily Sinnis do have a 48-litre top box available for an additional £85 which will take a full-face helmet – and I for one can see a lot of people taking that upgrade!

Now that large fuel tank, crash bars and luggage boxes come with a compromise and that is the fact the Terrain 125 weighs in at 162kg. So, as a 125 is concerned, this is definitely on the heavier side.

However, on the road, it doesn’t feel heavy at all. It is well-balanced and alongside those 17” wheels riding on rural and urban roads is a breeze and very enjoyable.

It goes without saying that a 14-litre fuel tank size is very good for a 125 and, with 100mpg expected, you should easily see over 300 miles on the entire tank – now that isn’t too bad!

The Sinnis Terrain is priced at £2999 (+ OTR), for this spec bike with great seating position, crash bars, and 66.5-litres luggage boxes, the Terrain 125 really does remain a great option for those after an Adventure Bike 125.

I think it is fair to say the Sinnis Terrain 125 hasn’t really changed a great deal since the Euro 4 version – the differences are negligible. The new liquid-cooled motor and six-speed gearbox haven’t really changed the Terrain’s sluggish ways, anything from 45mph+ and you’ll need plenty of time and tarmac to get there. The balance shaft does well most of the time but get in the red and you are met with plenty of vibrations as you search for that little bit more speed.

Top speed though it can hit 70mph on the speedo, you’ll more than likely struggle to get above 62mph. The T125 for me will be enjoyed most with a cruising speed around 55-60mph, there the bike is happiest and not so high in the revs which makes it more enjoyable.

It would have been nice to see some more changes for the 2021, maybe a bit more power to help it along and a few tweaks to the bodywork, LED lighting and a revised dash to help give the Terrain a new boost and make it a bit different, it is, however, just like the previous one. Though that isn’t necessarily a bad thing.

The T125 from Sinnis is a big seller in the UK for good reason. With that beak and small windscreen, it looks great. It is well sized and further bulked out by the luggage boxes and crash bars. With 17” wheels and large brake discs, chunky USD fork and that slim adventurous seat, the Terrain 125 really looks the part and performs well on the road. You’ll definitely get plenty of nods from bikers thinking it is more than a 125 and you’ll feel the part riding it too!

Yes, if you want a 125 that can get to 60mph pretty quickly and will spend its life maxing out then the T125 might not be for you. However, if you are happy to go at a more relaxed pace then the Terrain really does excel in offering you that something not many others are really doing in the 125cc market. 

• Affordable and cheap to run
• Plenty of storage space 
• Comfortable and easy to ride

• Still quite sluggish, wish it had a few more hp behind it
• Not much has changed since Euro 4 version 
• Windscreen could be improved

So there you have it! Here is my full test review on the Sinnis Terrain 125 (2021-onwards)...

If you have your very own Sinnis Terrain or perhaps another motorcycle you need to insure, make sure to get a motorcycle insurance quotation direct with Lexham!

Engine	125cc, 12.7bhp, liquid-cooled
Fuel tank	14L
Brakes	Front and rear disc
Seat height	780mm
Weight	162kg
Price	£2,999 (+OTR)