Tern GSD S10 with Bosch Performance Line (Just Hello!)

Steep roads, heavy weights, commuting on cold, stormy and rainy weather – all these were the use cases for my 14 days trial with the Tern GSD S10. I try to find the right words for these great experiences in more than 400 km / 250 miles.


“When the loaded GSD and I arrived at farmer’s market we were the attraction!”

Riding the Tern GSD is sometimes a real adventure. Our family was exploring the limits of this small and curious looking bike. 20 inch wheels with some genes of a long tail and the chest of a big cargo bike … yes, people are watching you and the GSD because on the first look it’s not relating to classic bike frames like diamond or step-through. If you don’t want to interact with other people, don’t buy a GSD! You will have to answer a lot questions.


I tested a few common use cases for a typical family in a hilly town. Here are my three favorites:

Just me, sunny, in a hurry, flat road with a steep hill at the end

I’m in a hurry. I’m late, as usual. The Bosch Performance is not working because I’m a lot faster than 25 km/h. The GSD is jumping over the humps on the road while the stuff in the front box clanks. Although the steady up and down is really annoying, the GSD saddle with the Ergon grips feels really comfortable. In combination with the big Schwalbe tires the damping behavior is surprisingly good. The shiny blue bicycle frame attracts attention, the people in the traffic jam are watching, I feel observed.

Stop at the first traffic light, I need a break, from now on I let the Bosch Performance do the work. The motor accelerates the GSD, but a lot slower than the Bosch CX with the EMTB mode, I’m a bit disappointed.

My district is 140m over the city center. I use a at maximum 12% steep road to go home. After passing the traffic jam and all the construction areas with endless curbstone up and down procedures I turn left, shift to the right gear and start pedaling up the hill. The Bosch Performance assists good, but not that good as expected. Is it enough motor power to drive me up the hill with additional load?

At home I searched for GSD photos and I note that nearly all photos were taken in flat areas. Really? Is the GSD just for non hilly cities?


Back in the Garage I saw that the upper derailleur limit ends before the biggest gear wheel. With a screw driver I correct this fault. The big cargo hold panniers hide completely the cassette, the derailleur and major parts of the wheel.

ust me, off road, trails and high speed

You have a son or a daughter? Time for sports or activities is rare, right? You have two, three or more kids? Well … the only chance to have a little fun every day is to adjust your commuter way. So do I. Sometimes take a longer route through the forest and the vineyards.

The first chapter is a slippy, small and curvy way in the forest that goes steep down over a creek and on the other side up again. Although there are small stones on the way, the Tern reacts calm and stable in curves and straight ways on high speed. A big advantage is that the rear wheel blocks very late, I think it is due to the heavy rear frame. But you can feel the weight in every fast curve, it tries to push you straight forward – it’s similar to fast moving sleigh with another person in the back and you try to steer. Short brake shocks a few meters before the curve decrease the weight influence. Steering the Tern at high speed feels safe.  Then the bike accelerates again. At the deepest point I cross the narrow bridge with more than 50 km/h. On the other side I slow down due to the steep way up. The Bosch Performance works a bit noisy while I’m pedaling with moderate force – PERFECT.

At the end of the forest up the hill begin the vineyards. A wide road goes 125 meters altitude down to the next village. This is a real race track! How will the GSD react in high speed curves? Open the fast tensioner and bring the handle bar in a lower and more forwarded position – done. Go! After a few seconds the motor reach the speed limit and stops the assistance. I continue pedaling at maximum speed. At 45km/h the cadence is moderate to high, at 50 km/h it is really high, faster than 50 km/h you feel like a hamster in his wheel. At 58km/h I stop pedaling and bend forward. Can I be streamlined on a GSD? I don’t know. 62, 63, 64 km/h – the GSD is stable, even small hump can’t change this. I have to turn in a few meters, I straighten up and bring the MT5 to the optimal operation temperature. Brute retardation is the consequence. With moderate speed I jump in the downhill way with cobblestones and slow down until I stop. Boxing stop. Photo shooting. Cool down. The adrenalin rush weakens. Once again! Tomorrow! Deal!


Heavy duty – get stuff done – all day!

On Saturday we go to the grocery store. Saturdays in Germany are also used to wash and clean the car. Since the GSD is part of the family we are driving the car only if we all together have to be somewhere far away. If one adult with one or more kids need to go to the city center, we are riding the Tern.

Today I have the possibility to use the cargo hold panniers for the first time. I open the cover and look a little sceptic into the flat panniers. In this moment the bottom is folding to the bottom and reveals the real size of the pannier – WOW – 20 x 34 x 60cm. Stuff, a lot stuff, a lot of big stuff is fitting there in!

After paying at the grocery store I put all articles in big bags. When arriving at the GSD I open the covers and put the whole bags into the panniers. The things that are not fitting in I put into the front box. At home it’s reverse, take the bags out of the panniers and bring them into the kitchen, no repack, no loss of time, AMAZING!

I want to use the panniers again, what else can I carry? While turning around in the garage I see a lot of crates with empty bottles. Okay, let’s do it. After packing two crates and a lot bottles in the panniers and fixing two crates on the transporteur rack, I wanted to start my tour. BUT … three kids saw my intension. Normally this is no problem because while I pay and load the beverages into the car, all kids get a lot jelly beans from the dealer. Today I have a fully loaded GSD with just two uncomfortable seats in the back due to the wide panniers, a third kid in the clubhouse? Impossible! One kid has to ride with his own bike! With a strict voice I determined the oldest one to ride alone. GO! … Four minutes later all three kids are in the clubhouse, it seems to be not that comfortable but all kids are quiet. Go, quickly!


The Bosch Performance starts to whir. The derailleur moves the chain to the biggest gear wheel. Four people, full packed panniers and a full rack are trying to ride with the GSD up the 15% steep road – the highlight! Now is the point that decides whether this use case has a happy end or is a tragedy. The GSD accelerates while the Bosch motor gets noisier. The 36 teeth of the biggest gear wheel bring the bike up the hill, slow but continuous. For the steepest part the motor is a little too weak and I have to pedal very hard for about 20 meters at a speed of approx. 7km/h. After that with minor steepness we accelerate again – YEAH, WE MADE IT!


After parking in front of the shop next to another bike and a trailer on one parking slot, eight people are standing around the Tern. I start to unload the GSD:

  • Three Kids
  • Two crates with juice bottles
  • One small crate with water bottles
  • One big crate with water bottles
  • Six single water bottles

The people are very amazed. I load nearly the same number of crates and bottles back on the GSD. At the end the 3 kids climb into the clubhouse with a few jelly beans in their hands. A picture is worth a thousand words.


There is no more space on the GSD – heavy duty transport. The felled bottles have an additional weight of 32kg. It’s time to ride home. The Bosch motor accelerates the heavy weight very unimpressed. The kids in the back are laughing. I think the jelly beans were delicious. Due to the humpsbacks on the road the crate on the front rack is wiggling. In my opinion the 14kg were too much weight for the rack. I saw this idea with the crate on the rack on a photo. I would not do this again.

Although the bike is carrying more than 180kg the GSD is still easy and safe to ride. Maybe responsible for that is the very low point of gravity. At the end of the trip we have to drive down the steep road with the heavy weight – second highlight! The heavy bike is accelerating, I pull the MT5 brake handle, the GSD slows down, the MT5 brakes very unimpressed until the bike stops. Okay, the second highlight was no highlight.

Can a GSD S10 with a Bosch Performance Line carry heavy loads up steep roads?

Can a GSD S10 being used for up to 25km / 15 miles daily commuting at all weather conditions?

Is it possible to carry more than two children with the GSD and clubhouse?
YES! (For additional trailer usage see Robert Axle Project!)



If you have further questions about the GSD, use cases or accessories then I recommend the Tern GSD Facebook group – a really great and helpful community!