In 2017 a new and slightly different emtb was introduced. While other emtbs were introduced with bigger 500Wh batteries, Focus decided less is more and went with 378Wh. Focus points at a couple of user surveys claiming over 85% of all e-mountainbikers were riding trips less than 35km (22 miles), so most of us don’t need the 500Wh battery. Distance travelled will probably vary between regions, but 378Wh will still be enough for some of us.
Smaller Battery
The advantages of reducing battery size are lower weight and easier frame integration. The Jam2 battery is located inside the frame and it can’t be removed easily. By attaching the battery inside the downtube Focus is saving additional weight. There is no need for a lock cylinder or battery clamps facilitating battery removal. Also there is no need to cut out a big piece of the downtube, that would require extra frame reinforcing and would add weight. Focus is saving up to 3 kg on their solution compared to many other emtbs with a removable integrated 500Wh battery.
Keep the bike cosy
If you’re riding in the winter and are experiencing temperatures below 0°C, you will need to store the bike indoors. If the battery gets cold enough it cannot be recharged. Focus has also thought about the people needing more range. The TEC-Pack add-on battery will take the battery capacity up to 756Wh.
The extra battery looks okay, but the frame toptube needs to be a bit high to make room for it. In an accident, the handlebar shifter can hit and damage the top tube. Handling does suffer a bit with the TEC-Pack that is sitting a bit high in the frame. The bike becomes heavier to handle and less nimble. For transport/touring that’s just fine, for having fun on trails I prefer not using it.
Tailored Energy Concept | The 378Wh TEC-battery is 2,3 kg including the cable
Equipment
The bike is 21,6 kg without pedals, that’s not a revolution but it is a good weight for a £4.229 bike. The Fox Rhythm 34 is an average weight fork and a good pick for this bike. It’s a pretty sturdy and well-functioning fork for trail riding. The Shimano XT/SLX drivetrain is all I need.
The Shimano Steps E8000 is a good emtb motor that offers a nice mix of power and control. For my kind of riding I’m not happy with the Maxxis Rekon+ tyres and I soon swapped the front tyre for a more grippy one. On slippery or rough trails the bike needs at least a new front tyre to show what it’s capable of.
The Shimano MT520 brakes are made for riding hard though. This is a new and cheaper four piston brake that I’m happy to find on more and more low/mid priced emtbs.
Shimano MT520 four pot caliper
The Fox Float DPS Performance is a well performing shock that can be found on more expensive bikes. The rear suspension linkage is a “single pivot” type that Focus has named FOLD (Focus Optimized Linkage Design). The initial part of the travel feels active and it swallows the small bumps just fine.
When speed increases it feels like the bike doesn’t use all its travel. The rear end feels a little firm, as if compression damping is a bit high. But the rubber O-ring on the shock confirms the bike does indeed use all of its rear travel. It feels a bit different from what I’m used to, but I think it works rather well on a mid travel emtb. Pedaling feels efficient while the suspension is quite active.
RIDING
Jam2 6.8 Plus isn’t a burly bike made mainly for the descents. It’s a nimble trail bike made for both flat and rolling trails. The battery and the way it’s integrated helps lowering both the bike weight and the centre-of-gravity, and that can be felt on the trails. I’m using less power than I’m used to when maneuvering the bike around or over obstacles.
The chainstays are 457mm long, this isn’t very long and I’m considering that normal. But I believe the strong points of this bike would have been even better if the chainstays were a tad shorter. Climbing abilities would probably suffer a bit from shorter chainstays though.
A 378Wh battery doesn’t just have less capacity than the 500Wh version, it’s also less capable at delivering current. An ebike battery consists of several 3.6V battery cells. By putting 10 cells in series we get 36V. But 10 cells in series is not any better at delivering current than a single cell.
Cells need to wired in parallell to be able to deliver enough current. A 500Wh battery usually has 4 and 4 cells wired in parallell. That’s more than enough for a regular 250W mid-drive motor, also at freezing temperatures where the battery is less capable of delivering current. The Focus battery has 3 and 3 cells wired in parallell.
I got to talk to a Focus engineer about this. He said the bike had been tested in the aerospace institute at the University of Stuttgart. They’ve got a climate room where Jam2 was exposed to temperatures between -10°C and +50°C. The current capacity of the 378Wh battery was sufficient even at -10°C. If one is constantly drawing max current from a battery, it will degrade faster. The engineer said that in real life riding one is not riding the motor at max very often so current draw is mostly well below max. They did not observe significantly increased degradation on the 378Wh battery.
Last winter I rode several Shimano bikes with 500Wh batteries and I was under the impression the batteries couldn’t deliver enough power at low temperatures and low charge. I observed this several times when the battery indicator suddenly dropped from 2 bars remaining to 0 bars and got locked in Eco-mode. The engineer told me this was caused by the E8000 motor programming and that was fixed earlier this year. I’ve had a couple of trouble-free rides with the Jam2 in -7°C so it seems the engineer was right.
