REVO 27.5 Crank drive overview.
Not all electric bikes have their motor (or motors) in the centre of their wheels. Some, like the REVO 27.5, have their motor between the pedals at the bottom of the frame.
They call these type of electric bikes crank drive and this post will give you an overview of one we just got into the shop.
In the picture (1) you can see the big lump bit between the pedals. That is where the motor lives.
On this bike they were sensible enough to tilt it upwards slightly and also make it higher than the front sprocket and chain. This is a good idea. Motors that point straight forward can result in a sudden stop if you hit a rock or hidden tree stump. Sudden stops can be a bit unpleasant.
The good thing about the motor not being in the wheels is that you are free to put any wheels you want on your bike including having a spare handy if you wreck one while out riding.
You can also see that the power feed to the motor is mostly within the frame. I don’t know why they didn’t put a hole and a rubber bung inside the frame and run the power fully internally, but the engineers probably have a reason. I have not taken the side cover off the bike, so it may be a space issue. It is likely that the terminals for the power connect to the outside edge of the motor so perhaps power run inside would be a safety issue.
If you are not familiar with these bikes I will also mention that the rectangular groove above the motor is the battery. On the E-Motion bikes the frame and battery are nicely integrated together and the battery is locked into place with a key. They have a charge port in the frame so that you don’t have to take the battery out to recharge it. To know how much charge there is you can either take the battery out to look at the charge indicator on the battery body, or look at the handlebar mounted computer.
The computer (2) is standard for these bikes and shows you the charge, speed, distance travelled and the plus and minus buttons let you set the level of assistance supplied by the motor.
The computer also lets you turn your lights on/off if they are fitted and if you hold the plus button the motor will engage which is useful if you have to walk the bike up a hill etc.
In front of the computer you can see the fluid reservoir for the hydraulic brakes fitted to this bike. Being able to stop is a useful feature that this bike has covered nicely with hydraulic disc brakes front and rear (3).
One of the great things about hydraulic brakes is that you don’t have to adjust them much at all. They have a disc brake pad like on your car and as the pad wears down the fluid fills the space in the system. These brakes give lots of feedback so that you know exactly how hard you have your brakes applied, not that big a deal since many bikes have hydraulic brakes, but it is good to see that the brakes here are up to the task.
This bike has front suspension only, so is not really a mountain bike as such, but is certainly more than enough to go riding the trails. Front forks are Fox units and have all the pre-load and lockout dials you’d expect.
I only took the bike for a short ride, so I can’t comment on the suspension or frame or balance of the bike, but I know these are quality forks so I’m sure they will be up to the task most riders might put a hard tail electric bike to.
The frame looks well made as usual. Welds are clean and consistent. The centre rail has a bump in it to make room underneath to get the battery out.
Picture 6 shows you the frame construction where the centre bar connects to the seat post. You can see that most of the wiring and cables on this bike run inside the frame. I like and dislike this. I like it because it makes the bike a lot cleaner and minimises the chance of a cable getting hooked on something. I dislike it because critters can live inside my bike frame and here in Australia, critters like to get everywhere.
Picture 7 shows you the front of the bike. This is also the top of the battery and the hump in the frame is so you can get the battery out of the bike.
Gearing wise this bike is deceiving. It looks like a single front sprocket, but if you notice the front derailleur then you will realise there must be a second sprocket which there is. A little guy on the inside living in an indent in the motor housing.
The rear cluster has ten sprockets making the bike a 2 x 10 = 20 gears bike.
One of things that can happen on an electric bike is forgetting the gears are there since the motor assists all the time, but it is a good idea to use them. The less the motor has to do for a set speed, the greater a range you’ll get (around 80km ish on a full charge depending on the terrain and how you’ve been riding etcetera).
One of the big differences in this bike compared to the rear hub drive bikes in the rest of the E-Motion stable is that it does not have a torque sensor at the back wheel, it has a magnet that passes a sensor. The result of this is that the bike doesn’t know you are pedalling until that magnet goes past, so sometimes it can feel like the bike has a delay providing assistance. You don’t notice at all when riding, only when you first start, and then it depends on how far the magnet is away from the sensor. You could turn the back wheel to have the magnet near to the sensor before you start, but why bother. I only noticed because on the other bikes, the moment you apply pedal pressure, the motor starts assisting.
The sensor on the rear wheel means that if you do decide to change wheels, remember to also change the magnet, otherwise the bike is just a heavy normal bike and the motor probably won’t assist at all (I say probably because I don’t know if there is also a sensor in the motor. There may be. I can’t find any literature to tell me, so may do a test one day to find out).
So there you go. That’s a quick look at the bike. There are two other REVO models, the Jumper and Scape that have suspension both ends. There wasn’t one on hand to do a comparison.
All the E-Motion bikes I’ve looked at so far have a lovely high standard of build. The battery fits into the frame nicely. All the welds and paint is finished properly. They are a lovely range of bikes. You should pop in for a look. 🙂
Or you can buy it from us here..
As always, feel free to make a comment or ask questions by contacting us or by using the form below.