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Anyone ride a carerra crossfuse or a boardman hyb8.9 E

Hi I am trying to find out a few things about these bikes .
Does the Wh value in the spec indicate the range that the battery charge covers . That is How many miles you can get out of a full battery .
Only my current bike is a carerra cross city e bike. And the spec says it is 313wh . Where as the boardman hyb 8. 9 says wh 250 so it sounds like it does less miles to the full battery and yet the spec suggests it does twice as much ( 60 miles as opposed to my old Carrera spec saying 30 miles )

Am I to trust the miles to the battery in the spec of these bikes
Also how do I know how they perform on a hill. Someone said they are all about the same power in wattage . About 250 w so you look at the torque .
I found out the boardman is 60 nm . The Carrera crossfuse 50nm . Can anyone tell me th carerra crosscity nm to compare please .
I dont want to buy either if there is no noticeable difference in range or power on hills obviously.
I want an easy fast cycle for 40 miles of flat basically , about 15 miles an hour on medium power and to get up the hills without getting off or standing up but with effort

Posts

  • The RookieThe Rookie Posts: 27,748
    edited April 2020
    Two very different bikes....
    The Wh refers ONLY to battery capacity, so motor and bike efficiency etc are not included which you need to carry out any sort of range calculation.
    The Boardman quite likely has a better motor, in addition, as it's mid mount, it's drive is through the chain and geared which improves efficiency and hill climbing ability (torque multiplication), so can never be directly comparable to a hub motor. The Boardman also has full sized wheels and narrower tyres so needs less power for the same road speed, it's also slightly lighter so needs less power up hills. So it's perfectly possible for it to give more assistance over the same ride from the smaller battery
    the Boardman quoted range is in 'breeze mode', it's more advanced than an old pedelec like the city and it monitors rider pedalling torque input and multiplies it so the range will change with whatever rider assist mode is selected, whereas the city just kicks in motor power when you start pedalling.

    Given all that, and making some big assumptions, I'd suggest that over a given route with a rider using similar assist levels on the Boardman so they get on the cross city (so a more aggressive mode than the breeze) it would give a similar range despite the smaller battery, for a longer ride it will be vastly superior as it will be nicer to ride with a flat battery or a less assistive mode can be selected to eak out range.
  • steve_sordysteve_sordy Posts: 2,311
    The allowable power output of an ebike is limited by law to 250 Watts. But how that is measured is not defined. Is it instantaneous, averaged over a set length of time, or over the battery life from full charge to empty? No manufacturer that I have heard of or read about use the instantaneous measure, they all use an average. So a 500W-hr battery using an average of 250W will last for two hours (2hrsx250W = 500W-hrs).

    However, the bikes are set up to deliver more than 250 Watts of assistance to you and your bike, but there is no free lunch and if you pull 500 Watts, your battery will be flat in in one hour.

    So, the energy in your battery is fixed and you can't get round it, once you have used it up it is gone until you recharge the battery. So how can you get more miles out of the stored energy?

    # Keep your weight down. If you carry a heavy bag that will put more strain on the battery. Your child will go further than you will!
    # Keep the weight of the bike down. A lighter bike will go further on one charge than a heavier bike, although the largest weight component by far is the rider and whatever is being carried by them.
    # Keep your speed above 25kph (15.5mph). By law the battery cuts out above 25kph. Once above 25kph, you consume no battery at all. That is the law in Europe, the USA has different limits.
    # Coast as much as possible. By intelligently timing your speed and braking etc, if you can avoid pedalling then you consume no battery. Coast up to the lights instead of storming up and then braking hard, only then to have to accelerate when the lights change.
    # If your bike has several power modes (Eco, Trail, Boost for example), then staying in Eco will extend your range. This means that you will have to work a bit harder. If you are doing more work the battery is doing less
    # Go slowly uphills. It is very satisfying to put the mode into Boost and to power up steep hills, showing those roadies what's what! But it consumes battery at a frightening rate.
    # Keep your cadence up. This reduces the torque you are applying to the pedals. The motor has a torque sensor which is used to decide how much power assistance it will give the rider. If you grunt along at low cadence, heaving on the pedals, the motor will provide you with more assistance and the battery will be depleted more rapidly.
    # Reduce your rolling resistance. Use narrow, fast rolling tyres with a hard compound and minimal tread. Keep the tyre pressure high. Ensure that your brakes don't bind and that the wheels spin freely and gradually slow down to a stop.

    Depending upon what units are used torque x revs = power. So if the maximum torque delivered by the motor is less than another motor, then it will consume the battery more slowly. Torque is expressed in units called Newton-metres (Nm for short). A 60Nm motor will provide more assistance to you in terms of pulling power up hills and acceleration compared to a 50Nm motor, but it will deplete your battery more rapidly. If you want max range fora given battery size and bike weight, then get the bike with the lower torque motor (lower Nm).

    By the way, I have reads a lot of mocking comment on the internet about the range claims from different manufacturers. For a given bike and bike set up, the range will depend upon rider weight, acceleration used, height of hills climbed, speed of climbs, whether there is a following wind or not. My take from it all is that whilst the range claimed may be achievable, it won't be common.

    A real life example: I have an eMTB with a 70Nm motor and a 378Whr battery. The bike has 29"x 2.5" tubeless tyres with big knobbly tread and a sticky compound. The bike weighs 20.4kg and in my riding kit I weigh 92kg. At the start of the ride, the bike tells me that I should be able to do 40 miles in Eco, 30 miles in Trail and 20 miles in Boost. Riding around the local trail centre, I typically get 22 miles with a few miles left in Eco. I hardly ever manage to get above 15.5mph and I have to use Trail a lot and Boost occasionally. During lockdown I have had to ride out of my drive and on tarmac. Consequently I have easily been able to get above the cut off speed of 15.5mph for longer periods. On Saturday, I cycled all around a nearby castle (always on a hill aren't they?) and a good distance on a public bridleway, very rutted, so slow speed. I managed 30 miles with 8 miles left in Eco. The range is dictated by where you ride and how you ride.
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