Hello so I soon plan to go from london to bathand was thinking, instead of taking the train I could take the bike. Its an 11 hour cycle and 129 miles for the journey. I currently work as a corrier sometimes doing 9-10 hour days that is around london.

 

Now my bike is an old road racer with these gears front 48 (gonna add a 38 in soon as well to give me a nice double for when I want to ride unpowered), and 13-32 at the back, I think it weighs about 20kg all in all including the battery and the motor.

 

My kit is a cyclotricity 36v/250w front hub motor, it can be riden without the motor although that becomes tiring very quickly because its a 20kg bike.

 

I have a 36v/10.4 ah bottle battery to power the bike. Is this goign to be enough for the journey if I keep it on low setting? Cycle normally on the flat and then turn it on for the hills? Im fairly fit but dont feel like doing this journey on a normal bike.

 

I havn't been able to find out much about mileage, some say you will get 30-50 miles out of one others say more, but I assume this is based on running the bike at full power.

 

https://www.google.co.uk/maps/dir/Kingston+upon+Thames/Bath/@51.3158583,-1.8906599,9z/data=!3m1!4b1!4m14!4m13!1m5!1m1!1s0x4876093778987453:0x4c3f21b23e3e35ec!2m2!1d-0.300689!2d51.41233!1m5!1m1!1s0x487178a6743ee12d:0x138b27d0d66d9a09!2m2!1d-2.3599039!2d51.375801!3e1

It sounds ambitious to me.

 

I have a 20kg bike with a 36V 8.8Ah battery and my limit is about 25 miles in hilly terrain. On the flat one low power it would probably manage about 45miles - and I'm only 53kg. 129 miles would be far beyond its limits.

 

If you're able to cycle without power for much of the route then you may get away with it but 11 hours on a heavy bike sounds like a slog, unless you're very fit. I'd run the route though an online mileage predictor (I note the one on the Woosh website isn't working...)

 

Good luck!

Funnily enough, I built my 'everyday' ebike with doing the reverse in mind - Bath to London and probably the return journey a couple of days later. However, life got in the way and I'm now the owner of (don't worry, no funny business going on here, they are mine) two small children. I'm still yet to attempt the journey, but hope to one day.

 

Range varies from rider to rider, but I'd say that your battery is inadequate to complete the journey. I had planned to do it with a 2750kWh (44.4V, 62Ah) battery and a full charge during an hour or so stop for lunch.

On level 1, the power is typically 60w, so you will drain your battery in about 4.8 hrs, assuming that it's in good condition. At 15 mph, that would be 72 miles. All the time you travel above the cut-off speed, you will use zero power. Only you know what proportion of your riding that is, but it would need to be nearly 50% to reach your destination. I did 129 miles on one charge, but I obviously had the power turned off a lot.

 

I found that my electric MTB on level 1 is more or less equal in speed and effort to my road bike. I would say that it would probably be better to use a light-weight road bike for that journey rather than an electric bike.

 

Lets say that you can average 180W and 14 mph on an unpowered bike. That's 1659wh from you for the whole journey. The 300Wh from the battery would be about 210wh, by the time it gets to the wheel. The added weight of the kit would take something like 20W to overcome, which means maybe 160wh during the journey, leaving you a gain of 30wh. That's a 2% reduction on your 1659W. They're only estimates, so that could be +/- 100wh. Whatever it is, the difference between powered and unpowered is not going to be a lot on a long journey like that with a relatively small battery, so it's better not to have the additional complication of electric.

So how much power do ppl think I would need? I do want to do this journey somehow amd wont be able to manage it on a road bike.

 

I read somewhere that its roughly 20 watt hours per mile, which means I would need 2000 watt hours without peddalling at all so not sure with me peddling how much i need. Is there a problem with carrying extra batteries in my back basket?

On level 1, the power is typically 60w, so you will drain your battery in about 4.8 hrs, assuming that it's in good condition. At 15 mph, that would be 72 miles. All the time you travel above the cut-off speed, you will use zero power. Only you know what proportion of your riding that is, but it would need to be nearly 50% to reach your destination. I did 129 miles on one charge, but I obviously had the power turned off a lot.

 

I found that my electric MTB on level 1 is more or less equal in speed and effort to my road bike. I would say that it would probably be better to use a light-weight road bike for that journey rather than an electric bike.

 

Lets say that you can average 180W and 14 mph on an unpowered bike. That's 1659wh from you for the whole journey. The 300Wh from the battery would be about 210wh, by the time it gets to the wheel. The added weight of the kit would take something like 20W to overcome, which means maybe 160wh during the journey, leaving you a gain of 30wh. That's a 2% reduction on your 1659W. They're only estimates, so that could be +/- 100wh. Whatever it is, the difference between powered and unpowered is not going to be a lot on a long journey like that with a relatively small battery, so it's better not to have the additional complication of electric.

 

 

thanks for that advice. Out of interest what is your motor a d battery size?

thanks for that advice. Out of interest what is your motor a d battery size?

It's a Q128c with a 48v 11.6Ah battery - 500wh nominally, but probably close to 400wh in reality.

So how much power do ppl think I would need? I do want to do this journey somehow amd wont be able to manage it on a road bike.

 

I read somewhere that its roughly 20 watt hours per mile, which means I would need 2000 watt hours without peddalling at all so not sure with me peddling how much i need. Is there a problem with carrying extra batteries in my back basket?

 

Since I have the trike without a motor I have gotten a little stronger. The other day I went shopping and got 5.82 Wh/km = 9.36 Wh/mi which for your journey would be 1210 Wh or so. That is 2 x 17 Ah 36v batteries fully charged. I pedal a bit but am over 60 yrs old...

So should be able to do this easily with 2X 17ah batteries + my bottle 10.4ah?

 

Is there a way to find out what your efficiency for the battery is? Im not able to see my % of battery power.

So should be able to do this easily with 2X 17ah batteries + my bottle 10.4ah?

 

Is there a way to find out what your efficiency for the battery is? Im not able to see my % of battery power.

 

I don't quite understand your second question. Are you asking how I know how many Wh I use?

 

I am using LiPo batteries which means I can read from the charger how many mAh I put back in at each charge. I have a watt meter between the battery and the controller which shows total Wh used so I can control what is coming out of the packs as well.

 

My main battery is about 18 Ah and depending on how I am feeling/how hard I am prepared to pedal gets me between 87 and 110 km range. Other factors are the weather (wind, rain, temperature), the load on the bike and the route (almost always hilly here). Traffic conditions don't really affect range on the open road but will if you are in a large urban area (stop and go from lights for example).

 

Personal experience is the best way to understand the range you can obtain, all the above numbers come from riding two different pedelecs over a 2.5 year period, both crank motor and rear hub, Li-Ion bottle battery and LiPo. Soon I will also bring aerodynamics into the picture when I mount the crank motor to my trike.

Mine wouldn't even get close. My 11Ahr got me about 35 miles when the battery was new. Now after 2 years of abuse, wearing studded tyres and in freezing weather I don't think it would get 20*

 

I'd go with d8veh's suggestion, use a light unpowered bike.

 

Unless there are places you can top up en-route? How long does your battery take to charge?

 

*Yes, I need a new battery but I can get by on my commute by charging at work and it's only got to last another 2 weeks.

It's all about the cells inside used , in a lot of cases 11ah use Samsung 22F (Green) which is only a 4.4a cell so if only 4p = 17.6a max or if 5P 22a max. With a 15a controller they can and will be pushed hard at times and 1- 2 years of top range would be good before they deteriorate.

Samsung 26F same problem as above.

 

Today if I was having a battery built for me or building my own https://eu.nkon.nl/rechargeable/other/sanyo-ncr20700b-lithium-battery.html would be my choice. 15 A constant output AND >4000 mAh capacity make it worth the 5.85€.

Samsung 26F same problem as above.

 

Today if I was having a battery built for me or building my own https://eu.nkon.nl/rechargeable/other/sanyo-ncr20700b-lithium-battery.html would be my choice. 15 A constant output AND >4000 mAh capacity make it worth the 5.85€.

 

Out of interest , does anyone use these cells ? Be keen to know of any real world usage