Checking off decision to convert

[Nosweat]

Hi, thanks to what I've read on these fora and after trying out examples on display at the NEC recently I'm looking to convert my touring/city bike (a Dawes steel frame with Nexus rear wheel hub gears) to electric. I have a 30 mile round commute which is quite hilly in parts so looking for high capacity battery (17AH). Feeling a bit hesitant about the reliability of crank drives and the additional wear put on the chain with a central motor so a front hub motor is looking a safer option. At the NEC I tried front hub bikes with cadence sensors and torque sensors and much preferred the torque option. Of the kits I've seen so far the Whoose torque sensor front hub kit most closely fits the bill given the compromises needed in converting an existing bike. The only downside is that wouldn't allow me to run a front hub dynamo nor draw current off the battery to power lights (according to Woosh) so I'll be forced to carry on using the bottle dynamo the bike already has - not a deal breaker.

Just a few questions therefore, with experience of front hubs particularly appreciated prior to putting in an order.

1. Battery voltage - Woosh mention both 36V and 48V batteries, are there any advantages to going for 48 or is it a case of one is for road legal bikes and the other is too powerful and therefore not an option for commuting? I've no intention of breaching the 250W/25kph rules.

2. Battery placement and security - my downtube is 61cm measured internally from headset to bottom bracket with a couple of drinks bottle lugs about 10cm and 20cm from the bottom bracket. Would I need to fit additional rivnuts? I saw a link to someone who had drilled through the metal plate in the battery controller unit which I guess I'd have to do if I was to reutilise the existing lugs - any thoughts on that? Alternatively I could go for a rear rack battery, but I already carry about 8kg of work gear in rear panniers so lots of load at the back. How secure are batteries attached - I'm aware they have some sort of barrel lock and key but the downtube attachment looks like a couple of rivets going through a plastic body that could easily be snapped off. A battery in the rear rack could be removed with just an Allen key.

So if I go with a downtube battery is it possible to lock or clamp batteries more securely to the downtube, especially if you have to leave the bike in an open space all day? If I go with a battery at the back, has anyone tried keeping both the battery and the controller it clips into inside a rear pannier bag, or would it be too fiddly to disconnect the combined controller and battery each time I wanted to stop somewhere? Without actually looking at a conversion I can't tell how many wires run into the controller and whether they could be repeatedly pulled apart from the controller (I assume the thing the wires feed into that the battery clips into is some sort of controller)?

3. Any other lighting options that I've not considered or would a bottle dynamo and LED lights tick the box? I tend not to cycle with daytime lights so it would only be needed when dark.

4. With a front hub motor and torque sensor what's the longest I could expect to climb without the motor cutting out? The worst hill of the commute reaches 1 in 10 in parts for half a mile.

5. Do torque sensors also measure cadence? If I was unfortunate enough to snap the chain but had a cadence sensor I could just spin the pedals and the motor would get me home if battery juice allowed. Would that happen with a torque sensor and wheel motor too or not?

 

[sjpt]

1. 48v will give more torque which will help on the hills. You will need to make sure controller and display are appropriate (Woosh will make sure of that if you buy from them). Should still fall within the 250w nominal rule ... all motors can generate quite a bit more than that even at 36v but remain legal. Nominal is the continuous power without overheating; probably no greater on 48v than 36v.

2. You could certainly add extra straps round the battery. More awkward to remove (part of the point). You may want to remove regularly it for recharge in the winter, most batteries don't like being charged at low temperature.

3. With batteries and bulbs so much more efficient these days a rechargable LED light works realy well (as long as you remember to recharge!)

4. I don't know an exact answer. We have a tandem with Woosh's XF07 front hub and it helps us up hills steeper than that without cutting out; I don't think we were anywhere near cutting out, but can't justify that. We have to work quite hard because of the extra weight (160kg for us + quite a lot for a basic tandem), it would be much easier for you.

5: No. It might be possible to fit both sensors, but the logic would not be straightforward as the torque one gives a continuous reading and the cadence an on/off. I'm sure Woosh will give much more precise advice. The chain on a gear motor bike takes a lot of extra wear, but on a hub bike it has less wear than on a regular bike.

 

[dwvl]

The chain on a gear motor bike takes a lot of extra wear, but on a hub bike it has less wear than on a regular bike.

Plus, your Nexus chain will be nice and wide and beefy anyway. I doubt that you seriously need to consider a snapped chain as a possibility with a hub motor.

 

[Nosweat]

Thanks - is putting the rear rack battery into panniers (ie use my existing rack, carry the barry and controller around in the pannier and plug the cables in when I need some epower) a remotely feasible option? Or does the thing the battery clips into not suitable for carrying in the pannier as opposed to on the rack?

 

[vfr400]

1. 48v system is legal, but night give too much torque for your forks. You must show us the forks you've got to confirm that.
2. A Dopwntube battery gives better handling. You will have to add one or two more rivnuts to your frame, which is no big deal. use a rack battery if you're ham-fisted.
3. Chuck the dynamo and get some decent battery lights. The back one isn't important. You can get some that last for months on a couple of AAA cells and are very bright. For the front one, get one with a rechargeable battery pack - about £12 from Ebay - must have a Cree XML emitter. You get longer use before the battery goes flat with the single LED types, but all of them have selectable power levels. This one is good and cheap.

5000 Lumen XM-L T6 LED Torch Headlight Headlamp Bicycle Bike Head Light SET | eBay

Can be used as Bicycle Light or HeadLamp. LED Bulb Type: CREE XM-L T6 LED. Reflector: Plating Smooth Reflector. Headlamp Color: Silver. Circuitry: 2800mA. 1 x CREE XM-L T6 Led Head Light Unit. LED Gloves.

www.ebay.co.uk

4. That hill shouldn't bother any motor kit.
5. The bikes you tried at the bike show most likely had crappy control systems using speed control. Many cadence systems use current control (Torque simulation in Chinese speak), which is much better. I've only ever found disadvantages with torque control systems for a commuter bike. Note that the type of sensor used has no bearing on the power algorithms used by the controller. You can get really crappy systems with torque sensors the same as you can get really good systems with cadence sensors, and vice versa. No, kit systems generally don't use both types of sensor simultaneously. My advice would be to stick with a cadence system for a commuter. Fit a system with a throttle. A throttle is really useful. I wouldn't want to be without it.

It's not a good idea to put a battery in a pannier. It will soon wear through. Use a proper rack.

 

[sjpt]

Thanks - is putting the rear rack battery into panniers (ie use my existing rack, carry the barry and controller around in the pannier and plug the cables in when I need some epower) a remotely feasible option? Or does the thing the battery clips into not suitable for carrying in the pannier as opposed to on the rack?

I think that a lot of kits have the controller integrated into the battery cradle (Woosh or vfr400 may correct that). If so, for pannier carrying you could extract it somehow (warranty?), or in extremis put the whole battery + cradle in your pannier. Downtube mounting will certainly be better if feasible.

One advantage of cadence sensors is phantom pedalling (as you mentioned above for chain breaking). Chain breaking isn't so likely, but it is very nice to be able to pedal slowly with NO effort if you are tired. Torque sensors typically give a max power amplification around 200%, eg you have to put in at least 1/3 of total power.

 

[vfr400]

I think that a lot of kits have the controller integrated into the battery cradle (Woosh or vfr400 may correct that). If so, for pannier carrying you could extract it somehow (warranty?), or in extremis put the whole battery + cradle in your pannier. Downtube mounting will certainly be better if feasible.

One advantage of cadence sensors is phantom pedalling (as you mentioned above for chain breaking). Chain breaking isn't so likely, but it is very nice to be able to pedal slowly with NO effort if you are tired. Torque sensors typically give a max power amplification around 200%, eg you have to put in at least 1/3 of total power.

Chain breaks do happen, but not very likely; however, problems like pedal arms coming loose and pedals falling off are real, and they will leave you stranded on a crank-drive bike.

 

[Bad Machine]

Chain breaks do happen, but not very likely; however, problems like pedal arms coming loose and pedals falling off are real, and they will leave you stranded on a crank-drive bike.

You won't be stranded if you've chosen a crank-drive system that includes a throttle. It's an option on several of the TSDZ2 conversion kits from Woosh (and other suppliers). Cranks and pedals coming loose will be as common on a pedelec as they would be on a non-powered bike. Are your nuts tight enough ???? (bolts etc...)

 

[Nosweat]

Thanks - sounds like the downtube is the way to go for the battery and cradle, but I will have to fit a couple of rivnuts as the ones that are brazed on for a bottle cage are 155 and 220mm from the bottom. Just hope they wont get in the way of the battery cradle!

My front fork dropouts are 3 or maybe 3.5mm thick steel (hard to measure exactly).

Why my stated preference for torque versus cadence sensor? At the bike show my hands-down favourite motor was the Activeline Plus, and I didn't like the sensation of riding front or rear hub motor bikes with cadence sensors (that curious lurch forward when start pedaling yet the bike continues under its own steam thereafter if I slow down my pedalling, at a predetermined speed according to which mode I was in). The Gocycle was almost my favourite bike and that had front motor with torque sensor. I'm not looking for a motor that does all the work for me, rather a motor that requires me to pedal less heavily all the time but still allows infinite control of my speed.

I will need to find out from Woosh whether their 250W front motors are compatible with 48V batteries. Maybe I need to reconsider the mid motor 48V option (which would at least allow a front hub dynamo...) Difficult to decide when costs are similar but there's no way to try both options out.

 

[vfr400]

My front fork dropouts are 3 or maybe 3.5mm thick steel (hard to measure exactly).

Why my stated preference for torque versus cadence sensor? At the bike show my hands-down favourite motor was the Activeline Plus, and I didn't like the sensation of riding front or rear hub motor bikes with cadence sensors (that curious lurch forward when start pedaling yet the bike continues under its own steam thereafter if I slow down my pedalling, at a predetermined speed according to which mode I was in). The Gocycle was almost my favourite bike and that had front motor with torque sensor. I'm not looking for a motor that does all the work for me, rather a motor that requires me to pedal less heavily all the time but still allows infinite control of my speed.

We used to get that 10 years ago. As I said, there are now cadence systems that don't do that. The Bosch uses a cadence sensor. I'm not sure about the Gocycle because I never had to fix one.

 

[vfr400]

We used to get that 10 years ago. As I said, there are now cadence systems that don't do that. The Bosch uses a cadence sensor. I'm not sure about the Gocycle because I never had to fix one.

How many bikes did you try that had that nasty trait? Which ones were they?

 

[Nosweat]

Cheers all. The worst hill I have to get up on my commute is Portway Hill which looks like this:

[link to photo]

and is a climb of 1:10 for just under half a mile. For gradient check out the jumps in height on the brick wall on the left.

Any idea how a XF07 would feel on that (assuming that I'm putting in some effort myself and have the controller on the maximum setting just for the hill)? Or how it would compare to the TSDZ2 crank motor? I am gravitating to the front hub on grounds of simplicity and reliability for a long commute but don't want to jump off every time I hit a hill.

Supplementary question, and I doubt many people will run a torque sensor and hub motor combination, how would a steep hill affect tht performance? My understanding was that the motor runs better at higher speed, and obviously a steep hill slows you down. But if maximum assistance comes from sensing higher torque, I would need to be in a higher gear to stimulate higher torque sensing, right? Which you don't want to do when on a steep hill. So how do you get a hub motor/torque sensor combo to recognise that you want it to give you more assistance despite changing down the gears (meaning less pressure on the pedals) at the foot of a steep hill?

 

[Woosh]

Any idea how a XF07 would feel on that (assuming that I'm putting in some effort myself and have the controller on the maximum setting just for the hill)? Or how it would compare to the TSDZ2 crank motor?

the TSDZ2T with throttle or the BBS01B will climb that hill better than the XF07.
Both can use your gearing to increase torque.

http://wooshbikes.co.uk/cart/#/product/uid-206-tsdz2t/tsdz2-cd-kit-48v-15a-250w-with-throttle-kit
http://wooshbikes.co.uk/cart/#/product/uid-178-bbs01-17ah/bbs01b-cd-kit-with-175ah-36v-hl-battery

 

[sjpt]

As Woosh says, the crank motors will give better hill performance.

The XF07 should get you up that hill fine, just not as easily as TSDZ. Even in a low gear you will be applying enough torque to the pedals that the torque sensor will ask for maximum possible power from the controller/XF07. Maximum power from XF07 at low speeds isn't that good; but adequate. https://www.ebikes.ca/tools/simulator.html?motor=MXUS_XF07&batt=B3614_PF&cont=cust_17_70_0.03_V&axis=mph

 

[Nosweat]

Thanks that's quite reasssuring, especially learning that the torque sensor knows when I'm going slowly due to struggling up a hill. Is there any risk of damaging the motor on the way down a long hill by freewheeling at 30+mph thanks to gravity - does it cause the motor to start acting like a generator if you descend fast enough?

At this point I'm leaning towards the XF07 with torque sensor both on grounds of simplicity and reliability as I need high reliability with minimal downtime or maintenance on the way to work. Can the Woosh XF07 run on 48V or not, for added boost on hills?

One further issue regarding the TSDZ. My Nexus hub gears have a coaster (back pedal) brake which despite being Marmite I actually like very much. I gather that there are two versions of the TSDZ; when pedalling backwards with the most common one it apparently doesn't move the chain backwards which would rule that motor out for me. The other version lacks a "sprag clutch"(?) and therefore permits use of a coaster brake. Which version do we get in the UK or can Woosh supply either? If I can't use the coaster brake with the TSDZ then that clinches the XF07. If not I might be tempted by the TSDZ which strangely for a crank motor is quite a bit cheaper than the hub motor with torque sensor.

 

[sjpt]

Is there any risk of damaging the motor on the way down a long hill by freewheeling at 30+mph thanks to gravity - does it cause the motor to start acting like a generator if you descend fast enough?

There is a clutch so the XF07 disengages downhill. No generator effect; there are a few bikes that have that but general opinion is that complication and weight do no justify the energy gained. The clutch also means that if you want to pedal faster than 25kph on the flat there is no motor drag ... still the extra weight of course.

Almost all geared hub motors have a clutch. One disadvantage of the cheap direct drive motors (which you sensibly seem not to be considering) is that they don't; so they create drag when not assisting, and are heavier.

Woosh will have to answer on the 48v. From the simulator I mentioned above ( https://www.ebikes.ca/tools/simulator.html?motor=MXUS_XF07&batt=B3614_PF&cont=cust_17_70_0.03_V&axis=mph ) I suspect the motor will be fine, but you need to consider whether the BMS and controller will be.

 

[Audio2]

Does the XF07 have a torque sensor? I thought the Woosh kit used a cadence sensor.

 

[vfr400]

As I said above, my advice is not to get a torque sensor hub-motor. Get a cadence sensor one instead. I can probably give the same advice with a crank-drive kit. The torque sensors seem to give a lot of trouble for very little useful advantage.

 

[Woosh]

Does the XF07 have a torque sensor? I thought the Woosh kit used a cadence sensor.

I can supply the XF07 with a torque sensor or a cadence sensor.
The torque sensor kit costs £50 more.

Torque sensor does not suit everyone because you have to pedal all the time and harder on hills but the reward is it keeps your legs strong while still flattening hills.

With cadence sensor:
http://wooshbikes.co.uk/cart/#/product/uid-197-xf07kit-17ah/xf07-front-hub-kit-2026700c-with-17ah-battery

With torque sensor:
http://wooshbikes.co.uk/cart/#/product/uid-222-xf07-ts17ah/xf07-ts-front-hub-kit-2026700c-with-17ah-battery

 

[Woosh]

As I said above, my advice is not to get a torque sensor hub-motor. Get a cadence sensor one instead. I can probably give the same advice with a crank-drive kit. The torque sensors seem to give a lot of trouble for very little useful advantage.

there is a difference between the TSDZ2 that I sell and the TS hub kit.

similarity:
Torque sensor does not suit everyone because you have to pedal all the time and harder on hills but the reward is it keeps your legs strong while still flattening hills.

difference:
The TSDZ2 requires you to choose the right gear.
The TS kit lets you ride in the same gear so much easier for hill start.

Where the TS kit wins:
The TS kit lets you keep that fully enclosed chainguard.