Author Topic: Cytronex ebike kit  (Read 1884 times)

Janner

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Cytronex ebike kit
« on: July 31, 2021, 09:34:15 AM »
Hi. I own a Thorn Raven Tour/Rohloff.
Looking for information about fitting the Cytronex front wheel drive system.
Does anyone here have any experience using this system particularly with a Thorn Raven?
Does the front drive axle fit the fork drop out width?
Anyone know what torque the Cytronex puts out, cant see it advertised?


Any other suggestions of similar systems for my Thorn with eccentric bottom bracket (excluding Pendix as its out of my budget).

Thanks

 

Andre Jute

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Re: Cytronex ebike kit
« Reply #1 on: July 31, 2021, 01:00:57 PM »
For us to say anything meaningful, you should tell us at least whether you ride on flat or hilly roads, and how far, and in what style. Also tell us if you will install the motor yourself or have it done by the vendor or your bike shop; there are posters here with experience of both models. I give you a general answer including some more things for you to think about before you blow a thousand pounds.

The Cytronex is over twice the price of a much better specified system with front wheel drive I fitted, and it not only does not offer any reason for being so expensive, it will be painful in use by most enthusiastic cyclists. See
http://coolmainpress.com/BICYCLINGbuildingpedelec1.html

The concentration on light weight is simply foolish. There is no generally capable electric bike installation that is not heavy. Lightweight installations disproportionately punish the owner by having to lug still substantial weight with very restricted range from a small battery, and a motor that will burn out sooner than you would expect. If you're building an electric bike for health reasons, I suggest you give up the Cytronex idea right here. If you're generally fit, read on.

Your question about torque is relevant but there is something even more important, which for shorthand I call Coulombs, like Jeremy Clarkson on Top Gear speaks of "torques". Basically a coulomb is a unit of electrical power delivered in a very short period of time, normally taken as one second. Practically, at every point in your ride, it doesn't matter how much total power is left in your battery, but how much it can deliver instantly when you need it, say if the hill steepens or you run out of puff near the top. In this regard, big batteries are more useful, because they can deliver more coulombs, i.e. more watts of power in the next second. The current Rolls-Royce built by BMW doesn't have a rev counter but a "Power Meter" which show instantly available power, on the same concept as your query about torque and my concept of coulombs.

The Cytronex marketers try to hide their inadequate battery by not telling you the rating in the normal form of Amp-hours, instead trying to bulldust you with the big-sounding "180Wh". That's only 5Ah. Amps measure real accelerative power, and is a good stand-in for torque, which electric motor makers often do not publish. On the Cytronex with that limp battery, I would not expect torque to be, at a guess, more than 35Nm.

On my first electric motor, the bottle battery was 9Ah and on my current mid-motor installation (not on a Thorn), the battery is, from memory, 14Ah. Both were/are adequate for my rides up to 25km in very hilly West Cork. I imagine the bigger battery would be okay to 40-50km but never went that far without recharging at a cafe or pub where we stopped. My batteries, with constant considerate care, are both going strong after many years of use. Even with obsessive care, I think that a 5Ah battery will be so heavily stressed all the time (that is, run close to its margins, which lithium batteries hate) that its life will be shortened. Since the battery is the most expensive part of the electric of a bike, it hurts only once to get the right size (to decide which we need the information in the first par), as opposed to getting a too-small battery which will hurt almost constantly by being inadequate in both distance and service life. It might surprise you to learn that the motor by itself in the above linked setup was less than £60 FOB China out of a total of £425 for an utterly complete kit delivered to my door by a British based dealer with excellent service.
« Last Edit: July 31, 2021, 01:11:56 PM by Andre Jute »

Janner

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Re: Cytronex ebike kit
« Reply #2 on: July 31, 2021, 04:01:21 PM »
Thanks for your detailed reply and you nailed a lot of points I was already thinking. I have fitted 3 front wheel drive kits to other bikes (wife, daughter and my old Marin), they have been going well for 2 years now, maybe from the same supplier you mention in your last paragraph. I would go this route again but the axle is too wide for the drop in on my Thorn and was considering something different. This may be the same issue with the Cytronex (waiting for a reply from them). I do like the simple and uncluttered design of the Cytronex and would like to support British manufacturing if the product was suitable, reliable and competitive. An alternative is to fit different forks that would accept the axle width. I had the same concerns about battery size and power. Think that for my riding it would not be very efficient. A second spare battery would be costly and your concern about motor longevity is a consideration  On my other (Chinese kit) ebikes I can squeeze about 40 miles out of the battery,  being about 20 miles up steep hills and 20 down with a bit of flat in between if I am lucky (Cornwall and Devon). I use my Thorn for short touring and overnight camping as well as general day to day riding.
Would like to have been able to fit the Bafang mid drive but the eccentric bottom bracket appears to be a show stopper.
 
I have had two very bad experiences with brand new purpose built expensive well known ebike brands, both mid drives. Brand 1 failed within the first week when I lost all power. Supplier couldnt figure out the issue so the alternative was to strip all the wiring out and re wire. No thanks, so they refunded me.Brand 2 from a different supplier and even more expensive, within a few miles out on my first ride I could feel a slight clunk at the crank. One of the motor bolts had sheared off. Supplier could not remove the bolt that had sheared so the entire bike had to be shipped back to the manufacturer.The bike was stripped and given a new frame. No thanks, second refund.  Both times, the suppliers customer service was great but has put me off ever buying purpose made ebikes again.
« Last Edit: July 31, 2021, 04:03:54 PM by Janner »

in4

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Re: Cytronex ebike kit
« Reply #3 on: July 31, 2021, 07:06:49 PM »
Do a forum search. Iím sure someone on here has retro fitted a Bafang ebike kit.
As a side observation Iíve noticed many ebikes are fitted with tiny chain rings and contrastingly huge group sets, if thatís the correct terminology. Iím thinking torque considerations but defer to the greater knowledge of others here.

Andre Jute

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Re: Cytronex ebike kit
« Reply #4 on: August 01, 2021, 12:58:59 AM »
Iím sure someone on here has retro fitted a Bafang bike kit.


I've retrofitted both the Bafang front drive, such as Janner needs, and the Bafang central motor, and can recommend them both. There are several others posters here who either fitted the front motor to a Thorn, or fitted the central motor to bikes without the eccentric bottom bracket.

The short answer is that the central motor can be made to work with a Thorn with the EBB, but only by making it less of a Thorn. You have to take off the EBB, because the Bafang mid motor hangs in the BB shell and is therefore built around its own bottom bracket, and then add an ugly drop arm and a jockey wheel for chain length adjustment, precisely the excrescences that you paid a lot for a Rohloff hub gearbox to avoid. Such an installation does not work with the extremely desirable Chainglider and thus condemns you to detailed, frequent maintenance. The next alternative is to have track frame ends welded on at the rear; they're long sliders which perform the same function as the EBB or the sprung drop arm and jockey wheel, but much more unobtrusively thant the latter. Now we're talking of warranty-threatening alterations to a frame that is known to work in its standard form. The motor in the front wheel is thus the most straightforward and easiest solution for Thorn bikes with EBB.

***
Janner: Double the price, plus some more, to support local industry is too high an entry ticket for my taste, especially when in my opinion the local product doesn't seem quite up to the job. But do let us know how you go, whatever you decide. And don't hesitate to ask further questions as they arise.

Janner

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Re: Cytronex ebike kit
« Reply #5 on: August 08, 2021, 01:16:52 PM »
Update. Ditched the Cytronex idea for now. Fitted a 250w front wheel motor and ebike kit I had another bike. Swapped my Thorn Raven tour fork for a substitute fork as it was necessary to file the axle support a bit wider to accept the axle (didnt want to adapt my original tour forks).
Thanks.
« Last Edit: August 08, 2021, 01:18:43 PM by Janner »

Danneaux

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Re: Cytronex ebike kit
« Reply #6 on: August 08, 2021, 05:30:26 PM »
Quote
Swapped my Thorn Raven tour fork for a substitute fork as it was necessary to file the axle support a bit wider to accept the axle (didnt want to adapt my original tour forks).
Not sure if this will apply in your case, Janner, but I installed a similar front e-wheel on a friend's bike last year and encountered the same interference problem.

I solved it not by widening the dropouts but by machining two flats on the axle. Once milled, the axle dropped directly into the fork ends. It wasn't far off and didn't require much. Though I used other means, careful work with a file could've done the job.

Best,

Dan.

Janner

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Re: Cytronex ebike kit
« Reply #7 on: August 11, 2021, 05:06:49 PM »
Yes, that was an option to consider. Thanks