Artmo 

I've installed the Cytronex C-1 system on our Macchiato to help us oldies up the hills, when we encounter them, as we will at GTR. Simple installation and easily removed, when not needed. We had our first run yesterday and it worked well. We have no relationship with this company, other than being a satisfied customer..

gracehowler

Pretty clean install.
R&J

Ludkeh

We had a lively discussion on this topic a while ago. If you search the thread " Calfee Tetra E-Bike conversion 1 year update" you'll some interesting discussions.

Artmo 

Leisesturm

I was about to comment on the size of the Captain's waterbottle but, never mind ...

jnbrown

That is really cool.
If you only use it only on hills how far does it go on a charge?
We our in our sixties and I think it is inevitable will need / want something like that someday.

Artmo 

I've only just installed it and ridden about 50 miles on mainly flat terrain, so the power assist did not come on much as were above 15.5 mph most of the time. It was recommended that we buy the Euro version which has a legal assist limit of that speed. This gives more torque and is preferable for a tandem. I think it would last easily 30 miles on undulating terrain. A friend has the system on a solo bike in the UK and rides in hills, but gets 50 miles. After our first ride, it was 75% full and on the second, longer ride, it was still in the green 75-100%. There are the options of a regular charger or rapid one taking 90 minutes for full charge from 0. We have the rapid charger, which we will carry with us on long rides, so we can top up at coffee stops!
The whole setup only weighs 3.6kg (just under 8 lb) and if you don't want to use it, simply reinstall the regular front wheel and take out the "bottle."

ArDachaidh

Hi, we live in Scotland where it's hilly and often windy. We have a Co-motion Primera and at a couple of years over and under 70 we are struggling a bit and not using it so much, even though it's got a triple and very low gear of 17". I was looking at the Cytronex among others. How good is it? Is their front wheel real tandem quality and does having the motor in the front affect the handling and braking? Have you any more data on battery mileage on hilly terrain? Thanks for any advice. Graham

twocicle

Roll the dice and take a chance.

Caveats:

Just about every legit E-Bike out there from singles onward, are overbuilt to some degree in order to deal with the extra loads put on most all components of the e-bike.

A carbon rim brake fork is obviously not designed to withstand much hub torque, let alone pulling +300lbs of team mass and the increased "Euro" motor torque model exasperates the issue.

Food for thought: Perhaps revisit the forum posts last year showing photos of the sad couple who tacoed their flimsy front wheel when hitting a pothole on a fast downhill.

PS: Please add me to your list of estate recipients.

ArDachaidh

OK, I agree that E-Bikes are engineered for the purpose. We have a WoundUp fork, disc brakes and weigh about 280lbs.

I've left you our SS-Couplers, assuming they're not damaged.

Or maybe I'll sell it and buy an E-Tandem.

Artmo 

I suppose any wheel, even a car wheel, when hitting a deep pothole at speed will be tacoed or severely damaged.

The Cytronex is specified for tandem use and ours seems considerably more substantial than the Spinergy it replaces.

I'm not an engineer, but I'm afraid I don't follow your logic regarding hub torque affecting the fork. Surely the torque is applied to the wheel itself and the only way torque would be associated with the fork is if the wheel is not tightly installed and it "rolls" out of the dropouts. Overall weight and speed on braking would affect the fork of course, but the additional weight of motor+battery is only about 8 lb. In our case, tandem + team=370 lb, so it's only an additional 2% . The motor would not be "on" while braking, so no force from that. We have ridden about 500 miles with the system, admittedly with no hill challenges, only wind, but we are very impressed by ease of ordering, customer support, ease of installation (30 minutes) and performance. The Georgia Tandem Rally next month will give it a real test. More then....

UniChris

There are two parts to this. First, with a front hub motor, it's easy to see that the fork is functioning as an oddly shaped cantilever "tow bar" to pull the heavy bike along. But also, the lower part of the fork is subject to a reaction torque from the motor. If you just bolted it into the dropouts, it would spin in them rather than move the bike, there has to be some sort of short lever arm that prevents the motor's stator from rotating in the fork while the tire stays stationary, and that imposes a torque load on the lower fork that it may not have been designed for.

The issue was not braking, but the comparison to braking. If you run rim brakes, then the braking load is applied only at the top of the fork. A hub motor would be more like a disk or hub-internal brake that applies a torque load to the lower end of the fork, albeit in the opposite direction.

twocicle

Excellent answers by UniChris.

Artimo, the best layman description I can make to this point is this...

If you put your tandem in a fixed frame holder and the fork dropouts were held by something akin to a fork mount (bike rack) holder, then you grab that front rack mount with all your body force throw your weight forward yanking on the fork. The Euro high torque motor is going to put forces into your fork in much the same manner. The fork you are using is not designed to be used with drive (forward pulling) loads, but simply rider/team weight plus rim brake load. I would anticipate possible fork failure points as 1) failure of QR dropout bonding to the fork legs, 2) failure of the alloy/AL QR dropouts themselves, 3) lower fork leg failure, 4) fork crown failure. Any one of these is likely to end up with a very bad day. If you have any interest in knowing more about what your fork is designed for and what it is not, then phone the fork mfr.

The relationship of this case to the tacoed (low spoke count, low rim profile, single bike max weight load) Zipp wheel case is simple in that both are highly sketchy component use on a tandem. Choosing to ignore the obvious deficiencies is just asking for a critical failure.

Wish you luck, but certainly do not condone this use for anyone else to consider.

Artmo 

Thanks, guys. As I said, I'm not an engineer!
I've asked Cytronex for their opinion. They seem to have gone into great detail in their design, so I would be surprised if they have not addressed your concerns.

DubT

When i was doing research on adding a motor to our Calfee i contacted Calfee and had a very detailed phone and email conversation with Rob Baird who at that time was the tech at Calfee. He recommended the mid drive motor rather than a front wheel or rear hub motor. The mid drive produces more torque and does not tax the wheels like hub motors. He told me what to buy and provided complete technical assistance with the installation.

We are close to the 2 year mark with our conversion and are still EXTREMELY happy with the results. Wind, hills, faster riders, starting from a standstill, starting on an incline all taken in stride.

waynesulak

I suggest not relying on the assumption that the seller thought about the fork. Everyone has different risk tolerances but it remains 100% the bike rider's risk. The seller and manufacturer can limit their financial liability and they have zero physical risk.


One possible work around to consider for a powered front wheel is a steel front tandem fork designed for disk brakes. The forces from a disk brake endured in an emergency stop from 40 mph should exceed what the electric motor could deliver. A steel fork would be the safest since a it would most likely be strong when both braking and accelerating and also less likely to be damaged by any bracket attaching the motor's arm. One might even be able to have a custom heavy duty steel fork made at a reasonable price (if you could get a builder to take on the project).


All that said it does seem to be an elegant setup.

Artmo 

This article puts my mind somewhat to rest because the Cytronex is only 250 W https://www.electricbike.com/torque-arm/

Artmo 

Dub, as you know from a previous discussion, we also have a mid drive on our Circe Helios and we have the same riding experiences as you do (except that our assist speed limit is 15.5 mph per Euro regs). There is a marked difference in riding with each system: with the mid-drive and torque sensor, the motor assistance is a function of the effort the rider puts in at a given assist setting, whereas with the wheel-mounted (no throttle) the assistance is constant at whichever setting is chosen. We like both, but the Cytronex has yet to be tested on real hills. Of course, the mid-drive is MUCH heavier. See you at GTR?

DubT

I do remember that you have the Circe Helios and that you like it. The issue with mid drive is that it is a total commitment, the front wheel drive can be removed and installed in a matter of minutes. We decided to make the commitment!

We will not be at GTR. We are going to the COWS gathering in Lake Geneva Wisconsin next month.

Artmo 

From the Cytronex C1 designer:

"The fact that something is not designed for a particular use does not mean that is not capable of dealing with the forces that result from that use, by virtue of what it is designed for. Forks are designed to deal with significant impacts – such as being tested with impacts on a dummy hub horizontally. This results in big peak forces greatly in excess of anything the Cytronex C1 250W motor hub can produce. Additionally, since we design and produce our own product with our own British electronics and software we fully control the characteristics and bring power in smoothly, we don’t for example apply full power immediately when switched on from a standstill and the torque would be at its greatest.

That said, since we do not know the history of a customer’s fork we are not in a position of course to guarantee its strength (although we do always recommend that customers check the roadworthiness of their bike if fitting Cytronex C1), but the inherent strength of forks is borne out by our 11 years of experience. We launched the first Cytronex bikes in 2008 – these were fitted to Trek FX models (I believe they were the first disguised electric bikes to be commercially available at the time), and since then Cytronex has been fitted to a huge diversity of bikes and models. Despite this, I don’t recall a single issue with a fork when the motor wheel has been correctly fitted and secured.

When the wheel nuts are done up properly, not only is there the inherent strength of the metal dropouts (carbon forks usually have metal dropouts too), but each side of the dropout is firmly clamped between the nut and the fork, which prevents any movement. Additionally we extend the lever with our torque washers. We cannot speak for anyone else’s kit and we would certainly not recommend anyone retro-fitting a 1KW hub motor to a bicycle or tandem, but our results evidence Cytronex C1’s safety.

It is true that many kits originate in countries with lax regulation and are supplied by companies that don’t need to concern themselves much about what happens to their products in use. But we are a British manufacturer, and we care very much about what we do, with 9 years of R&D behind Cytronex C1. AtoB Magazine did a very thorough review of Cytronex C1 when it was first launched, and I believe our approach is self-evident from their article: https://www.atob.org.uk/product/a-to-b-118-digital-cytronex/ "

Disclaimer: I am in no way associated with this company, other than being a satisfied customer.

trailangel

Did you tell Cytronex you were putting the hub on a tandem?
https://endless-sphere.com/forums/viewtopic.php?t=75216

Artmo 

Yes. Their ordering system asks this specifically, so the Mavic wheel is for a tandem The designer has the system on his Cannondale and has sold several for tandem use. As he writes above, he would not put a 1kW motor, which could apply max power from standstill, on a front fork not designed for very high torque. The C1 gradually increases power from standstill and, in any case, is maxed at 250W.

twocicle

Priceless: "the inherent strength of forks is borne out by our 11 years of experience."

Absolutely, as Russian Roulette survivors may attest that hand guns are perfectly safe for such use!

It would be most interested to have feedback from carbon fork manufacturers in regards to this type of use with this type of QR fork. Unfortunately Alpha Q (by True Temper) was discontinued back around 2010, so direct response from them is unlikely.

https://electricbikereview.com/forum...-motors.11255/
https://ebikebc.com/faq-items/isnt-d...rk-hub-motors/
https://lunacycle.com/bare-mac-high-...nce-hub-motor/

Artmo 

And tandem front wheels, like Bontrager, whose spokes tear from the hubs, as I've experienced twice and Topolino rims which crack, as has happened to two of mine. Both products spec'd for tandem use, with no weight limit.


No, I'm not promoting the Cytronex, any more than DubT was promoting his conversion. In response to some questions asked here, I asked the designer for his opinion after 8+ years with various bikes, including tandems and he has not experienced a single failure. The opinions on two of the sites you reference are based purely on guesswork, not experience and the third refers to a 1000W motor, so is irrelevant when we are discussing 250W. In any case, the weakest point on the fork where motors and disc brakes are concerned is at the dropout, not in the body of the fork, or fork crown, otherwise forks would be specified for team weight, wouldn't they?

As we normally have to put the tandem in our car to take it to ride start points and I have to remove the front wheel to do so, I can easily check the dropouts each time, if I remember. In any case, I will continue to ride with confidence, based on the information, not guesswork, we have.

Thanks for your concern.

twocicle

<quote>forks would be specified for team weight, wouldn't they?</quote>

Well actually, yes, many forks (and maybe most carbon forks) do come with a rider weight rating. Nevertheless, you are indeed guessing that the AlphaQ fork is capable of handling this motor hub - a setup the AlphaQ was never designed for. It is not like you are using the fork for it's intended purpose and design.

Beating a dead fish here and said my bit. Out.