carbon forks and hub motors?

[Nealh]

I find my Ute with tsdz2 an easy ride with no power and that is also towing my carry freedom , flat road terrain and on the Worth way as well.
Gearing and cycle fitness both play their part, with Ute I have a double chain ring set up 32/42t that works perfectly because of the LWB/ rear chain stay so have a full 1 eighteen gears if needed.

 

[PJ53YYY]

• So clearly views differ and I'd be pleased to hear from anyone who has fitted a hub motor to carbon forks and their experience.

I have a Swytch kit fitted to a Boardman Hybrid with a carbon fork. It has a torque arm fitted. I think probably just because I saw Swytch offering them and thought I should fit one. I have been using the bike regularly for 4 years without issue.

 

[Nealh]

Personally I prefer steel /chromoly forks simply because they feel better then CF, the one mtb bike I had that was all CF I got shot of because I just didn't like the riding.
Each to their own and how a bike rides /feels will differ to that which one will feel comfortable with.

 

[saneagle]

I understand where you're coming from of course, but these riders and others like them, aren't worried about the added weight and are happy to trade that off to get the assistance when they need it on the hilly parts.

I've stripped back one of my TSDZ2 bikes (allow frame, carbon forks, and just a tool bag and mudguards) and use an 8Ah battery and am able to comfortably ride on the flat with little or no assistance because the bike is light and I'm not carting around some heffer-lump of a 17Ah battery, but the power is there when I get to the hills: 50-60 miles for me on the 8Ah battery.

If I had the inclination to spend £1k on an ebike conversion, I think I'd rather like the Cytronex and would I put it on my carbon Trek Madone? Quite possibly.

I got myself a carbon roadbike. After I lowered the gearing a bit, I found that I could pedal it just as easily and fast as my electric bikes. At first the hills were hard, but it wasn't long before I could do 80 mile rides. If hills are hard, you just lower the gearing to make them easier. It's only a question of how fast you want to go up the hills.

 

[AndyBike]

There are carbon forks and there are carbon forks, I've used carbon forks(White Brothers Rock Solid) offroad with a 180mm rotor and 4 pot brake and they were fine, but I wouldn't put a motor on a pair. I just think thats too much.

I'm very much with the above. A set of good quality steel or even 4130 cro-mo forks wont go wrong, and the fork area is the very last place you want to have any issues with.

 

[Peter.Bridge]

There is a very particular niche requirement which I and probably many others have, and for which there is not yet a perfect solution.

I can no longer manage the small proportion of serious uphill riding without assistance.

How about a 1.44kg akm-75 hub 36v 201rpm motor, maybe build your own wheel , coupled with a 36v 10ah bag battery (1.8kg) with top quality cells (like the ones Woosh offers). Add a KT controller, little LCD4 and pas sensor. That's going to be less than 4 kg added. I think the 201 rpm version would be ideal up hills if you are adding a significant amount of pedalling effort and has low motor drag.

Just thinking , a 54 mile ride, 27 miles flat/downhill unpowered, 27 miles incline / hills powered - 360Wh/27 = average 13.33 Wh/mile, although compared to a analogue road bike, depending on the route, there is probably a good proportion of the incline / hills where they would be above the motor cut off speed (even if you pushed it to 17 mph)

 

[sjpt]

I think the best solution at the moment for very lightweight bikes and hills is still pushing. Maybe that depends on how bitter you find the taste of shame.

 

[Bikes4two]

• So clearly views differ and I'd be pleased to hear from anyone who has fitted a hub motor to carbon forks and their experience.

• I can't help you directly but I've been talking to cycling buddies in Portsmouth CTC (link) and to date I've come across three separate riders who ride with Cytronex in carbon forks.
• All of them were strong riders in their days and still are relative to their ages and use the motor sparingly and report zero problems.
• Yes, I get the point of 'walking up hills' or 'going to a lower gear' and I'm not bashful about both approaches, but when you're in a group, enjoying the companionship and pace, you really don't want to keep your buddies waiting.

I like the idea of the AKM-75 @Peter.Bridge , a lot more than I like the £1,000 Cytronex

 

[saneagle]

• So clearly views differ and I'd be pleased to hear from anyone who has fitted a hub motor to carbon forks and their experience.

The big question is why you'd want to do it in the first place, when a rear motor would be so much better. Fitting a motor to any forks makes the bike shite!

 

[Peter.Bridge]

I like the idea of the AKM-75 @Peter.Bridge , a lot more than I like the £1,000 Cytronex

The other "micro hub" is the 1.7kg Bafang G370 that @Nealh uses :

E.g.

Bafang e-bike hub motor H600 (spoked 26" 28") front wheel FM G370 36V 250W | eBay

The Bafang e-bike hub motor G370 is characterized by its high quality and compatibility. With this hub motor, almost any bike can be easily converted to an e-bike / pedelec. The motor impresses with its smooth running and high performance even at low speeds.

www.ebay.co.uk

@Nealh - is it the 201 rpm version you have ? - what top speed does that give on 700c wheels

I would use it with a KT controller and display and either the Panasonic celled 1.8kg 360Wh or the 540Wh (0.5kg heavier) bag batteries from Woosh

eta Both motors get a 100kg bike/rider combined weight up a 10% hill at nearly 15km/h with 100w of pedalling effort. Be careful of the rpm though - Grin only had a 328 rpm akm-75 so I compensated on the simulator by using 20" wheels

 

[Nealh]

201 rpm @36v , though I use it @44v.
One suspects it will manage a 10% gradient.
If one lives in a flat terrain which has not too many hills then it is a good chioce.
I have had it to 16.5mph assisted but as it rides nicely unpowered above the 25kmh limit , it is set to 15.5mph.
The G370 hasn't a typical axle with flats , it is 10mm in dia with two inboard small flats to sit in drops outs, one can't use torque arms and can only use one anti rotation washer due to the motor cable exit position.
The perfect fork for it is the Surly disk trucker fork as the motor sits straight in first time and sits in the dimples, fit the A/R washer on the RHS and simply tighten the nuts up tight .

Small light motor that has not torque effect on the steering , not yet had the wheel scrabble at all even towing 90- 100kg loads off road on ex railway route.

 

[Peter.Bridge]

201 rpm @36v , though I use it @44v.
One suspects it will manage a 10% gradient.
If one lives in a flat terrain which has not too many hills then it is a good chioce.
I have had it to 16.5mph assisted but as it rides nicely unpowered above the 25kmh limit , it is set to 15.5mph.
The G370 hasn't a typical axle with flats , it is 10mm in dia with two inboard small flats to sit in drops outs, one can't use torque arms and can only use one anti rotation washer due to the motor cable exit position.
The perfect fork for it is the Surly disk trucker fork as the motor sits straight in first time and sits in the dimples, fit the A/R washer on the RHS and simply tighten the nuts up tight .

Small light motor that has not torque effect on the steering , not yet had the wheel scrabble at all even towing 90- 100kg loads off road on ex railway route.

I'm really surprised it isn't more popular as a lightweight kit, it avoids a lot of the disadvantages of a front wheel kit, can be pedalled unpowered with very little drag , can choose a suitable generic battery, can use KT controller and display, much cheaper than Cytronex (or x35 bikes)
Could do a kit with 360wh battery for < 4 kg or 540wh < 4.5 kg
The link I posted was for a 260 rpm model, which I think would be a good solution at 36v for legalish speeds

 

[Nealh]

The AKM's are half the cost so would be a more popular choice.
Also the G370 needs a particular fork , for some reason people are sold by must having a bouncy fork even those with cheap £30 -£60 ones.
The only bike I have with bouncy forks is a mtb hiding somewhere in the garage with Rok air forks.

Tonxin and keyde are other lightweight small hub producesr but we don't see many of those either.
Using small hubs is horses for courses and more of a bespoke market here, it is dependant on the terrain so would not be a popular one fits al hub.
I weighed up four hubs before selecting the dearer Bafang and simply went for the known quality of the brand .
The three others were the AKM75SX which I felt may have been too lightweight for my needs, the other two AKM100SX and the TBK100AD clone/rebadged model.

 

[Bikes4two]

The big question is why you'd want to do it in the first place, .........

For those whose bikes have internal geared hubs maybe?

.... when a rear motor would be so much better. Fitting a motor to any forks makes the bike shite!

Well, over the next couple of months I'm about to find out about a front hub motor in that I've just acquired a used Swytch front wheel/hub motor (an AKM 100SX).

As the motor is built into a 700c wheel at the moment I'll be trying it on one of my bikes that has carbon forks (so I can show the build to my Cytronex/carbon fork friends - lol) although the long term aim is to have the motor in a 26" rim for that little bit of extra oomph we need on the tandem these days and the tandem is Rohloff IGH fitted so no rear hub motor option and the eccentric bottom brackets done allow for a TSDZ2/8 of BBSxx mid drive unit.

As a TSDZ2 user, I find myself now pondering on what controller to get and where to put it, plus finding a drive side PAS sensor for my Hollowtech 2 type BB and maybe a brake sensor (is one really necessary do you think?), none of which are needed on my TSDZ2 bikes - what a faff eh!

At least that's the rainy evenings sorted for the next few weeks .

 

[Nealh]

We know Cwah smoked his AKM100's as he has documented saying so ( makes me think what pranks he is up to nowadys) , we know 48v 20a is too much but one can always try 15 -17a .
d8veh is of mind to think that even 17a may strip the gears, if using 36v then one would say 17/22a should safe.

 

[Bikes4two]

Thanks for those amperage figures @Nealh - I'm undecided on what (KT sinewave) controller amperage to go for and was looking at lower figures than that.

This kit will be on one of my lighter bikes and I anticipate only needing a small amount of power (I ride my TSDZ2 almost exclusively in ECO mode only venturing one notch higher for the ocassional fun of it) so for me 15A I'm thinking should be fine?

In addition to this I'll be running on my 36v 10s 2p LG M50 handlebar bag mounted battery pack so I won't be pushing the current.

At the moment I'm wondering where to place the controller and had looked at the KT 30mm tubular controller that you posted about a while back but it does seem pricey and I can't see if the tubular aspect brings me any benefits.

All tips/advice welcome on controller choice and placement.

 

[saneagle]

Thanks for those amperage figures @Nealh - I'm undecided on what (KT sinewave) controller amperage to go for and was looking at lower figures than that.

This kit will be on one of my lighter bikes and I anticipate only needing a small amount of power (I ride my TSDZ2 almost exclusively in ECO mode only venturing one notch higher for the ocassional fun of it) so for me 15A I'm thinking should be fine?

In addition to this I'll be running on my 36v 10s 2p LG M50 handlebar bag mounted battery pack so I won't be pushing the current.

At the moment I'm wondering where to place the controller and had looked at the KT 30mm tubular controller that you posted about a while back but it does seem pricey and I can't see if the tubular aspect brings me any benefits.

All tips/advice welcome on controller choice and placement.
View attachment 60279

How are you going to bring the wires out of your frame tube with that controller?

Don't forget that the current is adjustable downwards with KT controllers.

 

[Bikes4two]

How are you going to bring the wires out of your frame tube with that controller?[\quote] My understanding is that that controller is 30mm diameter - neither of my bike frames has tubing that size - I was just looking at that particular controller and wondering if it's tubular shape may offer some advantage over the standard rectangular shape in terms where I place it on the bike. I wonder if it would inside a water bottle?

Don't forget that the current is adjustable downwards with KT controllers.

Ah yes, a good point - thanks.

I'm a real novice when it comes to hub motors as all my (4) conversions have been with the TSDZ2 but I thought I'd give one a go as there are so many fans of them, albeit rear hubs are the more popular choice.

Additionally when a friend brought his Swytch bike to me to look at his duff battery (I posted about that as you probably recall) and as he hd a second battery I took his Swytch bike for a spin and liked it, so ebay to the fore and I've got one to play with.

 

[Nealh]

The tubular one at 22mm could be a seat tube option but it does beg the question of cable exit.

 

[Bikes4two]

As I said I would in post #10, I have now popped into Cytronex in Winchester posing as a potential customer and amongst other things I asked about, was the fitting of their hub motor to carbon forks.

The guy I spoke with was very knowledgeable and has worked there for a good few years, so much more than just a shop assistant. It is a small concern and all kits are built on site (batteries are Molicell 21700 P45B I think and built on site too) with the BMS and controller made in Eastleigh.

Their kits go to a good proportion of those riding carbon forks and over the years he's worked there he estimates 500+ sales and none to his knowledge have ever reported an issue.

In terms of carbon folks with metal drop-out inserts, as with bikes with steel or aluminium forks/drop outs, the tightening torque they recommend is 35Nm. The exception to this is for carbon forks with carbon dropouts (yes, carbon dropouts) and for this it is 25Nm.

The motor they use is an Aikema but he wasn't sure of the exact model but it looked the same physical size as my AKM 100SX but could have been the AKM 85SX as they are the same size. What was interesting is that their motors are factory fitted with a mix of metal and plastic gears in the hub which gives more resilience than all plastic but quieter than all metal. On lifting the front wheel and giving is a spin by hand, there was virtually no rolling resistance. Oh, and the axle on their motor has 9mm flats on the axle so no dropout filing required.

I've yet to test ride one of their bikes (but was offered one) so I've no idea as to the starting torque in any of the 5 power level settings but having cycled alongside other Cytronex riders and I should imagine it is a soft start algorithm.

I pass this observation on for what they are worth to those who may be considering using carbon forks with a front hub motor.

As an aside, I really liked the look of their kit and the clear attention to detail (cables cut to length for your particular bike and neat little cable clips and the fact that their ystem is in-house in its entirety (apart from the motor). Various levels of customisation can be had including using your own wheel rim for the motor providing it's a 32 or 36 hole afair. Build lead time is two to three weeks depending how busy they are - he recommend at peak times they can do 6-8 kits per day.

The bottle battery which also houses the controller (blue tooth configuarable) is very distinctive in that the mounting cage, a very solid afair, sits proud of the frame a little due to its very solid cable connection system.

I also noted that all the bikes in their showroom with motors fitted had the motor cable entering the axle from the top side (conventional advice is to have it entering from the underside to prevent moisture entering the motor). Now whether they put extra sealent in the cable entry point or there is factory fitted sealant wasn't known but their installation looks that that much neater for that approach. (in this YT vid HERE at the 16.10 point, the hub axle in question has a sealeant injection point - are all axles like this?)



Not a cheap kit cost by any means and beyond my cycling budget but affordable by many it seems (and customers around the world including the USA who get a 20 mph speed limited system which is available to Eu/UK customers who sign a disclaimer that it's not for use on Eu/UK roads) and those owners I've spoken with in my local group do like them and no problems of any sort reported.