[alan]

Aging as I am, living in Devon with lovely hills to climb I am tempted to add an electric motor to my double pylon.
HAs anyone tried to add a swytch kit. They say they can build a 20″ wheel.

[Walter Barra]

There was a company called Nano that back in2017 built an electric motor into a TSR. There was also a video on youtube

[David O’Keeffe]

I’ve just put a Swytch 20″ into my APB. Works brilliantly, but the front drop outs needed a little filing for the axle. It’s a wide rim, may not suit Pylon

[Keith Hales]

Just roughly measured the front drop out width on my double pylon, it’s only about 70mm. Don’t think any hub motor is that slim.

[David O’Keeffe]

When you go on the website they take you through the measurements needed. The axle widths are ‘standard’ as in the gap between the drop outs, but the axle they use in the motor is slightly “old school” Filing drop out lugs to get it in was…tense!

[Tim Wong]

I just finally installed the Swytch kit on my APB (Shimano Plus). I live on a 22% grade hill in San Francisco. The biggest thing was filing down the dropouts to fit the wider axle. This took about 30 minutes. Over the years, I put on a compact crank on the bike, which I hated. The crank was very close to the frame and would not allow for the pedal sensor to fit. I kept the original Shimano RX100 crank and bottom bracket, so I put them back on and the sensor fit fine.

The current Universal Sensor from the latest shipments fit, but not perfectly. I had another sensor from a Brompton Swytch kit that I bought for my wife. So I tried that sensor and it fit better. Swytch had sent me a Brompton specific sensor after I received that kit.

I did a test ride running errands and riding up the 22% hill seemed like a breeze. I might explore mounting the battery pack on the APB front rack.

[David O’Keeffe]

One observation, the gyroscopic effect from the heavier wheel gives quite marked understeer compared to original!

[David O’Keeffe]

I have just had a catastrophic front fork failure (metal fatigue type due to spread load I think), wheel exited forks, I exited saddle, face-plant.

Be careful out there…

[Cameron]

Yikes. Hope you are all OK.

Do you have any more details on what happened? Was it a result of the spreading of the forks or the motor being too powerful?

[Tim Wong]

Hopefully David is OK from the face-plant. Never fun. So far, so good, but I am not riding the APB that much other than local errands (maybe 5 mile loops). Will keep my eye on fork wear. Where did the metal fatique occur? Wondering if filing down the drop outs to fit the axel may have caused the failure. Or the torque from the motor caused the frame itself to collapse (250 watts is a lot). When things open back up, I was going to use the APB for a beater commuter thru downtown San Francisco.

[David O’Keeffe]

I think the filing of the dropouts was uneven, the torque of the motor exceeded the torque of the wheelnuts and the metal just gave up and bent once stressed by he wheel’s departure. It happened within 200yards of home on an uphill section so I was pulling on the bars. Needed suturing in theatre, luckily I’m in the trade so my colleagues rallied. No fractures but shoulder neck and face took about 6 weeks to get right again. I worry about Brompton and Moulton since their front forks are not built for that level of torque. Some bracing might help but on a 30 year old slightly ‘tired’ APB I think I was an accident waiting to happen. I have the full Swytch kit and can donate if anyone wants to “fail better”!

[Clifford Slocombe]

Swytch Bike offer a torque arm recommended for older / weaker forks. No problems yet with my 1965 F-Frame. That said Google “Electric Bicycle Torque Arm” to get the same a lot cheaper!

Their web-site also recommends filing the axle rather than the drop-outs. Problem is the axle is hollow and they do not state how much material you can take off before compromising the strength! I took mine down to 9mm (0.5mm off each side), which is the width of the opening on a series 1 F-frame, but the drop-outs are V shaped so I still had to file then parallel to seat the axle.

[Clifford Slocombe]

I have a Switch kit on a Series 1 F-Frame. The small wheels and narrow handlebars made for problematic handling with the moving-mass of the battery mounted on the handlebars. I moved the battery to the fixed front rack using a 3D printed bracket of my own design. Then it is great; the small wheels make for quick acceleration compared to a larger wheel e-bike as the hub is driving it directly and seeing effectively a lower “gearing”.

However on an NS, I don’t think the battery mount will work with the wishbone stem. For the “Universal” conversion kit the motor hub OLN spacing is 100mm with axle 10mm across the flats. It took some brutal fettling even on the F-Frame. I would not contemplate doing that on an NS! The NS has 70mm OLN and I am not sure of the drop-out width, so not a chance with the standard kit. The Brompton kit has a 74mm OLN (and I think 9mm-flats axle) and the battery mounts on the luggage mounts; but that does not really help you either.

Also remember that the motor applies torque to the dropouts in a manner that they were never intended to take. On my F-Frame I used the optional torque-arm which clamps to the fork with a hose-clip (a bit like a coaster brake torque arm but shorter). It is not pretty, and I would not mess up a beautiful NS with such a kludge.

Moreover, even if you could make the Brompton motor fit, and persuade Swytch to sell you one on a 20″ wheel, the rim they use will not be anywhere near the same quality as the original and may be wider. It may also interfere with any mudguards you may have fitted. In my case, even the wheel build itself was poor, with the wheel far from true or even circular. You would ideally want to build the hub into your existing or new rims of your own choice perhaps. Swytch to claim to offer a “motor-only” kit for you to build your own wheel (or have it built locally for you), but when I suggested that they seemed remarkably reluctant to actually sell me one. In the end it was unnecessary because they had wisely stopped building the 16″ wheels radially spoked, which is wat I was concerned about.

I would suggest buying a cheaper used TSR or similar as a donor bike or even an F-frame and converting that or get a ready-made conversion from the likes of AARC.

All that said; discuss it with Swytch – I found them to be very helpful in my pre-order enquiries. I did it for the fun and challenge and knew a priori that I was fitting it to a far from conventional bike and would encounter issues to solve. While happy to risk an old F-Frame, I would not have attempted it on an NS (if I were lucky enough to own one!).

[Roger Cantwell]

Brompton front axles are a non-standard 8mm.

[NeillSlater]

ask Moulton if they recommend adding an electric motor to a DP.the answer is most likely to be No.as the DP tubes are very,very thin.they were Never intended to take the tremendous torques generated by a motor.a New DP costs the thick end of 20,000 Pounds.You Dont want your DP to end up wrecked.a repair will cost a pretty Penny..if steep hills are your problem,then simply speak to your local Moulton retailer about lowering the gears.A 9 or 10 speed cassette with a sprocket spread that runs 11-34 in conjunction with a 31-58 tooth double chainring combination is sufficient to climb almost any steep hill effortlessly.31-34.31 tooth chainring in conjunction with 34 tooth sprocket.if you need to go even lower then add a 3 speed Sturmey Archer CS-RF3 internal geared hub to the derailleur drivetrain.your low gear will be low enough for you to ride up the walls of your house and across the ceiling for good measure..

[Clifford Slocombe]

@David O’Keeffe are you still looking to pass on your Swytch kit? How much did you want for it? How far from SN13 are you?

Of course you might rather try again if you have another donor bike or replacement fork, and have not been discouraged the clearly dangerous catastrophic. Use of a torque arm (possibly one on each side) and filing the motor axle (precisely and evenly) rather than the dropouts is key to success and safety perhaps. Though a few more miles needed on mine before I’d be confident of that!

Back to the original question; don’t do it unless you are willing to accept it as “experimental” and potentially dangerous. An NS is not the bike to experiment on given that you could end up damaging it or yourself! At the very least find a rear wheel drive solution perhaps.

[Des Gibbons]

Failing that, fit a bafang mid drive but that means swapping out the original cranks which i bet are far nicer to look at and more useful, be ok on a cheaper model and takes all that worry away from from filing forks and touching the dropouts, also there is a device called a Rubbee, clamps to seatpost and has motor and battery combined with a wheel that touches rear tire so making it removeable and use when needed but this also means no rear mudguard or even rack, so everything has a compromise of sorts.

[Clifford Slocombe]

There were a couple of AM spaceframe mid drive builds at BoA this September. They were less than elegant IMO. You still have to mount the battery and controller, and route the cabling. I considered such a solution for the F-frame I converted, but it was remarkably less cost effective than the Swytch kit.

[David O’Keeffe]

Clifford,

Sorry was away from Forum. Do you still want the kit? Free to a good home if you cover postage etc?

David

[patrick]

Dear all

Fitted Swytch-set on my tsr27, but all trials to fit it to the existing crankset failed miserably. So using it with the thumb-system, which is neither really safe nor comfortable. All crankset adaptors from Swytch including the Brompton ones did not work. Any ideas?

Regards

Patrick

[Clifford Slocombe]

@patrick

I’ve had enough of this forum randomly deciding to hide my posts without explanation. Hopefully this one will not get taken down.

A standard bottom-bracket 12 magnet PAS sensor will work. You will need one with a suitably long cable. Most are too short for Swytch being designed for for frame mounted controllers. They are available with an 87cm cable which will suit.

This forum hides this post as soon as I add a link to the part you need which is unhelpful. Item number 355508185509 on the usual auction site for example.

You will need to remove the non-drive side crank arm with a crank puller, but it is a superior solution to the original Swytch sensor. I have replaced the Swytch sensor on my F-Frame conversion with one of these after it failed after one too many attempts at repositioning it.

[Clifford Slocombe]

… or search for KT-V12L (which defines the sensor head), then check for the correct connector (round orange or “WP”), and check the cable length is specified and sufficient.

[Author]

Posts