The Dog Trike

 Overview

If you are a returning reader and want to go straight to the electric trike click here

Some of you may have seen my dog trike, in Edinburgh. It is an adaptation of a cargo trike or Bakfiet as they are known on the continent where a human powered goods vehicle is a common site in many cities.

All the thumb nails lower down on the right can be enlarged by double clicking them. I am happy for any or all of the pictures to be reproduced subject to the following conditions. 

1) That the use is not malicious

2) That the origin of the pictures is acknowledged.

All opinions and methods are those of the author, Alistair Marks, writing as a private individual and no guarantee or warranty is given or implied.

My trike is based upon a Gustav Werner "Transport" which I purchased it from Henry Workcycles in Amsterdam www.workcycles.com

Henry Cutler, an American living in the Netherlands has an extensive, experience based knowledge of this type of  machines and is very approachable.

My shortlist was this model and a narrower brand called a Christiania from Denmark www.christianiabikes.com . This website has an English option and is sold both by Henry in Amsterdam and by Andrea Casalotti  www.workbike.org. in London. Andrea is similarly a very approachable and knowledgeable retailer and I can recommend wholeheartedly speaking with either or both of these companies if you are considering the purchase of a trike.

I found the most cost effective method of delivery from Amsterdam to Edinburgh was to have the trike taken to the ferry terminal in Zebrugge and then it was carried on the Superfast Ferry to Rosyth in Fife. www.superfast.com. The carriage for the trike (Sept 2004) was £27 plus VAT and the booking experience and collection at the port was efficient and friendly and comes highly recommended.

I have the disk brake model which is now I believe standard fit rather than an option. I have the cargo 5 speed hub which is a strengthened hub gear compared to the normal 3,5 and 7 speed offerings from SRAM, and is specifically made for heavy duty applications.  There is the option, albeit quite expensive, of having the SRAM Sparc electric assist fitted. I am considering the fitment of a Schlumpf Mountain Drive www.schlumpf.ch as my puppies mature to extend the gear range but I would echo the retailer's recommendation to ride the trike for a couple of months before making any changes to the gearing.

The Frame

The main modification I made was to fit a pair of steering damper. I found the trike totally scary to drive empty. I started by fitting a motorcycle steering damper described as "classic Kawasaki type" purchased through Ebay. This made a big difference and as well as damping out some of the influence of poor road surfaces it also minimizes the effect of the puppies treating their box as a wrestling ring as we all travel along. The damper body was fitted onto the box sub frame and the free arm fitted to the central frame tube using a theatrical lighting clamp which is lightweight aluminium and has a 2" (51mm) fitment - a perfect fit for the frame. A piece of gaffer tape was used under the clamp to protect the frame. I then decided to add a second damper and the free end attached to the clamp and the body end on a piece of stainless steel bolted to the other side of the box sub frame. I am currently riding on setting 5 of 7 on both dampers and it seems about right.

The rear lamp fitment is on the wrong side of the frame for UK use and the front lamp is part of the box and I  elected not to have the dynamo.

I exchanged the rear reflector for a 4D Toplight Permanent from Busch & Muller www.bumm.de . This battery rear lamp features a large reflective area as well as permanent rear and lateral illumination.

I decided to fit the b-seen 101 indicator and stop light system. Although quite a chunky system for a bicycle it is ideal for the trike and saves taking the hands off the handlebars except for a moment to press the switch. It seems, unfortunately to be out of production and I bought mine through ebay.

The standard fitment rack is wider than standard at 170mm compared to a more normal 130-140mm. I found the Altura Dryline Rack Pack from Edinburgh Bicycle an excellent fit and an appropriate style.  www.edinburghbicycle.co.uk 

I exchanged the standard saddle and post and pedals for a Specialised Mens Comfort, a suspension post and Shimano SPD pedal so that I would have the same contact points with my Giant Hybrid and my Cannondale Silk Road. Having tried the trike with the standard pedals, I would recommend a clipless pedal if you are used to them as it is simply far more secure, especially in the wet.

A pair of scooter wind mirrors completed the frame customisation.

The Box

My box is 1140mm x 750mm x 820mm. My two puppies are a Chesapeake Bay Retriever and a Hungarian Vizsla, both bitches. I used the standards for Air Travel in determining the box length and height for the larger dog as an adult. The width was constrained by the frame width but was 150mm more than the required width for the Chesapeake to turn around and therefore afforded ample room for the smaller Vizsla.

The reason for not making the box the full 1200mm length was that the cage is taller than the handlebars at comfortable height and rather than centring it, I "saved" the 60mm at the handlebar end which gave adequate clearance.

I mage the wooden component out of 12mm WBP (water and boil proof) plywood as the recommended Betonplex was not easily found in the UK. I used a height of 360mm which gave a compromise between frontal area (wind resistance) and shelter from the cold Edinburgh air in the winter for the short haired Vizsla.

Plywood is heavy and I decided to remove, using the router, half the thickness of the sides and front leaving a border around the edges and some strengthening ribs. 6mm ply weighs about 3.8kg per square metre and I removed half the thickness of about two thirds of a square metre and therefore removed about 2.5kg, a useful saving. The base and sides were glued and screwed for maximum strength. 

In order that none of the lighting wiring would be seen on the surface, I mounted the battery plus a connections and fuse box on the underside, missing the frame members and routered channels in the front vertical edge of the sides for the two lams and the rear vertical edge of the left hand panel for the switch and charger socket. I have 2 x 5W lamps and a lead acid 6V 4.5AH battery and found it to be more than adequate for night time city riding. I have the front light of the b-seen 101 as a backup should I experience a failure.  I use a "smart charger" from Maplin Electronics, www.maplin.co.uk rather than the normal battery fryers in budget lamp systems. My charger fast charges to 80% then switches to a trickle, meaning that the charger can, within reason, be left on indefinitely.

I chose to have a vertical sliding door on the left side of the rear face. This enables me to release and enclose the dogs without dismounting and gives me the security of knowing that the door is shut when on the move. In a very short period they have learned to jump in and out without assistance. 

The rear frames were made from some cut down recycled mahogany shelves which provides a stable seasoned timber. The corners are stabilised by hidden dowels and the mesh was fitted by drilling to allow insertion onto the frame as it was assembled and glued. Sadolin was chosen as the finish for it's waterproofing qualities and durability. The sliding door runs in aluminium channel and is sized to allow the insertion in the channel of self adhesive felt to prevent vibration. A slide bolt on the top both keeps the door shut as well as keeping it up for loading and stiffens the frame in terms of diagonal load when closed. A transverse rail supports the back edge of the mesh and stabilizes the channel for the door.

I used a lightweight veterinary fleece bedding on the floor. It is light, easily washed and non slip. I used some car mat fixings to fix each corner so that it is not displaced as the dogs jump in and out.

The mesh section was fashioned from a sheet of lightweight self coloured 2" (51mm) weld mesh. The material is easily bent by hand using a scrap of timber clamped to the bench at each end positioned at the desired position. I created a folded corner at the front and made a storage facility at the rear for tools and the rain cover. . This serves to stiffen the entire structure. A channel section was used to sit over the top edge of the wooden box, fixed with 4mm stainless set screws and nylock nuts The mesh was welded to it and the whole assembly powder coated. There is a door at the front. This allows access to the front of the box for changing the bedding.

I would recommend building the mesh section on a template with spacers to maintain the shape of the mesh during welding. That way you know it will fit!

The vertical surfaces were covered in road sign reflective material for maximum night time visibility. A strip of red reflective was applied on each side of the back so as to give following motorist early warning of the width of the trike. I sourced my material from www.reflectivesuk.com and found them to be very helpful.

The corners were further reinforced with 30mm aluminium angle screwed into the sides and bottom with stainless steel self tapping screws.

I had a rain cover made by a local sail maker. Although quite expensive it does mean the dogs are under cover should it rain and the design allows the use of the door without removing the cover. The rear section can be fully up or  half down for travelling and completely down should the trike need to be left out in inclement weather for a short period.

Transporting the trike

The trike is big at 2.4m x 1m and quite heavy and unless you have a long wheel base van at your disposal a trailer may well be the best option. I have a 1800mm x 1200mm approx utility trailer and made a shoe on which to mount the trailer before lifting and sliding  the whole assembly onto the flat bed of the trailer. This allows the trike to be loaded and unloaded quickly by one (reasonably strong) person.

Riding the trike

These trikes are nothing like bicycles to ride and you should plan some short acclimatisation rides at quiet times of the day prior to using the trike in rush hour.

Lock the front  wheels using the hand brake before getting on (and off). 

Take a wide grip on the handlebars for maximum stability.

Expect considerable flex in the rear frame especially if you are a heavy rider.

Expect the odd feeling of being tilted over when riding on a cambered road. You soon get use to leaning the upper body to correct this.

Take corners very slowly until acclimatised. Lean the body into the corner to maintain stability.

Thanks to Henry Cutler for some of the above points.

Riding for Lepra

The trike made a good base for a sign board during the 2005 68 mile Lepra ride from Edinburgh to St Andrews 

Notes

If I was making another, I would have used a laminated waterproof plywood board for the sides, for example a shower panel. This would have provided a better substrate for sticking the reflective vinyl. The vinyl has not stuck very well to my plywood  box and has some annoying bubbles in it.

I removed the b-seen 101 lighting kit, as car drivers simply do not expect a pedal vehicle to have indicators - or ignore them anyway! I have returned to hand signals only.

I fitted a 6V moped horn to the battery driven lighting system. This is loud enough not to be drowned out by general traffic noise when on the road. I still have my bell for cycle track use.

I did fit the Schlumpf Mountain Drive using a 42 toothed ring to replace the standard 33 tooth ring. www.schlumpf.ch. I had this fitted at Kinetics in Glasgow, website www.kinetics.org.uk. Ben at Kinetics has an encyclopaedic knowledge of unusual bike components, together with a superb fitting service and well worth the trip over there to have it done properly, first time. This has given me a higher top gear and halved the bottom gear enabling climbing of steep gradients with reasonable cadence and without the knees complaining. An excellent piece of kit and definitely recommended

The dog trike is dead

- long live the electric dog trike!

After about a year of use, I decided to revisit the dog trike and correct the mistakes I had made and improve it's (and my) range with an electric assist. 

I use one of Edinburgh's excellent off road cycle routes which has unfortunately been ear marked as a potential tram line which would mean the loss of the facility for some years as the track is laid and probably lost for ever for the trike with the reinstatement of a narrow cycle lane beside the tram rails. All alternative routes have significant hills meaning that unless I have plenty time and am feeling pretty fit, the use of the trike would be a major challenge.

I reckoned I should pre-empt this situation by designing an electric assist. The recommended hub motors are expensive and I would loose my hub gear in exchange for a less robust, higher maintenance derailleur. Also, the motor would be expected to work from 0-15mph including getting the trike started from stationary. Having spent a fair amount of time on the internet, I didn't find a turnkey solution so decided to make a custom solution - my CHEsapeake and viSLA drive. For the CHESLA drive, I reckoned that a crank driven system would be more efficient, driving the left hand crank which would allow the continued use of the Mountain Drive if needed. The motor would be geared down within my cadence range of say 60-75 rpm, except for starting and regardless of final speed as the gear selection and the gradient would determine that.

Before the alterations my trike weighed 60kg and that represents the weight limit for an electric trike in the UK. In top gear, at my comfortable cadence, I can ride at 15mph, the speed limit for an electric trike and finally the motor would not be running without me pedalling which is a requirement, I believe, for an electric trike in Europe but not in the UK.

Weigh saving could be achieved by re-manufacturing the box without the heavy mesh component, replacement of the aluminium steering damper clamp with a purpose designed component and removing the lead acid battery pack. Additional weight would come from the new battery pack, the motor, the controller, the switch box and the gearing.

Frame modifications

The damper clamp which weighed a kilo was replaced with a short section of drilled bar welded in the appropriate place. The mounting for the motor was made by welding two pieces of channel on the main boom tube

The new box

I remade the box in birch ply. This is a much better grade of ply compared to the WBP having 9 instead of 5 plies. I routered away most of the centres area of the base, excluding the centre which rests on the frame. I reduced the height of the flat front and introduced a sloping detail to the sides. The rear frames are part of the overall box and the sliding door is made from the 12mm ply in lightweight aluminium channel. The box is slightly shorter at 1050mm which is ample for the Chessie which means a shorter front overhang and less steering instability when the dogs leap from side to side. I retained the use of reflective panels on all sides for visibility and have most of a large roll of the road sign quality, silver sheet. Email me if you would be interested in buying a piece. The slots at the back and top of the sides and top surface give an alternative hand position for riding without  the assistance. 

The drive system

I sourced a 24V 20AH Lithium Ion Battery from GBP Battery Co. Ltd  in China. www.gbp-battery.com The contact there is a Zack Lee Email: zack.lee@gbp-battery.com   The specification (pdf) of my battery can be found here.

I chose a UK made 4QD Porter controller www.4qd.co.uk/prod/ptr.html which was mounted with heat sink compound onto the aluminium motor bracket. I don't need regenerative braking or reverse and the 50A capacity is more than ample. The battery condition meter and some of the wiring components were also supplied by this firm. The controller builds up to full power in 2 seconds and falls back in a second, which has proved ideal. Initially, I tried to fit a thumb throttle as the gears use a twist grip on the right side but the one I obtained elsewhere was not compatible and in a hurry to have a go with the system I simply fitted a 5 Kohm resistor and a switch. The assist comes in smoothly and falls off quickly although not instantly, so you do need to pedal for that extra second, something I do subconsciously, now. I have slightly refined this arrangement with a centre off push to make either way switch, one side being the 5k resistor, the other being connected to a small 5 K ohm potentiometer which was adjusted to give about 2/3 power. This has added a little flexibility although I generally use all or no assist. It has worked so well, I no longer intend to fit the thumb throttle.

The motor is a 250W geared motor from Unite Motor Co Ltd in China. www.unitemotor.com product code MY1018. The contact there is Zhongfeng Li, email sales@cn-dcmotor.com 

I fabricated a drilled aluminium bracket which would fit on the modified boom tube giving some fore and aft movement to tension the chain. On the right side is the switch box and on the left side is the motor and controller. The motor comes with a 9T fixed wheel and I removed this and using a small brass interface piece made by one of my clients fitted a LHD 13T BMX freewheel from Odyssey www.odysseybmx.com sourced through my local BMX store Odd Ball Mall www.obmx.co.uk 

I replaced the mountain drive cranks with a Thorn Power Pro captain's crank set from St. John's cycles www.sjscycles.co.uk. I removed the 39T timing ring and replaced it with a 54T ring and used a single speed chain (to accommodate the width of the teeth on the BMX freewheel) 

I used an aluminium enclosure to protect a 30A relay and house the battery condition meter, step down to 12V module for the lighting and fuses. Most of these components came from Maplin Electronics. www.maplin.co.uk 

The lighting system

One of the frustrations of the original trike was that the headlamps were often knocked out of position whilst the trike was in the garage in the surgery. Therefore I decided to go for integral headlamps. In addition to the vertical red reflecting strip, on each side of the rear face of the back of the cage, I wanted to add some rear flashing lights. I thought that this might prove a distraction when cycling and worked out that if they were about half way down the box, they would be obscured by my hands. At this height, they were still comparable with the tail lamps on cars.

Most lamp units work on 12V and so I added a 1.1A, 24V to 12V adaptor from Maplin. The circuit was split into a headlamp circuit through the blue illuminated switch at the left hand grip and a flashing side light circuit through the red switch

The headlamps are a pair of  45 degree beam  3W Luxeon MR16 Bulbs set into circular holes in the plywood using silicon sealer. Details are at www.superbrightleds.com/specs/mr16-wlx-spec.htm. Remember to include the sockets if you are purchasing. I protected the back of the bulbs with a small aluminium housing fabricated to suit. They provide an excellent light and although angled down to light up the road, the peripheral beam can be seen for several hundred yards.

The flashing front lights are a pair of 2 LED White Marker Lamps Black Frame from the Mobile Centre www.mobilecentre.co.uk. A technical drawing is included here

The flashing tail lamps are a pair of M5 Series Truck Clearance Marker Lights from www.superbrightleds.com/truck_lights.htm. Again remember to purchase the sockets and the sockets need to be protected as I broke my first pair quite quickly with the dogs' claws striking them. 

Flashing marker lamps are much better for alerting vehicle drivers to a bicycle but I needed a high flash rate like that of bicycle lamps rather than car flashing frequency, which might have caused confusion., A solution was found thorough a vendor on Ebay called wicanbiker email Das_Goose@yahoo.com . He was able to make me a solid state flasher unit with a customised high flash rate. It has worked flawlessly.

Having seen the size and weight of  a 24V truck horn, I retained my 6V horn but installed a 5 ohm 50W wire wound resister in series from the 24V supply.

Other changes

Replacing broken spokes has been, unfortunately, the major down side of using the trike on Edinburgh's rough roads and the proliferation of speed bumps has added to the spoke casualty figure, even at jogging pace. I decided it was time to junk the standard wheels and make up a front set with Hope hub, Odyssey BMX chromed rims and Halo BMX spokes

On the rear, the rim failed on one of the speed bumps and I replaced it with a Mavic downhill rim and ST Swiss Alpine triple butted spokes with brass washers. The BMX parts were sourced from Odd Ball Mall, the remainder from Biketrax in Edinburgh www.biketrax.co.uk who also built the wheels.

So far all three wheels have remained true and no broken spokes despite the higher electrically assisted speeds ( higher speed being a relative term here!).  If I were to start with a new trike, I would either specify these high quality wheels, have the trike without or live somewhere where the road surfaces don't appear to still be the originals as specified by  John Loudon McAdam (1756-1836)

All of the individuals and companies above were extremely helpful, especially given that I was only seeking advice and product for my single prototype. They are all to be recommended.

Riding the electric dog trike

The modifications have transformed my ride, meaning I can complete my commute in the same time I used to take on my hybrid bike. I charge the battery pack overnight each day but it will do just about 6 journeys or 30 miles before it's own protection circuitry begins to cut it out when faced with acceleration to protect the cells from excess drain. 

Intellectual Property

If my ideas have overlapped with those of others, I do not seek to infringe upon any existing patent nor profit from this article and place my ideas in a public forum for free (acknowledged, please) dissemination. 

I would commend the CHESLA drive idea to anyone with a tadpole trike, wishing to extend their range or capability.

National Coverage !

On 19th July 2005 our pictures appeared in four national newspapers. To see the clips please click here.

The electric dog trike was the featured readers bike in the August / September edition of Cycle - the magazine of the Cyclist Touring Club. A copy of the article is to be found here.

Perhaps trikes will become as common as Ford Fiestas -  or perhaps not!