The Story Behind The 20/20 Electric Tadpole Trikes
Article Submitted by Emma Wheatland (AKA "Twinkle")
With the great success of the voyager e-trike ( featured in the Feb 2014 AZ newsletter ) it soon became apparent that the physical size of the 20/26 wheeled trike would become a limiting
factor in where they could be used .
Emma's Home Built Voyageur Tadpole E-Trike
Transporting these big tadpole trikes was only possible using a trailer and although possible it would be inconvenient due to the size of a double trike trailer and that would
be impossible if towing a caravan. The full-size trikes do not fit comfortably inside an estate car and with electric assist a standard size e-trike would weigh too much to
be able to be lifted onto a roof rack, so it was a non starter to transport and use them anywhere away from home.
Looking at the possibilities of transporting trikes to use them away from home we decided to make a prototype trike using a 24 inch wheel mtb rear triangle.
This reduced the rear length by 4 inches and a tailored to fit front boom gained another 3 inches. At 7 inches shorter the trike fitted in the rear of the estate
but the 24 inch wheel meant that a rear rack could not be fitted as it hit the rear windscreen as the trike was too high.
This prototype we called the Terrier I,
a 20/24 21speed trike with USS and front caliper rim brakes. Already we started to discover some gearing issues and other shortcomings with using the slightly smaller
size rear wheel but in order to become viable we needed to reduce the wheel size down even more. Without going totally silly we decided that 20” wheels would be the smallest
that we could use.
The Original Terrier l and ll 20/24 prototypes weighed about 40 lbs each
The weight of the voyager with 48volt lithium batteries was still over 87lbs. It had been 120lbs with the original SLA batteries and a lot of weight still needed to be
removed for an e-trike to become manageable and a viable proposition to be lifted inside the estate on your own or lifted onto the roof by two people. The maximum weight
trike that I can lift inside the car was 75lb, so we set an optimum overall weight of 74lbs for the trikes.
We wanted to take two trikes on a caravanning holiday with us and were still debating how this could be achieved , what we really wanted was a pair of smaller ”full-size”
trikes with an electric assist “ geared “ motor and fitted with a rack and panniers and water bottle and a sensible range of gears.
Design started last May and in laying out the parts beside the Terrier MKll 24" trike ,almost another 3 " could be reduced from its overall length and the smaller rear wheel
would allow a rack and panniers to be fitted without the rack hitting the rear windscreen when the trike was stored inside the boot of the estate car as it was 3” lower. One
trike would need to be carried on the roof and a suitable roof bar mounting frame was also made. The trike would be secured to the roof frame with 2 toe straps on each of
the three mounting points.
The new trikes would need to have 20" wheels to ensure the optimal power output of a e-hub with all round with disc brakes if possible and Under Seat Steering , have a rack
with panniers and a 250 watt continuously rated geared motor and more importantly to be under 75lbs in weight .
Two set of frame boom components, the main and cross booms were milled to build the holiday trikes. The new trikes would be straight cross boom trikes to reduce the wheelbase
Using 20” children’s mountain bike rear triangles we saved some more weight and still retained the rear suspension that would become more advantageous with the smaller wheel
The seat tube was shortened and plastic bungs used to save weight.
The 37 v 9ah lithium bottle battery packs would help save weight and be compact. The disadvantage was these lightweight batteries would cost £250 per battery and charger.
I rescued a Currie electric motor from a scrap electric bike. It was usable but it only had the spacing for a single freewheel . The hub also had a built in band brake. We
fitted a jackshaft that limited the available gears to only 12 speed. The advantage of the Currie e-hub was it had a "geared" motor with a built-in freewheel thus reducing drag
when using pedal power only.
Jigging Up The Trike Frames For Welding
After milling the fishmouths, the front boom was built on on a home made jig in one piece and welded onto the completed main boom. In the second photo, the original Currie Single
speed motor has been fitted along with the USS Handlebars. The trike took about 2 ½ weeks to build.
Photo Taken at Seaford Head
The jackshaft assembly fits in the mtb triangles bottom bracket and drives the single speed rear wheel.
The photo was taken at Seaford head on one of the many test runs before painting and trimming.
So by the middle of June 2014 the prototype 20/20 was ready for extended road tests. After 100 miles or so we stripped and sprayed the trike in Italian racing
red with a cream seat and fitted the new “Terrier E-Trike “ decals.
Ken used the trike at the Southern Area Zombie Camping meet in July and it was a hit with everyone riding it around at the campsite.
Its real limitation was the lack of gears (only 12 gear 3x4) as the freewheel also doubled as the drive back to the rear wheel but the
jackshaft had adjusted the gearing (1.3:1) to compensate for the small wheels .
As the trike was destined to become a success, we decided to build the second one as it was just light enough, at 75lb all up, for two of us to lift it onto the
roof and I could lift it into the estate on my own.
Fleet of DIY Tadpole Trikes
Without using the jackshaft, the gear ratios using a 20inch rear wheel would be limited until we found some 11-30 and 11- 32 teeth seven speed freewheel units.
These units were designed specifically for electric bikes to allow easy pedaling and conserve battery life. Rather than the limited 25-70" gears of a standard
bicycle free wheel, these specially built freewheels would allow gears from 18" up to 86” using a standard 28-38-48 front chainset on the 20" rear wheel trikes.
However getting some was not an easy task and the only place I could source them from was a company in Germany and I ordered one of each with a special deep freewheel remover.
These freewheels were not in stock and unfortunately took well over 5 weeks to arrive.
Once the freewheel arrived we replaced the Currie wheel with a “geared” BMS Q100 unit these motor use rare earth magnets are relatively lightweight compared
with others in their class. We fitted the motor with a 160mm disc and the assembly was built into a 20” double skinned rim . The q100 had the provision for a rear
disc and we fitted a new controller with a lcd display that allowed variable pedal assist and gave an indication of power usage and battery condition as well as speed.
A set of BMX burnout slick tyres and the new 32h 20mm hub front wheels completed the upgrade to the red trike, this upgrade was a total success. The difficult part was
thinning the rear chainstay to clear the 160mm rotor.
Outside Our Bungalow Just Before Our Last Ride
The second trike was fitted with the original Currie motor and 12 speed jackshaft assembly for the holiday, this unit still works quite well as the terrain
was quite flat, but we knew that the Currie was only temporary until we could source a second Q100 unit.
The second trike were ready about 10 days before we went on holiday and I put about 80 miles on it and quickly resprayed it satin black before we set off on holiday,
Both trikes behaved faultlessly over the week and were used as our daily transport with several local people asking lots of questions about these strange looking electric assist
recumbent tadpole trikes we were riding.
Since our holiday the trikes have done over 500 miles together and all of the little problems have been resolved.
One On Top And one In The Car
Finally another Q100 motor came along and the second trike was upgraded with the other 7 speed freewheel and a smaller 140mm disc brake.
To compliment the upgrade, the all black trike was refinished with a blue frame, new white decals and different shaped handlebars with a pair of new mirrors .
The trikes are now virtually identical and have only silly little differences. Due to design improvements made in development, the second trike has a couple of
teeth more on the big sprocket giving a low gear of 17”. It also has a smaller 140 mm rear disc rotor.
This does not make any difference to the overall stopping power
but has increases the clearance between the rotor and the chainstay. This will make a rear wheel change easier. Both trikes use friction gear levers, On the e-assist side ,
the blue trike has a twist throttle and a three position switch for the assist power setting instead of the thumb throttle and 5 software controlled assist settings on the red one.
Both trikes use toe clips
On the road both trikes perform well and have proved reliable and stable. The disc brakes are very powerful and the Under Seat Steering positive, the 328 rpm q100
motors are quite powerful and have proved to be the right choice for these trikes. To be really critical, the shortcoming of both trikes is the 9AH lithium bottle
battery, the range over a mixed terrain is about 15 miles and an extended range of 30 miles per trike would make these trikes better for use as a touring trike.
Ride wise there is virtually no difference between these 20/20 and our bigger 20/26 e-trikes as these new 11-30 freewheels make the gearing similar to the 20/26
trikes that use a conventional 14-28 freewheel and the Thun quad chainsets.
The Second HubMotor Being Installed
I was surprised that the real difference seems to be better handling as the weight is less and the centre of gravity is lower. The rear suspension damper works hard
to eliminates some of the bumps and the20”x 2.1 slick Eastern Burnout tyres inflated to 40 psi currently fitted to mine have a very low rolling resistance and help
reduce the harsh ride usually associated with the smaller size tyres and wheels . We have another set of these tyres for the second trike when the current ones wear out.
The later addition of pedelec sensors on these 20/20 e-trikes rather than the throttle only of the bigger trikes have made the riding positions better as it’s easier to
find a comfortable hand position.
The disadvantage of fitting a larger battery would be the increased weight making the trike too heavy to lift onto the roof or for me to lift into the car on my own unless
the batteries were removed first.
I am currently investigating the possibilities of fitting a completely removable second 10ah battery on the rear rack to increase the range and modifying the wiring to accept
a second battery. Making it “an Invisible” upgrade when the second battery is not fitted.
This will necessitate a different ignition switch to be able to switch between batteries and an extension to the wiring loom to add a second battery lead.
An Autumn Ride Out To Brighton Pier From Peacehaven At The End Of November
These trikes will never be “finished “, and will always be modified as and when the need arises. They have become the new stars in the sequel of “in search of the perfect E-Trike”.
Home Built Rides By Simon Wissler From Norway
Photos Sent From AZ Krew Member Simon Wissler
Here is my Hammerhead Mountain bike. The first ride in 2015, and with brakes and my special
double DIY brake lever on the right side of the handlebars.
Amazing bike, the best Winter bike I have ever ridden!
There is lots of Snow and Ice in Norway... and it's comfortable to ride.
HammerHead Winter Trike By Simon
A dual-pull brake lever used to bring the 2 front brakes to a single lever. This way, the trike can have brakes on all three wheels.
A Dual-Pull Brake Lever For Both Front Wheels
The High Roller is in perfect condition, my best (and the most heavy) DIY recumbent bike I have built.
The bike is wonderful!! Thanks, Mr. Graham!
I will send better pictures when the Paint Job is done.
Simon's HighRoller - Work In progress
What Happened To The Forum Over the Holidays??
A Tale Of Computer Hacking By "Radical Brad"
if you tried to check in and see what was happening in our DIY Bike Builder's Forum over the holidays, then you were probably greeted by either a "Forum Offline" message, or a screen full of cyber-garble that only the most hardcore computer nerd could understand.
The reason for this week long downtime was because I moved the Forum to a stronger hosting account so it would be quicker to search and respond to posts. Some have noticed that our forum was "not so quick", and since we are growing in membership, I decided it was time to upgrade. Where we live, we only have a satellite internet, which is about as fast as dial-up, so the forum never seemed slow to us.
Fine Tuning A Website Takes Patience And Finesse!
Here is how we made the forum run faster (in Nerd Talk)...
The SQL database was backed up from the original shared hosting account, and restored to a blank database on the new VPS hosting account. All tables were updated and then the core forum files were moved to the new host. DNS pointers were changed, and then the config files were updated to reflect the new paths and database configuration. Of course, there were many glitches along the way, and the fact that the forum database is almost 1 gig in size made this a slow and painful process.
Here is how we made the forum run faster (in Human Talk)...
We forked out more $$$ per month for hosting and banged our heads on the keyboard for a week!
Yeah, I only do computer work because I have to, not because I like it! As many of you know, we run AtomicZombie in our spare time on an extreme budget, so we have to wear many hats to keep things running. Welder one day, writer another day, computer hacker on the weekend! But hey - this great community makes it all worthwhile, and we hope that your forum experience is much faster now!
The next thing to add will be classifieds to the forum and a host of bike builder's calculators.
Thanks again to our great DIY Community Members!