What’s New at Currie Technologies - IZIP & EZIP

Its 7.09am, I am at the foot of Mt Dandenong and I am 9 minutes late.
Its already 32 degrees. The notorious Melbourne north wind has already sprung
up, making my ride to the meeting point slower than expected. But this is the big
day, the big test, the day my baby gets its chance against the clock up the infamous
7km stretch of mountain road known as “the one in twenty” and the weather
conditions are not going to stop us now…. Read on as David Brockfield tells the story of Project Izip

Our designated test rider, Nigel Letty, chats with some curious onlookers prior to the test. Interest in the Izip has been amazing and indicates a real potential market for high performance E-Bikes

So here I am at the start, two Bicycle Superstore vans in the car park but no Superstore crew to be seen! Obviously they hadn’t waited and were already off to get a time on their normal road bikes to provide a comparison to the Izip. Nothing else to do but kick back and wait for the team to come back down the mountain, and after twenty or so minutes Nigel rolled into the car park. He is the only member of the Bicycle Superstore head office crew that fits the Izip properly and is therefore the designated test rider. He’s not at his fittest at the moment and although his best time up the mountain was in the fourteens back in his A Grade Blackburn Cycling Club days, his best time these days is around the mid nineteen’s. It is still a benchmark however, to measure against, but I know that Nigel does not like hot weather and he especially hates climbing in the heat.

Another twenty minutes pass and finally the rest of the crew return back down the hill and we bring out the Izip. As I watch Nigel readying himself and showing off the bike to some interested onlookers, I actually felt proud of what we had achieved, but I also began to worry – would the heat cause problems with the bike? Would the heat cause problems with Nigel? As it turned out, the results of this days test exceeded everybody’s expectations.

This is the story of Project IZIP

From the seemingly innocent suggestion from Nigel that “it would be cool to convert an IZIP Street Enlightened into a road bike” Project IZIP came into being.

For those not familiar with IZIP they are a range of electric assisted bikes designed by a company called Currie Technologies in California USA. IZIP make a number of different models ranging from basic twist throttle folding bikes with conventional lead acid batteries, through to more advanced machines that provide motor assistance according to the amount of rider input (the harder you pedal, the harder the motor kicks in).

The standard Izip Street Enlightened prior to its transformation. At 22kg it needed to go on a diet!

Project Izip was not undertaken purely on a whim, there is a purpose to the exercise. Bicycle Superstore recognizes the significance of electric assisted bikes, and with the costs associated with owning and running a conventional car increasing all the time it is inevitable that transport alternatives, such as electric bikes, will become more and more popular. But E-Bikes have an image problem. They are regarded by many as not being proper bikes and are certainly viewed as being very un-cool and slow. The original idea behind project Izip was to dispel these views by creating an E-Bike that was fast, exhilarating to ride and, most importantly, would be taken seriously as a genuine performance bike. We would then use this creation to promote both Izip as a brand and Bicycle Superstore as a credible retailer of electric assisted bikes. As it turns out, it looks like we created much more.

The bike chosen as a base for the project was an Izip Street Enlightened which even in standard form is a pretty impressive machine. One of the reasons it was selected is because the Nickel Metal Hydride battery pack is housed in the down tube portion of the frame and the electric motor is incorporated into the rear hub which results in it not really looking like an electric bike. The other major reason is that it is a Hybrid style bike and therefore uses 700c wheels. Range for the Enlightened is 50km with a limited top speed of 30kph. Net weight is an intimidating 22kg. This machine will need to go on a diet.

Early Days

The Izip frame with the V-Brake mounts removed and the conventional brake bridge welded into place.

First stage in the process was to strip the bike completely down to bare frame. This had to be done carefully as I was going into uncharted territory and was not familiar with the wiring etc. Everything had to be labeled and documented as it was removed. Although at first glance the wires and plugs looked a bit complicated, the disassembly process was actually very straight forward. With the frame now bare it was sent off to have the V-Brake mounts removed from the seat stays, and a brake bridge welded in so that conventional road bike brakes could be used.

The Street Enlightened in pieces on the floor. Only the rear wheel and the cranks would be used from these parts.

The Izip`s Nickel Metal Hydrid 24 volt battery pack is designed to fit into the down-tube portion of the frame. It is also a major contributor to the bikes intimidating 22kg weight.

The Izip has a lot of wiring and the above picture only shows a small portion of it.

    
 
 
Paintwork

It was then off to Paconi Racing frames in Breaside for painting. The colour scheme was designed to disguise the profile of the frame and make it appear more like a conventional road bike. Black was used in areas where switches and plugs were fitted so that they would not look as obvious, and near-straight lines were used on the curved down bar to make it look straight.

The design brief called for road bike gearing with STI shifters, but the standard bike is only 8 speed and uses a screw-on cluster and a single front 44 teeth chain ring. Because the rear hub on an Izip houses the electric motor we were stuck with the 8 speed cluster, so an old Shimano 105 18 speed STI group set was selected for the job.

Nine speed STI shifters will work with an 8 speed cassette (or cluster) as the spacing between the cogs is the same. The only minor drawback to this is that there is an unused shift position at the bottom of the range.

Crank Set

The cranks in their original form. In this picture the PTS (Pedal Torque Sensor) has been removed to reveal the magnetic plates inside. These cranks turned out to be a lot more sophisticated than first tthought.

The next design challenge was the crank set. The original idea was to simply remove what we thought was a basic cadence and flex measuring device from the original crank set, and transplant it onto the Shimano 105 cranks. Well that was the plan anyway. As it turns out, the cranks used on the Izip are very complicated and actually incorporate a strain-gauge mechanism within the spider assembly. This mechanism is essential to the operation of an Izip as it measures pedal revolutions and crank flexion – information that is fed to the bikes power output controller which in turn supplies power to the motor according to how much pedal effort is detected.

This meant that the existing cranks would have to be modified to accept both a 39t and 52t chain ring. The simplest way to do this was to cut away the original steel chain ring and turn it into a spider. Fortunately the cranks were fitted with chain ring guards and the 5 mounting holes formed a perfect 135 PCD which meant that with a bit of fiddling a set of 105 chain rings could be fitted. The end result was a rather neat looking set of Izip style power cranks.

The cranks in mid-modification. The single 44t chain ring has been cut away to form a 135 PCD “spider” allowing for the fitment of 39t and 52t rings. The end result- a neat looking set of “Power Cranks” Izip style. The black plastic cover in the centre houses the strain gauge mechanism.

A front derailleur would also be required. Fitting it to the frame was the easy part; working out a way to rout the cable was a bit more challenging.

Assembly

Now that most of the difficult stuff had been sorted out, it was time to assemble the machine. The original loose bearing bottom bracket assembly was used as we were not able to source a sealed unit that has a long enough axle. The strain gauge incorporated into the crank assembly makes it very wide and therefore an axle length of more than 145mm is required.

The battery pack, switchgear, power output controller and wiring assembly was re-fitted without any real dramas, and although the precautionary approach of labeling all the connectors during disassembly was helpful, the logical design and layout of the Izip internals made the job straight forward anyway.

A couple more rivinuts were used on the front of the seat tube in order to fit a bottle cage. A cage could not be fitted to the down bar as it houses the battery pack and there was not enough clearance for
the rivinuts.

More for the sake of convenience than any other reason the original headset was re-fitted, but the old Hi-Ten steel forks were replaced with a nice set of Columbus Carve Carbon forks. This would help reduce weight and also improve ride quality.

A Deda Magic head stem and handlebar combination was fitted, further reducing weight and providing a nice rigid platform for those out-of-the-saddle sprints. The 105 STI levers were fitted with cable adjusters on both. The Izip power gauge, which is used to adjust the amount of power assistance provided, and to indicate battery condition, had to be modified slightly in order to be fitted to the road bars. Standard issue black bar tape and an Echowell cordless computer completed the front end.

The 105 rear derailleur was fitted and the old 8 speed chain was shortened by a couple of links and re-used. 105 dual pivot brake calipers were fitted to take care of slowing things down. These would become a point of issue on test day.

A generic carbon seat post and a Ti railed saddle from an old Giant TCR were fitted in place of the old heavy alloy post and seat combo.

The original front wheel was replaced with a much lighter 20 spoke unit. The rear wheel of course remained unchanged and a set of Vittoria Rubino Intrepid 23c tyres were fitted to both wheels. The final step was to finish off the cabling and give the gears a bit of a tune up.

Test Ride

The build was complete, time for a test ride. The effect was immediate from the first pedal stroke – this thing felt much quicker than a standard Izip Enlightened. The combination of reduced weight and skinny low resistance tyres had obviously improved performance, but something else was happening. The electric motor was kicking in with much more force than usual yet there had not been any modifications made to the electronics. It appears that modifying the cranks to accept a much larger chain ring (from 44t to 52t) amplified the amount of flexion (bending and flexing of the chain ring under load) which means that the bikes electronic power output controller thinks that more pressure is being applied to the pedals than actually is, therefore sending more power to the motor. The end result is stunning acceleration – the harder the gear the harder it accelerates.

A quick tidy up, a bit of polish and good recharge of the batteries and Project Izip was ready for its first real test……. the one-in-twenty.(So called because the average gradient is a 1 meter rise for every 20 meters travelled: equates to 5%). Its not a difficult climb, 20 minutes is considered a good time for an average fit cyclist, but it takes a very fit and strong rider to get into the 15 minute range, and the record stands at around 13 minutes and 40 seconds.

So we’re ready to go. Nigel got on the bike and rode over to the starting point. The plan was for me to ride up the climb 1 minute ahead of Nigel so that he would have something to chase. Normally I would give him a 2 minute head start!. Off I went – I love hot weather and I had already ridden over 30k’s to the start which was a good warm-up so I wondered whether there was any chance of Nigel catching me on the Izip, especially when the extreme heat could affect the battery performance or the electronic power control devices. I felt good on the bike and had settled into a good rhythm which I estimated to be a high seventeen minute pace and was amazed to see Nigel fly past me at the 2.5km mark. I jumped on and tried to hold his wheel but I only lasted about 500 meters. He disappeared into the distance and I kept chasing. I never sighted him again for the rest of the climb. By the time I got to the top he was relaxed and had completely recovered.

He did the climb in 15 minutes and 29 seconds, almost 4 minutes better than his benchmark time, on a bike weighing 19kg (his normal road bike weighs 7.8kg) in weather conditions that he struggles in!

After a bit of chat it was time to go back down the mountain. With the Izip being such a heavy bike it was not known how well it would descend. We need not have worried; Nigel took off down hill like a man on a mission. The long wheel base and relaxed angles makes the Izip corner with grace and stability, the only problem is that it is so quick, that getting all that mass to slow down is a bit of a task. The poor old 105 brakes were not really designed for the job and were struggling to wash off speed. Despite this, the Izip went down the mountain just as impressively as it went up.

So that’s it, the end of the “Project Izip” journey. Or is it? This project has opened up a plethora of possibilities.

The Project Izip bike does have one major limitation and that is its inability to provide power assistance at speeds beyond 30kph. We are looking at ways to remedy this situation and I am confident that we will have an even faster machine in the months to come. Newer and more cost effective battery technology will allow us to extend, possibly even double the current 50km range. Project Izip will continue to evolve.

This project has also revealed a potentially huge market for “high performance” electric bikes and we are considering the possibilities of making similar machines available for sale to the general public.

What began as a simple challenge has grown into something much bigger. This is not the end of the journey, it is just the beginning……
David