Recumbent Cyclist News - This road test was published in RCN #51, May, 1999. RCN is published by Bob Bryant, P.O. Box 2048, Post Townsend, WA 98368, USA.
Web site www.recumbentcyclistnews.com
Reprinted with permission. Click on pictures for larger pictures.
The Greenspeed GTS
by Zach Kaplan
GTS Sports Tourer
My interest in tadpole trikes first began in 1983 when my father gave me a copy of a December 1983 Scientific American article on HPVs. The fully faired Vector racing tricycle of that time period was prominently featured in this article and I was immediately attracted to its shape and configuration. The sprint speeds listed for it were higher than the legal highway speed limits of the time. I heard the Vector was going into production and wanted one for my first car. Visions of cruising down the motorway and pulling up to the high school to the applause of my classmates went through my head.
In reality, the efficiency and extreme aerodynamic shape of the Vector made the traditional heavy, unaerodynamic piston engined car seem archaic and unnecessary. After some extensive daydreaming in class about riding the Vector I found out it was not a practical vehicle for the road due to its ultra low ground clearance, a very limited turning circle and limited cornering abilities. That beautiful and extensive clear canopy would turn it into a greenhouse in the sun and make it difficult to impossible to see the road ahead when riding in the rain or into the sun. Furthermore, I found out the impressive sprint times were achieved using strong athletes, so maintaining the minimum motorway speed limit for a sustained period would not be possible for an average rider such as myself.
When I bought my first recumbent in 1992, I glanced over the trikes as they were perceived as being too heavy, too wide, too low and in general too slow and awkward. It wasn't until I got into fully faired recumbent bicycles in 1994 that I started to become more interested in trikes. I found the greatest disadvantage of the fully faired bikes was crosswind sensitivity which resulted in dangerous handling and occasionally getting blown off the road. With the increased speeds of fully faired bikes, I also found myself falling down more due to loss of traction as a result of sometimes unseen sand, mud or gravel on the roads. Then I had some crashes due to parts of the bike such as a fairing or mudguard getting lodged in the front wheel. I realized that I needed to get a tricycle as my primary transportation vehicle in 1997 when the front tire of my Lightning F-40 blew out at 60km/h (37.2 mph), resulting in a long skid down the road, a totaled fairing and a visit to the emergency room for some stitches as a result of neglecting to wear my elbow pads. As someone who uses HPVs for all his transportation, I needed something with greater safety and reliability than a bicycle.
I was aware of only two fully faired production trikes, the refined Leitra from Denmark and the newer Flevo Alleweder from the Netherlands. Both seem best suited to flat terrain due to their weights and the Leitra has a lot of frontal area, though it offers excellent weather protection with everything (including the rider's head) enclosed. I live in a very hilly area and in order to get to or from town, I must negotiate a twisty mountain road with 190 meters (630 feet) of climbing in each direction. So I need a fairly light tricycle which corners well.
The Trike Expert
Ian Sims is the designer of the Greenspeed tricycles from Australia. He had mentioned that a full fairing was in development for the Greenspeed. I found him very approachable via email. Over the course of nearly a year I had many discussions with him about what a practical tricycle can be and what mine would be. I appreciated the fact Ian is also car free and designs his tricycles for practicality, durability and high performance in real world conditions.
In terms of production Greenspeed framesets the choice was between the GTR Touring model reviewed in RCN#30 or the GTS Sports Touring model. Given my terrain conditions and desire not to be much slower than a bicycle, the choice was easy. I went for the GTS. The GTS frameset has thinner wall, lighter frame tubes, a 10" seat bottom height, and a seat back angle of 30 degrees from horizontal. The GTR frameset has a heavier frame, 12" seat bottom height, higher ground clearance and a seat back angle of 35 or 40 degrees more upright custom seatbacks are available on either model.
The GTS complete trike as configured by Greenspeed generally has narrower tires and rims and narrower range gearing. Not having done much riding on recumbents with very laid back seats, I had some uncertainty about neck comfort, but Ian convinced me this wouldn't be a problem for someone of my build. Ian told me that of all his production trikes, the GTS is his personal favorite. From Ian's extensive postings to the HPV internet list (www.ihpva.org) it had become clear that on a trike, lower is better in terms of safety and cornering power. So even if there would be some initial discomfort with the 30 degree seat back, the increased cornering power and reduced tendency to lift wheels in corners combined with better aerodynamics and lighter weight attracted me to the GTS. I did go with wider range gearing and the relatively wide Tioga Comp Pool 47-406 tires and Araya MP-22 rims used on the GTR to better cope with the steep hills and rough roads in my area.
Part of the Greenspeed order form includes rider height, inseam, x-seam, seated shoulder height, shoulder width, seated arm length, hip width and weight. This way the frame length and seat size can be fine tuned to the rider as can the diameter and wall thicknesses of the frame tubes. I selected a main tube of 1.75" x 0.035" as that was Ian's suggestion and my feeling based on various monotube bikes I've had. I could have saved more weight by using a 1.5" x 0.035" tube, but that might prove too flexy, and I wanted a good overall compromise for my first trike.
The trikes normally come with braze-ons for a headlight, taillight and one water bottle cage in front of the seat. I ordered pump braze-ons and an additional set of bottle cage braze-ons out on the boom for perhaps mounting a headlight battery. Now that I look back on it, I would have also ordered the optional additional set of bottle cage braze-ons beneath the seat on the non-drive side. I was particularly impressed with the headlight braze-on. It consists of a small vertical flat plate on the front derailleur post or bottom bracket shell. It is very minimalistic and lightweight yet effective. Traditional European dynamo powered headlamps bolt right on to a hole in the plate and Ian also offers an adaptor to accommodate a higher power handlebar clamp equipped headlight.
Ian Sims is fond of the Sachs 3x7 hubs (now SRAM 3x8/9) and Schlumpf Mountain Drives (MD for the purpose of this article). Ian convinced me that it was about time I delved into the world of internally geared cranksets. I began researching the MD - www.schlumpf.ch , exchanging emails with Florian Schlumpf and planning out my gearing. I ordered a Type I MD ( 1:1 direct drive and 2.5:1 underdrive) combined with a 60 tooth chainring, a Sachs 3x7 hub and an 11-28 Shimano IG-50 cassette. This gives a very wide gearing range of 12 to 145 gear inches. The top gear proved to be unnecessarily high for an unfaired tricycle. The low gear is very reasonable and allows me to pedal at a comfortable cadence up steep climbs with heavy loads.
One nice thing about trikes is that you can pedal up a climb as slow as you want without having to worry about balance. Eliminating the need to spend energy on keeping the vehicle balanced may offset the tricycle's disadvantage of greater weight when moving slowly up steep climbs. If one gets tired out on the climb, one can soft pedal or even come to a stop without having to worry about balance or getting started again.
I find the MD easy to use. My Bebop pedals have enough float to allow my heels to press the shift buttons located where the crank bolt dust caps would be on traditional cranks. The main downsides of the MD are high cost and some friction losses from the internal gears. While the MD is heavy compared with a conventional triple crank and bottom bracket, Ian Sims pointed out that a trike configured to use an MD instead of a triple crank is actually lighter due to not having a front derailleur along with the front derailleur tube, shifter, cable, cable housing and cable housing braze-ons.
The Type I MD provides a wider range than any traditional crankset shifted by any front derailleur currently in production. One initial drawback I found of not having a front derailleur was that the chain would occasionally drop off the chainring on a rough road, particularly when going around a rough corner. As I wanted to avoid going to expensive and heavy chainring guard rings, I tied the upper chain tube to the forward bottle cage. This cut down on the incidence of chain dropping but much to my annoyance, the chain still dropped occasionally, especially on one rough corner. I think I've cured the chain dropping problem by going to a more rigid forward bottle cage.
One Greenspeed rider told me that if he was going to order another trike he'd pay extra for the optional disk brakes. He found the standard Sachs drum brakes to be rather weak and prone to fade on long downhills. Since I have to deal with many descents which involve doing heavy braking for corners it didn't take much thought to decide on going for the disk brakes.
While I was waiting for the GTS, the Sachs disk brakes Ian had been using became very hard to obtain. I wanted to avoid using the Sachs disk brakes anyway since they were a fairly old and heavy design compared to the latest disk brakes available for mountain bikes. We discussed using Hope or Hayes brakes instead. Hope didn't seem interested in working with Ian, but Hayes was very responsive. They had just entered the bicycle disk brake market in 1998 with a very light weight fully hydraulic design with dual piston retracting drag free pads. While their bicycle disk brakes weren't well proven at the time, Hayes had been making motorcycle and industrial brakes for many years and it seemed like a good design which could take a lot of heat without dragging.
Ian obtained some Hayes disk brakes, designed kingpins for them, and did some testing. They proved to be much more powerful than the Sachs disks he had been using and allowed the rear wheel to be lifted using one finger on each lever. So my GTS frameset ended up being one of the first two production Greenspeeds with Hayes disk brakes.
The Hayes disk brakes turned out to be an excellent choice. The braking power is incredible. I can come up to corners very fast and do all the braking at the last moment. While I can lift the rear wheel whenever I want, it only lifts when I want it to due to their excellent modulation. While the Hayes brakes don't create any noticeable drag, the sintered metal rotors do make a slight ringing noise as they gently contact the rotors during hard cornering.
Laid Back Ergonomics
The ergonomics of the GTS did take some getting used to. Some would call this laid back seat and high bottom bracket position extreme. It is much closer to lying down than the typical American recumbent or even the typical trike. My neck did feel uncomfortable on the first several rides but I soon acclimated. I put a rack top bag on top of the optional custom tubular CroMoly rear rack and occasionally I rest my head on this bag when doing a steep climb. The mesh Greenspeed seat is fairly comfortable in that it puts most of the rider's weight on his back rather than the working muscles. However, the seat bottom is flat and there is no lumbar support curve in the seat frame, unlike the other mesh seats I generally ride which have seat bottoms which slope up towards the front and lumbar curves.
The first time I did an 80 km (50 mile) ride on the GTS I had some pain at the base of my spine, possibly as a result of this lack of support. Since making the GTS my primary transportation vehicle, I've acclimated to the shape of the seat and haven't had any more of this type of discomfort. The seat frame is an integral part of the trike frame which makes for a stronger, more rigid, lighter frame. This also means the seat back angle cannot be adjusted, so someone buying a Greenspeed needs to give serious consideration to the type of riding they plan on doing and their physiology. I very much like the use of bright yellow mesh on the seat. I wish all recumbents came with high visibility seat covers. The seat mesh is laced together using elastic cord which is said to reduce road shock transmitted to the rider, though it seems it could also absorb some power.
I find the side stick steering hand position very comfortable and natural. The handlebars aren't adjustable for angle or fore-aft position, though, and I think my preference would be for a slightly farther forward hand position for better aerodynamics and even more comfort. The factory set up Greenspeeds have Shimano bar-end shifters which work very well on side stick steering.
Since this GTS is a practical vehicle for all weather transportation I went for the optional mudguards on all three wheels. These effectively keep most of the dirty road water off of the trike and rider. I wasn't pleased with the initial front mudguard mounts which threaded onto the kingpin bolts. These mounts were quite heavy with the whole mudguard kit weighing over 1000 grams and they only supported each mudguard in two places. The mounting method also required wheel removing, which is a hassle with disk brakes as the caliper or rotor need to be unbolted before the wheel can be removed.
Greenspeed is about the most responsive HPV manufacturer I know of. Ian's son designed and built some new front mudguard (fender) mounts which are lighter, support each mudguard at three points, and install and remove quickly with no need for wheel removal. I had the new prototype mudguard mounts within six weeks of my initial complaint - not bad for a manufacturer located halfway around the world. Ian said it doesn't rain much in his area and he doesn't use front mudguards so hadn't given the mounts much attention. He let me test out the prototype mounts since I do a lot of rain riding. So far I am very pleased with them. The whole mudguard kit now weighs 760 grams. The main change I would make is to use a flexible mudflap on the rear of the front mudguards rather than extend the rear edge of the mudguards down close to the ground. This would reduce the chances of cracking a mudguard on a road hazard. The front mudguards could also be narrower to reduce frontal area as they are presently wider than the Comp Pool tires, but this might reduce their effectiveness in crosswind conditions.
Using the optional headlight adaptor, I mounted a CatEye Stadium light. This 21 watt metal halide headlight sits just above the bottom bracket shell and bathes the entire road ahead for some distance with a brilliant bluish-white light. The Stadium light is brighter than most car headlamps and I consider it an important safety feature for riding at reasonable speeds at night on mountain roads.
In terms of tricycle cornering ability the GTS is in a class of its own. I find I can take corners on it much faster and with greater confidence than with any other trike I've ridden, including the GTR. The low laid back seat and wide track give it exceptional stability in turns. Unlike with most trikes, it is very hard to lift the inside wheel when cornering on the GTS. Going through the corners one can sit back and enjoy the sports- car like feel; leaning into the turns is optional. When getting onto other trikes after riding the GTS, I have to be careful I don't unintentionally get the inside wheel off the road in corners. Some trike riders like going through corners on two wheels, but I prefer having all the wheels on the road. Remember, I use this thing as a dependable vehicle to get me and my cargo from point A to point B in a comfortable and efficient manner - not as a toy for doing stunts. That said, I do derive a deep sense of pleasure from getting around turns at high speed with minimal use of the brakes and all wheels on the road. When really taking the corners all out, I do lean into them to keep the inside wheel in contact with the road. When using this technique the tires start to slide out before the inside wheel lifts. Leaning over with your ear close to the road hearing the tire start to slide is an awesome experience.
The GTS is very predictable at its limits due in part to its excellent torsional rigidity and geometry. The high traction, low rolling resistance Tioga Comp Pool tires help out with the cornering, too. I've found when it does slide out - such as when encountering some sand or gravel in a corner, it only slides slightly and still feels very controllable. Those are the conditions which would put a two wheeled recumbent down in a hurry. I did some braking and slalom tests on an ice covered street one morning and found the GTS very stable and controllable. I could hardly walk on the icy surface, let alone keep a bicycle upright, particularly a recumbent bicycle where one has less reaction time and can't use body English as well to compensate for sliding wheels.
So the GTS excels when road conditions are less than ideal. The stability and lack of a need for balance help prevent out of control situations and falls when encountering common road hazards such as sand, gravel, mud, wet utility covers, ice and wet stripes. These are the sorts of hazards that are often hard to see when riding at night, in the rain and or with a front fairing. All but one of my falls from a bicycle wouldn't have happened had I been riding a trike.
In those rare situations when conditions are ideal such as descending a smooth road on a sunny day, I find I am unable to take corners as fast on the GTS as on a bicycle. The non-leaning wheel tricycle configuration scrubs off a lot of speed in the corners. The GTS is fast by unfaired tricycle standards but not by bicycle standards. All the extra hardware and front wheels hanging out in the wind really increase aerodynamic drag. The GTS is much slower on level ground than a low racer bicycle of similar seat height and seat angle. It does still end up being faster than a typical American medium seat height SWB with more upright seat, though it isn't as fast as a European style recumbent with laid back seat and high bottom bracket.
While the GTS is light for a trike at 36 pounds including fat tires, wide rims, rear rack and 3x7 hub, it is heavy by bike standards. This results in slightly slower climbing but not dramatically so. When the rider-vehicle combination are looked at as a whole, the additional weight of the GTS over a typical SWB isn't much percentage wise. I think the high bottom bracket to seat height relationship and the losses from the internal gears slow the GTS down more on climbs than does its greater weight. We could have easily set this GTS up to be much lighter, but then it would be less practical, less reliable, less durable and less safe, plus it wouldn't have that super wide gearing range.
Overall I am very impressed with the design and quality of the GTS. It has become my primary transportation vehicle and I seldom ride bikes anymore though for a fast ride in ideal conditions I'd still take a bike. I look forward to the availability of the full fairing for the GTS to make it into a complete high performance practical transportation vehicle.
This article was originally published in 1998 by Recumbent Cyclist News. RCN has just published our Greenspeed GTO test. It is in RCN69 and is available for purchase from RCN. Later this year we will be publishing our long awaited Greenspeed GTT Tandem Trike review.
For more information on RCN, visit our website at: http://www.recumbentcyclistnews.com.