Pressespiegel - Recumbent UK Vol. 2
HP Velotechnik im Spiegel der Medien: Der folgende Text ist ein Ausriss aus der Zeitschrift Recumbent UK, Ausgabe 2 (Frühling 1998). Wir empfehlen für die komplette Lektüre das Originalheft beim Verlag anzufordern.
FAIRINGS 102 - THE PRACTICAL
Having waffled on at length about the theoretical benefits of fairings in the last issue of RUK, the aim of this article is to ask the all-important question - can you live with one?
Actually there's another issue to be tackled en-route, can you afford one?
Having already told you about the joys or riding under a fairing, I thought it better to start off with a few home truths - fairings are not perfect. Let's get the failings out of the way first.
One of the best ways to shock yourself silly is to ride a faired machine in heavy, gusting winds. High sided lorries and wheel disks don't help. Not only can a fairing significantly increase your profile (the bit that matters when the wind blows from one side), but it often increases it unevenly over the length of the cycle. As you add more side area at the front of the bike (compared with, say, the middle), steering can become unpredictable as the front end takes the brunt of the breeze.
It takes an extremely strong and very unexpected gust to make the bike dangerous - but you do need to match the bike to the weather. 1 have often either stripped one of my recumbents of the front fairing or taken a different cycle if the weather turned really windy.
Having survived 30 knot side winds, the next thing vou'll notice is the weight. Two kilos may not sound much - until you have to get it up to your second floor flat. Before you despair - on most rides, the weight penalty is forgotten in the aerodynamic gains - just don't pick it up!
Weight is not the only change, the bike may well have become much longer, much wider, and more unwieldy.
Storage is suddenly an issue, the Kingcycle that would once hang in the hail between rides has suddenly attained health & safety status.
Lighting may not be straightforward. While some fairings come equipped with ready made cut-outs for the front lights, others force you to rethink where you mount your front lights. You might think that a transparent fairing (such as the Zzipper) is the solution, you can simply shine a light through it. Not so in our experience. While some riders have reported satisfactory results, all of our experience shows that this both reduces the efficiency of the light, and (because of the inevitable reflections) the riders ability to see through the fairing.
And that's just when the fairing is new, clean and dry. As fairings age, they scratch which increases the amount of light reflected back into the rider's eyes. With raindrops on the surface, visibility drops to near zero. In practice, the lights need to be either mounted outside the bubble, or the bubble needs to be modified.
Finally, on my list of 'gotchas' comes noise. Fairings boom. No other word for it, as you ride over rough surfaces, a fairing can be very loud. The larger the fairing, the louder the boom. Fully faired bikes without some form of sound insulation can be very loud indeed (not to mention hot). It's something you get used to, but riding an unsuspended, faired bike can be a very noisy beginning.
By now you are probably wondering why you ever thought about a fairing in the first place - nasty, large, uncontrollable, noisy and expensive additions to the bike. There are plenty of reasons. They do make your bike faster in most conditions, they do make it a lot warmer in the winter, they do keep the rain off and they look very cool.
Our Test Suite
We have chosen to look at three quite different fairings in detail.
Zzipper Ryan: one of the grand-daddies of commercial Lexan fairings, available in more sizes and variants than anything else we know of. We tested a long tear-drop fairing designed originally for the Ryan. We ran it on a Rvan Vanguard (its normal home) and a Radius Viper (the bike tested in another part of the magazine).
HP Velotechnik Streamer: the new kid on the block. It uses a rather unusual quick release mount, designed to make it versatile, an umbrella as well as a windcheater. We fitted this to a Pashley PDQ a Kingcycle (in order to compare it with the regular fairing), and a Windcheetah.
Kingcycle: a purpose designed fairing, tuned to the Kingcycle geometry. We left it where it was.
For each, we have assessed: the efficiency - through a series of roll-down tests; the practical effect of these savings on a typical ride; the effect on bike handling; and inevitably, the reduction in the weight of your wallet. Before getting on to each fairing in detail, let's just take time out to look at how the tests were run.
There are many ways of assessing the effectiveness of a fairing. Short of the odd industrial size wind tunnel or two, we had to make do with local resources. For each fairing we took a long local hill and free wheeled down, ensuring we were travelling at a fixed speed (minimal acceleration) at the fixed start point and sampling the speed at one second intervals. We did this 5 times for each bike/fairing combo, 60 runs in all (that hill began to get sickeningly familiar). Conducted over 3 weeks, each run was made in as near identical conditions as we could, zero headwind, identical tyre pressures, similar temperatures, and all faired/unfaired combinations were run on the same day. From these measurements, we worked backwards to get the approximate drag reductions.
Each bike was also used as a commuter, with and without fitted fairing, over one week (40 miles with a fairing, 40 miles without). The route is a 20 mile return, mixed terrain with several short, stiff climbs, a couple of long gradients, and rolling middle. Commuting times were used as the basis for comparison of fairing efficiency over distance.
Carl Abbe has been producing Lexan fairings for almost 20 years, first for uprights and more recently, recumbents.
He produces a wide range of shapes and sizes, designed to fit most recumbents on the market today. We tested the Ryan specific model, designed for long wheel base bikes with a round section cross tube. Other mounts are available for the same shaped fairing, as is a slightly lighter model (0.4kg versus I.8kg).
The fairing is fitted to the top tube via a pair of screw clamps, although once the basic mounts are on, the fairing can be removed quickly. The rake of the fairing can be adjusted by raising and/or lowering the two mounts.
The mounts are fitted to the Lexan via washer reinforced bolts. The fairing we were testing has been in use for more than 5 years without the bolts failing or the fairing ripping. As the fairing ages, wear and tear begin to take their toll on transparency - at least relatively undistorted transparency. Zzip Designs provide a polishing kit to take scratches out of the fairing, and it works. The fairing we were testing has survived a couple of heavy falls, and many scrapes. While no longer pristine it is still very workable.
This brings us to an important part of fairing care - cleaning them up. Coming back from a typically wet and mucky autumn commute, the fairing often has a layer of muck and grit on it. Don't wipe it off with a cloth - that will scratch it. Pour water over the fairing from a jug - if necessary with a little soap mixed in with the water, it'll take the muck off without harming the surface.
This fairing folds, or rather it rolls. If you want to ship a bike, or alternatively stow the fairing' during the windier parts of a tour, this could be very useful. Despite this, when rolled out over the frame, the fairing is rigid and holds its shape well.
For our roll down tests, we mounted the Zzipper on both a Rvan Vanguard and Radius Viper. We experimented with the rake (the optimum will differ from rider to rider) on both. The average reduction in drag came to 22%, when mounted on the Ryan and 26% on the Viper. This made us about 2 kph (1.2 mph) faster on the. Intrigued by the difference, we spent some time experimenting with different mounting positions to no effect. Within (the relatively large) limits of experimental error, the fairing always had a greater effect on the Viper. The explanation for this probably lies in the Vipers higher bottom bracket. The fairing covers far more of the pedals on the Viper than it does on the Ryan, and this, combined with the slightly shorter wheelbase (which means the rider is more enclosed by the fairing) explains that 4% difference.
One of the commuting weeks was extremely cold, albeit still, and we took the opportunity to mount temperature sensors to the bike. The fairing was extremely effective at reducing the effect of windchill - hardly surprising. With an external temperature of -4C, under the fairing, it was a cosy +2C. This kept hands, legs and toes warm. Although we did not repeat this experiment with the other fairings, we would expect them all to behave in a very similar way.
On a sunny day you might expect a little more solar gain from the clear fairings, but there probably isn't much in it. All in all, a very well executed, mature product. Although the cost of the this model is similar to the other two we tested, some of the more sophisticated mounting systems can make for an extremely costly solution, but you get what you pay for.
The HP Velotechnik Streamer
The Streamer combines the screw clamp of the Zzipper with an unusual but effective bottom bracket fitting. Unlike the Zzipper, the mount is attached to the fairing by a pair of Velcro strips. HPV recommend front suspension if you want to use the fairing, although we very happily ran it for four weeks on an unsuspended PDQ before fitting Ballistic front forks. It stayed on. Having said that, if you are going to run a fairing on an SWB then you won't regret front suspension. The noise levels drop as does your inter-pothole stress.
HPV have used quick releases on the mounts which mean that the rider can change the rake of the fairing in seconds. Although not recommended while riding, this does mean you can shift from 'not too fast, but pretty dry' to a 'much faster, but you get wet' without tools. You can get to like this versatility.
The fairing is rigid, so storage requires more space than the Zzipper. Although the basic material used for the fairing is heavier than the Lexan Zzipper (for about the same area), it makes up for this by using a lighter mount. The light gauge tubing may well be one reason why HPV recommend front suspension. How well this stands up to wear and tear over the long term is obviously open to debate, but ours was still in good condition after almost 12 weeks of heavy, everyday use in all weathers.
The bottom bracket mount is an interesting choice. It keeps the front end of the bike clean, and does mean that you do not need a post on the boom to mount the fairing. Given the increasing use of the Sachs 3x7 by recumbent builders, this is probably just as well (the PDQ does not come with a post). You do need a conventional bottom bracket - as our photograph shows, the retaining ring., are used to hold the fairing mount in place. A little fiddly to fit, once in place it is discrete and the rest of the fairing mount can be removed without effecting it.
We ran the HPV on three bikes, a PDQ, a Kingcycle and a Windcheetah. Comparing its performance directly against the Zzipper was not possible, the differences between long wheel and short wheel base bicycles was too great. We did mount it on the Kingcycle and were able compare it with the Kingcycles custom fairing. Running it on the Kingcycle got us an drag reduction of almost 30% - almost 3 kph faster over our trial commute.
Running the fairing on the Windcheetah was a little disappointing. It was just too effective. Long, winding downhill runs feel like the Cresta Run at the best of times and the fairing removed that 'streaming eyes, wind in hair feeling'. At the same time, although a little awkward to get in and out of, the fairing gave a 30% improvement on the trikes drag - it all depends on what you want out of the machine. Commute by fairing, play outside.
The last thing we can't comment on yet is the longevity of the perspex. We made a few trial 'scratches' round the bottom of the fairing and tried out the Zzipper rubbing compound which restored the surface very nicely. We'll report on how well the fairing stands up to everyday use over the next twelve months.
The Kingcycle fairing is quite different from the previous pair. Designed specifically to fit the Kingcycle, this mounts via a special bracket onto the derailleur post. Adjustment is minimal (there is some scope to make small changes to fit handlebar variations) - you are left with exactly what the designers decided was correct. The fairing is also opaque - any colour provided you like yellow.
The mounting system is robust, some shock absorption is provided via rubber mounted buffers, but the fairing we tested has well over 5000 unsuspended miles on it, many over very poor surfaces without any sign of wear.
Luckily the designers got it right - at least as far as performance is concerned. Faired Kingcycles are familiar figures at many European race meetings and the Kingsburys have worked hard to develop a fairing that is efficient and practical. It is longer and thinner than either the Zzipper or the Streamer, completely covering the pedals. The fairing curves below the riders feet far further than either of the other fairings on test. It leaves no room for lighting, either on the front of the bike or the handlebars (it only just clears the top of the bars), and so the designers have incorporated an integral headlight. Although we did not test it for this article, the accompanying rear fairing box includes twin tail lights.
Not surprisingly, given a combination of its custom one-shot design and racing pedigree, this fairing gave the best drag reduction - 35% (the rear tail box was left fitted for all the experiments).
The only drawback was entering the bike. This is not a fairing designed for either toe-clips or large. feet. My (chief test pilot) feet are only size 10/11/45 (UK/ US/Euro respectively) and I was very glad to shift to clipless pedals. Miss the toeclips first time round and you are in danger of taking chunks out of the bottom of the fairing!
We had no controlled means of assessing the relative performance of each fairing in blustery conditions. Our most exciting moments came from the Kingcycle although the dual disk wheels probably didn't help. One of the fairings made the cycles uncontrollable, but all had to be treated with care in strong winds.
Once you are used to a fairing, it becomes difficult to kick the habit. Commuting, especially over longish distances becomes noticeably faster, warmer and drier. We averaged 2.5 kph improvement in average speed using a fairing - the aero advantage more than made up for any weight penalty.
Visibility is reduced by all of the fairings we tested. Neither of the 'transparent' fairings provide an undistorted view of the road below, you need to look ahead and anticipate potholes and road debris - a good habit anyway.
Light mountings have to be resolved on a case by case basis - we mounted lights in front of the Zzipper (via a bracket attached to the front fork) and on the handlebars of the PDQ. We didn't try the Windchectah.
Back to the matter in hand - comparing the three fairings we have been testing directly against one another is not fair - they have been designed for different bikes and different end uses. If you want a relatively low cost (about £230) fairing, suitable for most short wheel base bikes with a suitable bottom bracket and quickly adjustable to suit your mode of riding, the Streamer is the way to go. If you need to fit an LWB, or are willing to pay more for the heavier duty mounts and ability to roll (SWB models are available), then the Zzipper ($400/£250) is unquestionably the winner. If you own a Kingcycle, then the banana (£206) is your best bet - but act quickly.
Where and what to buy
Zzipper offer a wide range of fairings for both standard long and short wheel base bikes as well as 'experimenters kits' for anyone bold enough to want to roll their own, but without the facilities to fabricate. a Lexan tear drop. Zzipper Designs do ship overseas by mail order (although beware the cost + duty + vat trap - it might be cheaper to buy through a dealer - and are distributed in the UK by both Bike Fix (0171 405 1218) and Future Cycles (01342 822847). Zzip themselves can be contacted at PO Box 14, Davenport, CA 95017. Tel 408 425 8650, Fax 425 1167. HP-Velotechnik currently only offer the Streamer which is distributed by D-Tek (01353-64 8177) and Bike Fix (0171 405 -1218).
Kingcycle fairings are about to become very scarce (see our news pages). They can still be bought directly from Kingcycle (01494 524004) or a number of other dealers including Feet First (0121704 4412), London Recumbents (0171 635 9761), Norfolk Recumbents (01263 861720) and D-Tek (01353 648177).
These are not the only companies building and selling fairings. The only other companies we know of who provide third party fairings are Earth Cycles and Crystal Engineering.
Earth Cyclcs: produce a blown Lexan fairing, similar in shape to the HPV Streamer (USA - 612 335 5048)
Crystal Engineering: sell a large rear fairing / box to fit both the Trice, and the Speed Ross are apparently suitable for other machines with a 'conventional' 700c rear triangle (0132 637 8848)
Many other recumbent manufacturers provide custom fairings - some of which may prove useful on other machines. As we test more bikes, we'll look carefully at custom fairing options.
Finally, you can build your own in anything from high-tech carbon fiber to 'down to the garden' coroplast (corrugated plastic). Jim Wronski of People Movers sells a video (NTSC and PAL formats available) that demonstrates the art of home brew fairings. People Movers can be found at (A) 714 633 3663.