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Trikes much slower than bikes? Why?
In a recent posting to the bentrideronline trike forum, someone said
that a 200 km brevet took them 10 hours, 20 min on a Trice trike, while a similar ride took 7 hours, 16 min on a Bacchetta Aero. Although he mentioned that the course was more hilly on the trike ride, that's 42% slower. Someone else responded saying that they were seeing 5-6 mph reduction in speed on a Catrike Road vs their normal recument. Assuming they are normally riding 15-20mph, that's 25-33% slower, as well. So what could be causing that much performance loss on a trike (and can it be corrected)? Obviously there is a bit more rolling resistance with 3 tires instead of 2, but rolling resistance shouldn't be that large a fraction of the total energy expenditure. I would think that the aerodynamics of a low, reclined trike would be equal or exceed that of a standard LWB or SWB recumbent. Could it be losses due to the toe-in required on the front wheels? -- Tim Olson RANS V-rex rider considering a trike, as well... |
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#2
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Tim Olson wrote:
In a recent posting to the bentrideronline trike forum, someone said that a 200 km brevet took them 10 hours, 20 min on a Trice trike, while a similar ride took 7 hours, 16 min on a Bacchetta Aero. Although he mentioned that the course was more hilly on the trike ride, that's 42% slower. Someone else responded saying that they were seeing 5-6 mph reduction in speed on a Catrike Road vs their normal recument. Assuming they are normally riding 15-20mph, that's 25-33% slower, as well. So what could be causing that much performance loss on a trike (and can it be corrected)? Obviously there is a bit more rolling resistance with 3 tires instead of 2, but rolling resistance shouldn't be that large a fraction of the total energy expenditure. I would think that the aerodynamics of a low, reclined trike would be equal or exceed that of a standard LWB or SWB recumbent. Could it be losses due to the toe-in required on the front wheels? A combination of all of the above plus the extra weight, and maybe some power loss due to lower torsional rigidity. -- Tom Sherman - Earth |
#3
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Tim Olson wrote: In a recent posting to the bentrideronline trike forum, someone said that a 200 km brevet took them 10 hours, 20 min on a Trice trike, while a similar ride took 7 hours, 16 min on a Bacchetta Aero. Although he mentioned that the course was more hilly on the trike ride, that's 42% slower. Someone else responded saying that they were seeing 5-6 mph reduction in speed on a Catrike Road vs their normal recument. Assuming they are normally riding 15-20mph, that's 25-33% slower, as well. So what could be causing that much performance loss on a trike (and can it be corrected)? Obviously there is a bit more rolling resistance with 3 tires instead of 2, but rolling resistance shouldn't be that large a fraction of the total energy expenditure. I would think that the aerodynamics of a low, reclined trike would be equal or exceed that of a standard LWB or SWB recumbent. Could it be losses due to the toe-in required on the front wheels? -- Tim Olson RANS V-rex rider considering a trike, as well... I am the one who posted the 200 km brevet report the BROL trike forum and here as well. Trikes are slower than a bike of equivalent seat angle and bottom bracket height for a variety of reaons including: 1. Greater aerodynamic drag from the wheels and associated mounting and steering hardware to each side of the rider. Also most trikes have a USS hand position that puts the riders arms into a position of greater frontal area than the Bacchetta Aero I had the much faster 200 km time on. Also note my Trice XXL has front mudguards which are right out there in the airflow scooping air while my Aero doesn't have mudguards. I ride the trike when the roads are wet such as on the recent 200 km brevet and I ride the Aero if the roads are dry and speed is an issue. 2. Greater weight due to more material on the frame and in the steering system to support two front wheels plus the frame and wheels need to be built stronger to support the high lateral loads a trike places on them when cornering. The third wheel also adds weight. 3. Increased rolling resistance both from using smaller diameter wheels (three 406mm wheels on the Trice XXL vs. two 571mm wheels on the Bacchetta Aero) and due to tyre scrub from steering corrections and minor front wheel alignment changes that occur while making steering inputs and hitting bumps. 4. Less efficient drivetrains. My Trice XXL has a total of three chain tubes. They are Teflon and low drag but still have more drag than the Aero which doesn't have any chain tubes. Many small wheeled trikes also use internal gearing devices to get reasonable gear range. My Trice XXL doesn't have any internal gearing using a Shimano Capreo hub instead. However I believe the drivetrain losses are higher on the 9, 10 and 11 tooth cogs than on the larger cogs normally used on a larger wheeled bike. I think trikes are great for rides where stability is important such as riding at night where road hazards are more difficult to see and riding in wet or icy conditions. Also not having to clip and unclip at stops is convenient and allows a faster get away when the light turns green and with no need to balance one can go as slow as they want with a heavy touring load. When speed is a factor though such as club rides and faster transportational rides plus long distance events I'll take the greater efficiency of a good high performance bike unless the road conditions are likely to have traction hazards in which case I'd rather be on the bike and upright than on a faster bike falling down due to loss of traction. All recumbents are compromises and I consider them different tools for different jobs. Zach Kaplan |
#4
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Zach,
Good points here. I was wondering if building a 3/4 full fairing for a trike (head outside) would mitigate some of these issues. I've ridden fully faired single-track recumbents and they are very fast, but I wouldn't feel secure on the roads with them. A trike might be the trick (i.e. a velomobile). What sort of times are folks getting with 'velomobiles' like these: http://www.velomobiles.net/comvm.html I'm particularly impressed by the Versatile Velomobile by Flevobike. Thanks, Bill |
#5
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BikingBill wrote: What sort of times are folks getting with 'velomobiles' like these: http://www.velomobiles.net/comvm.html I'm particularly impressed by the Versatile Velomobile by Flevobike. Thanks, Bill Bill: John Williams has the only Quest velomobile in the U.S. He'll be at the Jack Frost time trial in a couple weeks. After that, we should know how fast it is on flat ground. John's very fast, but he was struck low by course conditions at the Wasco Wild West 75: http://www.ohpv.org/wasco2004/index.htm Jeff |
#6
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BikingBill wrote:
Good points here. I was wondering if building a 3/4 full fairing for a trike (head outside) would mitigate some of these issues. I've ridden fully faired single-track recumbents and they are very fast, but I wouldn't feel secure on the roads with them. A trike might be the trick (i.e. a velomobile). Note that the 861 mile UK End to End course record is held on a fully faired trike (a Windcheetah). As Zach said, it's horses for courses, and a trike /can/ go fast even if they're not going to do the maximum business at Battle Mountain. See http://www.windcheetah.co.uk/record.htm Pete. -- Peter Clinch Medical Physics IT Officer Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net http://www.dundee.ac.uk/~pjclinch/ |
#7
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Zach wrote:
I am the one who posted the 200 km brevet report the BROL trike forum and here as well. Trikes are slower than a bike of equivalent seat angle and bottom bracket height for a variety of reaons including: 1. Greater aerodynamic drag from the wheels and associated mounting and steering hardware to each side of the rider. [...] 2. Greater weight [...] 3. Increased rolling resistance both from using smaller diameter wheels (three 406mm wheels on the Trice XXL vs. two 571mm wheels on the Bacchetta Aero) and due to tyre scrub from steering corrections and minor front wheel alignment changes that occur while making steering inputs and hitting bumps. 4. Less efficient drivetrains. A local Velomobile builder thinks that tire scrub issue under #3 is a big issue. I bet if you controlled all the other variables, a bike would still be faster. Trikes have their place, but bikes are magical. They are only stable in motion. That seems more philosophical than logical. |
#8
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BikingBill wrote:
What sort of times are folks getting with 'velomobiles' like these: http://www.velomobiles.net/comvm.html I suspect that Quest and Mango are the fastest Velomobiles for every day use. There is a new Leitra Sport fairing coming, which also seems to have some speed potential as well as enough practicability for riding in traffic and carrying luggage. http://www.leitra.dk/ The downside of Velomobiles is their weight penalty uphill. http://www.liegerad-fernweh.de/503-pbp2003/IMG_3632.jpg This picture shows a Quest in Paris-Brest-Paris, not the ideal course für a Velomobile. But on the flats the superior aerodynamics rule. In this case a Quest is faster than a Lowracer with tailbox, Ymte, the builder, did about 51 or 52Km/h (31 mph) in a race. I'm particularly impressed by the Versatile Velomobile by Flevobike. The Versatile ist heavy and expensive, and if you order one today, it may take two years till you get one. But it looks nice and it seems to be more sturdy and robust than other quite fragile models. Kurt -- *recumbent cartoons* http:/bikecartoons.de |
#9
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Kurt Fischer wrote:
I suspect that Quest and Mango are the fastest Velomobiles for every day use. There is a new Leitra Sport fairing coming, which also seems to have some speed potential as well as enough practicability for riding in traffic and carrying luggage. http://www.leitra.dk/ ME WANT! ME WANT! ME WANT! ME WANT! ME WANT! When reasonable practical fuels cells become available (2007?), they could be combined with a small assist motor to help with acceleration and hill climbing, making a very efficient commuter vehicle. The downside of Velomobiles is their weight penalty uphill. http://www.liegerad-fernweh.de/503-pbp2003/IMG_3632.jpg This picture shows a Quest in Paris-Brest-Paris, not the ideal course für a Velomobile. But on the flats the superior aerodynamics rule. In this case a Quest is faster than a Lowracer with tailbox, Ymte, the builder, did about 51 or 52Km/h (31 mph) in a race.... Isn't Ymte Sijbrandij about 2 meters tall? If so, the Quest and Mango are larger and heavier than is optimum for those smaller than the average Dutchman. -- Tom Sherman - Earth |
#10
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Tom Sherman wrote:
[Leitra Sport] ME WANT! ME WANT! ME WANT! ME WANT! ME WANT! Due to the short wheel-base, the behavior of a Leitra is kind of twitchy or responsive, so it's recommended to steer it with only a light touch of your fingertips. When reasonable practical fuels cells become available (2007?), they could be combined with a small assist motor to help with acceleration and hill climbing, making a very efficient commuter vehicle. A good idea could be to build a trailer with integrated assist motor. So you had a relatively light vehicle in case you don't need an assist and could attach it only when help really is needed. Isn't Ymte Sijbrandij about 2 meters tall? If so, the Quest and Mango are larger and heavier than is optimum for those smaller than the average Dutchman. Yes, Ymte is tall, but not very heavy. Of course, Quest and Mange could be built in lighter versions, but the Dutch traditionally go for reliability and durability. And the outer shell of these two Velomobiles could be more robust: I know of someone who had to send his Quest in for repair, because a child climbed on the front nose and damaged it. It's not very likely that a Quest will be stolen, but my major concern would be vandalism in cities. And that's another problem with velomobiles: Where to park it safely? Kurt -- *recumbent cartoons* http://bikecartoons.de |
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