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Recumbent What IS that thing?! Recumbents may be odd looking, but they have many advantages over a "wedgie" bicycle. Discuss the in's and out's recumbent lifestyle in the recumbent forum.

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Old 03-01-05, 10:20 PM   #1
guitardave
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20" wheel efficiency vs. 26"

I just bought my first bent, a Bacchetta Giro. It just felt right, ergonomically. I know that inherently a larger wheel must be more efficient once rolling. I wanted to like the Strada better, but I did not. The bottom bracket was just too high for a beginner benter like myself. My question is, are there some solid studies on the relative effieciencies of the 20" vs. the 26" wheel? What did I give up?
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Old 03-02-05, 06:40 AM   #2
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It all depends on your goal in cycling. If you are out for fun, fresh air, running errands, etc. the small difference in speed between an large wheel and a small wheel is insignificant and immaterial. If you are riding timed events, competions, then you want all you can get from your bike. A bigger wheel with lower rolling resistance is what you would need. Have you checked Sheldon Brown for any info? He is a pretty complete resource on cycling.
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Old 03-02-05, 07:53 AM   #3
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This topic comes up every once in a while, the ol' 20" vs 26" wheel question: which is "faster", etc.? Usually the V-Rex or Rocket are the subjects of this question, for example. My opinion, coming from riding both wheel configurations is that this is little difference attributed solely to the wheel size. It is also the gearing of the bike and the engine. Comparing the V-Rex and the Rocket, for example, I could see no difference. The Rocket is geared a little higher than the Rex. The Rex has a 26" rear wheel. Personally, I considered the Rocket a faster accelerator and easy to maintain speed over distance. Rex traveled fast over distance, slower to start off. Go figure.

I think a few years ago this topic got going in fine detail over on BROL. If I remember correctly, after all the measuring and calculating, no definitive conclusion was reached. But it sure was a fine topic! Ride what you enjoy, what fits you and your style, and don't put so much stock in it as it probably doesn't matter all that much.
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Old 03-02-05, 02:23 PM   #4
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Roll down tests have been done to check out tire rolling resistance with some
validity, mostly in the European literature. The decreased 'resistance' of larger
wheels would be difficult to evaluate in the real world because it is swamped by
tire variances and the rarity of similar tires in 20 and 26" sizes though there are
a few that are available in both sizes. An even bigger problem would be air resistance
variances in the bikes themselves between frames for 20 and 26" wheels. Testing
would have to be done 'off the bike'.
Steve
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Old 03-02-05, 10:18 PM   #5
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If the surface is bumpy then the 20" wheel slows you down. I had a good test where a bike path and road ran side by side. the bikepath is wash boardy. it knocked off 2 miles a hour compared to the road.
this path didn to seem to slow me much on my road biek though it would give me a headache (G)
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Old 03-02-05, 10:19 PM   #6
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you can get 1" or 1.8" tires should speed you along.
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Old 03-03-05, 06:29 AM   #7
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Get a copy of Bicycle Science it has a very informative section on this sublect.

Jude
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Old 03-04-05, 04:44 PM   #8
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I've read test results on wheel efficiency a while back, but can't find it anymore.

In any case, suppose the difference between 26" and 20" wheels is 5-percent. However, on a 20/26 SWB, only about 40-percent of the rider's weight is on the smaller front wheel, so the overall efficiency loss is probably less than 5-percent. Maybe about 2-percent?

I suspect that these are very conservative figures and the actual efficiency losses are far less, so you likely won't notice the difference under normal riding conditions. In fact, if you aren't comfortable on a high BB 26/26 recumbent, then you won't go faster on it anyway. This is especially true for climbing hills.

NR

Last edited by NazcaRider; 03-05-05 at 02:56 AM.
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