Chain efficency

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mikesbytes
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Postby mikesbytes » 09 Jun 2011, 11:46

On the new inventors this dude has produced a front wheel drive recumbent. He says that it has a huge efficiency difference to a rear wheel drive recumbent.

Good or bad argument?

http://www.abc.net.au/tv/newinventors/txt/s3236719.htm

http://www.cruzbike.com/

patn
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Postby patn » 09 Jun 2011, 12:09

Interesting... I didn't notice where he said it was more efficient - I just got that it was
'better' basically on comfort grounds? Might have missed it though. Out of interest I
can't see why it would be more (or less) mechanically efficient than a normal bike?

Some comments:
I haven't ridden one but to me it seems like distributing your weight parallel to the
wheels would make it very hard to steer/handle. Having your legs hanging down the
side of the bike allows your legs to apply force close to the ground in turning.

Also, less of your weight is over your back wheel would make it harder to put power
through the back wheel. Like a porsche with the engine in the back.

That neck position looked really uncomfortable - does it have some headrest to keep
your head forward like that? that looks painful as! Also, when your head is forward
like that can you turn your head around to see behind you easily?

Hard to say without riding it, but I don't think Id want one...

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jimmy
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Postby jimmy » 10 Jun 2011, 07:34

On the new inventors this dude has produced a front wheel drive recumbent. He says that it has a huge efficiency difference to a rear wheel drive recumbent.

Good or bad argument?

http://www.abc.net.au/tv/newinventors/txt/s3236719.htm

http://www.cruzbike.com/
Personally? Bad argument.

Try riding it up a hill in the wet, watch the front wheel spin, there won't be enough weight on it to keep it from spinning.

Their site seems to be remarkably scant on details about why it is better. The only advantage I can see for it is that the length of the chain is significantly reduced in length, so you are less likely to snap it.

James

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Toff
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Postby Toff » 10 Jun 2011, 15:38

Agree with Jimmy. When you "effectively get out of the saddle" on this bike, you slide your arse back up the saddle. This reduces the traction over the front wheel. There will be times when this bike's front wheel will skid. A skidding back wheel is something I can live with, but a skidding front wheel is going to hurt. Alot...

I thought this frame might have some merit, since the main flaw with recumbents is they have no capacity to enable the rider to get out of the saddle. Then I went to the website. Same old rubbish that keeps getting dragged up every time someone with an agenda is trying to push their dodgy product. E.g. How's this one:

Website quote: "The [typical] saddle Causes (sic.) Erectile Dysfunction (ED) in 5% of men who ride more than 3 hours per week. :("

They forgot to mention that the earth is flat, the moon is made of cheese, and the bible is a historical document.

Bunch of crooks if you ask me.
Grrrr.

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mikesbytes
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Postby mikesbytes » 10 Jun 2011, 15:51

LOL, that's serious BS

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weiyun
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Postby weiyun » 10 Jun 2011, 16:17

The "Inventors" program is hardly a science program. It's full of hype on one's "investions" with many dubious claims. So don't take it too seriously.
Last edited by weiyun on 10 Jun 2011, 16:48, edited 2 times in total.

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mikesbytes
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Postby mikesbytes » 10 Jun 2011, 16:41

I remember the bike where you stood and pushed platforms down kinda like climbing stairs. The author noted how it eliminated seat and back problems. Which is probably true.

However after riding from Ashfield to Tempe without a seat, I hope I never do it again

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jimmy
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Postby jimmy » 10 Jun 2011, 17:18

Website quote: "The [typical] saddle Causes (sic.) Erectile Dysfunction (ED) in 5% of men who ride more than 3 hours per week. :("
I seem to remember hearing somewhere that they did do a study between cyclists and swimmers and found a slightly higher rate of ED in cyclists.

But when you actually look at the study, you find a pretty big flaw. It was between elite levels in the two sports.

Average age of the swimmers < Average age of the cyclists.

So, was the correlation because the cyclists were older? or because they were sitting in the saddle.

But I do in general agree with Toff, you want to convince me that it's more efficient? Easy, slap a power meter on it, attach the rider to a HRM, and crack out the speed gun. Get some proper hard evidence that shows what you are trying to push and I'll listen.

Until then, testimonials, statements and other logical fallacies won't get you very far.

James

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weiyun
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Postby weiyun » 10 Jun 2011, 17:29

Average age of the swimmers < Average age of the cyclists.
Can't just look at the average. Was the age difference statistically significant between the two groups?

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Toff
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Postby Toff » 10 Jun 2011, 23:21

A couple of years ago we talked about this on BNA:

http://www.bicycles.net.au/forums/viewt ... 12&t=16644

In relation to ED I wrote:
"It's complete fiction. Years ago, Jobst Brandt outed the flawed studies these spurious findings were based on. In a study, where cyclists were compared to swimmers as a control to assess the occurance of erectile dysfunction, the results indicated that the cyclists suffered a much higher rate of ED. What was omitted in the announcement of the results was that the average age of the cyclists was much higher - a good 10 years, and all ED sufferers were older than 50. Also omitted was the fact that both groups (including cyclists) had lower reported cases of erectile dysfunction than the general population. Not surprisingly, it was a saddle manufacturer spruiking these findings in order to push a redesigned saddle.

Read Jobst Brand's information here."

You won't see any references to peer reviewed research on that mendacious website.

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weiyun
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Postby weiyun » 10 Jun 2011, 23:33

One can't be too categorical based on just one study, whether flawed or not. Fact is, Perioneal paresthesia is a real entity in the cycling community and is directly linked to the activity.

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Toff
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Postby Toff » 11 Jun 2011, 10:52

Perioneal paresthesia is not the same as ED. That's like saying a headache is the same as a brain tumour.

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weiyun
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Postby weiyun » 11 Jun 2011, 11:37

Are you sure? Time to review innervation of the appendage and related functional structures.

Headache is a symptom and peroneal paresthesia is a diagnosis. The analogy is inappropriate.

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Toff
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Postby Toff » 12 Jun 2011, 00:00

I'm no doctor, but peroneal paresthesia sounds like a "numb bum", or pins and needles down there.

Anyway, my point is that peroneal paresthesia is not the same as erectile dysfunction, and I hear a great deal of noise, but to date no-one has ever been able to show me some quality peer reviewed evidence that riding a bike causes erectile disfunction in cyclists. I have however, seen evidence that cyclists have lower erectile disfunction rates than the general population, and I indirectly cited one reference to it in my link to Jobst Brand's discussion.

So it is probably more accurate to say that cycling defers, prevents, and potentially can reverse erectile disfunction symptoms.

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weiyun
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Postby weiyun » 12 Jun 2011, 10:26

...peroneal paresthesia sounds like a "numb bum", or pins and needles down there.
...
So it is probably more accurate to say that cycling defers, prevents, and potentially can reverse erectile disfunction symptoms.
No patient will come in complaining of peroneal paresthesia/paresis. Hence the term is a diagnosis. And "numb bum" can be attributed to many other nerve and cordal pathologies.

You are pushing the improbability barrier. An absence of study in literature does not mean there's no or negative correlation, it commonly reflects a lack of interest or need in studying that particular relationship per one's criteria. And given the known association b/n peroneal dysfunction and saddle contact in cycling, and the clear role of peroneal nerve in erectile functions, it's just not reasonable to make the above statement.

We may be cycling lovers and advocates, but it does not mean we have to overlook any potential fault and risks of cycling.

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Toff
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Postby Toff » 12 Jun 2011, 11:21

Quoting Jobst Brant, who used to work at Avocet:

"I am referring to the study by Dr. Minkow who got national press
coverage on his discovery that bicycling caused ED and that it was a
major problem for bicyclists. It was this study that introduced the
Specialized saddle. The press asked Avocet what their response to
this was, considering that Avocet had pioneered the variable thickness
saddle shell and women's saddles designed with the anatomical
differences of male and female pelvic spreads as models. The
"study" was not available in the literature so no comment was possible.
After much digging, the embarrassing results came to light. The study
in fact showed that bicyclists were less likely to suffer from ED than
others. That is, if the data were age normalized and interpreted with
national averages as comparison."

Jobst's comments and reference support my statement.

I just want any legit evidence from someone to refute it. Never seen anything yet.

The benefit of cycling vastly outweigh the risks, whether you talk in general health terms, or specifically in relation to vascular and erectile disfunction issues.

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mikesbytes
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Postby mikesbytes » 12 Jun 2011, 13:27

Its fairly easy to check your clearance, if you have clearance then what's the problem?

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weiyun
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Postby weiyun » 12 Jun 2011, 17:04

...The benefit of cycling vastly outweigh the risks, whether you talk in general health terms, or specifically in relation to vascular and erectile disfunction issues.
You have just changed the term of reference of the present contention. Fine to spin in a parliamentary speech, very naughty otherwise.

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Postby jimmy » 14 Jun 2011, 08:20

But at the end of the day, this is what I'm reading

Recumbent cyclists tout that a "normal" bicycle saddle can cause ED issues.

This, as per the discussion above, is based upon a flawed study. Now, as Weiyun pointed out, this doesn't mean that there is no correlation between sitting for hours on a bicycle saddle and ED, but as there is no scientific data on it, pushing it as an advantage of recumbents is flawed.

So in a nutshell, there may be a link, but as you can't prove a negative, then all you can state is that the quoted study is flawed, at as yet there is no evidence to support riding a recumbent purely because of fears of ED.

James

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mikesbytes
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Postby mikesbytes » 14 Jun 2011, 09:54

I'd bet my back teeth that the most likely way to get ED is to have poor diet and a sedentary lifestyle


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