Another Good Reason Not to Trust Medics

[Trunnions]

"Bicycle weight and commuting time: randomised trial"
http://www.bmj.com/content/341/bmj.c6801

Not only is he a shameless plodder (1 hr. 47 min to ride 43km!) but the British Medical Journal sees fit to publish such shoddy "research". Doubtless the peer reviewers are also medics.

That aside, I share his preference for steel over plastic.

However, on my 40 km commute riding, at the same perceived exertion, my figures are:

Steel (14kg) 1hr. 20min.

Aluminium: (10kg) 1hr. 10min.

Ten minutes out of 80, is a highly significant 12.5 percent reduction.

So, on an even lighter plastic bike I'd go quicker still, but not according to that medic's "research".

Let's get a decent sample size. Anybody else here able to post their times on; steel, aluminium, and plastic for the same commute?

 

[ultimobici]

"Bicycle weight and commuting time: randomised trial"
http://www.bmj.com/content/341/bmj.c6801

Not only is he a shameless plodder (1 hr. 47 min to ride 43km!) but the British Medical Journal sees fit to publish such shoddy "research". Doubtless the peer reviewers are also medics.

That aside, I share his preference for steel over plastic.

However, on my 40 km commute riding, at the same perceived exertion, my figures are:

Steel (14kg) 1hr. 20min.

Aluminium: (10kg) 1hr. 10min.

Ten minutes out of 80, is a highly significant 12.5 percent reduction.

So, on an even lighter plastic bike I'd go quicker still, but not according to that medic's "research".

Let's get a decent sample size. Anybody else here able to post their times on; steel, aluminium, and plastic for the same commute?

Have you considered the terrain he encounters? He's commuting through the Peak District with a 500m altitude gain on that journey.



Where are you commuting from and to? How much altitude gain?

 

[Trunnions]

Q/
Have you considered the terrain he encounters? He's commuting through the Peak District with a 500m altitude gain on that journey.
/Q

For the purposes of his conclusions the terrain is irrelevant, his point it the difference between, a modern light bike and an old heavy one for the same rider on the same route.

If his route involves a reasonable climb, the bike weight difference would amplify, not diminish the difference.

Q/
Where are you commuting from and to? How much altitude gain?
/Q

My route is an ironing board; but even there, my lighter bike gives me a 12.5 percent faster ride. If it was a climb the difference would be even greater than that.

Let's have some of your time comparisons...

 

[ultimobici]

Q/
Have you considered the terrain he encounters? He's commuting through the Peak District with a 500m altitude gain on that journey.
/Q

For the purposes of his conclusions the terrain is irrelevant, his point it the difference between, a modern light bike and an old heavy one for the same rider on the same route.

If his route involves a reasonable climb, the bike weight difference would amplify, not diminish the difference.

Q/
Where are you commuting from and to? How much altitude gain?
/Q

My route is an ironing board; but even there, my lighter bike gives me a 12.5 percent faster ride. If it was a climb the difference would be even greater than that.

Let's have some of your time comparisons...

Although I ride every day for my job I don't have a regular commute to compare.

However I have used a Garmin for several years and have made several trips to Lake Como with different bikes that I can compare.

Despite a 2kg weight difference my average speed on the same route is barely affected. You have to also bear in mind that while the extra weight may be a hindrance uphill, it is also a benefit on the descent.

Also weather conditions and fitness/health are factors not allowed for.

 

[Archibald]

I commute through london - 15-17kms each way depending on which way I go.
Regardless of whether I use my aluminium singlespeed road bike or whether I use my MTB (aluminium too), I record 40-45mins (occasionally longer). The main difference is traffic lights. A good run with them means the closer to 40mins that I get (obviously), and that's regardless of what max speed I reach between each intersection/pedestrian crossing...

 

[forty four]

dont refer to carbon fiber as plastic actually its the best material currently available for bike frames when all is considered.

 

[Magnus]

"Bicycle weight and commuting time: randomised trial"
http://www.bmj.com/content/341/bmj.c6801

Not only is he a shameless plodder (1 hr. 47 min to ride 43km!) but the British Medical Journal sees fit to publish such shoddy "research". Doubtless the peer reviewers are also medics.

That aside, I share his preference for steel over plastic.

However, on my 40 km commute riding, at the same perceived exertion, my figures are:

Steel (14kg) 1hr. 20min.

Aluminium: (10kg) 1hr. 10min.

Ten minutes out of 80, is a highly significant 12.5 percent reduction.

So, on an even lighter plastic bike I'd go quicker still, but not according to that medic's "research".

Let's get a decent sample size. Anybody else here able to post their times on; steel, aluminium, and plastic for the same commute?

Why do you think it's 'shoddy' ?

 

[Trunnions]

I commute through london - 15-17kms each way depending on which way I go.
Regardless of whether I use my aluminium singlespeed road bike or whether I use my MTB (aluminium too), I record 40-45mins (occasionally longer). The main difference is traffic lights. A good run with them means the closer to 40mins that I get (obviously), and that's regardless of what max speed I reach between each intersection/pedestrian crossing...

Yes, a series of traffic lights in such a short commute would really roger the stats and null the test.

 

[Trunnions]

dont refer to carbon fiber as plastic actually its the best material currently available for bike frames when all is considered.

You clearly haven't considered a Bamboo bike.

I have, and can assure you bamboo bikes are better in many respects than modern plastic bikes.

And a lot cheaper, which seems to be the point of the BMJ article conclusion.

 

[Trunnions]

Why do you think it's 'shoddy' ?

Poor experimental method, design, and conclusions, typical of medics.

They just included it in the BMJ as Christmas stuffing. Fluff.

Let's have some more time comparisons, Chaps!

 

[Trunnions]

Also weather conditions and fitness/health are factors not allowed for.

Indeed! And a 2 kg weight difference is not great enough.

 

[Magnus]

Poor experimental method, design, and conclusions, typical of medics.

Care to elaborate?
Given the objective it seems reasonable?

 

[ultimobici]

Indeed! And a 2 kg weight difference is not great enough.

Nor is the difference in the two bikes the Doc used.

If the rider weighs 70kg there is only approximately 5% difference in weight. That is the more relevant comparison as you have to lug your own weight up climbs.

43.5km in 1:47 is an average of 24.4kmh. On a route with 500m of climbing that's a respectable time. Your whippet fast time is achieved on, by your own admission, a pan-flat route.

If your assertion was correct average speeds in the Tour would have rocketed by a similar margin. But they haven't. The average speed of the Tour in 85 was 36kmh, in 2010 it had risen to 39.6kmh, barely a 9% rise. A respectable weight in 85 for a top road bike was 10kgs a full 3kgs over the UCI limit we have now.

 

[soOpOSMthanks!]

The fact that people do this sort of research for commuting is stupid in itself.

It's just commuting.

 

[Magnus]

It seems most people didn't bother to look at the objective of the study:

"To determine whether the author’s 20.9 lb (9.5 kg) carbon frame bicycle reduced commuting time compared with his 29.75 lb (13.5 kg) steel frame bicycle."

Off course the study doesn't arrive at anything you didn't know all ready but if that was the yard-stick for good research I'd say there exists very little good research.

And why is it stupid to do research about commuting? I'd say it's an important (or at least time consuming and thus big) part of many peoples lives.

 

[pedaling squares]

To accurately determine the effect of the frame on my time, I would have to do several runs with the same gearing, tires, clothing, baggage, etc in the same weather conditions and quite frankly I can't be bothered.

 

[Martin318is]

Guys back up a second!

I am lead to believe that this article is part of an annual end of year Christmas thing where the BMJ publishes the best/most humorous written piece on non medical research. As was written by a respondant to the article as posted on theage.com.au:

...The BMJ always publishes a series of light hearted "reserach" papers in the Christmas issue, and it's considered a great honour in the medical profession to get your article so published. Previous highlights include a study on the rate at which tea spoons vanished from the hospital tea room (the value of the spoon made no difference) and another that concluded there was no support for the use of parachutes; as there was clearly a significant rate of injury due to parachute use and there were well documented survivors who did not use a parachute.- Jackson | Bendigo - December 14, 2010, 10:45AM

 

[Special_oz_ed]

Give the Medico a fair go

Trunnions,
I think the Medico's point was that, for those with more than a few extra kilos to lug around, it makes no difference whether you have a 4kg difference in bike weight when you might be carrying, say, an extra 10-20kg on your person. Lose the 10-20kg first, then go out and buy a super-expensive and light carbon bike.

On the other hand, if you're 6ft tall and weight 69kg, then the extra bike weight of 4kg makes a big difference.

 

[Martin318is]

actually the point that is completely lost in it is that the difference in the two bikes isn't normally just weight, its also quality of components and drag/resistance in moving components like bearings etc.

But as I said - its borderline just a jokey article

 

[sagard]

Traffic lights and wind effect commuting time far more than bike weight.

 

[Martin318is]

Only if you have to go through traffic lights - I don't.

As to wind, I find that the difference between my MTB (high end with road slicks but 11kg) and training road bike (8.5kg carbon) is more than 3minutes on my best days irrespective of wind conditions. In other words, if I go truly flat out, I will be at least 3 minutes faster than my best time on the MTB.

As I said though, its not the weight of the bike its the quality of the componentry - gearing - etc.

 

[For The World]

Recently, I've been able to get out and ride early in the morning on a very similar route to what I travel when I commute. With traffic lights, traffic calming, traffic jams and hills, 35km takes me 1hr 20min. Even before I've travelled 500m, I've been stopped at traffic lights for 1min 30sec.

There's at least 20 sets of lights on my journey to and from work, so even if I don't get stopped at every light, I'll still wait up to 20 mins for lights (I've taken notes on how long I spend waiting). The joys of riding in Sydney.

 

[Trunnions]

43.5km in 1:47 is an average of 24.4kmh. On a route with 500m of climbing that's a respectable time.

For a plodder it's respectable. You're forgetting, the zoom effect of going downwards. His was a round trip.

And 500 metres in 40 km is hardly "climbing".

In any case, your guess-timate of 500 metres may well be markedly out of kilter. Does the article mention any climbs? Are you certain of his route?

Your whippet fast time is achieved on, by your own admission, a pan-flat route.

I'm certainly no Whippet!

My commute is a bowling green, but my training run has the profile of Alpe D'Huez, approximately 8% for 14km.

Naturally, I see even more significant Steel v Aluminium time differences on the climbing route. And if my mates would dare lend me their plastic bikes, I'm sure I'd break my PBT.

If your assertion was correct average speeds in the Tour would have rocketed by a similar margin. But they haven't. The average speed of the Tour in 85 was 36kmh, in 2010 it had risen to 39.6kmh, barely a 9% rise. A respectable weight in 85 for a top road bike was 10kgs a full 3kgs over the UCI limit we have now.

Even using your rough numbers, a 9% rise would be highly significant statistically. What fraction of that would be due to cycle-mass would require far better experimental methodology than medics could manage.

 

[Trunnions]

... its borderline just a jokey article

Obviously. The kitsch irony being, "Hey the BMJ has a sense of humour, look we have fun, but we really are serious about proper research."

As if ...

 

[ultimobici]

For a plodder it's respectable. You're forgetting, the zoom effect of going downwards. His was a round trip.

And 500 metres in 40 km is hardly "climbing".

In any case, your guess-timate of 500 metres may well be markedly out of kilter. Does the article mention any climbs? Are you certain of his route?

I used bikely.com's route creator & profile tool. His route is in the Peak District of the UK. Having ridden the roads there I can assure you that it is not an easy ride in both terms of terrain and road quality. Unless you want to risk life & limb on the main A61Dronfield Bypass you have to use the minor roads that have a surface that grips your tyres like a leech.

I'm certainly no Whippet!

My commute is a bowling green, but my training run has the profile of Alpe D'Huez, approximately 8% for 14km.

Naturally, I see even more significant Steel v Aluminium time differences on the climbing route. And if my mates would dare lend me their plastic bikes, I'm sure I'd break my PBT.

Do both your bikes have the same quality of components in the same condition? Are your wheels the same? What's the road surface like? If it's anything like the climbs I have done in Italy then there is a major difference in road surface.

Even using your rough numbers, a 9% rise would be highly significant statistically. What fraction of that would be due to cycle-mass would require far better experimental methodology than medics could manage.

The difference is also due to the change in rider's training methods as well as improvements such as integrated shifters & clipless pedals.