Marginal Gains and real world riding

ugo.santalucia

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

Just to be clear... are you saying that like for like where before you were doing 20 now you do 23 mph? A 15% gain in speed is significantly more in power output (or power saved if you prefer).
And you are of course 100% sure of this...

Boardman did 49.4 Km in an hour on "Eddie Merckx's" bike and did 56.3 with a monster special bike built for the hour record... which is less than 15% faster.... who knows how fast you could go with a time trial bike... I say at least 50% faster...

ai_1

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

A 15% speed increase due solely to a change of bike is not credible unless there are some dramatic differences in your position. Neither the Allez nor the CR1 has ultra aggressive geometry but they are both roadbikes not upright city bikes so I'm VERY sceptical. 15% is more than I would hope to get switching from a road bike to a TT bike! Much more likely , in my opinion, that there were differences in the weather/road conditions, different route, mis-calibrated bike computer, bigger rider effort, better rider fitness, etc which either caused the difference or magnified it.

rower63

frisbee wrote:

blinddrew wrote:

frisbee wrote:

Power required to overcome aerodynamic drag is proportional to speed cubed...

Actually that depends, the more steamlined the body the higher the order. A basic cycle (with a person on it) is pretty un-aero so squared is about right. As you move to more streamlined shapes (faired recumbents, sports cars etc) you get closed to a cubed ratio.

No, a fat old granny on a shopping bike with a big basket on the front or Graham Obree on his face first streamlined recumbent will both follow the power to speed cubed relationship.

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed. The actual formula is

aero power = 0.5 . rho . Cd . A . (v+u)^2 . v

where

rho = air density
Cd = drag coefficient
A = projected frontal area
v = ground speed of cyclist
u = headwind

diplodicus

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

I upgraded my old CAAD 8 to an lovely carbon Evo and according to my garmin I am exactly....................no faster!

I do enjoy riding the Evo more though

paul2718

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed.

Assuming Cd is constant with speed....

(Which it doesn't have to be, but for cycling between 15 and 30mph probably is.)

Paul

rower63

paul2718 wrote:

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed.

Assuming Cd is constant with speed....
(Which it doesn't have to be, but for cycling between 15 and 30mph probably is.)
Paul

The given formula doesn't assume Cd is constant, nor does it say that power varies only with the cube of speed. The point is that amongst the variables present, speed is one, and it appears in cube form.

surrey_commuter

Ai_1 wrote:

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

A 15% speed increase due solely to a change of bike is not credible unless there are some dramatic differences in your position. Neither the Allez nor the CR1 has ultra aggressive geometry but they are both roadbikes not upright city bikes so I'm VERY sceptical. 15% is more than I would hope to get switching from a road bike to a TT bike! Much more likely , in my opinion, that there were differences in the weather/road conditions, different route, mis-calibrated bike computer, bigger rider effort, better rider fitness, etc which either caused the difference or magnified it.

I love this - I tell you a fact and you tell me that I am wrong :shock:

I commute 20 miles each way and switched bike midweek so all the variables you mention are negated.

ai_1

Surrey Commuter wrote:

Ai_1 wrote:

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

A 15% speed increase due solely to a change of bike is not credible unless there are some dramatic differences in your position. Neither the Allez nor the CR1 has ultra aggressive geometry but they are both roadbikes not upright city bikes so I'm VERY sceptical. 15% is more than I would hope to get switching from a road bike to a TT bike! Much more likely , in my opinion, that there were differences in the weather/road conditions, different route, mis-calibrated bike computer, bigger rider effort, better rider fitness, etc which either caused the difference or magnified it.

I love this - I tell you a fact and you tell me that I am wrong :shock:

I commute 20 miles each way and switched bike midweek so all the variables you mention are negated.

No. You asked a question. I attempted to suggest some possibilities. You disliked my answer and told me I was wrong.
I don't see how all the variables I mentioned (in a non-exhaustive list) are negated by your rides being commuting. Some are, since it's the same route and rider fitness being essentially the same. Others like weather and rider effort are not. You might have other evidence such as weather and heart rate data but I haven't seen it.

surrey_commuter

Ai_1 wrote:

Surrey Commuter wrote:

Ai_1 wrote:

Surrey Commuter wrote:

I have just upgraded from a Spesh Allez to a Scott CR1 and I am 15% quicker. I am still puzzled as to why as it can not be the 1-2kgs drop in weight. Is it geometry and if so did I just get lucky that I bought a bike perfect (?) for me?

A 15% speed increase due solely to a change of bike is not credible unless there are some dramatic differences in your position. Neither the Allez nor the CR1 has ultra aggressive geometry but they are both roadbikes not upright city bikes so I'm VERY sceptical. 15% is more than I would hope to get switching from a road bike to a TT bike! Much more likely , in my opinion, that there were differences in the weather/road conditions, different route, mis-calibrated bike computer, bigger rider effort, better rider fitness, etc which either caused the difference or magnified it.

I love this - I tell you a fact and you tell me that I am wrong :shock:

I commute 20 miles each way and switched bike midweek so all the variables you mention are negated.

No. You asked a question. I attempted to suggest some possibilities. You disliked my answer and told me I was wrong.
I don't see how all the variables I mentioned (in a non-exhaustive list) are negated by your rides being commuting. Some are, since it's the same route and rider fitness being essentially the same. Others like weather and rider effort are not. You might have other evidence such as weather and heart rate data but I haven't seen it.

Sorry me being sensitive - and I only expected 5% gain so have been astounded

Commuting was my way of saying that the route has been ridden dozens (if not hundreds) of times in all weathers. I agree that a new bike can have a placebo effect on rider effort but I have seen my spread of journey times drop from 80-85 to 70-75mins. As some parts are speed limiting this means a significant gain on the rest. The first few rides lit up Strava like an Xmas tree and had people wondering wtf I had done.

More anecdotally a w'end ride had me going from traditionally falling off the back of the group to sitting on the front for long periods. My PB up Box Hill went from 11:30 to 9:30 and no I was not on my knees afterwards.

I agree it sounds unbelievable and wonder if I inadvertently fluked the benefits of a bike fitting (ie not saying these results would apply to all). I definitely feel like I am pushing the pedals forwards more rather than a previous up and down motion.

Another mate had a fitting/bought a new bike and took 3 mins off his Richmond Park lap times which is in the region of 12%

imposter2.0

Gotta get me one of them there CR1s - I need an instant 15% speed gain....

VmanF3

Imposter wrote:

Gotta get me one of them there CR1s - I need an instant 15% speed gain....

I was just thinking the same;

Here's what they say, "Scott CR1 10's are a comfortable, carbon, easy to ride bike. CR1 is a balance of speed and comfort. Manufactured from Scott's carbon technology the CR1 is really a thing of beauty. If you are looking to do a sportive or a leisurely Sunday ride then the Scott CR1 great for any cyclist."

You'd think they'd mention upto 15% performance boost...

ugo.santalucia

Surrey Commuter wrote:

More anecdotally a w'end ride had me going from traditionally falling off the back of the group to sitting on the front for long periods. My PB up Box Hill went from 11:30 to 9:30 and no I was not on my knees afterwards.

I think you are at a stage where you improve fast. It's classic when you take up cycling. No offence, but I think my wife with a shopping bike should go up in about 12 minutes, hence it is entirely possible that your improvements are coincidental with the arrival of the new bike. If you go back to the other (and it is in decent conditions) you will realise that the difference is not so dramatic.

paul2718

rower63 wrote:

paul2718 wrote:

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed.

Assuming Cd is constant with speed....
(Which it doesn't have to be, but for cycling between 15 and 30mph probably is.)
Paul

The given formula doesn't assume Cd is constant, nor does it say that power varies only with the cube of speed. The point is that amongst the variables present, speed is one, and it appears in cube form.

The definition of CdA is a convenient simplification, and it works more than well enough for this purpose.

Anyway we're way off the point, sorry.

Paul

keezx

VmanF3 wrote:

Imposter wrote:

You'd think they'd mention upto 15% performance boost...

They will carefully avoid making such claims being not stupid...
On a Dutch forum there was a guy with a new carbon bike with "aerodynamic" wheels who claimed to be 3 km/h
(2 M/h) faster average with his new bike.
I told him that a Chinese filosofer stated that "faith moves mountains" , I was almost banned there....

surrey_commuter

I did start by looking for suggestions as to why I could cycle so much faster on a different bike and even put out there that I may have fluked the perfect geometry for me and the placebo effect. I will now consider the possibility that the weather is now much better for cycling and that I woke up fitter.

surrey_commuter

ugo.santalucia wrote:

Surrey Commuter wrote:

More anecdotally a w'end ride had me going from traditionally falling off the back of the group to sitting on the front for long periods. My PB up Box Hill went from 11:30 to 9:30 and no I was not on my knees afterwards.

I think you are at a stage where you improve fast. It's classic when you take up cycling. No offence, but I think my wife with a shopping bike should go up in about 12 minutes, hence it is entirely possible that your improvements are coincidental with the arrival of the new bike. If you go back to the other (and it is in decent conditions) you will realise that the difference is not so dramatic.

absolutely none taken - I am well aware that I am appalling on hills... but now with my new magic bike I can at least stick with the women and children

cougie

Blimey 15% is a massive improvement.

I'd look at the old bike and see if the brakes are rubbing or something.

ugo.santalucia

Surrey Commuter wrote:

I did start by looking for suggestions as to why I could cycle so much faster on a different bike and even put out there that I may have fluked the perfect geometry for me and the placebo effect. I will now consider the possibility that the weather is now much better for cycling and that I woke up fitter.

As I said, you are not the finished product yet. At your stage, you will improve massively, then marginally, then you will plateau regardless of the bike. At my stage, it took me 3 years to improve my Box Hill PB of 5 seconds... :?

pinno

ugo.santalucia wrote:

Surrey Commuter wrote:

I did start by looking for suggestions as to why I could cycle so much faster on a different bike and even put out there that I may have fluked the perfect geometry for me and the placebo effect. I will now consider the possibility that the weather is now much better for cycling and that I woke up fitter.

As I said, you are not the finished product yet. At your stage, you will improve massively, then marginally, then you will plateau regardless of the bike. At my stage, it took me 3 years to improve my Box Hill PB of 5 seconds... :?

Maybe you should purchase a pair of factory hoops

ugo.santalucia

pinarello001 wrote:

ugo.santalucia wrote:

Surrey Commuter wrote:

I did start by looking for suggestions as to why I could cycle so much faster on a different bike and even put out there that I may have fluked the perfect geometry for me and the placebo effect. I will now consider the possibility that the weather is now much better for cycling and that I woke up fitter.

As I said, you are not the finished product yet. At your stage, you will improve massively, then marginally, then you will plateau regardless of the bike. At my stage, it took me 3 years to improve my Box Hill PB of 5 seconds... :?

Maybe you should purchase a pair of factory hoops

I'd wreck them, like I wrecked a pair of Aksium I had 10 years ago and a pair of DT Swiss Mon Chasseral (1450 grams) I had soon after...

Why do you think I started building wheels?

ai_1

rower63 wrote:

paul2718 wrote:

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed.

Assuming Cd is constant with speed....
(Which it doesn't have to be, but for cycling between 15 and 30mph probably is.)
Paul

The given formula doesn't assume Cd is constant, nor does it say that power varies only with the cube of speed. The point is that amongst the variables present, speed is one, and it appears in cube form.

Cd is specific to the configuration in question. i.e. shape and orientation, size, surface finish, fluid density, fluid viscosity and of course velocity.
Changes in air velocity can have anything from negligible to dramatic effects on the airflow over an object and as such anything from negligible to dramatic effects on Cd. Reynolds number is usually used to gauge similarity of conditions. For a similar Re number the flow should behave similarly.

iPete

Depressingly perhaps, I've taken only 17 seconds off my Box Hill time in 2 years since from my first 'proper' effort.

My first proper effort being on a fixie too. The bike or wheels isn't going to make a big difference on such a 'climb'.

pinno

iPete wrote:

Depressingly perhaps, I've taken only 17 seconds off my Box Hill time in 2 years since from my first 'proper' effort.

My first proper effort being on a fixie too. The bike or wheels isn't going to make a big difference on such a 'climb'.

I'd argue with that but I won't. Borrow a high end bike and see if there is a difference. I''ll lend you my Wilier

[Warning: More off topic stuff]

@Ugo - you must weigh 15st. No one wrecks Aksiums. I had Ksyriums and they were far too stiff for me.
My first handbuilts were 36 hole Mavic MA2 on Chorus then MA40's on Chorus again - nice wheels. Then a pair of 32 hole Mavic Sup 2 Reflex on Record titanium hubs. Until I bought a factory set, I didn't realise how unforgiving the handbuilts were until I rode the one up from base level campag; the Sirocco's. Great wheels, much more forgiving and responsive, superb hubs.

ugo.santalucia

pinarello001 wrote:

iPete wrote:

Depressingly perhaps, I've taken only 17 seconds off my Box Hill time in 2 years since from my first 'proper' effort.

My first proper effort being on a fixie too. The bike or wheels isn't going to make a big difference on such a 'climb'.

I'd argue with that but I won't. Borrow a high end bike and see if there is a difference. I''ll lend you my Wilier

[Warning: More off topic stuff]

@Ugo - you must weigh 15st. No one wrecks Aksiums. I had Ksyriums and they were far too stiff for me.
My first handbuilts were 36 hole Mavic MA2 on Chorus then MA40's on Chorus again - nice wheels. Then a pair of 32 hole Mavic Sup 2 Reflex on Record titanium hubs. Until I bought a factory set, I didn't realise how unforgiving the handbuilts were until I rode the one up from base level campag; the Sirocco's. Great wheels, much more forgiving and responsive, superb hubs.

11 stones... but unlike others I do actually ride my bike... 7-8,000 miles every year, mostly on one bike only.
I don't own a bike since last November which I have used twice...
It's pretty easy to wreck a pair of Aksium, especially that model that had a recurrent flange problem... this problem


Then I had a set of the above mentioned Mon Chasseral... pure breed climbing wheels... where I broke 3 spokes in the space of 600 miles... that until I replaced the original hair thin spokes with some DT comp at a price of 150 grams... then they never broke again... however, the rim cracked a few thousand miles later... :evil:
I can honestly say I have never broken a spoke on one of the wheels I built or had any other problem...

You like the DA CL 24, which is great... they won't work for me, they'd do me one year at best... then obviously I'd have to fit them on a disc braked bike, which is another problem...

blinddrew

rower63 wrote:

frisbee wrote:

blinddrew wrote:

frisbee wrote:

Power required to overcome aerodynamic drag is proportional to speed cubed...

Actually that depends, the more steamlined the body the higher the order. A basic cycle (with a person on it) is pretty un-aero so squared is about right. As you move to more streamlined shapes (faired recumbents, sports cars etc) you get closed to a cubed ratio.

No, a fat old granny on a shopping bike with a big basket on the front or Graham Obree on his face first streamlined recumbent will both follow the power to speed cubed relationship.

frisbee is right, power consumed against aerodynamic drag always varies with speed cubed. The actual formula is

aero power = 0.5 . rho . Cd . A . (v+u)^2 . v

where

rho = air density
Cd = drag coefficient
A = projected frontal area
v = ground speed of cyclist
u = headwind

My apologies, I stand corrected. Well, I'm sitting at the moment but I don't think that's relevant.

daxplusplus

What the hell, I'll throw my opinion in to.

Marginal gains? It's what performance improvements to a bike will always be about .. how can they ever be anything different? Unless you fit an engine or significantly change what a bike is in some other way then gains will always be marginal.

For anyone that thinks that these marginal gains don't make a massive cumulative effect then try a TT bike, with a skin suit, aero helmet, deep profile wheels and some good tyres and then compare it to a cheap road bike while wearing baggy clothes and a more sit up and beg position on the bike.

Also anyone that thinks we there's no real room for improvement then try taking a Bianchi Infinito fitted with tubs for a test ride and I'm pretty sure you'll be impressed by it's comfort over bad road surfaces - just wish my bike was the same :-(

As for the future: my situation would be improved with a lighter, more aero bike (and that includes lights, mudguards and the clothes I wear) but I'd just be happy with components that last a whole lot longer than my current set-up.

For more left field improvements I'd like to see better training aids that essentially act like your own coach - giving you more feedback, in real-time, on bike. Integrating all aspects of training, including power output, fatigue monitoring, training routines, calorie counting and performance analysis.

Actually I was wondering if you could combine the above monitoring with an ebike - so that your training could be perfect regardless of how quickly you actually wanted to travel. The systems would decide how much power was supplied by yourself and how much was topped up by the electric motor. Would mean you could commute\ride whenever you liked and the software would ensure you didn't over train.

That could perhaps ensure riders trained perfectly .. and surely that would supply much better marginal gains than those from the bikes themselves