Road Cycling

BennyC said:
Can anyone advise what the small plastic/rubber sleeve that sits inside the barrel adjuster on the rear mech is called?
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I'm fairly sure the common name is 'the small plastic/rubber sleeve jobbie thingymabob from the rear mech' in any LBS workshop :D

SoliD said:
Could be worse, you could be my friend who flew out to do Ironman 70.3 in Chatanooga last weekend, swam a great leg, got to his bike and his Di2 although fully charged the night before was dead. Ran back to his hotel got his charger, but the system was died, managed to borrow a bike and finish in time limit though, but he was hoping to qualify for worlds like he did a couple of years ago!
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Doh! Awkward and very disappointing to know his performance was compromised over it!

Bit similar to Harry Tanfield on the 10MTT in the ToB, his Di2 died and stuck in 58x13! :o

BennyC said:
What's the weight difference between them? I'd look at the estimated power output (or actual if you have a PM, presumably not though) and times the average (not the weighted average) by 3.6. Rather than the calorie projection.

On a similar topic I'm trying to find a study or explanation to back up whether power output is a complete absolute or whether heart-rate variance carries any bearing on calorie expenditure. My logic is that when on the extensions on my TT bike my HR is higher and I am less efficient so for the same given power as my roadie my HR is higher. Whilst no extra energy (watts) are being produced the load on my CV system and bodies attempts to cool are higher which I should think carries some extra caloric burden?...

I'm not using any more energy but I'm less efficient which must indicate a marginally higher burn?
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I was always under the impression the calorie burn was more closely linked to HR (actual effort) than power (results of effort). You could be on absolute flier of a day and easily pushing 300W in Z2 burning next to nothing (on top of the world!), yet another day utterly emptying yourself into a headwind at 300W and Z4 just to make (slow) progress. Efficiency is key to the burn (I think?), that first day you're hitting maybe as high as 90% and the bad day you're at something like 65%. Strava I think works it out from intensity which comes directly from your power data/zone, not your HR data?

Interesting info about bike weights considering I actually weighed my two a couple of days ago... My Diverge has always felt heavy vs the others I ride with!

Fully loaded up with guards & saddle bag running mitch pro4e 28's on the Axis4.0 wheels it comes in at 11.5kg. The wheels weighed alone (with tyres & cassette) are 3.1kg so most of my weight is there (& will only get heavier with winter tyres!).
My Defy with TT bars, no guards, RS81's, gp4000sii and the same saddle bag is 10kg. Considering they're a light wheelset there's not quite the difference I was expecting! :o
 
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SoliD said:
Does anyone know how the calorie calculation works on strava when changing bikes? I don't ever use it, but seems to vary massively, with my Pinnacle recording 239, Ridley 153, Felt 149, Cannondale 153 and Scott 239 also. Is it literally just on the record weight of your bike?
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It mainly depends on the bike category as it uses that as a best guess on the type of terrain you are riding on. Therefore for the same ride the calorie burn will be lowest on a road bike, higher on a cylocross and higher still on a MTB. Even is the weights of the three bikes were set the same.

My two road bikes vary by about 2 Lbs and swapping between them makes very little difference to the estimated power and therefore estimated calorie burn.

AFAIK a HR monitor will still over write any assumptions made on bike weight/type and estimated power though.
 
I keep saying I'm 74kg but that was at the height of summer. I'm now mostly around 76kg which was my winter weight last spring. I'm figuring it might increase this autumn/winter! :o

Power2max NG Eco looks very tempting... Most of the features you want, but a few extra you can pay to 'unlock' when/if you need them in future. Keeps the initial costs much lower! :)
 
Roady said:
Fully loaded up with guards & saddle bag running mitch pro4e 28's on the Axis4.0 wheels it comes in at 11.5kg. The wheels weighed alone (with tyres & cassette) are 3.1kg so most of my weight is there (& will only get heavier with winter tyres!).
My Defy with TT bars, no guards, RS81's, gp4000sii and the same saddle bag is 10kg. Considering they're a light wheelset there's not quite the difference I was expecting! :o
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Would be 8kg if you didn't have your saddle bag on there :D

Mine's 6.6kg - Do I win a prize? Then my backpack weighs 100kg, so that kinda counters it.

Anyone want to ride home for me tonight? It's ******* down.
 
Roady said:
I was always under the impression the calorie burn was more closely linked to HR (actual effort) than power (results of effort). You could be on absolute flier of a day and easily pushing 300W in Z2 burning next to nothing (on top of the world!), yet another day utterly emptying yourself into a headwind at 300W and Z4 just to make (slow) progress. Efficiency is key to the burn (I think?), that first day you're hitting maybe as high as 90% and the bad day you're at something like 65%. Strava I think works it out from intensity which comes directly from your power data/zone, not your HR data?
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I had worked on the presumption that, with power being an objective measure of work done HR was largely irrelevant. That said if you treat it a little like currency there is an 'exchange rate' between power produced and intensity/HR some days, positions or conditions (sick/fatigued, TT position or low inertia for instance) it'll be less favourable.

Perhaps we're looking at the wrong end of the stick and the burn is no different but the 'exchange rate' so to speak is physiological load on the body. Being greater due to requiring more recovery time as a result of more time spent in higher HR zones.
 
It wouldn't surprise me if simply changing what type of bike under "gear" has an effect upon Strava's estimates, being more upright on a mountain bike is going to ramp up the aero drag as you get faster.
 
Calorie burn varied for the same power? Only of your efficiency is varying massively. As for heart rate - it's utterly useless for measuring calorie burn as it gives no idea of what energy you were expending - to get an idea of energy expenditure you would need to measure.. Power
 
I actually think Benny has a point to be honest. Common theory is that power is all that matters and it certainly seems to be the most important factor by some margin. However, I find it hard to believe (and I don't think I've seen any studies that conclude things one way or the other about this) that outputting the same power at a different HR does not lead to different calorie burn. Now, that could simply be because, as oli said, the difference in HR is simply an indication of a difference in efficiency. Or it could be that on a particular day you're ill, so your HR is elevated and you're burning more calories. Or even that your peddling style/positioning is engaging different muscles and so you're putting a different strain on your system.

I think the question really is how much of a difference does any of the above make. I'd guess (but again, I've not seen any evidenced studies) that the difference is small enough that it almost doesn't matter when compared to variance caused by PM inaccuracies, unknown efficiency of energy expenditure, etc. Could be wrong though.

edit: Also interesting point about effect on the body and recovery instead of kcal burn of the activity itself.
 
I agree with FT - I weigh more, too, so I would most likely have a higher calorific burn than someone outputting the same power, no? Normally, you'd be able to work that out through load/ HR, surely? If I'm doing 200w, and at 170bpm, I'll be burning more calories than someone easily putting out 200w and hovering at 100bpm.

That would make sense?
 
randomshenans said:
I agree with FT - I weigh more, too, so I would most likely have a higher calorific burn than someone outputting the same power, no? Normally, you'd be able to work that out through load/ HR, surely? If I'm doing 200w, and at 170bpm, I'll be burning more calories than someone easily putting out 200w and hovering at 100bpm.

That would make sense?
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No, it doesnt make any sense whatsoever. Has nobody heard of the laws of thermodynamics? This is really simple physics..

At a lower weight a 50kg rider doing 200w will go up a hill a lot faster than a 100kg rider. The energy they expend is the same for the same period they ride.. For the same distance it does of course change things

Just don't relate heart rate to calories. Heart rate can approximate effort that may approximate power which you can use to derive calories but you're getting so far away that it's going to be inaccurate
 
randomshenans said:
OK, I hear you.

So why do people use fitbits etc for general activities? Genuine question lol not trying to be a ****, I'm interested.
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Well walking and running are easier to calculate calorie burn for - it's pretty close to the distance you've travelled - obviously hills and weight do affect it though. Cycling is v much terrain, weather, weight, distance etc dependent so is much more complicated
 
OK, but then I know this woman, she a big old lady... she's like 20st and losing weight, and her workouts, tracked using a "fitness tracker" burn a **** load, or appear to, of calories for something that would not be showing the same for me. That's why I ask, in my naivety! :D
 
randomshenans said:
Would be 8kg if you didn't have your saddle bag on there :D

Mine's 6.6kg - Do I win a prize? Then my beergut weighs 100kg, so that kinda counters it.
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Edited for you. ;)

For clarification my saddlebag weighs 380g :P

Always chatting at the end of group rides over a coffee people are amazed my bike weighs so much (as am I about how light theirs are!). Just goes to show much of it is the rider - I'm 76kg and riding a 11.5kg bike. They're 85kg and riding a 7.8kg like bike, yet amazed I can climb better. :rolleyes:

Going to Cali said:
Surely 300w is 300w regardless of the weather, gradient, cycle of the moon.
Maybe it's just me, but if I try and hold 300w then I sweat - a lot.
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You're probably right, but 300W can feel different and can tax you differently - specifically depending on energy & fatigue levels.

300W is fairly 'easy' for me on gradual short drags as I'm fairly conditioned to riding them at that pace, but throw me at a longer hill I find I have to ease up below 300W if riding for more than a couple of minutes to not utterly empty myself. Admittedly I'll tend to hit climbs harder than that carrying momentum (& work to maintain it for as long as possible, I guess @350-400W?) before settling into a grind/spin at probably around 250-280W. I guess I'm just expending more energy earlier so having to recover rather than pacing it from the first hint of gradient.

BennyC said:
I had worked on the presumption that, with power being an objective measure of work done HR was largely irrelevant. That said if you treat it a little like currency there is an 'exchange rate' between power produced and intensity/HR some days, positions or conditions (sick/fatigued, TT position or low inertia for instance) it'll be less favourable.

Perhaps we're looking at the wrong end of the stick and the burn is no different but the 'exchange rate' so to speak is physiological load on the body. Being greater due to requiring more recovery time as a result of more time spent in higher HR zones.
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To be fair it's probably a combination of the two - the 'exchange rate' of riding power from energy, with positions, conditions & fatigue all having an impact. The physiological load on the body probably having an impact on recovery by similar exchange rates also determined by fatigue and conditions which in turn impact the initial exchange rate.

Nature is complicated! Push pedals harder, go faster? ;)

UTmaniac said:
It wouldn't surprise me if simply changing what type of bike under "gear" has an effect upon Strava's estimates, being more upright on a mountain bike is going to ramp up the aero drag as you get faster.
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Yeah but PWM and HRM data would show the results of this - i.e. more power and effort to sustain the same momentum. :cool:

oli collett said:
Calorie burn varied for the same power? Only of your efficiency is varying massively. As for heart rate - it's utterly useless for measuring calorie burn as it gives no idea of what energy you were expending - to get an idea of energy expenditure you would need to measure.. Power
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Meh. I explained it a little wrong from what I was trying to imply - I always thought efficiency varied quite a bit and power obviously doesn't show that, I kinda expected HR to be the only real measure of contributors, like fatigue?
 
I never stated weighing more increases calorie burn as related to power output.

Increased HR at the same power output level burning more kcal is completely feasible. Claiming that it's obviously not the case because of thermodynamics is a very simplistic view. As already stated, it's possibly simply an effect on efficiency - which with power output vs kcal burn is already an estimate - hence the talk about the difference probably being small enough that the margin of error may dwarf it.
 
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