I just completed my recent threshold testing. I’m at 1.54 watts/lb. While I’ll continue to work, I’m pretty sure the biggest gains will be done getting lighter. I have about 5% of my body weight id like go drop giving me a 1.67 watts/lb. If nothing else changes in my power output bow does this apply to speed given all things, conditions etch the same?
anyone have experience? Or know a equation given the assumptions?
How did you determine your threshold? It’s an unusual value.
In general, a higher W/kg from loss of excess body fat will result in higher speeds since most riding involves going up hills at some point. On flat terrain it’s power and aerodynamics that determine speed.
I just completed my recent threshold testing. I’m at 1.54 watts/lb. While I’ll continue to work, I’m pretty sure the biggest gains will be done getting lighter. I have about 5% of my body weight id like go drop giving me a 1.67 watts/lb. If nothing else changes in my power output bow does this apply to speed given all things, conditions etch the same?
anyone have experience? Or know a equation given the assumptions?
The short answer is… it depends. In May, I did a 6.75 mile hill climb tt with 2620ft of elevation gain on my road bike. Time was 49:13. In June, I did a 20.93 flat tt with 160ft of elevation gain on my tt bike. Time was 49:21. I averaged 280w and 281 normalized for both. My w/lb was 1.54 for the first and 1.57 for the second.
Actually the biggest gain will come by using kilo’s instead of pounds.
How did you determine your threshold? It’s an unusual value.
In general, a higher W/kg from loss of excess body fat will result in higher speeds since most riding involves going up hills at some point. On flat terrain it’s power and aerodynamics that determine speed.
20 min warm up
2 X 20 min threshold test
Avg 265watts
265 watts / 172 lbs= 1.54 watts/Lb?
Is that not correct?
What is this lb rubbish.
Actually the biggest gain will come by using kilo’s instead of pounds.
Winning!
How did you determine your threshold? It’s an unusual value.
In general, a higher W/kg from loss of excess body fat will result in higher speeds since most riding involves going up hills at some point. On flat terrain it’s power and aerodynamics that determine speed.
20 min warm up
2 X 20 min threshold test
Avg 265watts
265 watts / 172 lbs= 1.54 watts/Lb?
Is that not correct?
Yes, just unusual to mix SI and imperial units.
Longer repeated intervals is a good way to estimate FTP, especially when you demonstrate repeatability.
In any case improving performance is an integral of many things. Losing weight is often a big factor for those that have excess body fat to lose but don’t discount the opportunity to also improve sustainable power, as aside from aerodynamics, that’s what will be most important for improving flat land speed.
Good luck with your training and progress.
W/kg (yes, use kg instead of lbs) correlates fairly well with speed for climbing on the bike, and for running (which is basically a power/weight sport).
For flat roads, weight only matters in that it increases frictional losses, which are only 10-20% of what’s holing you back; and that a larger body has to punch a bigger hole through the air (depending on where the extra mass is though…a beer gut is actually more aero than a six-pack, but broad shoulders will slow you). That’s why there is no rule of thumb on how increasing W/kg will help your cycling.
Losing a few lbs won’t improve your time trialing all that much…but you will run a lot faster.
3.39watts/ kg 
Feel faster already.
And I don’t have a 6 pack just because it’s less aero.
Appreciate the feedback.
I gained 8lbs from last year. At the same wattage, I’m not seeing much change in speed at all. Uphill is slower but downhill is faster. Most races it’s either wind or flat for most of it. Weight won’t really matter since aerodynamics are mostly independent of weight.
I gained 8lbs from last year. At the same wattage, I’m not seeing much change in speed at all. Uphill is slower but downhill is faster. Most races it’s either wind or flat for most of it. Weight won’t really matter since aerodynamics are mostly independent of weight.
You should be less aero (marginally) at a heavier weight and since most tris start and end at the exact same elevation you should gain most of the potential energy “back” by T2 assuming that most does not evaporate in braking or get bled off due to really high terminal velocities (more work done just to move air out of the way at high speed, so all the potential energy does not convert back totally). But also when you gained weight, did you not gain watts? I don’t gain and lose watts at my FTP W/kilo, but it seems that every time I gain a kilo, I gain a couple of watts and as I lose weight, I lose a few watts per kilo. It’s still a net win losing weight because the numerator losses don’t have the same impact as the denominator losses!
W/CdA is more important unless all you do is climb.
I gained 8lbs from last year. At the same wattage, I’m not seeing much change in speed at all. Uphill is slower but downhill is faster. Most races it’s either wind or flat for most of it. Weight won’t really matter since aerodynamics are mostly independent of weight.
You should be less aero (marginally) at a heavier weight and since most tris start and end at the exact same elevation you should gain most of the potential energy “back” by T2 assuming that most does not evaporate in braking or get bled off due to really high terminal velocities (more work done just to move air out of the way at high speed, so all the potential energy does not convert back totally). But also when you gained weight, did you not gain watts? I don’t gain and lose watts at my FTP W/kilo, but it seems that every time I gain a kilo, I gain a couple of watts and as I lose weight, I lose a few watts per kilo. It’s still a net win losing weight because the numerator losses don’t have the same impact as the denominator losses!
Sure, it might be less aero, but not nessesarily. Air flowing across an solid object, is funny like that. Maybe having my hip bones ticking out creates some turbulence and my love handles and less pronounced vertebrae improve airflow across my back. Only 1/2 pink.
Don’t get me wrong, I’m hoping like hell that if I drop weight for next season (too late to salvage this season much) I magically gain some more speed. I hope so.
Although you may be going downhill faster, overall you will be going slower. If you lost 2 minutes on a climb, you will not gain 2 minutes back on the descent. You may gain 15-20 seconds at best. This is simply due to the fact that increasing the speed of a fast object takes much more force than a slower one.
Although you may be going downhill faster, overall you will be going slower. If you lost 2 minutes on a climb, you will not gain 2 minutes back on the descent. You may gain 15-20 seconds at best. This is simply due to the fact that increasing the speed of a fast object takes much more force than a slower one.
This is what I was saying about not “getting all your potential energy back”…you just use proportionally more energy moving air out of the way for every extra kilometer per hour of speed at high vs low speed ( proportional to v^^3). But it kind of depends on the type of course. If you have a lot of 6-12% climbs and descents, then this is certainly the case since climb speeds are low and descents fast. If you have a lot of 2-5% climbs (ex Kona), then not as big a deal (the run of course is another matter).
Actually the biggest gain will come by using kilo’s instead of pounds.
For the win.
Although you may be going downhill faster, overall you will be going slower. If you lost 2 minutes on a climb, you will not gain 2 minutes back on the descent. You may gain 15-20 seconds at best. This is simply due to the fact that increasing the speed of a fast object takes much more force than a slower one.
That and the opportunity for improvement is asymmetrical since one spends far more time on climbs than on descents.
e.g.
a 78 kg rider+bike with CdA of 0.28m^2 @300W on a +5% climb takes ~2:45 per km.
Add 10kg of extra mass for same power and it takes ~3:00 per km, a loss of 15 sec/km.
On a -5% descent, even if they coasted it takes only 69 seconds and an extra 10kg will only shave off another 4 seconds.
That small time gain on the descent is reduced further if the rider applies power on the descent.
say they still pedal at 200W on the descent. The lighter version of the rider does 60sec/km, and the extra 10kg means he does it in 57.5s/km, or a saving of ~2.5sec/km.
As a guide for a 300W 78kg bike+rider, each extra kg on a
+/-2% symmetrical hill adds ~ 0.3 - 0.5 sec/km
+/-5% symmetrical hill adds ~ 0.6 - 0.7 sec/km
+/-10% symmetrical hill adds ~ 1.5 sec/km
Of course the exact time losses vary with different combinations of rider mass, power, aero etc but there will be time loss on non-zero gradient courses if W/kg is less and CdA is the same.