Power output - Watts ?

[dylanparry]

I have recently started to ride my bike again but taken a keener interest this time. I only have a mountain bike (almost more of a track bike as it has knobbly tyres), and I am using it for road use.

I am using Strava and have inputed my weight, bike weight etc and it is quite interesting seeing times for my rides and segments on Strava improve in the last 3 weeks.

My Power Output in Watts has been lately just under 170 and with a short time trial I gave myself the other day I achieved 177, keeping in mind there is one extreme hill on that ride which is quite challenging. My average speed is around 10.5 to 11mph - again it is a track bike and heavy and there are many hilly sections in my area so I am fairly pleased to keep my pace at 11mph-ish.

Can someone tell me though if I had a road bike, would my Watts power output be greatly affected? I assume my speed would improve but what about my Watts power output?


Thanks.

 

[Sittingduck]

Welcome

Firstly - unless you have a power meter, the watts are just strava guesstimates. Don't get too analytical over them and if you want to get a proper power meter. Secondly, watts is watts - regardless of bike, you will be putting out the same if at max effort. Although I accept that positioning can affect this. For example on the mtb with knobblies you may actually be putting out 150w and changing bike will not magically see you able to hit 200w, you will still be around the same power output but may be faster on the road, due to aerodynamics, resistance changes and so forth. Best advice for early speed increase is to change to slick tyres for road and keep riding for a while. You should see improvements, especially in the early days and as your fitness increases.

edit to add - keep on riding the heavy bike in the hilly area - this will pay dividends when you inevitably decide to upgrade to a fancy road bike in the coming months

 

[figbat]

Exactly that. It's like taking the engine out of an SUV and putting it in a coupé and asking if the engine will be more powerful - it's the same engine but you get more speed/acceleration for the same output.

 

[dylanparry]

Thank you for answering. I had thought that this was the case but when I searched the internet I saw speed as a part of the equation on some websites so I thought hmmmm if I was going faster with a road bike would that mean my Watts would be higher. Thanks for explaining it everyone.

 

[si_c]

Thank you for answering. I had thought that this was the case but when I searched the internet I saw speed as a part of the equation on some websites so I thought hmmmm if I was going faster with a road bike would that mean my Watts would be higher. Thanks for explaining it everyone.

Strava calculates the power output looking at your weight and speed and the road gradient and performing a calculation of the work done to get your estimated power. It doesn't take into account a lot of variables that influence speed, not least of which is wind, but also air density and temperature amongst other things.

It's a rough guide, not really comparable ride to ride let alone bike to bike.

I'd go off perceived effort for the time being, a proper power meter will give you hard data, but it's overkill for most riders.

A road bike will go faster on the road for the same power output, or the same speed for less effort, which will allow you to ride further and faster than an MTB, but the same can be said for a good road hybrid bike, the type with no suspension.

 

[Venod]

I have been on rides uploaded to Strava where my estimated power output was considerably lower than a fellow rider with a power meter, I did a ride last week with a massive relative effort of 208 (based on heart rate I believe) and the average watts were abysmal.

I would not take Strava power data too seriously.

 

[Ming the Merciless]

Strava‘s power estimate is a work of fiction.

 

[dylanparry]

Thanks for that reply. At this early point I’m not taking the statistics too seriously, just enjoying the rides and seeing improvement.

However, when I looked online and found that a beginner has Watts output of a certain range and I was within that range I was rather disappointed, as I thought I had enough leg power to be above just purely beginner level.

The good thing is when I updated the gear I have in Strava, and gave details of the bike my Watts shot up. Haha. I had not inputed this when I started so I updated it by guessing that the bike weighted 14Kg but this morning I actually weighed the bike and it was over 16Kg. This gave me a Watts of 177-ish on recent rides and I guess I would say that I’m ok with tjat figure.

I’m planning new routes around the area to try soon, probably in between some hill walking and weight training to beef up my leg power. I may need a change of exercise routine for a couple weeks to make sure the bike riding doesn’t become stale, and then return to it with new routes and increased leg power. I am trying to build up my routes to 10-15 miles over the next month or so. I have to say, my track bike feels a bit heavy to be doing that many miles especially with many fairly uphill sections.

On a competitive note- there is a particular segment on Strava near me which I have attempted. It is only about 0.36miles. My first effort I took over 5:20 to do it (don’t judge- my fitness had waned haha), but I have eventually reduced my time to 3:47. Keep in mind this is with my heavy track bike. The leaderboard is led by someone who did it in 1:25! It seems impossible for it to have been done in that time from where I am now. I console myself with the fact that I am using a track bike, and sometimes kid myself that with a proper road bike I too could do it in less than 2 minutes! :-) …(as if).

 

[Ming the Merciless]

What I would do is find a Strava uphill segment between 5 - 20 mins. Then periodically go up it as hard as you can. Then compare your times for previous efforts. It’ll give you a good indication of how your top end is improving.

 

[figbat]

Can I just check what you mean by “track bike”?

 

[vickster]

Get some lighter slick tyres for your bike if you want to boost your speed. Leg weights won’t do much for cycling, do more cycling

 

[vickster]

Can I just check what you mean by “track bike”?

He means a trail ie mountain bike i think

 

[dylanparry]

Can I just check what you mean by “track bike”?

It is a heavier bike than an usual mountain bike as I have had them before, and it has knobbly tyres, more track type of tyres than mountain bike tyres. The whole bike weighs more than 16kg.

 

[IanSmithCSE]

Good afternoon,

I am quite happy to make a fool of myself in public so here goes;

The numbers are so generic that a power meter will say, wow that guy is so wrong his is a prat so ignore him, but if you want a starting point and get that it is only a back of a fag packet number and understand that the question is unanswerable!

�

Power And Energy Required To Cycle @ 12MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	61 watts	209	17
RoadBike_Racer (Hoods)	53 watts	181	15
RoadBike_Racer (Drops)	51 watts	176	15
RoadBike_Racer (TriBars)	49 watts	170	14
RoadBike_Tourer (Tops)	87 watts	300	25
RoadBike_Tourer (Hoods)	79 watts	272	23
RoadBike_Tourer (Drops)	77 watts	267	22
RoadBike_Tourer (TriBars)	76 watts	261	22
Hybrid (Tops)	94 watts	323	27
MountainBike (Tops)	124 watts	428	36

�

Power And Energy Required To Cycle @ 14MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	88 watts	302	22
RoadBike_Racer (Hoods)	75 watts	257	18
RoadBike_Racer (Drops)	72 watts	248	18
RoadBike_Racer (TriBars)	70 watts	240	17
RoadBike_Tourer (Tops)	119 watts	408	29
RoadBike_Tourer (Hoods)	106 watts	363	26
RoadBike_Tourer (Drops)	103 watts	354	25
RoadBike_Tourer (TriBars)	100 watts	346	25
Hybrid (Tops)	126 watts	434	31
MountainBike (Tops)	162 watts	557	40

�

Power And Energy Required To Cycle @ 16MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	122 watts	421	26
RoadBike_Racer (Hoods)	103 watts	354	22
RoadBike_Racer (Drops)	99 watts	341	21
RoadBike_Racer (TriBars)	95 watts	328	20
RoadBike_Tourer (Tops)	157 watts	542	34
RoadBike_Tourer (Hoods)	138 watts	475	30
RoadBike_Tourer (Drops)	134 watts	462	29
RoadBike_Tourer (TriBars)	131 watts	449	28
Hybrid (Tops)	166 watts	572	36
MountainBike (Tops)	207 watts	712	44

�

Power And Energy Required To Cycle @ 18MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	166 watts	570	32
RoadBike_Racer (Hoods)	138 watts	475	26
RoadBike_Racer (Drops)	132 watts	456	25
RoadBike_Racer (TriBars)	127 watts	438	24
RoadBike_Tourer (Tops)	205 watts	706	39
RoadBike_Tourer (Hoods)	178 watts	612	34
RoadBike_Tourer (Drops)	172 watts	592	33
RoadBike_Tourer (TriBars)	167 watts	574	32
Hybrid (Tops)	215 watts	740	41
MountainBike (Tops)	261 watts	898	50

�

Power And Energy Required To Cycle @ 20MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	219 watts	753	38
RoadBike_Racer (Hoods)	181 watts	623	31
RoadBike_Racer (Drops)	173 watts	597	30
RoadBike_Racer (TriBars)	166 watts	572	29
RoadBike_Tourer (Tops)	263 watts	905	45
RoadBike_Tourer (Hoods)	225 watts	775	39
RoadBike_Tourer (Drops)	218 watts	749	37
RoadBike_Tourer (TriBars)	210 watts	724	36
Hybrid (Tops)	274 watts	943	47
MountainBike (Tops)	325 watts	1117	56

�

Power And Energy Required To Cycle @ 22MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	283 watts	975	44
RoadBike_Racer (Hoods)	233 watts	802	36
RoadBike_Racer (Drops)	223 watts	766	35
RoadBike_Racer (TriBars)	213 watts	734	33
RoadBike_Tourer (Tops)	332 watts	1142	52
RoadBike_Tourer (Hoods)	281 watts	968	44
RoadBike_Tourer (Drops)	271 watts	933	42
RoadBike_Tourer (TriBars)	262 watts	900	41
Hybrid (Tops)	344 watts	1183	54
MountainBike (Tops)	400 watts	1375	63

�

Power And Energy Required To Cycle @ 25MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	403 watts	1386	55
RoadBike_Racer (Hoods)	329 watts	1132	45
RoadBike_Racer (Drops)	314 watts	1081	43
RoadBike_Racer (TriBars)	300 watts	1032	41
RoadBike_Tourer (Tops)	458 watts	1576	63
RoadBike_Tourer (Hoods)	384 watts	1322	53
RoadBike_Tourer (Drops)	369 watts	1270	51
RoadBike_Tourer (TriBars)	355 watts	1222	49
Hybrid (Tops)	472 watts	1623	65
MountainBike (Tops)	535 watts	1841	74

�

Power And Energy Required To Cycle @ 30MPH
BikeType (Position)	Power Required	kcal/Hour	kcal/Mile
RoadBike_Racer (Tops)	673 watts	2315	77
RoadBike_Racer (Hoods)	545 watts	1876	63
RoadBike_Racer (Drops)	519 watts	1787	60
RoadBike_Racer (TriBars)	495 watts	1704	57
RoadBike_Tourer (Tops)	739 watts	2543	85
RoadBike_Tourer (Hoods)	611 watts	2104	70
RoadBike_Tourer (Drops)	585 watts	2015	67
RoadBike_Tourer (TriBars)	561 watts	1931	64
Hybrid (Tops)	755 watts	2599	87
MountainBike (Tops)	831 watts	2861	95

Bye

Ian

 

[si_c]

Rider size definitely comes into it as well, those numbers Ian has put up make sense for a lighter rider, bit I know it's a fair bit more for me.