Bike weight importance

How important is the weight of the bike on hill climb?

Example:

Bike #1: 6.8 kg
Bike #2: 8.0 kg

The weight of the driver and accessories is the same in both cases.
What would be the theoretical difference in the time traveled on the climb at the same watts:

Distance: 13.4 km
Elevation: 968m
Grades Avg: 7.2%

I’ve run a couple of numbers through the cycling speed calculator and the difference was very small but of course matter for pros. What I do notice when I remove my large saddle bag (total weight around 1.5‐2kg)for commuting is that my bike handles much snappier

With this calculator you can run your numbers and see how much it differs in your example

1 Like

Insert gpx file of the climb and experiment.

Purely theoretically, at 200W, rider 70kg, clinchers, hoods, 25deg C:
6.8kg bike = 70.49min
8kg bike = 71.48min

So, basically a 1 minute difference over 1h10min
Interestingly, averaging 203W on the 8kh would bring the completion times back to equal.

Lots of other variables when it comes to feel, rotational inertia, etc. though

2 Likes

for 6.8 kg (and 75 riders weight):
“If you apply 250 watts of power, you will ride at groundspeed velocity 13.69 km/h.” (for 13,4 58:45 minutes)

for 8.0:
If you apply 250 watts of power, you will ride at groundspeed velocity 13.51 km/h . (for 13,4 59:30)

I also used the calcluator linked above, and it’s pretty similar, I left the weight n 72, so the total is a but less and the difference is then 50 seconds (compared to 45). So you can expect something around that 50 seconds on a 1 hour 7.2 climb when you ditch 1.2 kg. (could also be bottles, tools, body weight…)

for the 250 watts you have to pedal on the 6,8 bike, you would have to pedal 254 with the 8.0 bike to match, those 4 watts are easy matched with (possible) aero gains, but weight uphill is real, specially in competition.

1 Like

Putting the speed numbers aside, a light bike feels light, and kind of gives a little bit of motivation.

Even a set of good light wheels can make it feel different.

But if you regularly use a light bike, the zippy feeling becomes the norm, and a heavier bike will feel like a tank.

A lot of people train outdoors in the winter on heavy/old/crappy bikes… then hit their light bikes in the spring.

2 Likes

What % of the riders weight is it. If they are both light riders its a bigger % and matters slightly more. Conversely the heavier the riders are it a smaller % and matters less.

For a rough indication: every x% of the total weight of bike plus rider that you can drop will lead to an increase in speed of that same x%, once it gets steep (e.g. > 8% incline).

For more accurate estimates I like to use this tool: http://bikecalculator.com/

For most amateur cyclists that are looking to increase their performance, there is much more to gain from loosing body weight and becoming stronger than from getting better equipment. Now at the same time, having a nice bike also brings joy and motivates you to ride more!

2 Likes

1 minute is a lot in a race.

I’m glad you said for most :joy: I remember just before I’d got into cycling as a sport, bringing my bike home on the train a few weeks after a bout of Pancreatitis which had saw me go from around 11.5st to 9st in a few months. A roadie was sat in the same carriage telling me I’d be better to lose a few pounds than get a lighter bike :joy:

2 Likes

Without giving us a course and adding rider weight and power, we cannot give an answer. Weight matters more at lower speeds, but the faster you go, the more important aero drag becomes. So it matters more for light riders with small power output (both, in absolute and in relative terms).

Usually, for most of us, it is far more important and efficient to save weight on the rider rather than the bike. And then to raise power of said rider. And you shouldn’t forget pacing, which is a crucial skill for hill climb TTs.

i would say that makes a big difference. Anecdotal, but go smash a climb, and then try it with your water bottles removed. The bike feels snappier, more responsive (since there’s that two lbs removed from the frame as we throw it side to side whilst smashing a KOM)…seems insignificant but it matters.

1 Like

Due to breakthroughs in metallurgy and the use of new materials in both frame construction and components, bicycles are getting lighter and lighter every year. So we should choose a light bike because it will be more agile, climb slopes better, accelerate faster and simply say, cycling is more fun.

The 1 minute in a 70 minute climb sounds about right and can be negated by pushing 203 watts vs. 200. Or focusing just a bit more on the climb. Or any number of things. But the weight doesn’t make an appreciable difference in the time.

On the other hand, the lighter bike will probably feel better…a lot better. And pushing a nice efficient, light bike that you like up a long climb makes a difference.

So for time? Not worth it. But you feel what you feel and that can definitely make it worth it.

Joe

1 Like

This makes me lol. Putting out 3 watts more differences out the time (3/200*100% = 1.5%). So trying 1.5% harder evens thing out. But the theoretical price difference between those two bikes is prob $2000-3000 usd!

1 Like

Yeah agreed!!
I’m debating a wheelset upgrade at the moment and although there are a lot of other factors apart from weight to consider, the weight saving impact on low-speed climbs is so minimal for the cost.
I’m probably better off leaving a water bottle and my saddlebag at the bottom of the climb!

2 Likes

My favorite internet bike debate that usually ends in “I don’t need a lighter bike, I’ll just take a dump before the ride and save $X”

What if you had the lighter bike and also took a dump? Or added 3W? Or discarded the bottle?

Disclaimer, I ride a 10 year old entry level bike and it’s plenty fast for me. But I fully acknowledge I’d be a little bit faster with a lighter one :smiley:

A more interesting question for OP would be if you have the money for that difference in bike weight, is that the best way to spend it to get faster? Probably not for most…

3 Likes