Weight of Bike vs Weight of Rider

Equipment
1

Finally i am able to travel again and ride in Taiwan again after 3 years. My plan is to finish the route that i DNF in 2019.

I was running my numbers through a calculator and i was wondering why at 3.25wkg, i will take 4.14 to finish the ride vs a female friend who is 3.4wkg who will take 4.22 to finish the ride.

I realise the weight of the bike plays a big part in proportion to the rider weight.

There are a few discussions on w/kg vs system weight or total weight. Does anyone know at what percentage or w/kg or etc does the bike’s weight start to have a negative effect on w/kg?

2

I realize I likely don’t understand how you’re thinking about this - when could it not have a negative effect? Rider + bike > rider. Also: if you are lighter, the bike is a bigger % of the system weight. But, in the real world, a lighter bike versus a heavier bike may be 5 pounds, slightly over 2KG. That’s a pretty small difference relative to the weight difference found in riders.

3

Sorry my question is not clear in the original post. What i was asking was at what percentage of the rider’s weight will the bike’s weight have a lesser impact on the timing?

In my calculation, the bike’s weight was input as 8kg which i think is a normal weight for a bike with water and etc.

I weigh 80kg and she weighs around 50kg. Forgot to put this in as well.

4

w/kg matters as things get steep. I guessing parts of the route are likley flat or downhill and this is where absolute watts matter more than w/kg.

e.g. a 300W rider at 100kg (3w/kg) and a 150W rider at 50kg (3w/kg) will travel at different speeds on flat terrain.

Even if your friend is higher w/kg sounds like you have a higher FTP so will go faster on flat/downhill sections (and even lower grade uphill)

2 Likes
5

It’s a weird question. Just go ride your 4.xx hour route together.

1 Like
6

Actually i would but i was thinking i will get dropped by her since her wkg is higher

7

I don’t think that a 2kg frame weight difference is meaningful in events longer than 2-3 hours
I do marathons/xcm races and i have a 4.2kg steel full suspension frame

8

Ok. So what? You’re not racing. You’re going out and doing a ride together. Can she not wait at times for you if you were dropped? What about stopping for coffee/food/pictures etc. This is my point…

9

Whats the route profile and what are your actual weights and FTPs?

Like others said, if there’s a big gap in weight and absolute ftp, the lower ftp (higher w/KG) rider could benefit a lot by riding in the draft on the flats, saving a ton of time. On the climbs they could just “relax” a bit more and you’d have a nice big ride together.

10

It will be for a cycling event/race. I don’t think she will wait since she wants to best her PR. That’s also why i want to make sure i finish the ride within the time cut.

11

Its a mountain route. Around 3275m at the top.

She is 170w, around 50kg. I am 260w around 80kg. She will not likely want to wait for me if i slow her down.

23424242345
23424242345790Ă—321 31.7 KB

12

You cannot separate the rider’s weight from the bike’s weight. The rider’s power (W) has to move both up the hill, and gravity will move both down the hill. You always have to think about the total weight of rider+bike.

3 Likes
13

Gotcha. So things are becoming more clear. Here’s what I understand:

  • You are registered for an upcoming mountainous cycling event, in Taiwan.
  • You are doing this event with a friend.
  • You’re worried that she will drop you.
  • In the mathematical prediction of race timing, you are confused that a rider with a higher W/kg would calculate out to a slower time than another rider with a lower W/kg. Why? This is your question.

So, my take on this is that all this other information is irrelevant. Your event is irrelevant. Who you’re riding with, where you’re riding (kinda) is irrelevant. What we need to do to actually answer your question is explore the actual calculator you used to have this prediction of the lower W/kg rider being faster.

Keep in mind that your predicted times of 4.14 and 4.22 are super close (5mins!) given the length of the event and all the other variables of riding bikes outside. I mean, really, it’s not like you’re going to turn on robot mode and ride at your predicted W/kg from start to finish. In your posted diagram, there’s also a rest station at the base of a Cat 1 climb. So many things to affect your overall “time” in the event.

Also, this. :slight_smile: Rider+Bike is the object. Separating is not a thing. @rogerchua Where’s the calculator? This could help immensely.

14

There might be a difference in aerodynamics between a lighter rider and a heavier rider - the lighter rider is often smaller, and often more aerodynamic.

15

Actually not worried she will drop me. I have already assumed i will get dropped since i am heavy and have not ridden all the way up before.

The calculator is here. It is in traditional chinese though.

Website

The data is from the information from strava so its pretty spot on so far. I think its a bit optimistic since there are still alot of variables like aerodynamics, etc.

I think 4.30 or 5hrs might be a bit more realistic for me to finish the ride.