MTB weight obsession - unnecessary?

[DieselnDust]

2 hours ago, JayLow said:

Lots of calculation errors in there but yes, for racing lighter would be better, all other factors being equal. However the effect is very very small: in the example it's 4cm/s or 2.4m/min for a 3.3kg difference in weight.

My point is that the gains in performance with going lighter are not commensurate with the cost to reduce weight (for the vast majority) of riders.

Lots of calculation errors in there 😂

its 6 cm per second so 3.6m per minute and still roughly 40 sec after just 2km

 

the value of the cost of the weight reduction is dependent on the purpose and reasons behind it.

i agree for most people its not worth it and hence they don’t give a Phuq; ride what they like when they like for sits and giggles 

for guys chasing podium that’s the difference between turning up to compete or not bothering and going for a coffee ride instead. 
an XCO lap is roughly 2km of climbing over 4km, so a 40 second time loss per lap x number of laps is an embarrassing loss. Over 5 lap race that’s 200 seconds or 3min 20seconds,  that’s before rider power to weight is even considered.

and then throw in the e-bikers one has to compete with so weight is very very important

Edited May 21, 2024 by DieselnDust

[Jewbacca]

Armchair science!

hahahahahahaha

Dudes and Dudettes, for MOST, a few grams to a couple of kilograms means very little.

To some it means more but weight can be offset by aero, handling, comfort etc..... What works for me may also not work for you.

This discussion has way too many absolutes and false information posing confidently as fact.

IMHO this discussion is endless, it has no correct answer and involves way too many swing variables that will affect the outcome of the conclusion for very specific circumstances.

 

[DieselnDust]

9 minutes ago, Jewbacca said:

Armchair science!

hahahahahahaha

Dudes and Dudettes, for MOST, a few grams to a couple of kilograms means very little.

To some it means more but weight can be offset by aero, handling, comfort etc..... What works for me may also not work for you.

This discussion has way too many absolutes and false information posing confidently as fact.

IMHO this discussion is endless, it has no correct answer and involves way too many swing variables that will affect the outcome of the conclusion for very specific circumstances.

 

Agreed, there’s waaaay too many variables for the conclusions to be meaningful so I’m just talking to the data presented from the bike calculator in the first post. Comments are made within the bounds of that data. The power output is a set value and  rider weight is pegged at 80kg. The only variable is the bike weight. 
 

In reality there’s a lot more to consider but when trying to determine the potential performance benefit of weight reduction, the tabulated data is sufficient to determine that there is benefit. Does it mean that the heavier bike won’t win a race or be fastest under a different rider ? No it’s meaningless from that context. If only applicable to one person making a choice in how to spend their bonus cheque, rather put that cash into your wheels or suspension or preferably your house (jokes, cyclists don’t do that)

Edited May 21, 2024 by DieselnDust

[JayLow]

3 minutes ago, DieselnDust said:

Lots of calculation errors in there 😂

its 6 cm per second so 3.6m per minute and still roughly 40 sec after just 2km

 

the value of the cost of the weight reduction is dependent on the purpose and reasons behind it.

i agree for most people its not worth it and hence they don’t give a Phuq; ride what they like when they like for sits and giggles 

for guys chasing podium that’s the difference between turning up to compete or not bothering and going for a coffee ride instead. 
an XCO lap is roughly 2km of climbing over 4km, so a 40 second time loss per lap x number of laps is an embarrassing loss. Over 5 lap race that’s 200 seconds or 3min 20seconds,  that’s before rider power to weight is even considered.

and then throw in the e-bikers one has to compete with so weight is very very important

For the sake of completion  

The table states 18.15mins, which is closer to 18m9s, not 18m15s.
Likewise for 18.53mins which is 18m32 (not 18m53s).

This brings the 38 second difference down to 23 sec.

And that's for a 3.3kg difference, which is extreme, and it assumes all other factors being equal.

Agree, if you arrive at a XCO event with a Enduro bike you will (probably) get smoked. You may be in with a chance if your bike is within 2kgs and you had a good sleep...

[droo]

48 minutes ago, JayLow said:

Agree, if you arrive at a XCO event with a Enduro bike you will (probably) get smoked. You may be in with a chance if your bike is within 2kgs and you had a good sleep...

The biggest difference here is geometry - I've tried long days out on the big bike and it hurts, but mostly because the big bike is designed to either go up or down. Flat is murder in terms of pedalling dynamics and riding position, so you end up being way more fatigued after 2 or 3 hours in the saddle than you would on a bike that's designed to do distance.

Look at the earlier example of the base spec Cypher - the 11kg one will be quicker, but the 15kg odd one will pants a trail or enduro bike for anything over a 2 hour ride.

[Kuys]

Don forget tire tread pattern. 

Rear tire tread pattern makes a bigger difference than weight. 

Therefor I wish for a strong (read heavy) tire casing but with less aggressive knobs 

[Shane S]

Simple really , go as light as your pocket will allow and make the rest up with effort .

[V18]

(Trying to contribute to threads these days after my recent tangential moments.)

Posterchild of heavy bikes here. Ask @droo. I used to believe heavier doesn't matter for me since I'm the problem. Untill I got some light tough carbon rims and W2w appropriate tyres. I was wrong. So wrong in fact that when I put back heavy schwalbe sg/St tyres... I went back after ONE RIDE to lighter casings with a minimalist insert.

In my experience. Lighter wheels tyres make all the difference. The rest... *Slaps belly.*...I need to change myself first. 

 

[Mook]

2 hours ago, MORNE said:

 

Not completely true, although lower rotational mass will get rolling faster, higher mass will keep that speed easier.  If you can find that place where you arent loosing too much momentum in, over or around things, heavier wheels might actually help purely because its harder to slow down a heavier spinning thing and its centrifugal force.  
 

These days a properly strong carbon wheelset for gravity riding is chosen more for feel than weight anyway. They basically weigh the same. Same with big hitting carbon bike frames. Ive had steel bikes lighter than my plastic bike lol.  They feel different though.

My point exactly. With your plastic bike you will take the polkadot, BUT I will get to the coffeeshop at the bottom faster because I weigh 10kg more than you.😝

[Chadvdw67]

2 hours ago, JayLow said:

Agree, if you arrive at a XCO event with a Enduro bike you will (probably) get smoked. You may be in with a chance if your bike is within 2kgs and you had a good sleep...

Willie van Eck won the MP XC series on a Pyga Slakline, 160/170 Enduro bike, and then also wins the MP Enduro series riding the Slakline with a 36T chainring 🫠

[DieselnDust]

4 hours ago, JayLow said:

For the sake of completion  

The table states 18.15mins, which is closer to 18m9s, not 18m15s.
Likewise for 18.53mins which is 18m32 (not 18m53s).

This brings the 38 second difference down to 23 sec.

And that's for a 3.3kg difference, which is extreme, and it assumes all other factors being equal.

Agree, if you arrive at a XCO event with a Enduro bike you will (probably) get smoked. You may be in with a chance if your bike is within 2kgs and you had a good sleep...

Eish ok you win….. I’m having steak and beer now while watching the shananigans of todays giro stage 

[MORNE]

8 hours ago, DieselnDust said:

giro

Mushroom steak and malt drink? 
😅

[peetwindhoek]

11 hours ago, Chadvdw67 said:

Willie van Eck won the MP XC series on a Pyga Slakline, 160/170 Enduro bike, and then also wins the MP Enduro series riding the Slakline with a 36T chainring 🫠

Not sure what this says more about. The MP mtb depth, the Pyga or Willie.

[DieselnDust]

3 hours ago, MORNE said:

Mushroom steak and malt drink? 
😅

Eish bru it’s not Friday yet…😂

 

real steak and real beer , bru’ed with czars hops en ek gebruik baardoilie, want eks n #rowebliksem

[Shebeen]

I know it's roadbikes, but principles are similar.

UCI limit is 6.8kg, has been for years. there was even a cannondale TdF bike about 20 years ago where they put a lead weight on the top tube to bring it up to scale as a form of protest.

If weight was the be all and end all, then all the top pros would be on 6.800kg plus a ballhair?

not even close.

https://tempocyclist.com/2023/07/24/bike-weights-of-the-tour-de-france/

 

 

[JayLow]

31 minutes ago, Shebeen said:

I know it's roadbikes, but principles are similar.

UCI limit is 6.8kg, has been for years. there was even a cannondale TdF bike about 20 years ago where they put a lead weight on the top tube to bring it up to scale as a form of protest.

If weight was the be all and end all, then all the top pros would be on 6.800kg plus a ballhair?

not even close.

https://tempocyclist.com/2023/07/24/bike-weights-of-the-tour-de-france/

 

 

Ah such an interesting perspective - wonder what the equivalent XCO or XCM table would look like... 

Granted, being less than 1 kg over is not major, but for these multiple hour stages it just demonstrates again that weight is not the dominant factor. 

The rule of thumb I'm using from now on is that for every kilo your kit is heavier, you need to make up about 5 seconds for every 100m of vert (it's less than that - the example loses 3.5 seconds per kg over 100m).

Would be interesting to see some real experimental data on the impact different factors in converting watts to speed. Lifting the weight against gravity is just a small part of the equation of getting a bicycle to move.

Edited May 22, 2024 by JayLow
UoM