Is a full road bike quicker ?

[jimboalee]

In my experience FBA more than makes up for TBA going up hills. You can pull out massive chunks of time on climbs only to be overtaken and have that plus a couple of minutes taken out on the descent. FBA seems to have some magical properties on the flat where they can cruise along as 20mph forever.

My racebike is much faster than my road bike. On a long run I posted I did on a racebike it was 6mph quicker than the hybrid on average. On other runs it took 3 hours out of the century run. Three hours!

Dangerous word round here.

Fortunately, the 'M' word in this instance is "Inertia".

 

[marinyork]

I just meant, these people who talk of FBA tend to have some very bulky muscles and are able to cruise along at very high speeds on the flat. That or it is very flat where all these people live and they started out on fast bikes.

 

[jimboalee]

I just meant, these people who talk of FBA tend to have some very bulky muscles and are able to cruise along at very high speeds on the flat. That or it is very flat where all these people live and they started out on fast bikes.

Indeed. The muscular guys who have the kgs, and also have the W/kg to match; the guys who easily find 360W to get up a 14% in 39 x 23 ( 4.5 W/kg ), jest continuously about FBA.

BTW, that's 80kg.... and in cycling circles, that's heavy

 

[Davidc]

Force = Mass x acceleration.

Seeing gravity never changes, more mass gives more force.

It's called "Fat Boy's Advantage".

Which is also acceleration = Force/mass, so the extra force downhill is (exactly) used up accelerating the extra mass, the rest of the time the extra mass just reduces acceleration on the flat and takes extra force to shove it up hills!

Looks a lot like thin boys advantage to me.

 

[marinyork]

Which is also acceleration = Force/mass, so the extra force downhill is (exactly) used up accelerating the extra mass, the rest of the time the extra mass just reduces acceleration on the flat and takes extra force to shove it up hills!

Looks a lot like thin boys advantage to me.

I'll race any of these people who dub themselves fat on the flat or downhill. I wager they'll beat me by a long way .

 

[Sittingduck]

I'll race any of these people who dub themselves fat on the flat or downhill. I wager they'll beat me by a long way .

I don't believe in FBA on the flat but on a downhill I know it's legit

 

[jimboalee]

One method of determining the Coefficient of Drag of a wheeled vehicle is to measure the time it takes to reduce speed ( in Neutral ) along a flat road. The longer it takes, the better the Cd. In other words, the more Inertia ( mass for the same shape and volume ), the longer the vehicle will keep rolling.

Another method of determining the Coefficient of Drag of a wheeled vehicle is to measure the 'equilibrium velocity' it attains down a known slope.

The latter is easiest for a cyclist as Cross section area need not be known to calculate Power vs Velocity.

Watch out Marinyork, the 'Holy grail' is within reach…

Both of these methods DO NOT involve the vehicle to be powered. A car can be tested by pushing it to speed and then let it coast-down along a flat strip of test track.

The upshot of this is a vehicle with more mass for the same shape and volume will roll further along the flat and faster down the hill.

On a flat roadrace stage, it is a balancing act between mass for inertia and lightweight for the short climbs. This is usually done with bottles of water.

 

[Dan B]

I don't believe in FBA on the flat but on a downhill I know it's legit

Yeah, but the question is whether it's FBA or TBA overall on a course that has the same amount of up as down. My intuition says TBA - uphill speed is limited by power to weight ratio, but downhill speed is probably more often limited by roadholding unless it's a straight run down with no curves on it

 

[Sittingduck]

Yeah, but the question is whether it's FBA or TBA overall on a course that has the same amount of up as down. My intuition says TBA - uphill speed is limited by power to weight ratio, but downhill speed is probably more often limited by roadholding unless it's a straight run down with no curves on it

If that's the Q, then certainly skinnies win!

 

[marinyork]

The FBA wins for the simple reason that riding in a group you're expected to wait at the top or part way up a hill whereas going down nobody waits .

 

[amnezia]

In my experience FBA more than makes up for TBA going up hills. You can pull out massive chunks of time on climbs only to be overtaken and have that plus a couple of minutes taken out on the descent. FBA seems to have some magical properties on the flat where they can cruise along as 20mph forever.

My racebike is much faster than my road bike. On a long run I posted I did on a racebike it was 6mph quicker than the hybrid on average. On other runs it took 3 hours out of the century run. Three hours!

which is why all the TDF riders are 20st blokes at 5'6 high.

 

[marinyork]

which is why all the TDF riders are 20st blokes at 5'6 high.

Which relates to the quantifier "in my experience", how? Even if they were 20st blokes 5'6 high they'd still be faster.

 

[Dan B]

The FBA wins for the simple reason that riding in a group you're expected to wait at the top or part way up a hill whereas going down nobody waits .

Heh, yes

 

[jimboalee]

"In my experience".....

It's PBA, ..... Powerful Bastard's Advantage.

I can climb quicker than 95% of the 'D' riders although I am three stone heavier.
I can climb quicker than 50% of the 'C' riders although I am two and a half stone heavier.
I can climb quicker than 10% of the 'B' riders although I am two stone heavier.
I don't know about the 'A' riders, they disapeared over the hill while I was looking at my front mech.

 

[J4CKO]

Its cos the heavier guys legs work harder all the time carrying their bodies around.