Why is one of my bikes faster?

[Robertb]

To preface, I have no scientific basis for this for example a power meter, simply riding routes and loops I know well at similar HR/RPE.

I have two aero road bikes;
one: 2014 Argon18 Nitrogen rim brake, ultegra 6800 11s and Prime 50mm on 25mm Conti GP4000Sii with tubes.
two: 2023 Orro Venturi disc, super record EPS wireless 12s, 40mm Fulcrum Wind on 28mm Vredestein Fortezza with tubes.

My position is near as dammit identical. Orro has narrower bars and no exposed cabling at all.

But the Argon18 is quicker... 1-2km over an hr ride. It feels like it punches through and cruises at higher speeds.

The Vredestein tyres are noisier... a pronounced 'suck' from the surface.

Could an extra 10mm of rim depth make that much difference, or the tyres? I cant believe the frame would make that much difference, given what the bike actually accounts for in terms of drag.

[POIDH]

Riding position to me is what makes me faster...

[Siao]

I'd imagine a combination of many small things, rather than a big evident one. Gearing also would make a bit of a difference, possibly?

[CoupeKid]

Tyres and inner tubes.

GCN do videos on this regularly.

Get some latex inner tubes for the slower bike and see what difference they make then get better tyres.

[leyorkie]

Try swapping the wheels over?

[Robertb]

leyorkie said:

Try swapping the wheels over?

Annoyingly one bike is rim-brake, one is disc. I could swap the tyres over I guess, to at least rule that out.

I'll start with new tyres/tubes (may try tubeless) and see if that helps.

Gearing on the Orro is great; the 12s is perfect for keeping a consistent cadence, so I imagine thats ok.

[troc]

Yeah , I would give both bikes the same tyres/tubes first and then see what the result it.

Basically remove as many variables as possible.

[sean ie3]

Could It possibly be, more drag from the disc brakes? 😕

[Robertb]

sean ie3 said:

Could It possibly be, more drag from the disc brakes? ??

I wondered, but unlikely I think. … The wind-facing profile of the disc is barely 2mm and the calipers pretty slimline compared to the rim brakes assembly and cables.

[Caddyshack]

Robertb said:

sean ie3 said:

Could It possibly be, more drag from the disc brakes? ??

I wondered, but unlikely I think. … The wind-facing profile of the disc is barely 2mm and the calipers pretty slimline compared to the rim brakes assembly and cables.

I read the drag as maybe the pads dragging on the disc at times?

[Simon_GH]

I believe aerodynamics has the greatest influence. Tyres, wheel weight etc all help but body position is likely to be your answer. Just look at the reduction in effort for riders in a slipstream,

[Caddyshack]

Simon_GH said:

I believe aerodynamics has the greatest influence. Tyres, wheel weight etc all help but body position is likely to be your answer. Just look at the reduction in effort for riders in a slipstream,

The original post says near
Identical body position.

[Robertb]

Caddyshack said:

Robertb said:

sean ie3 said:

Could It possibly be, more drag from the disc brakes? ??

I wondered, but unlikely I think. … The wind-facing profile of the disc is barely 2mm and the calipers pretty slimline compared to the rim brakes assembly and cables.

I read the drag as maybe the pads dragging on the disc at times?

Hmm, not thought of that. Will check.

[okgo]

I doubt any single thing is making the difference, potentially a combination of a load of things and of course it could be position on the bike - even when these feel similar they can differ.

Are both bikes the same size?

[Robertb]

okgo said:

I doubt any single thing is making the difference, potentially a combination of a load of things and of course it could be position on the bike - even when these feel similar they can differ.

Are both bikes the same size?

Yes, frames are the same size. Saddle is in the same position, I’ll measure the stem height tomorrow.

The guys at the bike shop basically looked to duplicate the set up.

The background is the new bike was a surprise and very generous gift from my wife for my 50th, built around the mega Campag groupset.

I feel like I struggle a bit on it, relatively, and I’d love to make it so I feel at home and quick on it like I do my old bike to do it justice.

[Caddyshack]

Robertb said:

Caddyshack said:

Robertb said:

sean ie3 said:

Could It possibly be, more drag from the disc brakes? ??

I wondered, but unlikely I think. … The wind-facing profile of the disc is barely 2mm and the calipers pretty slimline compared to the rim brakes assembly and cables.

I read the drag as maybe the pads dragging on the disc at times?

Hmm, not thought of that. Will check.

They could rub when leaning but might not show when spinning a wheel. Maybe back them off and try to compare?

[IroningMan]

The Argon has a lower BB than the Orro, which may have resulted in your bike shop not managing to duplicate the setup from one to the other: I think I’d look at that first. Position is the most likely source of difference in performance.

The Argon is also exceptionally good at absorbing road vibes - the Orro is pretty solid by comparison, so lower tyre pressures might help a little.

N.B. - racing certainty that you won’t get the 28mm tyres to fit the Argon; there’s not enough clearance at the back of the seat tube.





Mine are on 25mm and 28mm GP5000 tyres on 65mm Light Bicycle and 60mm Vel rims respectively, but my position is identical - although it doesn’t look like it because I can’t photograph bikes to save my life - and my best times over a favourite rolling 3.25km segment are 4:41 (41.9kmh) on the Argon and 4:42 (41.8kmh) on the Orro.