Compact gearing doesn't feel smooth? Really?

[RedRacer]

I was reading the Wilier Zero 7 review in the latest Procycling magazine and a comment by ex-pro Marcel Wust really caught my attention.

"I really like to ride standard chainrings because a 39 is so much smoother then (sp?) a 34."

Really? Am I so numb to feedback that I have never noticed this or is Marcel just uber-sensitive after years as a pro?

[fromtrektocolnago]

I find riding in the higher gears smoother as well, provided I can maintain a good cadence.

[mentok]

Maybe he's talking about the fact that riding the 34 leaves you lower in the rear cassette for an equivalent gear? I know I find myself cross-chained more often on my compact compared to my standard.

In theory the larger ring should have lower friction due to the smaller bending radius though i'd be surprised if you can feel it.

[kgt]

Marcel Wust is right IMO.

[mattr]

FWIW, I've found that you can feel the chain settling into each link/tooth more noticeably on a smaller chainring than a larger one *in the workstand*. (And that's swapping brand new stuff, standard to compact, so no wear/misalignment/compatibility/lubrication to worry about).

On the road. Hmmmmm.

I reckon chainline is more likely to be the cause.

[jekyll man]

I found that power (as recorded, not felt) was more "choppy" on a compact than a standard chainset for a similar power/cadence

[de zwarten]

You turn around more with your cranks before your body + axle interlock. So especially after coasting, but also going up a hill with varying power intensity, you have a sloppier chain and less torque throughout your pedal movement.

[Marin]

-1

[Rick]

I don't notice anything about "smoothness" while pedaling, but the shift from small to large is definitely a bit more brutal on the compact.
But I need the compact for the terrain around here. If I didn't I'd ride a 42-53!

[AJS914]

I've settled on a 52/36 as my compromise solution. That said, I did a really hilly ride the other day and I missed the 34 because I get a better rhythm and spin on climbs with it.

"I really like to ride standard chainrings because a 39 is so much smoother then (sp?) a 34."

When I run a 50/34 you hardly ever use the 34 unless I'm on a climb. Overall though I don't miss grunting out climbs in a 39x25 like I used to do in the old days.

[zerodish]

This is called chordal action. Gears are not round but n sided polygons. No one outside the bicycle industry uses gears smaller than 15 teeth.

[Marin]

If that was such a factor, the cassette would have a much larger effect than the chainrings - even the largest road cogs are smaller then the smallest chainrings.

[tymon_tm]

other than some serious hillclimbing and junior bikes, I can't see any purpose for compacts. oh wait, there is one actually - you can sell the same bike to both "highlanders" and "flatlanders".

[AJS914]

What do you call serious hill climbing? It's fairly hilly where I live and I prefer the 34 chainring. It allows me to spin much more. I'd rather climb at 90-100 rpms instead of slog up hills at 60rpms.

[deek]

If that was such a factor, the cassette would have a much larger effect than the chainrings - even the largest road cogs are smaller then the smallest chainrings.

If one could feel a difference, it is definitely due to the cassette cog. With a smaller chainring you will need to use a smaller cog to reach an equivalent gear ratio.