Big ring vs small

I can’t seem to find any definitive advice on whether or not riding in the big ring vs small ring (assuming gear ratios are the same for each) is better - you get more torque, leverage etc thereby making it easier or faster for same effort.

It really comes down to personal preference. I know that, for me, I prefer the big ring as I feel like I spin too much in the small ring (even though the gear ratios are the same).

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I ride whatever ring will keep me at (or closest to) my preferred cadence.

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I agree. My friend was arguing that the big ring is best. I couldn’t find the evidence to prove that. I’m a curious sort.

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I think I would go for which one gives me the straightest chain line

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Maybe I should have asked if there is a mechanical advantage to big ring given same gear ratio when compared to small.

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Friction Facts has tested this. (NB: FF was an independent outfit, then it got bought out by Ceramicspeed and the owner works for them now.) Basically, the big ring is generally faster than the small ring. You want to avoid small-small combos. We usually aren’t talking about huge power savings, but FF measured nearly a 3W differential between 39/11 and 12 and the equivalent gears in a 53.

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In a lab, you lose watts to drivetrain inefficiencies by forcing the chain to bend more so bigger gears are better… anecdotally, I feel like I spin out smaller gears more quickly and don’t like to be in the small ring unless I’m climbing and need to be… practically, do what feels right to you and don’t worry about it.

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Thanks this is what I was looking for!

Theoretically the optimal power transfer would occur in the biggest chainring/cog with the best chainline (which is obviously impractical) in practical terms if you get the right chainrings for your needs this becomes more about and which gears you have quick access to unless you’re on a long steady ascent in which case you can usually hear if the chainline is bad and adjust. I use a standard, in the 53/39 for me at least it feels like you can still carry great speed with the 39 and you get more useable gearing as the gradient increases so I always shift down at the base and run a subpar chainline for a few seconds in exchange for not having to shift the FD in a steeper grade the aforementioned might not work in a compact since the gear spread is larger.

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if you can be in the big ring, use that. end of.

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Interesting. When I rode Standard (53-39) I was often in the small-smallish combos. Riding a 50-34, I’m mostly in the big-biggish. I imagine the ratios are similar. Riding in the 34 is mostly reserved for climbing or warm ups.

If you need more torque in the rear (riding offroad maybe), the small chainring will give you that at the same gear ratio. So there are times when either ring can be better, depending on the results you want :slight_smile: (IMPORTANT NOTE: as pointed out below, this is probably wrong, lol) (But not the next part)

The big ring will also give you more tooth engagement in your drive wheel. And that means less stress per chain link where the torque is higher. It will cut down on friction as well–the bigger the gears, the less friction, due to the chain having to make the turn at less of an angle. And the changes in size at the chainring are larger, and will more than make up for the changes in size at the cassette.

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Think I agree with this - whatever gives you the best chain line. Ages ago, I read that Bartoli used a 23 on the back, not because he wanted to use it, but so that the 21/19 ran more efficiently.

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Most people forget they have a small ring in the front.

I see everyone else with the Big-big combo. And at stoplights they stay in the big ring, so it takes forever to grind through the lights.

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Why would staying in the big ring add to the time to get through lights? I always do this, and find it far easier to shift from big big down through the cassette than dropping to the small ring. Unless your stoplight is on a hill, I can’t see accelerating from a stop requiring the small ring.

there’s exactly zero correlation between stop lights and small chainrings.

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The torque at the rear will be the torque applied at the crankset times the gear ratio, so if the gear ratio is the same the torque will be the same. There is a small difference due to lower losses in a big ring but this works in the opposite direction.

There’s nothing magical about torque, it’s just the rotational analogy of force. Just as power = force x linear speed, power = torque x rotational speed. Since the ratio of rotational speeds of the crank and wheel are identical for identical gear ratios the torque will not change.

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I think the point was that when starting from a stop(light), if you’re in an equally low gear on either chainring, then shifting from the small to the big ring is fewer shifts than solely on the rear.

Back when I had friction shifting, that’s how I did it so I wouldn’t be reaching down to the downtube so often, but now since the front derailleur doesn’t shift as well, especially under power, I only shift the rear at stops. But it sure is a lot more cogs to grind through than back when I had a six speed freewheel.

I usually prefer a bigger ring just because the chain tension isn’t as high, so wear on the whole drivetrain is also proportionally less.

When I’m in the big ring approaching a red light, I’ll often just dump it into the small ring, so I can quickly accelerate back up to my previous speed and throw back up to the big ring once I’ve got the pedals turning over. Assuming the terrain after the light is the same as before, I’m back into the same rhythm, speed, and gear pretty quickly.

Similar to @M_McEwen1 above, when I had a 42t small (or middle) front ring, I could regularly spend a whole ride in that gear, especially on relaxed group rides etc. and only switch up to the 52 when really in a hurry somewhere.

Now I’m on a compact on both my road bikes, and I’ll very rarely be in the small ring. I don’t like to cross-chain past 34x14 (on a 12-27 cassette), and that’s really not a gear for riding on the flat.

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