The reason you can get away with a 1x in MTB and gravel is speed and grade. At low speeds and going uphill, torque is readily available to get the job done because there is so much resistance for your legs to work against. At high speeds, the momentum of the wheel is already "running away" from you so much, it's more about keeping an ideal cadence for human legs than torque. To do so, you need a bunch of gears up top with very fine jumps in teeth. Notice the jumps in teeth for your lowest gears on MTB are huge compared to a road bike.
Proof in point, notice that as gravel gets way faster as people truly start to race it, elites are opting for double chainrings. A lot of us are riding gravel at 14 mph on a good day, but pros are racing at 20+ easy.
Higher speeds require finer teeth spacing and bigger front chainring, but that's incompatible with also the times when it gets steep and gnarly, so we revert back to what we know works - a double instead of a single. Also think of the distance covered per pedal stroke at high speeds are way bigger than at low, so just a few teeth increase at low speed is fine, but too massive to overcome at high speed.
So the physics has worked out to - low speed is great with big teeth jumps. High speed needs tiny tooth jumps. And that's why a single chainring is a problem if you're using a bike for both.
As I've gotten better (faster) at gravel, I'm starting to see where I could benefit with a double front or a Classified hub. My current gravel bike is very optimized from 1 to 17 mph, but the higher I go than that, the cadences get wonky to keep up the pedal pressure at ideal cadences I'm used to from my road/tri bike. I ride about 50/50 gravel/road, so there's plenty of times where I'm coasting on pavement or at a weird cadence that is definitely sub-optimal.
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Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com
Proof in point, notice that as gravel gets way faster as people truly start to race it, elites are opting for double chainrings. A lot of us are riding gravel at 14 mph on a good day, but pros are racing at 20+ easy.
Higher speeds require finer teeth spacing and bigger front chainring, but that's incompatible with also the times when it gets steep and gnarly, so we revert back to what we know works - a double instead of a single. Also think of the distance covered per pedal stroke at high speeds are way bigger than at low, so just a few teeth increase at low speed is fine, but too massive to overcome at high speed.
So the physics has worked out to - low speed is great with big teeth jumps. High speed needs tiny tooth jumps. And that's why a single chainring is a problem if you're using a bike for both.
As I've gotten better (faster) at gravel, I'm starting to see where I could benefit with a double front or a Classified hub. My current gravel bike is very optimized from 1 to 17 mph, but the higher I go than that, the cadences get wonky to keep up the pedal pressure at ideal cadences I'm used to from my road/tri bike. I ride about 50/50 gravel/road, so there's plenty of times where I'm coasting on pavement or at a weird cadence that is definitely sub-optimal.
----------------------------------------------------------
Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com
Last edited by:
ZenTriBrett: Feb 27, 23 8:13