Track gearing
01/11/22 21:13 Filed in: Gear
I recently wrote about road gearing. In the aftermath of Ganna's amazing Hour Record recently, track gearing has been a topic of conversation amongst my cycling friends. So I decided to write about that today.
English speaking cyclists tend to reckon in "gear inches". Which is an arcane measure of how big the front wheel of a Penny Farthing would be if you were riding one! Because they were direct drive, the biggest wheel that could fit between your legs was the size you used (assuming you could afford to commission a brand-new custom bike back 150 years ago). A 700C road bike wheel is roughly 27" in diameter. Of course this depends on the tyre size (a 42mm gravel tyre is MUCH bigger than a 20mm track tyre on the same rim). But this reckoning is strangely tyre independent.
I ran a "fixie" commuting bike for a while. Fixed-wheel bikes demand that you pedal as long as and as fast as you are moving. So a particularly small gear requires lots of leg speed, particularly down a longer hill. Conversely a bigger gear demands leg strength on the way up any hill. For a few weeks my gear selection on the commuter was a ridiculously small 39/17 gear combo: 61". I then tried 52/13, which is a crazy big gear: 108". It was a couple of weeks before I was able to muscle up the hill to my home, but I was happy to finally make it up there.
On a Friday afternoon about 3 km from home I decided I had had enough of commuting on a fixed-wheel bike and resolved to swap back to gears over the weekend (before going to work on Monday). The decision was taken away from me when the light turned green. As I stood to power away from the intersection, the threads on the hub holding that 13T sprocket in place sheared off for good to end my fixie fixation. I scootered home and replaced the drivetrain on the bike with gears.
There are no hills on a velodrome, but acceleration is critically important to racing success. So, a gear in the high 80s would be a typical warm-up gear. Then, a gear in the low 90s would be good for actual racing. At an event like Nationals these tend to go up a little because everyone is riding faster and is fitter, plus the good wheels come out for these occasions; allowing bigger gears. The big change in world level track racing in this century is going to bigger gears and going much faster. I remember when the team pursuit first went under 4:00 for 4000m, but now the individual pursuit has also gone under 4:00. In the 90s, Graeme Obree could often catch national teams in demo events where he raced them solo: his ability to do a sub-4:20 time put him on par with a decent team pursuit team.
For the Hour Record, Ganna used 65/14. That's about 125 inches. Much bigger than anything I've ever used, even in fun. I remember trying out different gearing for club track racing and one night I threw 108" on the bike and managed to get a gap over the field in the final scratch race of the night and no one could catch me thanks to my big gear. On the pursuit side I turned nearly identical times on everything from mid-90s inches up to 110" because the limiting factor was neither strength nor fitness; but power. A Watt is a Watt and it takes more Watts to go faster no matter how fast or slow you turn your legs over.
But if you watch the 5 minute highlight video (or the entire hour replay) for Ganna's record ride, he starts out very slowly. He's young and strong and fit but that gear is still a huge effort to get going. Ganna's speed works out to 15.75 m/s average. Or 945 m/min. Or roughly 450 wheel rpm (obviously tyre size dependent but that won't change too much regardless of what rear tyre he ran-maybe 5%). With his gearing selection that is a very comfortable 105 rpm for his legs. In contrast, on a 90" gear (50/15) that's more like 136 rpm. I can do my FTP output for an hour at 105 rpm. I can do it at 136 rpm for maybe 1 minute before something in my legs tightens up and I have to slow down.
So 125" is a huge gear, no doubt. But it is right in the sweet spot for a good track rider to pedal for 60 minutes. Which suggests if you plan to ride 57 km in 60 minutes you need an amazing combination of fitness and strength permitting use of such a monster gear choice.
English speaking cyclists tend to reckon in "gear inches". Which is an arcane measure of how big the front wheel of a Penny Farthing would be if you were riding one! Because they were direct drive, the biggest wheel that could fit between your legs was the size you used (assuming you could afford to commission a brand-new custom bike back 150 years ago). A 700C road bike wheel is roughly 27" in diameter. Of course this depends on the tyre size (a 42mm gravel tyre is MUCH bigger than a 20mm track tyre on the same rim). But this reckoning is strangely tyre independent.
I ran a "fixie" commuting bike for a while. Fixed-wheel bikes demand that you pedal as long as and as fast as you are moving. So a particularly small gear requires lots of leg speed, particularly down a longer hill. Conversely a bigger gear demands leg strength on the way up any hill. For a few weeks my gear selection on the commuter was a ridiculously small 39/17 gear combo: 61". I then tried 52/13, which is a crazy big gear: 108". It was a couple of weeks before I was able to muscle up the hill to my home, but I was happy to finally make it up there.
On a Friday afternoon about 3 km from home I decided I had had enough of commuting on a fixed-wheel bike and resolved to swap back to gears over the weekend (before going to work on Monday). The decision was taken away from me when the light turned green. As I stood to power away from the intersection, the threads on the hub holding that 13T sprocket in place sheared off for good to end my fixie fixation. I scootered home and replaced the drivetrain on the bike with gears.
There are no hills on a velodrome, but acceleration is critically important to racing success. So, a gear in the high 80s would be a typical warm-up gear. Then, a gear in the low 90s would be good for actual racing. At an event like Nationals these tend to go up a little because everyone is riding faster and is fitter, plus the good wheels come out for these occasions; allowing bigger gears. The big change in world level track racing in this century is going to bigger gears and going much faster. I remember when the team pursuit first went under 4:00 for 4000m, but now the individual pursuit has also gone under 4:00. In the 90s, Graeme Obree could often catch national teams in demo events where he raced them solo: his ability to do a sub-4:20 time put him on par with a decent team pursuit team.
For the Hour Record, Ganna used 65/14. That's about 125 inches. Much bigger than anything I've ever used, even in fun. I remember trying out different gearing for club track racing and one night I threw 108" on the bike and managed to get a gap over the field in the final scratch race of the night and no one could catch me thanks to my big gear. On the pursuit side I turned nearly identical times on everything from mid-90s inches up to 110" because the limiting factor was neither strength nor fitness; but power. A Watt is a Watt and it takes more Watts to go faster no matter how fast or slow you turn your legs over.
But if you watch the 5 minute highlight video (or the entire hour replay) for Ganna's record ride, he starts out very slowly. He's young and strong and fit but that gear is still a huge effort to get going. Ganna's speed works out to 15.75 m/s average. Or 945 m/min. Or roughly 450 wheel rpm (obviously tyre size dependent but that won't change too much regardless of what rear tyre he ran-maybe 5%). With his gearing selection that is a very comfortable 105 rpm for his legs. In contrast, on a 90" gear (50/15) that's more like 136 rpm. I can do my FTP output for an hour at 105 rpm. I can do it at 136 rpm for maybe 1 minute before something in my legs tightens up and I have to slow down.
So 125" is a huge gear, no doubt. But it is right in the sweet spot for a good track rider to pedal for 60 minutes. Which suggests if you plan to ride 57 km in 60 minutes you need an amazing combination of fitness and strength permitting use of such a monster gear choice.