I gotta say it: I love singlespeeds. There’s just something about how darn simple they are that just tickles my fancy: Everything you need and not a single ounce more than you don’t to ride! I’ve built hardtails for myself that could take gears, but when I’m honest with myself… I’ve got a geared bike in my Snakedriver FS and when it comes to a hardtail, give me a dedicated singlespeed. Full commitment with this one. Waxing over dedicated singlespeeds aside, over the years I’ve built my fair share of prototypes for myself, honing in on geometry and handling but also “perfecting” my fit. I put that word “perfecting” in quotes on purpose. Over the course of those 30 plus prototypes, my fit (so saddle tip to center of handlebars) went from short and upright to quote long and stretched out only to shrink back to just about where I started. And along the way, I’ve taken notice that window of “fit” seems to be around 1-1.5″ of what I’ll tolerate comfortably. That window basically represents how the front center has grown as my stem has gotten shorter (from 90mm down to 30mm..), travel has increased (120mm now up to 140mm) and how the head tube has gotten slacker (70° to now 66°, on my hardtail at least!). Those are quite some changes but that is what progression does: It is a crucible of change.
I did a deep dive into geometry definitions and how those all relate to handling characteristics. If you haven’t read this piece, its a good read worth your time. One of those areas I’ve been fiddling with is 2 fold: Wheelbase and how front center and rear center play with handling characteristics. In short, over time, I’ve noticed that as front center has grown, rear center (or rather chainstay length) must follow too. Read: It needs to get longer too. But how much longer? I settled on 16.75-16.9″ slammed. When a 32×20 combo is tensioned, the chain length determines two distinct lengths which are dictated by link length. The first is 16.5″ / 419mm. So slammed I’d build to 16.45″ and that leaves just a hair of room to tension a new chain and allow for a lot of chain growth. That next jump? You need to add two links, and that length is approximately 17″ / 432mm. So that’s where I landed which has actually been a revelation coming from my Snakedriver project. Longer chainstays allow for less chain crossover in a geared setup, so less time the chain is cross over, the less wear you have on your drivetrain, which can be exasperated with newer 12 speed setups and those large cassette cogs. I’m actually still on the same chainring and cassette over the course of 3 prototypes. There’s wear, but the system still very much has a lot of life left in it. But that longer chainstay length on a singlespeed and hardtail didn’t effect handling in tight terrain or make the bike any less snappy. I found it only aided in smoothing out the ride quality and making hits less abrupt. But with that growth in front center due to slackening up the head tube and moving to a short stem (30mm, I don’t want to go shorter than that…), I felt as though I needed to real in front center, keep my head tube angle the same (66° for a hardtail). So where am I going to find some real estate? Really the only thing that can budge now is my cockpit length. Building up several Snakedriver prototypes this whole time showed me that not only could I shorten up my cockpit, I actually needed to since the front centers on the bikes were SO darn long which made maneuvering the bikes a chore, especially as slow speed. I knew that comfortable number could be as short as 19.5″ or even slightly less for me. 20″ seemed to be the new sweet spot. Shortening all this up now resulted in a front center of approximately 30.5″ / 775mm with a rear center of 17″ / 432mm and a wheelbase of 47.5″ / 1207mm.
Out on the trail? Ok.. this bike has that pop of those first handful of prototypes. And by “POP”, I’m talking about the ability to very quickly pick up the front end and man handle the bike up and over obstacles both at speed and at a crawl. Especially at a crawl, which a lot of the terrain here in New Hampshire seems to have situations where you’re churning up a short punchy climb, and behold! There’s a rock yonder that you need to pop up and over. Those longer front centers I was facing made that sequence of moves arduous. That pop of those first bikes I built which had very short front centers now was back in full effect, but with a relatively long wheelbase, longer front center, slack front end and short stem. All this translates to more stability at speed, the bike “wanting” to seek a straight line but is still incredibly maneuverable in tight techy situations and your hands being very close to the axis of steering so less input by the rider to bring the bike back under control, you can lean that bike hard too through corners and you’re no longer really “steering” the bike by pushing with your weight but rather pulling with your weight (short stems/long front center/slack head angle puts your hands just behind the steering axis when you drop a vertical line from handlebar center – I’ve found this really eases input from the rider and how it effects handling – basically look at your hands in space in relation to stem length and head tube angle and you’ll have your answer). The below diagram helps show whats going on now:
This is all a balancing act. In my hardtail, I’m looking for a well rounded bike. One that climbs and descends equally well while delivering a lot of playfulness in between those hills and descents. So the questions become: How much can you get away with in wheelbase and front center before the bike becomes too long and adversely effects the bikes handling characteristics that you’re looking for? How slack of a head tube angle can you get away with before the bike moves from being good at climbing and descending before its too biased to descending? How short can your cockpit be before you’re feeling cramped up and find yourself trying to find length where there’s none to be found? Building out the Snakedrvier project and dealing with moving parts aided me in finding those limits and windows. The knowledge I gathered and experiences I had with the FS project forced me to think of these issues from different angles I normally wasn’t viewing them from. I transferred that knowledge and experience over to my hardtails and applied those concepts but looking through a lens of a hardtail rider. And that unlocked a lot of possibilities I wouldn’t have imagined previously. Progression as I said truly is a crucible for change!
PS: Aside from the geometry and handling features I updated with this latest prototype (which basically is a stock Marauder large for the record), I also made some improvements and refinements to the yoke design. Internally, it now has a strut much like an i-beam but on its side inside of a circle. So laterally its quite stiff (internal testing showed me that the tubes fail long before the yoke). I also made refinements to the overall shape of the yoke in the vertical plane with improved surfacing and transitions to match my formed chainstays (basically reverse engineering that process). The last and most important update was smoothing out the transition from 22mm to the cutaway that achieves chainstay clearance. Here’s a few close ups of that new yoke design (some of the images appear to show the chainring quite close to the yoke – its the camera angle, there’s about .25″ / 6mm of clearance between the chainring teeth and yoke):
PPS: And of course… My vanity project of an ALL matte black fork is finally realized. Thanks to Fox for finally offering some black top caps!
Dedicated Singlespeed
I gotta say it: I love singlespeeds. There’s just something about how darn simple they are that just tickles my fancy: Everything you need and not a single ounce more than you don’t to ride! I’ve built hardtails for myself that could take gears, but when I’m honest with myself… I’ve got a geared bike in my Snakedriver FS and when it comes to a hardtail, give me a dedicated singlespeed. Full commitment with this one. Waxing over dedicated singlespeeds aside, over the years I’ve built my fair share of prototypes for myself, honing in on geometry and handling but also “perfecting” my fit. I put that word “perfecting” in quotes on purpose. Over the course of those 30 plus prototypes, my fit (so saddle tip to center of handlebars) went from short and upright to quote long and stretched out only to shrink back to just about where I started. And along the way, I’ve taken notice that window of “fit” seems to be around 1-1.5″ of what I’ll tolerate comfortably. That window basically represents how the front center has grown as my stem has gotten shorter (from 90mm down to 30mm..), travel has increased (120mm now up to 140mm) and how the head tube has gotten slacker (70° to now 66°, on my hardtail at least!). Those are quite some changes but that is what progression does: It is a crucible of change.
I did a deep dive into geometry definitions and how those all relate to handling characteristics. If you haven’t read this piece, its a good read worth your time. One of those areas I’ve been fiddling with is 2 fold: Wheelbase and how front center and rear center play with handling characteristics. In short, over time, I’ve noticed that as front center has grown, rear center (or rather chainstay length) must follow too. Read: It needs to get longer too. But how much longer? I settled on 16.75-16.9″ slammed. When a 32×20 combo is tensioned, the chain length determines two distinct lengths which are dictated by link length. The first is 16.5″ / 419mm. So slammed I’d build to 16.45″ and that leaves just a hair of room to tension a new chain and allow for a lot of chain growth. That next jump? You need to add two links, and that length is approximately 17″ / 432mm. So that’s where I landed which has actually been a revelation coming from my Snakedriver project. Longer chainstays allow for less chain crossover in a geared setup, so less time the chain is cross over, the less wear you have on your drivetrain, which can be exasperated with newer 12 speed setups and those large cassette cogs. I’m actually still on the same chainring and cassette over the course of 3 prototypes. There’s wear, but the system still very much has a lot of life left in it. But that longer chainstay length on a singlespeed and hardtail didn’t effect handling in tight terrain or make the bike any less snappy. I found it only aided in smoothing out the ride quality and making hits less abrupt. But with that growth in front center due to slackening up the head tube and moving to a short stem (30mm, I don’t want to go shorter than that…), I felt as though I needed to real in front center, keep my head tube angle the same (66° for a hardtail). So where am I going to find some real estate? Really the only thing that can budge now is my cockpit length. Building up several Snakedriver prototypes this whole time showed me that not only could I shorten up my cockpit, I actually needed to since the front centers on the bikes were SO darn long which made maneuvering the bikes a chore, especially as slow speed. I knew that comfortable number could be as short as 19.5″ or even slightly less for me. 20″ seemed to be the new sweet spot. Shortening all this up now resulted in a front center of approximately 30.5″ / 775mm with a rear center of 17″ / 432mm and a wheelbase of 47.5″ / 1207mm.
Out on the trail? Ok.. this bike has that pop of those first handful of prototypes. And by “POP”, I’m talking about the ability to very quickly pick up the front end and man handle the bike up and over obstacles both at speed and at a crawl. Especially at a crawl, which a lot of the terrain here in New Hampshire seems to have situations where you’re churning up a short punchy climb, and behold! There’s a rock yonder that you need to pop up and over. Those longer front centers I was facing made that sequence of moves arduous. That pop of those first bikes I built which had very short front centers now was back in full effect, but with a relatively long wheelbase, longer front center, slack front end and short stem. All this translates to more stability at speed, the bike “wanting” to seek a straight line but is still incredibly maneuverable in tight techy situations and your hands being very close to the axis of steering so less input by the rider to bring the bike back under control, you can lean that bike hard too through corners and you’re no longer really “steering” the bike by pushing with your weight but rather pulling with your weight (short stems/long front center/slack head angle puts your hands just behind the steering axis when you drop a vertical line from handlebar center – I’ve found this really eases input from the rider and how it effects handling – basically look at your hands in space in relation to stem length and head tube angle and you’ll have your answer). The below diagram helps show whats going on now:
This is all a balancing act. In my hardtail, I’m looking for a well rounded bike. One that climbs and descends equally well while delivering a lot of playfulness in between those hills and descents. So the questions become: How much can you get away with in wheelbase and front center before the bike becomes too long and adversely effects the bikes handling characteristics that you’re looking for? How slack of a head tube angle can you get away with before the bike moves from being good at climbing and descending before its too biased to descending? How short can your cockpit be before you’re feeling cramped up and find yourself trying to find length where there’s none to be found? Building out the Snakedrvier project and dealing with moving parts aided me in finding those limits and windows. The knowledge I gathered and experiences I had with the FS project forced me to think of these issues from different angles I normally wasn’t viewing them from. I transferred that knowledge and experience over to my hardtails and applied those concepts but looking through a lens of a hardtail rider. And that unlocked a lot of possibilities I wouldn’t have imagined previously. Progression as I said truly is a crucible for change!
PS: Aside from the geometry and handling features I updated with this latest prototype (which basically is a stock Marauder large for the record), I also made some improvements and refinements to the yoke design. Internally, it now has a strut much like an i-beam but on its side inside of a circle. So laterally its quite stiff (internal testing showed me that the tubes fail long before the yoke). I also made refinements to the overall shape of the yoke in the vertical plane with improved surfacing and transitions to match my formed chainstays (basically reverse engineering that process). The last and most important update was smoothing out the transition from 22mm to the cutaway that achieves chainstay clearance. Here’s a few close ups of that new yoke design (some of the images appear to show the chainring quite close to the yoke – its the camera angle, there’s about .25″ / 6mm of clearance between the chainring teeth and yoke):
PPS: And of course… My vanity project of an ALL matte black fork is finally realized. Thanks to Fox for finally offering some black top caps!