SRAMcast - Gearing Revolution
How did drivetrain gearing design end up where it is today? How has it affected the riding experience? Where might drivetrain gearing go in the future? Daniel Slusser interviews SRAM’s Road Drivetrain Chief Systems Engineer, Anthony Medaglia in the latest SRAMcast to answer these questions. Listen to the interview or read an edited excerpt of the interview below.
Let’s start at the beginning. Bicycles started with one fixed gear, then evolved from one, to two, to three, etc. Today most road bikes have 22. From a performance standpoint, what are modern gearing options delivering that weren’t possible in the recent past? Fundamentally, why do we need gears on a bicycle? Are all the changes necessary or is this just a race to more?
Well, I think there's always been a need for wider gearing range and maintaining tight steps between the gears it's just been a matter of developing the technology to achieve that, whether it's a manufacturing or design process. Shifting has become so smooth and effortless now, especially with electronic shifting, that It makes it feasible to shift the gears a lot without incurring this huge burden of wasted time during a shift—like back in the day. With non-indexed downtube shifters, all the way to today where we have electronic shifting that changes at the touch of a button, shifting a lot is not really a problem anymore. And making the components that offer you all those gears, a wide range that is tightly packed, is now achievable. So, to achieve a wider range of gears while also maintaining tight steps, I think the answer you typically land on is the solution that you need more gears. As we've been able to achieve that over time, that's why you’ve seen an increase in the gear count.
So with these modern drivetrains, I think what we've really learned more than anything is that maybe we need to get outside of that mindset of thinking in terms of standard tooth counts and looking more at ratios between chainring and cogs? And nowadays we have all these different tire sizes and even wheel sizes now, in the road market and that plays into it as well.
It's more a game of ratios. I think a lot of people get fixated on tooth counts because it's familiar to us—that's what we're calibrated to. If you are used to riding 53/39 chainrings for years and then you throw something like a WiFLi cassette on there with an 11-30, you just have to go back and do the math to see what your equivalent rings in the front would need to be. It's just a little bit of math to do, but sometimes it's tough for people to let go of what's familiar to them. So anytime I’m faced with looking at a new cassette option versus new ringset option, I just go back and run the ratios and compare it to what I already know and make the comparison based off of that because oftentimes things like a single tooth on a 52 chainring has much less effect than a single tooth on the low end of your cassette. One tooth in 52 is not the same as one tooth in 50. We can all do the math on that, but sometimes people get caught up in tooth counts and that's not how it works.
Tire rollout plays a role as well. Everyone seems to be moving to 28’s these days. When you compare that to a 23, you're talking about the equivalent of almost a full tooth on a front chainring difference in gearing just from that larger circumference of the wheel.
Yeah, I think you want to look at the whole system. Everything from your chainring all the way back to your wheel diameter. So if you're changing any of those variables, you have to recalibrate what your gearing should be.
So you go to a 28c tire and your 53-tooth chainring just became a 54, effectively.
Yep, so you might need to regear.
With all these changes we’ve seen, is there still a place for traditional gearing?
I think that's a good question. Given what we know now, with the power of the data that you have—from the power meter, from your GPS, Strava—you can look at your time spent at what cadence, time spent at what speed, all the emerging physiological information we have and training data about what your cadence should be, how to tune your FTP, I think it really begs the question, ‘Does the normal rider really need super high gearing or super narrow range gearing?’ All of that information wasn't available a couple of decades ago, so I think back then it was more of an egotistical contest to see who could run the biggest chainring—not conceding that you need lower gears. I think the smarter rider will see through that and choose what's most appropriate and have a more enjoyable riding experience or go faster and win more races.
So if traditional gearing is going away, that begs the question, ‘What does the future hold?’
I think that on one hand the tooth counts that people are really familiar with and really calibrate on, the market has already shown that people are willing to look at other options. It's not all 53/39 anymore. It's not all 50/34 either. So I think there's an opportunity there to play around with tooth counts to achieve more favorable ratios. I think the other thing worth looking at is that people want to extend the range, possibly in the lower direction, they also want to maintain tight steps between the gears—they don't want big jumps. I think the technology and manufacturing processes and design processes are available to achieve that. So I think that's something that we might see coming down the pipe in the future.
So, translation: 2x isn't going away.
I don't think so.