Jim’s Tech Talk
by Jim Langley
Recently, RoadBikeRider.com supreme leader Lars Hundley, former head John Marsh and yours truly were trading emails discussing new developments in road bike gearing options. SRAM had just announced their new for 2019 AXS 12-speed parts group with its X-Range gearing.
The most interesting feature of this innovative drivetrain is the use of a 10-tooth smallest cassette cog (versus the 11-tooth that is the current high gear standard). In part, thanks to that 10 tooth cog, SRAM’s X-Range offers wider gearing (higher high gears and lower lows), more closely spaced steps with each shift, smoother shifting, and it saves a little drivetrain weight, too.
SRAM’s X-Range boasts some pretty unique cassette and chainring choices. For the former, there’s a 10/11/12/13/14/15/16/17/19/21/23/26, 10/11/12/13/14/15/16/17/19/21/24/28 and 10/11/12/13/14/15/17/19/21/24/28/33 cogset (all 12-speed). And on the SRAM Red AXS Power Meter crankset you choose from a 46/33, 48/35 and 50/37.
If you’re interested in learning more about SRAM AXS and how your gearing compares to theirs, they’ve got an online gear calculator that will show you their calculation of how much wider, smoother and smarter (SRAM’s word, not mine), their X-Range is.
Knowing Your Gearing
If all this gearing talk has you wondering about the range of your drivetrain, the easiest to use online gearing calculator I know of is on United Bicycle Institute’s site here: https://bikeschool.com/index.php/resources/gear-calculator.
To use it, simply count the number of teeth on your cassette cogs and chainrings (often the number is written on them but it can be hard to see). Then plug your cog and ring numbers into their calculator, choose your wheel size (probably 700C), hit Submit and their My Custom Gear Chart will display what you’re running.
Knowing your numbers is helpful when you consider different cassettes, chainrings or new drivetrains.
My New Easier Gearing
I haven’t had a chance yet to try SRAM’s new gearing. But, I told Lars and John when we were discussing it that – related to their 46/33 crankset with 10-33 cassette – I understood and appreciated having lower gearing. Here are my observations.
Road gearing has gradually gotten easier as cranksets with smaller chainrings have become more available and common. While at one time most road bikes came equipped with 53/39 cranksets (and before that 52/42), it’s now more common to see 50/34s. SRAM goes a little lower with their 33.
I have been riding a 50/34 crankset for about a year on my Cervelo S5. But, I recently went to a 48/32 Praxis Zayante Carbon crankset and kept the same 11-28 11-speed cassette I’ve been using right along. To accept the 32T ring, the Praxis crankset’s spider has two different chainring bolt circles, one for large rings, the other for small. (Full disclosure: I work at Praxis.)
The reason I shrunk my chainrings was for the steep climbs we have here. But, I was worried that the lower/easier 32 x 28 versus 34 x 28 lowest gear would cause me to have to pedal too quickly over-revving my legs and heart and I would struggle to keep up with the group I normally find myself with on the long climbs.
Yet, luckily for me, that hasn’t been the case. I do spin faster – I felt that right away. But that doesn’t seem to cause problems. It takes a little getting used to going from about a 87-90 rpm cadence to 93-97 rpm, but it doesn’t hurt much different, maybe a little less actually. Note that on the steepest stuff, I can’t pedal in the 90s, but I am still pedaling more quickly than with the 34.
Harnessing Heart Power
The thing I’m finding fun and surprising with this lower gear, faster cadence cycling – and especially climbing, is how it takes the pressure off the legs and switches it to the heart. For years on the hills, I would beat up my legs to hang. As I’ve aged, I’ve had to back off and slow because of the discomfort from pushing the legs so hard.
With the lower gearing and faster spin, I have significantly less leg pain. It feels like I’m no longer muscling up the hill with my legs, but just spinning faster and breathing harder. There’s a little discomfort from breathing more rapidly and focusing on keeping the cadence high but my legs never give out on me because I’m not pushing all that hard anymore.
This may not be entirely accurate physiologically, but I believe I’ve discovered something I maybe should have realized a long time ago. Which is that the heart may be a better, more dependable muscle to use for hard efforts than the legs. And, there’s no question that the heart has had more conditioning over the years than the legs, too. So, in theory at least, it could indeed be stronger.
Choosing The Right Gearing
The key thing in order to take pressure off the legs is to have the right gearing. This has to do with where and how you ride and your fitness level. But it’s an easy call.
All you have to do is pay attention to your average pedaling cadence. If you bog down on rides and have to put excessive pressure on the pedals to keep going, you will probably improve your riding performance by switching to smaller rings or larger cogs or both. Even better, you’ll likely start enjoying riding more, too.
When Training With Watts
One last lower gearing observation for those who do watt-based training using a power meter. I think you’ll find that it’s easier to focus on the RPM (cadence) reading on your device display rather than on the WATTS reading during hard efforts. By easier I mean less mentally challenging.
When watching watts, the number usually starts out high and then drops, sometimes to depressing numbers. As you tire, you may not be able to get it back up. That can be frustrating.
But, when watching Cadence, you get to shift into easier gears and spin faster versus push harder, so you are usually maintaining and feeling pretty good. Your watts may drop but they won’t drop as much and you’ll stay more motivated during the workout/ride.
Ride total: 9,205
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 8,000. Click to read Jim’s full bio.