By Jim Langley A couple of great questions came in in response to last week’s Tech Talk, which provided tips to help new road cyclists conquer any “gear fear” – the fear of shifting their derailleur-equipped bike. We’ll answer those questions today.
But first, I wanted to share something else that happened as a result of our shifting tips because it’s pretty cool. This past weekend I was contacted by my friend Leo Jed, who serves on the Santa Cruz Regional Transportation Department’s Bike Committee with me.
I didn’t know this until he contacted me, but Leo’s also one of the instructors of the Almaden Cycle Touring Club’s ACTC Academy, a 12-week program for teaching new cyclists safe road riding. Leo reached out to ask permission to share our tips to their students and incorporate them into the school’s curriculum.
The ACTC is among the largest clubs in the South Bay of California (greater San Jose area). They were founded over 40 years ago, now have over 1,1000 members and put on over 150 rides a month! They also host the spectacular Tierra Bella Bicycle Tour https://tierrabella.org/index.php , which I rode a few times many years ago and enjoyed a lot. If you live in or near San Jose and are looking for some friendly folks to ride with, check out the ACTC http://www.actc.org/clubinfo/ .
Two Bicycle Shifting Questions
Crossing the chain
The first query came in from a roadie named “Stew,” who asked, “I was cautioned against “crossing” my chain. That is, using the largest ring with the largest cog, and conversely, using the smallest ring with the smallest cog. I don’t know if this is a concern any longer for folks with electronic shifters, but for most mechanically shifted bikes, I believe it puts undue stress on the chain and cassette, shortening their lifespans, and isn’t really the “right” way to shift. Do I have this right?”
That’s a great issue to discuss and understand, “Stew,” thanks for asking. The first thing to knowis that this isn’t an issue on 1x (say “one-by”) drivetrains – those with a single chainrings. It’s only something that can occur on drivetrains with multiple chainrings.
“Crossing your chain,” sometimes called crosschaining or “being in a crossover gear,” is when the chain is on the two extreme gears on the bike. They put the chain at the widest angle in relation to the sprockets and this can result in noise, the chain rubbing on the derailleur, and faster component wear.
To appreciate why this is, try putting your bike in one of these extremes while holding the bicycle off the ground and pedaling by hand. Then stand next to the bike positioned so that you can look directly down at the chain and sprockets.
Whether you shifted into the big chainring, big cog combination or the small/small combo, you will see the same issue. First notice that the chainrings (front sprockets) and the cassette cogs (rear sprockets) are parallel to the centerline of the bicycle. Next look at the extreme angle the chain makes between the two sprockets it’s on. It should be pretty obvious that the gear combination puts the chain at super wide angle and it is no longer running anywhere near parallel to those two sprockets it’s on.
However, how bad riding in these crossover gears is depends on the specific frame and components on the bike. On some bikes it shouldn’t cause many problems and might not even be noticeable when riding. On others it can be so bad you know right away from the noise and crunchy pedaling that you’ve shifted into an “unhappy” gear.
One way you can end up shifting into these gears by mistake is by not paying attention as you shift. For example, on a nice descent during a ride you will probably shift onto the large chainring. If the ride continues for awhile on fast terrain, you will shift a few times with the rear derailleur to fine tune the pedaling effort. And then, if you encounter a climb, you might forget you’re on the large chainring and keep shifting all the way up the cassette to what you think is your easiest gear – not realizing that you forgot to shift onto the small chainring.
I’m a very experienced roadie and I still make this mistake – usually when I’m tired. But sometimes, It’s easier to put it in that gear and get over a short section at the top of a climb than to shift to the small chainring. Because a derailleur shift is quicker.
Still, to be safe I recommend riders try to avoid those 2 extreme crossover gears, and to stay aware when shifting so they don’t mistakenly shift into them. Yet, if they actually work fine, without noise, rubbing or grinding, then it’s okay to use them sometimes. Just know that some drivetrains are much more tolerant of crossover gearing than others.
If you do experience crossover gearing issues, note that on most road bikes, there are usually other gearing choices that aren’t extreme that offer about the same pedaling effort.
Tip: To determine exactly what gears you have on your bike, requires doing a little math. Here’s a nice online gear calculator to help:http://www.bikecalc.com/gear_inches
Shift cable concern?
The second question was from George, who asked, “I was told by a rider with a lot more experience than I have to always shift onto the smallest front chainring and smallest cassette cog when I getback from rides. The reason is because leaving the bike in gear, puts stress on the shift cables and derailleur springs and it can cause the cables to stretch and the derailleurs to wear out too quickly. Is this true?”
I’ve run into riders who believe this, too, George. But, it’s not something I would tell newbies to worry about if I was mentoring them. Note that electronic drivetrains use wires not cables (or are wireless). Wires don’t stretch, so it’s a moot point with electronic bikes.
But, for road rigs with shift cables, as long as they were installed correctly, they should be properly pre-stretched and tensioned and unlikely to stretch much if at all once you’ve logged about a month of rides. Most new bikes come from the bicycle shop with a 30-day check where they will inspect the cables and fine tune the tension if they stretched. Once that’s complete, it’s unusual for cables to stretch more.
Also, if a shift cable were to stretch slightly, on most road bicycles today it’s a simple matter to turn a cable adjustment barrel by hand and remove the slack. And, once they’ve stretched, they won’t keep stretching.
With the derailleurs, I have never seen any issues from leaving them “in gear” when parked or stored. So, I wouldn’t worry about either of this issues and see it as unnecessary.
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.