So, two Sundays ago, I’m only six miles into the 62-mile Mount Hamilton Road Race — less than halfway up the opening and epic 19-mile climb (with 365 corners, one for every day of the year) — and I hear a “sproing!” Nope, not a broken spoke, a snapped titanium seat rail. Luckily for me, the other rail hung in there and I was able to finish, albeit with a sore left hip from sitting crooked for so long.
I really like the seat, a Selle Italia SLR with a full-carbon top, and like most quality road saddles these days, it cost a small fortune when I upgraded to it about five years ago. So I thought I’d try to fix it, maybe repair the rail by sticking a plug into the now two-part hollow rail, to join the broken pieces. But it was obvious that wouldn’t work because the seat could twist.
Then it occurred to me that I might be able to order a replacement rail and fix the seat that way. Yet, as I was unsuccessfully searching for rails, I realized that even if I could get the right one, it would be nearly impossible to install it. I know this because I’ve fixed a few el-cheapo cruiser seats over the years by prying the loose rail back in place with a screwdriver and even that was touch and go.
I decided my only option was to contact the Selle Italia distributor ProNet http://www.pronetcycling.com to see if they could fix my seat. And the conversations I had with ProNet’s saddle gurus, Mike and Bob Kalmbach, resulted in an education on rail repair and care that I’m sharing here because I think it can help a lot of roadies riding high-tech lightweight-rail saddles like mine.
Tip: Note that ProNet services only Selle Italia saddles, but the fact that they fix theirs suggests that your saddle maker might, too. The bike shop where you purchased your seat will probably know. Or, you can find the company online and contact them.
Why rails break
I’ve personally broken seat rails made of titanium, other alloys and steel, so I realize they’re vulnerable (I haven’t broken my only carbon-rail saddle, yet). I know that it’s important to install the seat so that the seatpost clamp is holding the center of the rails or within the markings found on the rails on many seats today. Otherwise, there’s too much pressure on the wrong part of the rails, which can contribute to failure.
What I didn’t know, and what Mike explained, is that some seatpost clamps don’t fit the rails correctly and can create stress risers that slowly but surely cause the rail(s) to break. In his 15 years of seeing broken rails, Mike says that 95% break within 1 to 3mm of the rail exit point from the seatpost clamp cradle. And he has observed some cradles less than 30mm in length (front to back), and side-clamping cradles, and both are more likely to break rails due to the short clamping surface and minimal rail support.
Tip: Mike and Bob also explained that riding technique and where you ride impacts rail longevity. Roadies who bounce their upper body with each pedal stroke stress the rails much more than smooth pedalers. Cycling over rough roads has a similar effect.
Save the rails!
If you’ve suffered a broken rail or are installing a new saddle, Mike and Bob recommend carefully inspecting the seatpost clamp and how it holds the rails. What you want is for the recesses in the top and bottom parts of the clamp to match the rail diameter exactly and to rest fully on the rails. If the recesses are under- or oversized, they will stress and could break the rail over time.
Also, seat clamps composed of an identical top and bottom are the way to go. These provide equal holding force on the top and bottom of the rails, fully supporting them. Clamps with different tops and bottoms usually concentrate the force on one part of the rail, which can lead to breakage.
Another problem-causer is clamps that are squared off at the ends (where the rails exit the clamp). Since the rails need to flex, the square clamp edges can eventually break the rail, the same way bending a piece of metal back and forth repeatedly can cause fatigue.
If your seat clamp is too short, doesn’t fit the seat rails correctly, clamps the sides of the rails, or has a different top and bottom, you should consider a new seatpost if you value your seat. If everything else checks out, but your seat clamp has squared off ends, the ProNet guys recommend carefully rounding the ends with a fine, round file so that the rails can flex more freely.
Tip: To prevent overtightening, which is another cause of rail problems, ProNet has a helpful saddle-rail torque chart on their website. They say that it’s critical to first lubricate the threads and head of the seatpost clamp bolts in order to get an accurate torque measurement.
After all my fussing, it only took ProNet a couple of days to fix my saddle and return it (the cost was $39.50 with free shipping; for anything except ti rails, it’s $24.50). Here’s the cool tool used to install the new rail: http://www.jimlangley.net/ProNetRailInstallTool.jpg
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.