Tech Tuesday: Why Is It So Hard To Reinstall Saddle Rails?

Note to reader: WTB does not recommend any attempt to repair a saddle either at home or on the trail. If a saddle rail pops out of the socket, it’s possible the base, rail sockets and/or rails themselves could be damaged. Trying to repair the saddle could lead to saddle failure, resulting in injury. If a WTB saddle is damaged in this way, the rider should submit a warranty claim through WTB customer service. The topics in this article merely discuss past experiences. This article serves to provide background on the installation process at the factory as well as explain why it is so difficult to perform such a repair.

Chances are, if there’s a component on your bike that you’re unable to take apart and put back together yourself, you shouldn’t ever need to or want to. Bend one side of your derailleur’s parallelogram, and you’ve probably bent all four. Blow the damper on your rear shock, and you’ll be better off leaving the repair to the experts. But pop a rail out of your saddle in a crash? How hard could that be to fix?

Well, if you’ve ever tried, you know: It’s really goddamn hard. The moment you line up the pieces, it becomes clear that there’s got to be some magic trick to it, like one of those trapped-ring puzzles. Or maybe it’s a more industrial trick, like the rails are shaped at the same moment that the’re attached to the saddle. Or maybe they’re partially inserted into the injection mold while the saddle’s plastic base is created. The truth, it turns out, is a lot simpler.

I spoke with Mark Slate, co-founder of WTB, to compare our experiences dealing with the mysteries of the saddle / rail relationship. Not surprisingly, he’s had more of those experiences than I have. But very surprisingly, we’ve each, at some point, found ourselves in a pinch, needing to mend a rail dislocation without a replacement saddle or a specially made hydraulic press at our fingertips.


“It’s a slippery operation if you’re by yourself,” he warns. “It takes some real leverage, but I’ve done it.” The most important thing to remember if you really want to fix a saddle yourself is that the final step needs to be inserting the front end of the rail assembly. It’s pretty hopeless to try and re-insert a rail at one of the sockets in the rear. Unfortunately, though, that’s where they tend to pop out. Likely because it’d be unlikely for the underside of the saddle nose to hit the ground in a crash. But if a bike goes ass-over-tea kettle, the rear of the saddle is in harm’s way, and anything can happen.

You need to start by removing the one rail that’s still inserted in the rear socket, which is no easy task in itself. But it is possible thanks to the added flexibility offered by a partially dismembered saddle. With the saddle upside down and the foremost two inches of the nose secured to the edge of a solid surface (I used a woodworking clamp and a sturdy workbench), you just need to pull up on the rail while pushing down on the rear edge of the saddle. Really hard. I recently went through this process on a WTB Volt saddle, and it became clear why you need to go nose-last if you ever want to get back in that saddle again. On the Volt, the rails are inserted about 18 millimeters into the rear sockets, but the bend that tucks into the nose of the saddle went in only about 14 millimeters.


The re-assembly process works a bit like using a shoehorn to get your heels into a stiff pair of wingtips. A flat wide tool like a motorcycle tire lever is probably ideal. Using a clamp or, better yet, an extra set of hands, secure the saddle upside down to a flat surface, putting something underneath it to force it to flex. Like laying on a therapeutic roller to stretch your back. Press down on the nose, hook your tool into the cavity where the front end of the rails belong, and arch it towards the rear of the saddle, pushing against the nose of the rail assembly and letting it slide down into place. This, of course, is also really hard.

At the factory, Slate says it’s a lot simpler. “Basically, we fit the two ends in the rear sockets with the rail clamped securely, and then the shell gets bumped from the top with the pad and cover already in place.” There’s no standard rail-installation machine, though, so some manufacturers do it differently. Often, it’s a high-tech version of the DIY shoehorn method, but they’re all fundamentally the same process. There’s enough flex in the saddle shell itself that the two pieces can be connected in the blink of an eye. Ironically, though, it’s exactly because this method is so easy that repairing a saddle is so hard.


“We have had saddles in the past with screw-in nose parts. Saddles where the rear tips plug in, and a cap screws into a hidden t-nut at the nose to hold the rails in,” explains Slate. “That makes sense for the idea of having people more easily change rails, but it costs more. A lot of what we do in the saddle game is OEM.” It’s a winning proposition for a brand to get their parts specced as original equipment on complete bikes. Volume is higher and overhead is lower, but Slate says the competition is fierce. “You’re so often fighting with cost and profit margin. It gets pretty brutal, so we’ve gotten away from doing bolt-in rails.”

That doesn’t mean Slate is totally satisfied with the system that’s in place now. He made mention of WTB experimenting with SDG’s I-Beam interface, but that it made it too difficult to engineer any natural flex in the saddle, so nothing ever went to production. He also liked aspects of the Pivotal interface, which dominates in the BMX world, but lacks adjustability as well as any natural flex.

Then, in a reminder that no standard is safe, Slate daydreamed about a sky-is-the-limit approach to saddle design. “It sure seems to me that there should and could be a better way to do it. It would certainly be more cost, but the way I look at it, if you’re going to throw away the playbook and just get what you really want, wouldn’t you want a saddle that’s like your car that was electrically adjusted and could tilt and go fore / aft and perfectly position you? That’s the sort of thing that I think would be a nicer embodiment of the structure.” Of course, WTB isn’t actually working on an auto-tilt saddle, but if they were, it may actually be easier to repair than what we have now.

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