The LH Thomson stealth and 27.2 dropper seatposts are both prototypes, but they show where the company’s heading.
The stealth version is further along and could be ready by the end of the year. Its the same cartridge as the original, just flipped. So all they need to finalize is the pull mechanism and put it through a little real world testing.
The 27.2 required a complete rework. The current cartridge wouldn’t fit in the tube, so the insides of the cartridge are placed directly into the slider shaft, and the upper part of the post become the shell of the cartridge. So, the machining has to be extremely precise. The other challenge is that the oil that makes it work is held in place by about 15 quad rings and O rings. And they have to hold back 200psi of nitrogen and oil. If one fails, the whole thing fails. The originals have more room or bigger seals – the 27.2 requires smaller parts, which are tougher to make as reliable. They’re hoping to have it out in the spring, but it’ll all depend on how we’ll it tests between now and then.
Drop in to see more pics and their new titanium riser bar…
They’re testing two different methods of cable routing. This one’s silver piece in the middle is shaped to hold the ball end of a shift cable, which would then feed to the lever, where it would be clamped tight. The alternative is to have the leading end of the cable at the lever like the current version, clamping at the bottom of the post.
As the cable pulls the silver piece out, an internal rod reciprocates by pushing into the cartridge, which releases it to drop or rise. The prototype lever is at the top and feeds the cable end into, then under, the lever, folds around and clamps so the end is facing away from your thumb. Our hunch is they’ll stick with the original so long as they can make a clamp for the bottom of the post strong enough to secure the cable over repeated pulling.
They’re also developing an inline barrel adjuster to take up slack in the line. It feeds directly into the lever.
A Titanium Riser Bar is hard to do. Thomson’s brand manager Dave Parrett says they put about 34 total hours of heat treating into it – 10 hours to prep it, 10 to soften it so they can work on it, then a final heat treatment to harden it.
The “work on it” part of that involves butting it to make it thick where it needs to be. At that point, the whole bar is 31.8 in diameter. Then they have to swage it to make the ends thinner to fit the grips. That pulls it about 20% wider than it started. Assuming it hasn’t cracked during either of those processes, it then gets bent to make the riser. And it has to be done in Asia because there’s no one in the US that can do it, and they know they won’t sell enough to justify the expense if adding a whole new building and a couple million dollars in tooling and machinery to make it themselves.
The alloy Trail bar gets a 20mm extension from the carbon bar’s width and is downhill tough, beating DIN standards.
Retail on the titanium riser is $349.95, weight is 345g. Alloy is 295g and $109.95.