Mountain Gear

Tech FAQ: Talkin’ 26er-29er Tubes's Tech Meister, Lennard Zinn, weighs in on tubes and drop seatposts.

Dear Lennard,
I ride with a bunch of guys — sometimes road, sometimes mountain. In either case, I’m often the one who is prepared and ends up changing the flats because I bring what I need and I’m fast at it.

But I ride a 26er, and some of the guys have new 29ers. I don’t want to carry an extra tube for a bike I don’t even own, but I also know I’ll be the one coming up with a solution if one of them flats and they don’t have tubes. Question: Can I put a 26-inch inner tube in a 29-inch wheel?

Dear Frank,
Yes, you can, and I know from recent experience. While normally I carry lots of tools and parts and am often the one in the role you describe, I wasn’t last week. When we left for our VeloNews/ editorial retreat in Fruita last week, I threw my stuff together in a matter of minutes and forgot both my seat bag and my hydration pack.

Then when I flatted out on Steve’s Loop on my 29er, I stuck in a 26-inch tube that Ben Delaney had brought along. It worked great. No problem.

Dear Lennard,
What do you think about adjustable-height seatposts? Should I use one? Which one?

Dear Sam,
They are here to stay. Unless you’re a weight weenie, I don’t know why you wouldn’t use one, other than the expense. I haven’t ridden the Specialized, Gravity Dropper, or Kind Shock posts, but I have ridden the Maverick Speedball and Crank Brothers Joplin (same design) and the RockShox Reverb.

I really like them all and use them constantly on three of my bikes that have 30.9mm seatpost diameters.

I have one bike that has a 27.2mm post, and I don’t have one for it since most of height-adjustable seatposts don’t come in that size. Kind Shock has a cool 27.2mm one I saw at Interbike but didn’t ride. It has one of the hydraulic cylinders outside of the post, under the saddle; that’s their solution to the problem of not being able to fit both chambers (the oil flows from one chamber to the other when it goes up or down) inside the skinny 27.2mm seatpost.

Zach White did a great series testing a variety of height-adjustable seatposts on in late July. Check out “Tested: Specialized, Rock Shox and Crank Brothers Drop Posts”


Readers can send brief technical questions directly to Lennard Zinn.

Technical writer Lennard Zinn is a frame builder (, a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”

Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn.

Follow Lennard on Twitter.