Speedub.Nate

I've been contemplating a mountain tandem for the past couple months for my wife and I. Never one to take the easy way out, I'd like to go the tandem / solo convertible route (similar to the Rodriguez 8ball hardtail https://www.rodcycle.com/eightball.html), but with 29" wheels.

I am presuming we'll use the bike mainly for fireroad and non-technical trails, but steep climbs and descents typical in Northern California. I also anticipate some road touring on this bike, but not epic distances. The key is a trunk-stowable, transportable bike that we (or I) can easily carry & store incognito, easing worries of theft when traveling on non-bike vacations, and getting my wife out on some trails she otherwise might not want to tackle solo on her own bike. Plus just a little bit of variety added to the normal routine.

Couple of roadblocks:

- Getting a 29" frame built seems to be no problem, but what about a fork? Are there any 29" compatible tandem rated suspension forks featuring an air spring or an air assist spring that will allow them to work with a solo rider (me @ 200 pounds) or with two riders? Or do I just go rigid with this setup?

- Any thought on the geometry issues involved with two different sized riders and a convertible setup? I typically ride a 19-20" frame and my wife a 15-16" frame. She would be the stroker, meaning when the bike is in the solo configuration, I'd be riding on her smaller half of the bike. I'm supposing that as long as I get the reach right, I'll just have a really low top tube with a whole bunch of seat post showing.

- I'm definitely planning on a Speedhub for this setup (making a single-sided drivetrain practical). I am confident in the proven 32 hole Speedhub standing up to off-road tandem duties in a 26" application, and touring in a 700c configuration, but any thoughts on a 32 hole 700c/29" wheel standing up to off-road abuse?

...and thinking Avid 8" discs are the way to go for ease of conversion (plus I use them on all of my other bikes and like 'em). His & hers Thudbusters (short travel & long travel) would round things out.

Thoughts?

crosswater

Check out https://www.zinncycles.com/bikes.aspx ...I also found the crank arm length article rather interesting... They seem to have the bases covered on the frames and crank arms for big guys and gals. The case they make for 29" wheels is intriguing... I thought I had bought my last bike...oh, well.

ElRey

Stick with what's readily available at first: I'd buy a used standard Mt. Tandem and see if you really want/need those 29"ers... A custom order on one's first try at anything seems overly ambitious.

galen_52657

For the type of riding you are describing, a standard fork would work.

TandemGeek

We had a similar discussion on my off-road tandem enthusiast's forum about 2 weeks ago. I'm not sure if any consensus was reached; however, I would encourage you to post your same questions to our off-road forum as I'm sure it will stir up some responses as there are several other teams who have an interest in the 29" bikes.

More information and links to the forum: https://www.thetandemlink.com/Double_Forte.html

Speedub.Nate

Thanks, everyone, for the replies.

I'm very much sold on the 29"er aspect of this project. I have been riding a 29" hardtail since fall of '02 and am sold on the workings of the larger wheels. I'll jump to a 29" solo full suspension when the right bike comes along. As it is, my thinking is that for a non-suspended tandem, the 29" wheels will provide a significant advantage in rolling smoothness (sort of "built in" suspension if you will) and if I'm forced to hit the trails on a rigid bike in the solo configuration, I'd have it no other way.

On one hand, I am slightly concerned about going "all out" with a custom build out of the gate. On the other hand, my wife and I have rented ill-equipped tandems on a few occassions and done some decent riding on them, including some choppy trails in the Marin Headlands, and we both agree this is something we want to persue. Specing a rigid fork and rebuilding the Speedhub of my 29"er into a tandem-worthy wheel will make a significant dent in initial costs.

TG, I signed up for your Yahoo! group and will check out the thread as soon as you approve my request for membership.

TandemGeek

You're approved. Again you may want to repost your questions as part of an introduction note to the other forum.

The YahooGroups search engine is awful; however, the 29" discussion has been pretty recent and those posts should be easy to find. You'll also find that several of the regulars are using the Rohloff hub, to include our dealer-member Alex who specializes in off-road tandems. Sherwood Gibson (Ventana) will occasionally chime in as well.