carmie

I spent some time last night searching this forum for information regarding wheel diameter size, but couldn't seem to find an answer.

For two riders of similar height and weight : 5'8" and 160 lbs each, would a 700c wheel work as well as a 26" wheel? I should mention that we are probably going to do some loaded touring in the future.

We have our eyes on a DaVinci Joint Adventure.

Thanks again for your help,
Martha

TandemGeek

Here are links to a few threads that address both 26" vs. 700c and one that speaks directly to the daVinci tandems and 26c vs. 700c (I think)

https://www.bikeforums.net/tandem-cycling/410689-da-vinci-tandems-anyone-ride-one.html

https://www.bikeforums.net/tandem-cycling/460462-26-road-wheels-tandem.html

https://www.bikeforums.net/tandem-cycling/144469-what-better-tandem-touring-26-700c-wheels.html

https://www.bikeforums.net/tandem-cycling/481640-anyone-here-riding-26-inch-wheel-tandem.html

carmie

Thanks, TandemGeek! You are a overflowing font of information!!!

Martha

duppie

Martha,
I have nothing to add to the discussion 26" v. 700c. However, you may want to confirm what the widest tire is that will fit the frame. By my conservative estimate your tandem will weigh 400+ LBS when you are doing loaded touring. The DaVinci you mentioned comes with tires in an unspecified width. You may want to go with a tire that is 32 or 35 mm wide.
Here is our misadventure with a Conti Gatorskin 700*28c. Admittedly, I will never know whether this was simply a bad tire, or whether it was caused by our weight, but talking to a Schwalbe rep (Conti didn't bother to respond to my email), he mentioned that 28c and narrower tires in general are not rated for that kind of weight. After the failure, I replaced mine with Schwalbe Marathon Supremes 700x32c that I had lying around. I am considering going to 700x35c once they are back in stock.
Duppie

rdtompki

Martha, we have 700c x 28mm tires on our tandem. Our full-up weight in day ride configuration is about 390 lbs or so. My executive management liked to look of the 700c wheels better so that tipped the scales, but I was leaning toward 26" tires just 'cause I'm an aerospace engineer, a bit design-conservative by nature, and we weren't going to be racing anyone (note: group rides can become a bit of a race). Even assuming 700c wheels are "faster" it kind of gets down to a "who cares" argument; are we talking 1%? Do they just feel faster? I did check with daVinci and Todd said the frame, brakes and rims would accommodate up to a 700cx38mm tire so that gives us some margin and to use 120 psi rear and 115 psi front for our team weight. The 40 spoke rims do seem very stout and I hit one invisible pothole last week at speed with nary a problem.

Flip side - when we test rode the DV (with these same Conti Ultra Gatorskin tires) I double-flatted about a mile from the shop on a shoulder that must have had a very sharp, invisible piece of gravel resident. The gravel looked shale-like so it had very sharp facets and there is nothing to say a 26" setup wouldn't have done the same thing. We've ridden about 600 miles so far with only a minor sidewall problem that had little to do with tire width - more like the wheel falling in a road crevice with sharp edges.

You can double-check on the ability to fit up to 35mm tires on the 700c wheels (38mm wouldn't seem necessary) or just go with the 26" wheels which would also, I believe, make for a lower stand-over height. You will loose a tiny bit of top end, but with a 60-11 you can still pedal up to a fairly good speed.

Summary: Day rides, short and long: no reason not to stick with 700c. Loaded touring: 26" would seem to make sense (IMHO)

WebsterBikeMan

One other thing is that if you intend to get a coupled bike the 26" wheels are easier to fit in 26" cases. The 26" for touring thing is partly an outside-of-North America thing, as I'm told 26es are easier to find elsewhere. But 26" tires here tend to be wider and beefier, making for a better choice if you're putting a lot of load on it.

For touring be sure you have room not only for the larger tires but also fenders. Regardless of the wheel size you spec.

justcrankn

From the DaVinci website "Our road and unsuspended offroad frames are interchangeable; the angles and tire clearance are the same." DaVinci lists 26" tires up to 39mm wide.
It's interesting that their "enduro" tandems keep the bottom bracket height the same as a road tandem. This would be good for a touring application.

zonatandem

Differences between 700c and 26" as stated in other posts.
In favor of 26": With S&S, wheels will fit better in travel cases. Great availability abroad (important if you are headed there). Ability to handle less than perfect/paved roads and trails.
In favor of 700c: big tire choices, especially in US. Great road tires. Higher pressure.
Having said that, have ridden 14 miles of mountain curves/horrendous road (dirt/sand/gravel, rocks) with 27" tires (similar to 700c) successfully without crashing back in the early 80s. Do-able . . .but 26" would have made that easier; however 26" wheels/tires were not readily available then, especially on tandems.
Just our input/experience.
Pedal on TWOgether!
Rudy and Kay/zonatandem

embankmentlb

The wife & I have a 26" wheeled Burley road tandem. We have about 1000 miles on for this our first season. I continue trying to justify moving to a more normal 700c bike but so far the 26" wheels work great. One advantage is being able to carry the bike in our van & truck with wheels on. We have hit some pretty major pot holes & uneven RR track crossings without problem. I am very pleased. The only thing, at every stop, almost without fail, someone asks if we are running 650c wheels. That's not a "bad" thing, it's always fun to talk about. The only other draw back for some people would be that a low spoke "engineered" wheel is not available in 26".