TIRES - 700c vs 26 inch for long tours AND S&S Couplers

[rvklassen]

I'm really confused.  How do couplers increase the likelihood of getting water in the down tube?

By themselves, they don't make a perfect seal; so if the front tire is throwing up a constant roostertail of water at the down tube, a little bit can get in, unless you take one of the measures mentioned above.

Wow.  They seem like the teeth ought to mesh well enough to make a perfect seal.  But I have fenders, so I guess I haven't actually done the experiment.

[John Driz]

So is there any consensus as to whether 700c actually ride faster than a 26inch?  It would make sense.  Another thought is that a 26 might actually give you a lower center of gravity increasing stability.

[whittierider]

So is there any consensus as to whether 700c actually ride faster than a 26inch?  It would make sense.  Another thought is that a 26 might actually give you a lower center of gravity increasing stability.

Neither is true.  700c will have ever so slightly less rolling resistance in the tires, but ever so slightly more wind resistance-- not enough difference to matter.  Lowering the center of gravity would require lowering your panniers (which might be marginally dependent on wheel size), and more importantly your body whose CG height is determined by your position and how high the bottom bracket, seat, and bars are.  That all starts with the bottom bracket, which has to be high enough to avoid pedal strikes in the turns, regardless of the size of the wheels.  The height of the seat follows that, and the height of the bars follows the height of the seat.

[DaveB]

I'm really confused.  How do couplers increase the likelihood of getting water in the down tube?

If the threads are properly greased, they don't. 

Another vote for the S&S couplers.  I have a CoMotion single factory fitted with them and they are a perfect addition to a travel bike.  No downside at all except cost and a very minor weight penalty.  You do have to check them for tightness every so often but that's no worse than checking that your brakes work before a ride.

As to a retrofit, of course Co-motion recommends you buy a factory-fit frame, they make them and don't do retrofits.  I've also heard very good things about Bilenky's retrofits but they aren't cheap.

[paddleboy17]

Better frames have weep holes in case you get water in the frame.  Look down by the lugs.  There are ways to get water in a frame, and I would not dwell on the coupler. 

[John Driz]

Just one thought from a novice is coat the inside with linseed oil or frame saver and forget about it.

[TwoWheeledExplorer]

I have a Bianchi Volpe with 700c WTB All-Terrainasaurus' on them and a Novara Safari with 26" Conti Town & Countrys. I make better progress into the wind on the Volpe, but it also has drop bars, where the Safari has that "butterfly" thing. Maybe it's an illusion, but I feel I "eat up" more road on the 700s. Both the WTBs and the Contis are wide enough to use on dirt/gravel roads, although I would give the T&Cs a slight edge for handling in those conditions. As for 700s being any faster, I did my fastest bike speed ever, downhill on the Safari, (39.7 MPH)  and just last weekend working as a medic on my Trek MTB with 26" All-Terrainasaurus' on it, did 32.7 responding to an emergency call at the event we were working.

When we were in NW Russia in '97, our guides all had 700x32 tires and we were on Trek MTBs with their then stock tire on them. The guides had a hard time going slow enough to allow us to keep up. That being said, on their website now, (http://home.onego.ru/~pashkov/index.html) I see equal numbers of mountain and touring bikes. For the Lewis and Clark Trail this summer in South Dakota, I plan on using the Volpe again.

Ride safe,
Hans

[ericb]

I think the case for 26" in certain parts of the world is a little too anecdotal. It seems reasonable and is probably basically true (I've lived in Asia, and you see way more 26" and odd 650-ish sizes than 700), but I have to wonder how true it really is in practice. Seems like half the travel journals I read on CGOAB describe having to order tires no matter where they are. When cheapo tires are picked up locally, they are often described as unsatisfactory and short-lived.

It would be really interesting to do a proper survey of tire use and availability in Asia, South America and Africa

Anyway, the issue didn't stop me getting a 700c (aka 29er) "expedition" touring bike.

[pptouring]

Add another yes vote to the S&S couplers. My wife and I have them on our Co-Motion NW Tours and have had no issues so far; of course, we've only had the bikes for about 1 1/2 years, but....... they've been to Europe twice now. 

[sanuk]

I suppose I could search for the website, but can anyone tell me what S&S couplers are?  Sounds kinky!

[whittierider]

It's a very solid tube joint that can be assembled and disassembled any number of times.  With these in key places on the frame (normally one at the rear of the top tube and one near the bottom of the down tube), this bike:



fits into this 26"x26"x10" suitcase:



(See http://www.sandsmachine.com/ )

[aggie]

On the day I got water in my downtube I was on a supported tour.  I had just crested a summit and it started to rain, hard.  It was about 3 miles downhill to the rest stop so I rode as fast as I safely could.  I was throwing up quite a roostertail.  No one was expecting rain so we were without rain gear or fenders.  Lets just say me and the bike were wet and dirty.  After that I got fenders for the bike.  That ended the problem. 

[Galloper]

One thing that doesn't seem to get mentioned in the 26" V 700 debate is weight, the smaller wheelset and tyres must give a saving of some kind.

Damn.   Now I'm going to have to go and buy a set of accurate scales to check this out!

[whittierider]

26" gives a slight reduction in weight and slight increase in rolling resistance, but not enough to matter.  The slightly better spoke bracing angle on the 26" does make for a stronger wheel with the same number of spokes though.

[waynemyer]

This 700C vs 26" is an interesting one to me.  I have a unique position in that my bicycle can take 700C and 26" because it has disc brakes.  I have two custom wheelsets, that are roughly the same build, although the weight nod goes to the 26" wheelset because of lighter hubs and lower spoke count.  Using the same tires originally (Panaracer t-serv), the 700C wheels give me a higher average speed on my daily commute, ~13.8 MPH vs ~15.6 MPH.

Now this is purely anecdotal and not something everyone can try on their own steeds.  But I know what the wheels do for me on my bike.

Similarly, Co-Motion gives 700C the speed advantage in tests, although now I can't find a link to the article that was on their site.