26 inch wheels on a 700c frame?

[Byronius Maximus]

Hi,

I am looking at getting a new frame for a 5 month trip down through South America later this year ( ). Much as I'd prefer to ride on 700c wheels, it seems a littel foolhardy given much of the advice about availability of tyre sizes/rims/spokes should I have any mishaps.

I'm currently looking at the Surly Disc Trucker or the Trek 520, depending on geometry and fit, and am open to other suggestions. I am pretty certain I'll go with discs, so would there be any problem with running 26 inch wheels on a frame designed for 700c wheels? Obviously it will result in a lower BB and standover height (and it may look slightly odd) but I'm not sure if that would have any real effect on handling.
Of course, the most simple solution is to get a frame designed for 26" wheels, but I would prefer to have one that takes 700c for when I return and want to use the bike back in the UK.

Thanks,

[hemo]

The main issue will be tyre width in the drop outs. more so the rear then front.
Wideest I can fit sensibly in rear of my 700c is 40mm.

[Brucey]

in the above post I think he means 'chainstays' when he says 'dropouts'.

If you use 26" wheels in a frame meant for 700Cs then (with the same tyre width fitted) the BB will be 31.5mm lower than it is meant to be. This is a lot; I'd ground the pedals round every corner. The steering will also be affected.

If I were you I'd buy the frame meant for 26" wheels and then sell it on when you get back.

Vs. what you were planning on doing anyway it'll cost you the price difference between a new frameset and a used one, assuming you sell the 26" frame on and buy a new one for 700C wheels.

cheers

[cycle tramp]

Personally i wouldn't believe the hype about 700c wheels being faster than 26 inch wheels... it all depends on tyres, areodynamics and even road surfaces....
...Equally, not all 700 wheels are weaker than 26 inch wheels. Theres things like spoke counts, spokes and rims to consider....
And i'd try not to get hung up too much about 'what are you going to do with the bike after you've toured'. Sure Africa is a big wide exciting place... and cycling across it may wear out parts of the bike that even Brucey would struggle to name...
So in short... think about buying a bike just for the trip... who knows, if it the bike survives you may even get a taste for riding canal paths, fire tracks and the odd off road bit, when you return to Bighty...in which case you might be glad of a bicycle with strong wheels...

[catsnapper]

Well...in cycling - as in many other things - the best answer is, it's possible, but is it worth it?

For me, the answer is yes. I had a spare 51cm Pompino V4 frameset, a Sturmey Archer 3 speed hub with drum brakes, matching front hub and plenty of suitable 26" rims. We need to move substantial quantities of mineral water back home every week, so a modded Pomp with 26" fat tires, a rack and probably a trailer suits our needs. A quick build confirmed it was feasible.

The Pomp has a relatively high BB and can use 38mm 700c tyres, so the 26" Panaracers are not a problem. It has 170mm cranks, low gearing and BMX handlebars.
The pedal clearance is acceptable, it's not going to be going to be fully cranked over at high speed on bends. Handling is stable, it's surprisingly comfortable and easy to ride.
If needed as a 700c fixed gear bike, switching it back is a straightforward job.

It's regularly used for pottering around, so ends up on the beach as well as rough ground - its reliability and simplicity makes it popular with reluctant cyclists

Catsnapper

[Byronius Maximus]

Thanks for the replies everyone, a few things to think about there. Brucey - I take you point about the lower BB, which is lower by a fair amount really, but I'm still not sure how much of an issue this would be.

I think I am probably just going to end up going with a bike specifically for the trip, then decide what to do with it when I get back...maybe just head out on another long tour somewhere...

Possibly going to have a look at some bikes this weekend so will post here with my thoughts.

Cheers

[Brucey]

to assess whether the cornering clearance is likely to be a problem, try taking a bike with a 'normal' BB height, same Q, same pedals, etc and leaning it over a block of wood that is ~32mm thickness.

It'll vary with the pedals fitted etc, of course, but I'd expect you to find that the usual clearance is enough to allow a lean angle of ~30 degrees without the pedal grounding, but with the lower BB that will be significantly reduced. At the very least it will be something that will take some getting used to, if you normally pedal round corners.

BTW if it were me, and budget was an issue, I'd convert an old steel framed MTB for a jaunt like this.

cheers