New bloke on the block asking questions???? 26" tyre into a 700c Cannondale
 

Hello everyone.

By my calculations, (&I could be wrong) a 26" x 2.1" tyre is approximatly the same diameter as a 700C X 28.

The 26" being 680mm Dia Outside Diameter
The 700c X 28 being 668mm Outside Diameter

So my question is.....

Will the 26" tyre, being wider than the 700c fit into a Cannondale Frame.

(Reasoning.)
My wife, I and two kids are looking at extended touring in 2014. We like the Cannondale Tandems however they don't make a MTB fframe anymore. So we are left with one with road bike geometry and hardware. I don't really wish to tour with 700c wheels as i have read it can be difficult to get 700c tyres around the world in various spots.

I have looked at the Co-motion but wanted to go alloy frame.

Cheers.
les.

Any advise here would be greatly appreciated.

2.1" tires are pretty fat. We use 26x2" tires. Cannondale 700c single frames of old certainly have very little tire clearance even on their touring frames. Are you sure you can fit a 2.1" tire + fender into a 700c tandem frame? For touring in 3rd world countries, steel frames with 26" wheels are preferred as they are easier to repair. IMHO of course.

thanks heaps for your reply,
No i'm really not sure about the frame at all really.
Yes i'm also thinking about the co-motion mocha, upgraded with dt swiss hubs and ultraga gearsets.
any advice with this.

we are looking at around 4000 ish for each of the two tandems.

OK. I just went down to the bicycle basement and tried putting some mountain bike wheels on the Canondale RT2 road tandem. A 26 x 2.2 tire (WTB Wolverine) fit in the Cannondale's "fatty" front fork with about 3/4" clearance on both sides. A 26 X 2.125 tire (Panaracer Fire XC Pro) fit on the rear with about 1/4" clearance on either side at the chainstays and gobs of clearance at the seatstays. It was difficult to get a precise measurement on the rear because of the different axle lengths. 26 X1.75 is another very viable alternative if you want more chainstay clearance.
Brent

I was about to point you out some used Cannondale MTB tandems for sale when i realized you're in Australia. Even so, you might check the major tandem dealers here in the US and see if they will work with you. Cannondale MTB tandems aren't rare, you ought to be able to find what you need for much less than the $4,000 you mentioned even including shipping from the US to you. Tandems East, Mt. Airy Bikes and Precision Tandems are the more well-known dealers that I'm familiar with. Other folks on this forum can probably add a few more. Tandems East might even have some new ones left, while Mt. Airy Bikes seems to have a few used ones if their web page is correct.

The C'dale road tandems have quite a low BB at around 260mm. Their Mtb tandems are a lot higher at 300mm. This may or may not matter depending on the terrain.

I work at a bike shop in Switzerland, and we have a new Cannondale MTB tandem for sale, I believe it is a 2009 or 2010 model, but has not been ridden. I believe the size is Large for the captain and Medium for the stoker, but I can check that tomorrow. The original price was 5000 Swiss Francs, but it is now 4000 CHF (US and Oz dollars are close to 1:1 exchange at the moment to the Swiss Franc). If anyone is interested, then PM me, and we'll see about shipping it.

Cheers Brent.
That sorts that idea out. I think we will need need a specific bike for 26" wheels. the co-motion and santana look good atm.
Just don't know about wieght of the steel frames, as we will be travelling internationally with the bikes.

cheers again.
les.

thanks for the lead on the shop.
I'm on their trail now. will check the sites out this arvo.

thanks again.
les.

For calculations, convert to ISO tire/wheel sizes, then it pops out easily.

For example: 700c x 28 is 28-622; NOMINAL overall diameter is 622+28+28=678
26 x 2.1 is 54-559: NOMINAL overall diameter is 559+54+54=667

Other choices in the middle are ISO 590 and ISO 584. ISO 590 is the old English 26 x 1 3/8 size, and quite widely available. ISO 584 is the old French 650b size.

I am building up a set of ISO 590 wheels for my 310 to make it more suitable for commuting with fenders using Sun CR18 rims.

re Is is ok to amuse the nooby?
 

Well, before going into all the gymnastics of how to convert the bike to 26" wheels and tires (I am personnally own such and if I was starting to plan a tour into the back woods I would buy a bike that used them), suggest you may want to first attempt to validate your assumption that 700C's are hard to find in the planned boonies. I don't know but kinda doubt it. Why not look up a few towns along the tour path and email them or call them and ask if they carry what you might need or would be willing to order them in for you for a specific month/year you plan to be through there.

Other option is to look up a few towns along the way and solicit for names of a few bike / tour friendly folks and bike shops in those towns where you could ship a few tires ahead so you could pick up and use them if you need them. If not needed, then just sell them on the spot, strap them on the back rack, or sent them a few cities ahead.

All of this is a ton cheaper than modifying and re-fitting your bike. And what if you get there and find that they only carry 700C's...that would be an oops! Basically research and planning beats the heck out of guessing!

Hope this helps....

Just pack a replacement folding 700c tire and some tubes. Problem solved.

With disc brakes you may be able to swap 700c for 26" wheels without too much trouble. But with cantis or other brakes you will have difficulty as the brake bosses will be in the wrong places. Plus, the 26" wheels are a LOT smaller. If you are riding huge mountain bike knobby tires then the outside diameter of the tire may not be that far off from the outside diameter of a 23x700c road tire. But if you take your 26" rims and install some high pressure road tires for road use you will find they are a lot smaller.

Da Vinci has an entry-level model with 26" wheels. I asked them about using 700 wheels in that frame, they said "Well, you can do it, but it raises the pedals, too". I don't know the difference in height.