You know, like fat biking for the road.

Why not?

What size tyre on a 26″ rim gives the same diameter(ish) as 700×23?

I’ve always noticed that an 26″ MTB wheel is roughly the same OD as 700c road wheel, so pretty large. 26×2.1 was a pretty common commuter tyre IIRC.

If you have an old school cycle computer, they often have a chart of wheel & tyre combinations vs. OD (for setting up the circumference etc.). One of these might help.

Not much in in though.

Because it’s slow and heavy.

23 mm diameter means a radius of about 11.5 mm

Bead on MTB is 559 mm, bead on 700C is 622 mm. Hence 622+2*23c = 559+2x
x ~ 54.5, so you’ll be wanting an 50-60c tyre. That’s pretty fat. A 48c will get you half-way.

And yes I know tyres are not circular in cross section, with the exception of tubulars.

I ride a voodoo wazoo for a 15 mile round-trip road commute with my kid 3 days a week (I didn’t think fat-bikes were particularly good for anything, so it got downgraded to a commuter with a wee-ride on). That has 26×4″ pretty slick tyres (there’s a tread pattern, but its maybe 2mm high)

even without him on it, I’d estimate my riding speeds to be approximately 1/2 of what it is on my drop-bar commuter (which itself has 700×35 scwalbe marathon plus tyres on – so not exactly a lightweight itself). I have to run 30psi in the fat tyres to get it to go even that fast. Its slow, picks up tonnes of crap off the road, noisy, not particularly fun. I should probably get rid of it but there’s a slim hope it might snow down here over the winter, so I guess it’ll have 1 day of being superior to a proper bike then.

The width will screw you if you’re trying to fit it in a road frame way before the height will

is 86c is a 3.4″ tyre in old money? Or is my maths bobbins?

There’s a lot of 26 x 2 inch (50mm) commuter tyres out there..

Why not?

Well, you’ll need a big tyre. As above, something like a 2.2″ will equate to a 700×23 (see here), but in terms of considering BB height that doesn’t account for sag. (If sag is negligible, it means you’re running the tyres hard, in which case you’re gaining nothing except weight.) So you’re looking for big tyres, and good luck getting even a 26×2 into most 700c framesets, or you’re dropping your BB height, which you may not have the margin for. The chances of your 700c frameset having an already high BB and massive clearance are probably roughly zero, but we don’t know what you’ve got…

And then what are you going to gain by having big tyres? If your commute covers a lot of unsurfaced tracks then it makes sense but if it’s all tarmac you’re probably just going to end up with a bike that feels a bit vague and wandery.

Sticking 700s in a 26″ frameset for road use is something I’ve seen quite a few times; I’ve never seen anyone do the opposite 😉

I’ve got a home brew ‘multi-wheel’ commuter, based on a 26in MTB frame but can take 700x35c, 650bx~47c, or 26x as big as you like. It’s the result of a decade’s worth of trying different stuff from a 700x23c drop bar SS road bike, through tourers, converted MTB and everything in between. It’s still not perfect but its 90% of the way there!

It spends 90% of it’s time running on 26×1.75 Paselas, comfy, good for hauling loads, which this bike does a lot of, robust, ‘fast enough’ for urban commuting.

I actually prefer the smaller wheels round town from a handling pov, especially at slow speeds, with a full load or with the trailer on the back, it’s just a lot easier to manoeuvre than when it has bigger wheels in it,a nd the extra rubber width seems to add some stability too so its a kind of win-win. Also drops the BB a bit which is very useful for stop/start riding with heavy loads as easier to stick a foot down.

Depends on your commute though and circumstances, if it’s a 15+mile A road blast with a saddle bag you’ll be wanting a very different setup to someone hauling full panniers around in town, and if I have to travel further I often take another bike entirely instead!

My Wazoo has recently been changed back into something vaguely like it was sold as, fitting the rear fat wheel for the first time in months.

FatNotFat 29er wheel with 2.35″ G-One at the front (at ~35PSI)
Fat 26er wheel with 4.0″ Jumbo Jim at rear (at ~30PSI)
Gives a reasonably level setup (perhaps a tiny drop towards front)

Having recently changed to winter uniform (trousers, long shirt and heavy winter jacket; from shorts/short shirt/gillet), it’s hard to give great comparisons to when I was running two FatNotFats with 28mm Grand Sport Races. I’m slower, but it’s good fun, plus it makes hill reps on the way home more challenging. 😈
https://www.strava.com/activities/1294104088

Stood my old MTB commuter with 26×2.0 Big Apples and my SS with 700×25 next to each other and the highly unscientific eyeball measurement says the SS is about 5mm bigger diameter. To be totally honest the 26″ is way more fun/bettererer to ride for the reasons amedias gives (my use is also primarily city-centre stuff with occasional heavier loads).

Okay, good info, ta.

Reason I ask is, I have a Moda Immer kitted out for panniered commuting, winter bike and trundley light touring duties.

It will take, as I’m currently using, a 700x35c slick tyre with full guards, just. However, it’s spaced for 135mm hub at the back and I’m currently using a 130mm hubbed wheel with a couple of washers as spacers. I’m aware that this is a far from ideal solution but I don’t want to shell out on a new set of wheels.

However, I have a set of HopeXC/717 26″ wheels knocking about the garage doing nothing. My thinking is to stick a big slick on them and use them on the Moda.

It’s a disc frame, so brakes no an issue

Why not just give it a go? 😉 Try bare wheels with whatever tyres you have kicking about first to see how much clearance there is (from what I can see of the frameset from a quick google, I suspect you’ll struggle to get an adequately large tyre in it). If a worthwhile tyre fits then move the rotors and cassette across and ride it and see what happens to the BB height and the steering. If it’s still good, buy some more suitable tyres.

Why not just give it a go?

And not agonise over it on here for weeks beforehand? Whaaaaat?

Stop busting my groove man.

If a discussion tending towards “it probably won’t fit and whatever does fit will probably ride like crap” is your groove then hey, groove on 😉

There is a table here:

http://www.bikecalc.com/wheel_size_math

700 wheel with 23 tyre gives a diameter of 668mm

26″ mtb wheel with 2.125″ tyre gives diameter 667mm

Personally I would go for the lightest tyre you can find. If you have the dollar these are perfect:

https://www.compasscycle.com/shop/components/tires/26-inch/compass-26-x-2-3-rat-trap-pass/

A 26′ wheeled bike with LIGHTWEIGHT fat slicks or semi slicks makes a great commuter. Don’t get heavy kevlar banded puncture proof wire bead tyres.

You won’t “feel” as fast as you don’t get so many vibrations due to softer tyres – but check your times you will see you are barely slower, but much more comfy on fat tyres and able to go much further.

I’d still suggest trying out whatever’s in the shed before spaffing £140 on a pair of tyres that won’t fit 😉

Much as I hate to give into Buzz Kill Bez, for £140 I could buy a pair of the correctly sized wheels, and I’ve not come here for that kind of obvious advice…

HoratioHufnagel – Member
Because it’s slow and heavy.

Nah.

My 26 inch touring wheels with 2.1 tyres are as fast as the 29ers with 45’s on my wife’s tourer.

Much lighter too.

My 26 inch touring wheels with 2.1 tyres

Wot tires m8?

is 86c is a 3.4″ tyre in old money? Or is my maths bobbins?

Your maths is Bobbins!

I’d still suggest trying out whatever’s in the shed before spaffing £140 on a pair of tyres that won’t fit

Agreed… A set of worn(ish) 2-2.1″ 26″ knobblies will suffice for now.

I suspect, on a frame that “will take, as I’m currently using, a 700x35c slick tyre with full guards, just“ that you might find the limiting factor is not diameter, but width between the stays, most probably chainstays will be the pinch point, but I’m not familiar with that bike so only you can say for sure by whacking a wheel in and having a look!

Yeah, the width between the chainstays is definitely where the ‘just’ bit comes in at the moment.

IHN – Member
Wot tires m8

Marathon Supremes.
Fast, light, puncture resistant.

Bloody marvellous things.

is 86c is a 3.4″ tyre in old money? Or is my maths bobbins?

Your maths is Bobbins!

No, your maths is bobbins

86 / 25.4 = 3.38

I remember (from setting up a bike computer for 2 bikes) that a 700×23 is the same rolling diameter as a 26×2.1

Though it sounds like you may have other issues.

Wide, fast rolling tyres are available these days.

No, your maths is bobbins

86 / 25.4 = 3.38

Thanks, so what does the 3.38 in your calculation refer to then?

Compass tyres out of the US do a lot of large diameter ‘slick’ tyres.

Surly bikes have a lot of options for people doing this sort of thing, I’m currently building up an Ogre with 27.5+ tyres (3”). They have a similar overall diameter to a 29/700c wheel. Why? N+1, why not? It’ll be comfy and shouldn’t be too slow on the road with a small tread tubeless tyre. Using a WTB ranger currently.

Do it!

Just buy one of these

When a TT bike and a fat bike have a baby… The Fat Trek Equinox is born

Just started using those Conti city rides work great commuting 26×1.75 roll well look a bit chunky and half that puncture protection on them which is good on cycle paths etc.

IHN – Member
No, your maths is bobbins
86 / 25.4 = 3.38

Thanks, so what does the 3.38 in your calculation refer to then?

He was saying you are right. He quoted mboybut quotes don’t stack.

86mm is about 3.4 inches yes.

C is irrelevant as it refers to the tyre size required to get the number of the final circumference with tyre.

700c equals 700mm radius with tyre on.

Which would actually be quite a usefulstandard again with disk brakes.

One 700mm frame could take 700a,b or c aslong as the stays were wide enough.