A little project I’m working on.

Two 4″ tyres on a 132mm rim – with no air that’s over 6″

I’ll expect with Big Fat Larry’s to be 8″ uninflated, and maybe 9″ inflated.

Now I have to cobble up a frame and fork – expect some Heath Robinson type construction… 🙂

(That will be once I’ve worked out the best combo for the rims, so later.)

That’s enough internet for today!!

😯

does it have a bead in the middle of the rim?
what does the inner bead seat onto?

I was wondering the other day if it would be possible to lace 2 narrow rims side by side onto 1 fat bike hub? Then run two 2in tyres in a fatbike fork? For no particular reason of course

Then the Mrs gave me some actual jobs to do and I forgot about it……until now!

I was wondering the other day if it would be possible to lace 2 narrow rims side by side onto 1 fat bike hub? Then run two 2in tyres in a fatbike fork? For no particular reason of course

That’s pretty much how fat biking got started, Didn’t take long for people to realize it was rubbish and the first 50mm rims and 4″ tyres appeared.

#TryingTooHard? 8)

I can think of no reason that you shouldn’t do this

If you do a bit of scouting around, you may find that more appropriate tyres already exist:

OK, no-one else has asked yet, so…

…how heavy is that set up going to be?

I expect spoons **shakes fist** 😆

I guess without a centre bead you be relate on one tyre holding the other in place?

Boost spacing 😉

letmetalktomark – Member

I guess without a centre bead you be relate on one tyre holding the other in place?

I was assuming there was a dual centre bead in there

That is digustingly silly – I like it! 😀

http://www.pinkbike.com/news/now-that-was-a-bike-1993-mbs-clark-kent-fat-bike-2016.html

A thought. If you didn’t line the treads up exactly, could it cause a wobble as they bit into the dirt at different intervals ?

http://www.pinkbike.com/news/now-that-was-a-bike-1993-mbs-clark-kent-fat-bike-2016.html

haha Brilliant!
Just shows if you can think of it – someones already done it

Won’t cornering be a bit erm….interesting. You’ll have to almost rock the bike from it’s upright stance onto an edge.

Looks like a fun project though!

you could run 2 entirely different tyres, possibly a semislick and a full fat knobbly, it’d make the corners more interesting.

You need to develop a system on the lines of bionicon that would transfer pressure from a slick for fire roads etc to a knobbly for the techie stuff.

http://www.pinkbike.com/news/now-that-was-a-bike-1993-mbs-clark-kent-fat-bike-2016.html

haha Brilliant!
Just shows if you can think of it – someones already done it
Well they did it the conventional way by attaching the rim to a hub using spokes. This is far more radical than that.

fred whitton next year>?

You need to develop a system on the lines of bionicon that would transfer pressure from a slick for fire roads etc to a knobbly for the techie stuff.

like this….

adaptrac

Ha ^^ love it.

Its a bit different to my Clark Kent!

Pfft call that fat?

So new Boost+++++++ standard anyone? 😉

James

OK, no-one else has asked yet, so…
…how heavy is that set up going to be?

Any extra weight gained will be mediated by not needing a kickstand

How are you going to drill the spoke eyelets? Do you have some kind of fancy pants machine? 🙂

The problem is, you’ve probably ended up with only 1.75* the volume of a 4″ tyre. A proper 8″ tyre would be more like 4*.

Also, having ridden 40c Small Block 8s to the point at which the tyre becomes effectively square, it can be properly dicey/weird when initially turning in…

jam bo – Member
fred whitton next year>?

Now why didn’t I think of that?

For those recoiling in horror at this wheel, don’t worry it will take at least 10 years before it attains compulsory nicheness, which gives you enough time to get fat enough to need tyres that size.

It’s not a new idea. I’ve seen 3 rims ganged together in Africa on a cart in the 1950s.

Some technicalities: (or reasons it probably won’t work)

There is no current frame that will fit this. One that fits is going to have a horrendous Q factor unless I use a treadle type transmission and a long wheelbase. I have drawn up a plan, it’s hideous, and needs more work.

Two tyres on one rim is just inviting getting large rocks wedged in the middle so there’s going to have to be huge tyre clearance as well.

I may sew 2 tyres together to make up a really fat one, but first I want to try it like this as proof of concept. Using 2 tyres on one rim can lead to heap of other problems, but I’m hoping that the low pressure I will be using will obviate that – it’s a suck it and see job.

Then there is the very simple question, will I be able to actually pedal the thing?

What I am trying to achieve is to be able to ride over this sort stuff:

Not the pools, but the tussocky and soggy bits between. For the record, I don’t think it will work and I may end up submerged in a bog somewhere tyres up. 🙂

I will also try it on my imaginary Antarctic Expedition later this year, ie deep snow around Ben Wyvis.

shermer75 – Member
How are you going to drill the spoke eyelets? Do you have some kind of fancy pants machine?

What I have always used to drill spoke holes, a hand held drill – at least it’s electric these days. 🙂

Daffy – Member
The problem is, you’ve probably ended up with only 1.75* the volume of a 4″ tyre. A proper 8″ tyre would be more like 4*.

Also, having ridden 40c Small Block 8s to the point at which the tyre becomes effectively square, it can be properly dicey/weird when initially turning in…

Yes, 2 tyres are not ideal. If the concept works I’ll cut the one bead and sidewall of 2 tyres, and then sew them together to make one very fat tyre.

The geometry should be “interesting”. Probably very steep and not much trail. Seeing as I’m going to have to make the fork, I’ll have adjustments built in so I can alter HA and offset.

Might I suggest one of these:

Surely the effort required to foot propel this thing would be at least equivalent to what you’re proposing?

Could you attack it from another angle, and put the drivetrain in the centre, with a wheel each side?

Yes, it would be a fat trike of sorts

A really really long wheelbase would cure the Q-factor problem by allowing the chainstays to widen after the crank+foot rotation position.

Epicyclo, what is the issue when riding through that kind of terrain? Is it an issue with not enough traction? Or do you just need more float? I find that dropping the pressures helps the most on that kind of terrain. How does a Big Fat Larry or a Bud fare on it? You might be able to get a hold of those 5.6″ prototype Vee Snowshoe 2XLs if you truly really hard! I think the production ones are 5.05″ or something. The prototype ones would be perfect on that size rim!

Also what you could do, which would be fantastic for actually completely offload stuff is add suspension in addition to the fat tyres. I have a set of Monster Ts which I bought because they’re completely modular, including the fork crown, meaning it would be possible to get wider crowns machined in order to fit a fat tyre! Halo do a 160mm x 20mm front hub, which would be perfect too! I really wanted to do it, but I have never had the money ):

I cant wait to see the finished article 🙂

I would’ve thought a Snowshoe 2XL would be close to 6″ on that rim, so when the 3XL or 4XL come out, they should suit that rim quite well!

officerfriendly – Member
Epicyclo, what is the issue when riding through that kind of terrain? …

Basically flotation. I’ve tried 5″ tyres on wide rims and there’s not enough for what I want to try riding. (I prefer 4″ for general duty)

I’m sure wider tyres will appear, but that could be several years. My riding life will probably come to an end in the next 5-6 years, so I figure I’d better try this while I’m still able.

I’ve been saying for quite a few years now that we need 8″ tyres for bogs etc, but of course, no one really knows if that would work.

I’m aiming for 1 – 2 psi, and that will present a few problems in itself, such as tyre retention, slippage etc. With 2 tyres on the rim, it will be more like 3 -4 psi – mainly to keep them working together.

It’s unlikely a commercial operation would take the risk and spend the R&D money.

However a simple bodger like myself has no such constraints… 🙂

I won’t be adding suspension. In fact the bike will be as minimal as I can make it, otherwise it will be a really heavy pig, and even minimal, it’s not going to be light. Definitely a “Keep it simple, Stupid” job.

I’ll suggest it as no one else has, can’t you Heath Robinson up some form of track that’s attached to the rim instead. Surely if you’re riding boggy terrain it’s not suspension effect of big tyres you need but super wide footprint. A track based wheel may be easier to bodge than an 8″ tyre too.
I’m no engineer 😆

How did you make the rim? It’s so shiny…..:-)