Hey Eric, I was wondering how you figure out how long to make the circumference of the sewn up tire. I was thinking about doing one of these myself and that’s the only part I was unsure about.
What I had been doing is cut and peel back the edges and cut the first tire full length and measure how long it was flattened on the floor. take that number and divide by 559pi (for a 26" tire, 622 for a 29" tire) to get a correction for the wobble in the bead when it is just sitting there. sew one connection and measure out to 787pi*correction = where the next join should be.
I recently had a slap forehead “why didn’t I think of that sooner” moment and instead of doing all that stretching and measuring I counted how many times the tread pattern repeats itself multiply by 787 and divide by 559 (or 622)
The last tire that blew off was within 0.1% of what it should have been according to the last method so I am shrinking the next one by about 1% and hope it makes enough difference.
When I am done this next one I am planning on writing up a full tutorial.
Thanks Eric! A full tutorial would be awesome!
I was wondering if you think this might work with a Big Apple 29x2.0 “kevlar guard lite skin”. I believe it is wire bead (or kevlar bead possibly?). I have an extra one of these tires hanging around so I would just need a second one.
Scott: I had a heck of a time getting the tread to separate from the casing on the Racing Ralph, I am guessing that the Big Apple would be easier since there should be more rubber in the tread area but who knows until someone tries it.
I wouldn’t do a wire/cable bead again but it did work.
You should have seen the look on my face when the bike arrived in pieces - took me at least an hour to put the steerer tube through the fork/headset/fork. Eventually I had to have a proper mechanic take it apart and put it back together as the GripLock gaskets were very finicky and wanting to slip out of their grooves when pushing everything through. With usch a large and heavy wheel the leverage put on it while riding was pushing the steerer tube up through the fork and loosening the headset so our clever fix was to install a star nut on the bottom so a top cap could be used to tighten everything up. Since then I’ve had no issues riding it pretty hard.
Eric - This is some impressive work you’ve done with these tires.
Maybe it’s just that it’s late and I have a headache, but I’m not quite following you on the length calculations.
It’s a proportion:
y ------- x
___ = ___
559 —787
Where y is the number of tread pattern repeats on the 26er tread. Eric is solving for x (the number of tread pattern repeats needed for the 36er) by his multiplications and divisions.
Got it, thanks!
Eric, if you were to choose a tire to sew up for a road tire, what would you choose? Based on lightness, ease of sewing, and best tire for road. Personally I really like the Big Apple 29x2.0 because it’s quite light and the profile works well on camber and when geared up. I know you said above that a wire bead is more difficult to sew so what would you recommend? Thanks.
For the short period of time I got to use the tiger claw on the road I really liked it. It felt nice and nimble, turned really well and I didn’t notice any rolling resistance.
I think a road tire of equal size and shape would roll even better and last much longer.
Wire bead might be fine, when my cable/wire beaded 32" blew out it was at 130 PSI.
But I would really stay away from flexible cable beads. Once you cut those things the little pokey ends will constantly be jabbing your hand while you are trying to work on the tire, then you need to put some tape over the ends to prevent them from busting your tube. not fun.
I’ve been working (slowly) on joining a pair of folding Schwalbe Marathon Racer 700 x 38mm tires to make a road 36. That’s narrower than might be ideal (it’s 1.5 inch) which means it needs higher pressure to ride well (putting more stress on joins).
I’d strongly recommend folding beads - they help the joins to flex and mean that the change in shape of the tire from one diameter to another is not an issue. When I tried joining with wire beads it deformed badly on the joins; I think it was due to the wire bead not accepting the new curvature. If any tyre is going to join it’ll be a folding bead one.
I haven’t made my frankentyre work yet. When I had both joins stitched and glued up well I tried pumping some pressure into the tube. It shaped up well and I got to what felt like riding pressure (I don’t have a gauge but I’d guess 60-80psi), but then the stitches around one of the overlapping bead sections split (thread snapped). I managed to deflate it before it blew out, so I saved the tube and the rest of the join. If I can get the joins to stay together it will take some time holding at high pressure before I trust it enough to ride it though!
I love the idea of stitched tyres, but it seems they are about as sketchy as you’d imagine them to be.
Sam
Thanks Sam. I would be worried about going with something that thin since the rim itself is 38mm wide. I would feel better with a 700x45 (or 50 like the Big Apple 2.0). Does anyone know of a slick 29er tire wider than 38mm that is folding bead? I can’t seem to find any online.
For those interested, finally wrote up a tutorial on how I spliced my last tire.
Did someone make new frankentires?
Could someone give advice about slick tyre around 45mm with foldable beads?
Considering It as experimental i don’t want to use expensive tyres
For now I can think about the Schwalbe Big One that is a 2.5 folding road tire. There should be others but none comes to mind right now…