Join Date: Jul 2008
Location: San Mateo
Bikes: 3 Bromptons, M2L-X, S6L-X/BWR. S6R/SRAM/Schlimpf, Novara Roadbike
Video of How to Fit a Tire (example - Marathon Plus)
I've encountered cyclists struggling to fit tires, particularly the stiffer Marathon Plus, and also for Brompton where the size of the depth from top of rim to the bottom of the well is relatively large and so the tire's little stretch isn't enough and brute-force usually fails.
The "Wave" method is to push the bead of the tire into the well, it will tend to bounce back out of the well so takes multiple waves, progressively flipping a bit more of the bead over the rim. The TRICK is to NOT USE STRENGTH, because all that strength does is firmly lock the bead over the rim so when you use the WAVE it too tight all-over to really be moved much into the well. You need JUST enough tension at the bead-rim boundary to tend to keep the bead where you put it, too much tension and it won't move, too little and it will just bounce back out of the well. There's no skill initially required, as initially if you've pushed too little of the tire over, the first couple of waves are not doing much but then later it will be doing it enough. With practice one remembers how much force your thumbs should be applying before the first wave, I'd say about 10%-20% of max thumb strength.
Multiple Waves, little strength, and just be patient. At no time should strength be used, a child's hands could do this method.
For a new tire about 4-10 waves are needed, in the video this is using an old tire and this example only 2 waves needed.
In the video I've omitted some commonly-known facts like the tube needs to be partially inflated so it tends to not get caught.
No knuckles were harmed with the making of this video. Enjoy.