Originally Posted by DocHolliday
You know, Roger, now that I've thought about it, I have to wonder about the length issue. Stretching a width just involves forcing the leather to give a bit. But wouldn't length require stretching the footbed? How would that be done?
I don't think any stretching of the footbed is ever in the picture with shoe-stretching, and, if I'm understanding the physics involved correctly, shouldn't be any more required for length- than for width-stretching. In the link below, the foot length and width is provided with each shoe size and width (in the US, UK, and Euro systems). In this table, it will be seen that a one-letter width increase (e.g., from D to E) corresponds to a .1875" increase in shoe width. As for length, we see that a .5-unit increase (e.g., from 9 to 9.5) corresponds to a .167" increase in foot
length, which we might expect to correspond to approximately the same increase in shoe length. Thus the two increments (one letter of shoe width and .5-unit of shoe length) are approximately equal, which might account for the folk wisdom regarding the limits of safe stretching--length and width.
Now, as for your conjecture about length requiring alteration of the footbed, whereas width not requiring this, why should this be true? If the width can be stretched approximately .19 without any stretching of the footbed, why should a corresponding (or slightly lesser) increase in length require this? To see this in a different light, consider that a .167 increase in length would require approximately .08" (a little more than 1/16") at the toe and a corresponding amount at the heel. If enlargement of the interior volume of a shoe via width-stretching can be done without any change to the footbed--and that would be by stretching the uppers slightly further out over the sole extension to provide greater volume--why couldn't length stretching accomplish the same thing by stretching the leather slightly further out over the sole extension at the toe (particularly) and at the heel? Remember that we're talking about something close to only 1/16" here.
TheHoff's point is a good one too. By width enlargement in the vamp area, particularly near the toe, this enables the foot to extend further towards the toe of the shoe. In fact, if we study the profile (seen from above) of the vamp, we see that width enlargement near the toe actually provides more usable length, since the foot rarely sits with the toe right against the inside toe of the shoe, and, with many lasts (like the C&J 337, for example) it sits well back (close to 1") of the toe of the shoe. So this is another way in which stretching can buy you both width and
(usable) length enlargement.
Originally Posted by jml90
I would imagine it would also make the shoe narrower.
This would be true only if the leather weren't actually stretched, since the volume would remain the same in that case, and all that would be changed would be the proportion of width to length. However, the leather is
actually stretched, which allows a greater interior volume, not merely a change in the proportions.http://www.geocities.com/handy_feet/shoesize.html