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What Experts Can Tell You About Toe Allowance (Part 2)

Last week, I've discussed what shoe measuring device makers, and professional shoe fitters consider a sufficient, or ideal toe allowance. These groups differ slightly in their opinion, the first using a value of 2 UK/US units, while the latter recommends a value of 1.5 UK/US units.

Here's the second part, where I look at podiatrists, and shoes manufacturers.

What the experts say… (part 2)

Podiatrists and orthopedists

According to Forbes, podiatry is the 15th best paid profession in the United States. This is the field of medical specialists for feet, legs, and the lower back. Surely, they should know about what allowance is best!

Let's look at the recommendations found in the podiartic literature. Discussing the ideal length of a shoe for adults, Merriman (2002, p.257) writes:

Correctly-fitting shoes should have a gap between the longest toe and the front of the shoe to allow for elongation of the foot, which takes place when walking. This gap should ideally be about 12 mm.

There's no source or proof for the value, unfortunately. However, it's close to 1/2 inch (12.7mm). Many units in the article are slightly off (a UK/US unit is said to be 8.4 mm, and a EU unit to be 6.5mm; the true values are 8.5mm and 6.7mm, respectively), so this is probably a rounding error.

Another value is mentioned by Dr. Norbert Becker, orthopedist and foot specialist from Tübingen. Accompanying the largest most recent study about foot and shoe sizes in Germany, he's quoted in the press release of the "Initiative Passender Schuh" by saying (my translation):

In front of the toes, there must be sufficient allowance to roll over, but also not too much. 10 millimeters are ideal.

A slightly more careful formulation is used by Williams (2006) in her shoe fit assessment guide:

Generally 1 cm. space at the end of the toes is considered sufficient.

While this seems to be a broad agreement, remember that allowance is said to differ with regard to the shoe style, and heel height. It's quite astonishing that neither is mentioned by the experts cited above.

So, where do these values come from? One would think, professionals are able to back up their claims with evidence. For instance, it would make sense to figure such values by finding the least risk of developing foot problems or injuries. To the contrary, a typical study seems to use the following procedure:

  1. A participant's shoe size is measured by a “standard” device.
  2. The “correct” size is defined to be the measured size plus/minus half a size.
  3. Participants are then split into a “correct” group and a “wrong” group with respect to the shoe sizes they were actually wearing, according to the label. The actual inner length of the shoes is not measured or recorded.
  4. Statistical tools are then used to confirm a correlation with other variables such as foot deformations, wounds, foot insensibilities, or medical history.

The description is a bit simplified since shoe widths are usually recorded and compared, too. However, the general outline is correct. The method was used by Burns, Leese, and McMurdo (2002), Nixon, et al. (2006), and Harrison, et al. (2007). Two used a “standard 'Clarks' shoe shop measuring stick”, and one used an Apex 1141 “Ritz stick”. The Clarks device should apparently be used when a person sits, while the Apex stick should probably be used when a person stands.

There are many obvious problems with the approach: For instance, the authors offer no reason why the results of these devises were considered “correct” in the first place. They offer no explanation why a deviation of half a size is considered acceptable, and larger ones were not. They also do not say how long, say, a UK 8.0 or US 9.0 is in centimeter or inches on these devises, so the results are hard to repeat unless you have one.

An exception is a more recent study by Meyr and Creech (2011) who used a Brannock device. In contrast to the above studies, they seem to have used an exact match as their definition of a 'correct' size. 28 out of 129 participants got the 'right' shoes, which is a surprisingly large percentage when you think about it. But the authors do not discuss whether they have ignored its arch length measure or not. There's no hypothesis they actually tested. Additionally, they mixed up one of their references.

Given these rather dubious methods, readers like you and me are left guessing what all this actually implies. From a scientific point of view, these studies – cited widely in the literature – seem hardly acceptable to me. Anyway, if we assume these devises to be calibrated with 2 full units (as indicated in part 1), the authors seem to think that a nominal allowance between 1.5 and 2.5 units (1/2 to 5/6 inch) is acceptable.

This is a rather wide range, compared to the recommendations of their colleagues who seem to find a value of around 3/8 to 1/2 inch more appropriate. The reason for the difference is probably the uncritical use of a measuring device.

Manufacturers

The most valuable recommendations are, of course, the ones made by shoe (and last) makers. At least, they should know what toe allowance is best.

Unfortunately, nearly no one publishes the relevant values. An exception is the Austrian company, Ludwig Reiter. In their "Musterbuch" (pattern book), the company provides the total allowance for some of their lasts. Here's the list, amended by splitting the data into a minimum value and the difference:

Last Total allowance Minimum value Difference
Ungarischer 12mm 12mm 0mm
Alt Wiener 15mm 12mm 3mm
Neuer Wiener 20mm 12mm 8mm
Karree 20mm 12mm 8mm
Engländer 23mm 12mm 11mm

Three things are worth noting: First, the list does not mention shoes sizes. In other words, when wearing a shoe made on the “Ungarische” (Hungarian) last, you should always have a free space of at least 12mm in front of your toes – whether you wear a UK 8 or a UK 10! If you have much less, your feet are too long for the size you're wearing. If you have much more, your feet are too short for the size you wearing.

Second, the allowance of the shortest last is consistent with all the recommendation mentioned above: It's more than the minimum value of 10mm, and very close to the common recommendation of 1.5 UK/US units (1/2 inch or 12.7mm).

Third, the allowance of their longest last is nearly twice that of their shortest one. That means, when you wear a shoe made on the “Engländer” (English) last, it's supposed to look longer on your feet. Strictly speaking, you should not size down to reduce that space. For the last designer almost certainly knew what he was doing when he gave the last a large allowance. Otherwise, he would have made it shorter, wouldn't he? He probably changed other dimensions as well to take its length into account. Of course, you're free to change that by using a smaller or larger size for yourself. But why should you disregard the last maker's expertise?

These numbers might just be a coincidence. So, here are the numbers from another manufacturer. This time, it's one of the best-known and largest shoe brands in the world, Converse. While we usually do not talk about sneakers here, it has the advantage of having Japanese (or Asian) shoes sizes printed on its shoe boxes.

The Japanese shoe sizing system is one of the most sane in the world. All you need to do is measure your foot length in centimeter, and round-up to the next half. No need to know about allowance. This is all left to the shoe and last maker.

In other words, a JPI shoe size is basically just the foot length. By converting the UK size into the nominal length, and subtracting the foot length, we're able to reconstruct the nominal allowance used by Converse. Here's a table with a small sample, converted to millimeter for better comparison:

UK size Nominal length Foot length Est. Allowance
5.5 258mm 245mm 13mm
7.5 275mm 260mm 15mm
8.0 279mm 265mm 14mm
8.5 284mm 270mm 14mm
10.0 296mm 285mm 11mm
12.0 313mm 305mm 8mm

Overall, these values are rather close to the expected value of about 13mm, given the errors resulting from converting the numbers. The last value might constitute a counter-example, though.

If a company like Converse is able to print sizes on their boxes that are close to the expected value, why should we expect quality shoe makers to be unable to do so? That's hardly imaginable.

Summery

While all these numbers may sound confusing, at first, there's a roughly consistent trend among experts to recommend a toe allowance of 1.5 UK/US units (1/2 inch or 12.7mm). The value is suggested by professional shoes fitters, and by podiatrists in their theoretical works. And there are at least two manufacturers who do seem to follow it: The premium brand Ludwig Reiter, and the mass-market brand Converse.

The data from Sizeadvisors also reflects the value, on average.

It's hard to believe why any quality shoe maker would ignore or disregard such a convention. It seems shoe sizes are consistent; they are just not meant to do what many consumers want them to do. Consumers want a shoe size to mostly reflect widths and girths measurements, for these determine the subjective fit of a shoe.

But this is not what shoes sizes appear to be made for. They are not meant to signal fit but sufficient allowance.

The exception to the rule seem to be measuring device makers. For some reason, their devices appear to be calibrated to 2 UK/US units. Maybe, this is just an old value, and they forgot to change it. After all, the market can hardly be called innovative. Maybe, they are anticipating the typical behavior of consumers – that is, the tendency to ask for a smaller size if a pair feels “too wide”. Or maybe, they are just trying to be on the safe side.

Anyway, getting measured with any of these devices is probably an improvement, when you consider that a remarkable share of consumers differ greatly from the recommended value.

The “thumb rule”, however, seems to be more misleading than helpful. Without knowledge about the last, its heel height, and another person to help, its usage may still result in shoes that are too short, or too long. The sizing labels of quality shoe makers seem to be more reliable in comparison.

That does not make sure that a pair of shoes fits, of course; due to the differences among lasts and widths. But it will almost certainly make sure there's sufficient toe allowance.

References

Burns, S.L., G.P. Leese, M.E. McMurdo (2002): "Older people and ill fitting shoes." Postgraduate Medical Journal, Vol. 78. No. 920 (June), p. 344-346.

Harrison, S. J., L. Cochrane, R. J. Abboud and G. P. Leese (2007): "Do patients with diabetes wear shoes of the correct size?" International Journal of Clinical Practice, Vol. 61, No. 11 (Nov.), p. 1900-1904.

Merriman, L. (2002): "Footwear assessment", in: L. Merriman and W. Turner [Eds.] (2002): "Assessment of the Lower Limb", 2nd ed., London: Churchill Livingstone, p. 245-265.

Meyr, A. J., and C. Creech (2011): "Perceptions of appropriate shoe size in diabetic patients presenting for initial podiatric evaluation", The Journal of Diabetic Foot Complications, Vol. 3, No. 2, p. 40-42.

Nixon, B. P., D. G. Armstrong, C. Wendell, J. R. Vazquez, Z. Rabinovich, H. R. Kimbriel, M. A. Rosales, and A. J. M. Boulton (2006). "Do US Veterans Wear Appropriately Sized Shoes?: The Veterans Affairs Shoe Size Selection Study", Journal of the American Podiatric Medical Association, Vol. 96, No. 4, p. 290-292.

Williams, A. (2006): "Footwear assessment and management", Podiatry Now, p. S1-S9.



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