We examine the implications of the widely used, force‐free, constant‐αflux rope model of interplanetary magnetic clouds for the evolution of these mesoscale (fraction 1 AU) structures in the heliosphere, with special emphasis on the inner (≤1 AU) heliosphere. We employ primarily events observed by the Helios 1 and 2 probes between 0.3 and 1 AU in the ascending and maximum phases of solar cycle 21 and by Wind at 1 AU in a similar phase of solar activity cycle. We supplement these data by observations from other spacecraft (e.g., Voyagers 1 and 2, Pioneers 10 and 11, and others). Our data set consists of 130 events. We explore three different approaches. In the first, we work with ensemble averages, binning the results into radial segments of width 0.1 AU in the range 0.3 ≤rh≤ 1 AU. Doing this, we find that in the inner heliosphere the modeled average central axial field strength, 〈B0〉, varies with heliospheric distancerhas 〈B0〉 [nT] = 18.1 ·rh−1.64[AU], and the average diameter increases quasi‐linearly as 〈D〉 [AU] = 0.23rh1.14. The orientation of the axis of the underlying magnetic flux tube in our data set is generally found to lie along the east–west direction and in the ecliptic plane at all values ofrh, but there is considerable scatter about these average directions. In the second, we monitor the evolution of magnetic clouds in snapshot fashion, using seven spacecraft alignments. The results are in broad agreement with the statistics reported under step 1. In the final approach, we obtain the functional dependence ofB0andDpredicted by an analytic expression for a freely expanding Lundquist flux tube. We findDto vary linearly withrh, broadly similar to that obtained under approach 1. The maximum field strength scales asrh−2compared to arh−1.3dependence obtained from statistics. We compare our findings with those of Bothmer and Schwenn (1998), who used a different methodology. The results obtained form a good background to the forthcoming Solar Terrestrial Relations Observatory (STEREO) and Sentinels missions and to multispacecraft studies of magnetic clouds.