[Montesa]

I am looking at the Mavic A317 and TN719 for use on a sturdy road/gravel commuter.

A317 - recommended tire widths: 28 to 47 mm
TN719 - recommended tire widths: 38 to 58 mm


Which rim would be better for tires in the 38 to 42mm range (max that will fit the frame). I am partial to Schwalbe Marathons.

This relates to the optimum tire profile I guess.

 

[meltingfeather]

The A317 is a great rim and should serve you well. They will also cost you ~$35 less per rim. :thumbsup:

 

[Fix the Spade]

TN719 is perfectly happy with narrower tyres, but for a commuter bike is massive overkill in strength terms.

Get the 317 and spend the extra on some beers.

 

[Montesa]

I'm not sure I will go with either of these rims. I was wondering what the advantages of a wide or narrow rim is on tire profile.

 

[One Pivot]

wide rims support wide tires better, if you have a wide tire on a narrow rim the tire can flop around when cornering. too narrow of a tire on a too wide of a rim can cause pinch flats.

the tn is massively overkill for that kind of riding though.

 

[meltingfeather]

I'm not sure I will go with either of these rims. I was wondering what the advantages of a wide or narrow rim is on tire profile.

The wider the rim, the more it opens up the tire profile, increasing air volume & making the tire more laterally stable. As the mfr specs suggest, there is a range of appropriate-width tires for each rim width, though the specs can be pushed a bit. When you get to extremes, a very narrow rim with a very wide tire will make the tire more squirrely and susceptible to pinch flats, while a rim wider than the tire is asking for blow-offs and rim damage.
For the use and tires you are proposing, the A317 is a great match. I don't see a reason to go any wider.

 

[hikerdave]

I'm not sure I will go with either of these rims. I was wondering what the advantages of a wide or narrow rim is on tire profile.

A wider rim effectively increases the diameter and circumference of the tire. Since the tread has a fixed width, using a wider rim means that the knobs on the tire contact the ground at a slightly less lean angle.

In other words, a wider rim makes the tire profile a bit more "square."

When you ride a wider rim, given the same tire, means that you will lean the bike a bit less to bite into a berm or corner, depending on the tires. I don't think that this effect makes a big difference, though. On the other hand, you probably have a bit more margin for error with a narrower rim and rounder profile, because if the tire slides out and increases the lean angle of your bike you'll get a bit more traction instead of sliding off onto the sidewall.

Probably not a big deal either way. I haven't noticed a huge difference in traction going from Shimano WH-775 to Mavic 823 rims recently.