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Any advantages of having narrow depth rims?

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Any advantages of having narrow depth rims?

Old 04-25-21, 01:33 AM
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PimpMan
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Any advantages of having narrow depth rims?

Many "tour de France" type of riders care much about aerodynamics so they use deeper rims presumably for less air resistance.

I have retro city commuter bicycle with skinny frame and 700c wheels that i mostly use to cruise in the city and sometimes ride little fast.

Want to know difference i've seen they two types of rims sold at about same price range, provided both rims are double walled aluminum, what advantages/disadvantages of having deeper 30mm rim vs more narrow 18mm depth?

IMHO

Advantage
- Smaller depth (18mm) rim has less weight and this could be advantage for cruising
- Smaller depth (18mm) rim is more flexible so it could be advantage as well for bumps
Disadvantage
- more prone to deformation
- slightly more air resistance.

Last edited by PimpMan; 04-25-21 at 01:37 AM.
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Old 04-25-21, 05:34 AM
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The deeper rim will be stronger in the long run. As for aero advantages don't count on it unless the rest of the wheel is built for aerodynamic advantages and the wheel speed is at a point where spoke/rim/hub combination make an aerodynamic impact. For commuting the deep section rim makes more sense, but doesn't look as nice as shallower rims. Oh, for what it is worth, bright silver is faster. lol
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Old 04-25-21, 06:57 AM
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I believe the deeper rims have beside being aero a second reason for being, which is higher rigidity, since the spokes are shorter.

Often the front wheel doesn't even have spokes crossed which again means the increase in rigidity. Not sure if the goal is the higher rigidity, or if the aero wins all the way and the rigidity you just have to live with, maybe compensate for it by some flex elsewhere in the bike, including good bar wrapping and padded gloves.
Probably both the aero and rigidity are the goal, comfort takes back seat. Racing is not meant to be a comfortable pursuit

Mind you, the deep wheels are probably even lighter than the shallow rims, they just give heavier impression (but that depends on the price bracket). I'd say, on retro city commuter bike you don't need the aero and discomfort of rigidity, besides that, it stops the bike looking retro but a more a mishmash of styles.

Last edited by vane171; 04-25-21 at 07:06 AM.
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Old 04-25-21, 07:19 AM
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Deeper rims act may be more sensitive to cross-winds, acting as more of a sail.
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Old 04-25-21, 07:29 AM
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18mm is a tall rim. If deformation occurs at all it is trivial. If flexing happens at all it will drastically reduce the life of the spokes and of the wheel.

Vintage aluminum rims can be as little as 10mm in height. If the wheel is well built there is no problem. Taller rims will survive substandard builds better than shallow rims. Loose and uneven spoke tension will always degrade the way the wheel rides, it will however last longer if done with a tall rim.

Tangent spoked wheels are much stronger and stiffer than radial spoked wheels. If the rim is extremely stiff it won’t matter for most purposes on a front wheel. Tangent spoked wheels will still last longer.
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Old 04-25-21, 10:45 AM
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A 30mm rim will be stiffer, which when paired with a typical 24-h wheel build will provide a stiffer, more responsive, 'lively' ride.
The 18mm rim will usually be a 32-h or even a 36-h, which is built with lower individual spoke tension and gives a more compliant ride.
A higher-spoke wheel will also usually be stronger, since there are more spokes to distribute the load forces, that's why they're used more often on touring bikes and for heavier riders.
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Old 04-25-21, 01:50 PM
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shorter profile *may* allow for more give when installing a very tight tire & jackers are MIA.
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Old 04-25-21, 02:01 PM
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With the shorter profile you don’t have to worry about the stem length of the tubes you have on hand. A deeper rim will make a heavier wheel, a consideration if you do a lot of climbing but will probably ‘cruise’ better on a flat road.
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Old 04-25-21, 02:48 PM
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Originally Posted by Ironfish653 View Post
A 30mm rim will be stiffer, which when paired with a typical 24-h wheel build will provide a stiffer, more responsive, 'lively' ride.
The 18mm rim will usually be a 32-h or even a 36-h, which is built with lower individual spoke tension and gives a more compliant ride.
A higher-spoke wheel will also usually be stronger, since there are more spokes to distribute the load forces, that's why they're used more often on touring bikes and for heavier riders.
Good point. 24 hole has become typical and for that hub a tall rim is far more realistic. If you could find an 18mm rim in 24 hole it would be better for lighter riders.

There are circumstances where lower spoke tension could give a more compliant ride. That compliance is coming from a soggy basket of spokes more than from the rim. Again best reserved for lighter riders. Go too far down that road and the spokes will fatigue quickly. And handling may be compromised. The downside for building with high spoke tension is negligible, most builders use the same tension for any number of spokes, any size rider.

For touring loads you have to consider that the unsprung weight of laden panniers puts massive loads on the spokes. Very heavy riders are not often as agile as smaller riders and will behave a lot like unsprung weight. In those cases it makes sense to use lots of spoke. Commuters who carry lots of stuff besides themselves would do well to also use lots of spoke.
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Old 04-25-21, 02:51 PM
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Some interesting takes in this thread.

A deeper rim is usually a vertically stiffer rim. Not necessarily a laterally stiffer one. So you get less rim deformation. This makes the wheel more reliable (less likely to go out of true) but less comfortable. How much the wheel compliance matters depends on the entire system. If you're riding a race bike with tires at 120psi and a bare carbon saddle, you might notice a slight difference. If you're riding a more compliant setup like a leather sprung saddle, maybe not.

A deeper rim increases the spoke bracing angle and allows for potentially higher lateral stiffness. But this assumes that your rim is very very stiff and you're not better off just leaning on the spokes. If the rim is noodly, a deep rim is worse than a shallow one. The depth is not the only indicator of how resistant to lateral deflection a rim is. In fact, as the rim gets deeper, it must be built stronger because there is a greater distance between the bead seat and the spoke anchor point.

For example, imagine what would happen to a paper thin rim under lateral load.

Now, that being said, if 2 rims are of similar construction, and one is deeper, the deeper rim has more material and thus is better equipped to transfer lateral load to the upper spokes rather than simply bending. Wide rims also help with this (and are more effective). This is what causes brake rub - the stiff rim transfers lateral force from the ground to the top of the wheel. The stiffer your rim, the stiffer/more spokes you need to eliminate brake rub.
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Old 04-25-21, 02:54 PM
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The deeper rim on the right has more of a triangular structure, my guess is it's stronger. Back in the day the shallower rims were made with 36 spokes, 36 hole hubs were the norm. Now the deeper rim, 32 spokes are more common.
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Old 04-25-21, 03:21 PM
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Trade off between weight and aero when considering same and similar quality rims. Which do you need?
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Old 04-26-21, 02:34 AM
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Not having to worry about valve stem length when buying tubes.
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Old 04-27-21, 12:46 AM
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Thanks everyone for reply, since i don't mind to adjust the spokes every now and then i made following conclusion for myself.

- For classic look + comfort + weight advantage small (depth) rim, even single walled aluminum rim.

- For better aerodynamics and rigidity, including off-road use (i ride 700c off-road often) and jumping on/off the curbs deeper rim 30mm rim.
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