Any advantage to having a narrower front rim?
10-23-22, 07:19 PM
#26
Senior Member
Join Date: Oct 2020
Location: Phoenix, AZ
Posts: 910
Bikes: 1964(?) Frejus Tour de France, 1967(?) Dawes Double Blue, 1979 Trek 710, 1982 Claud Butler Dalesman, 1983 Schwinn Paramount Elite, 2014 Brompton, maybe a couple more
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 310 Post(s)
Liked 679 Times
in
331 Posts
Likes For albrt:
10-25-22, 11:40 AM
#27
Sock Puppet
Join Date: Oct 2022
Location: Planet Earth
Posts: 1,701
Bikes: 2014 Cannondale Synapse Carbon, 2017 Jamis Renegade Exploit and too many others to mention.
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1031 Post(s)
Liked 863 Times
in
573 Posts
I don't agree. All things equal, a wheel with a heavier rim, with more metal in it, will be less likely to break spokes than one with a thinner rim. Dish also matters a lot. Dishless tandem wheels can be very strong in spite of a low spoke count.
First, I used to tour on a 36 spoke rear wheel made with a Mavic MA3 rim (470g weight), and broke three rims and ten spokes before lacing the same spokes and hub to a Rigida Sputnik (745g weight), and it has not had any trouble under the same conditions. Same builder (me), same spokes, same hub.
Second, Look at Santana's tandem-specific Shimano wheels, which only have 16 spokes, but are dishless and have special, heavier rims. According to Santana, they were subjected to the same mechanical test trials as Santana's 40-spoke wheels and the 40-spoke wheels broke first.
I would also love to have more spokes, yes. But above 36 you get into specialist tandem components. Heck, even getting 36 is hard sometimes. I put an ad up looking for a 135-spaced silver 36h rear cassette hub and have had no responses in two weeks. And even tandems are going to heavier rims with fewer spokes now.
First, I used to tour on a 36 spoke rear wheel made with a Mavic MA3 rim (470g weight), and broke three rims and ten spokes before lacing the same spokes and hub to a Rigida Sputnik (745g weight), and it has not had any trouble under the same conditions. Same builder (me), same spokes, same hub.
Second, Look at Santana's tandem-specific Shimano wheels, which only have 16 spokes, but are dishless and have special, heavier rims. According to Santana, they were subjected to the same mechanical test trials as Santana's 40-spoke wheels and the 40-spoke wheels broke first.
I would also love to have more spokes, yes. But above 36 you get into specialist tandem components. Heck, even getting 36 is hard sometimes. I put an ad up looking for a 135-spaced silver 36h rear cassette hub and have had no responses in two weeks. And even tandems are going to heavier rims with fewer spokes now.
Your anecdotes above - 40 spoke wheel vs. 16 spoke wheel - were two different rim types, correct? The rim is usually the weakest link in any build. It's common sense that given exactly the same rim make and model, more spokes spread out the stress on that rim. Greater number of spokes make for a stronger and less flexy wheel.
So then you may think a wider rim is stiffer, right? Wrong! There is an article on Slow Twitch "Debunking Wheel Stiffness" that explains why just the opposite is true. I am not allowed to post it yet, because I still have Newbie status here, but it's easy to find if you Google it.
And not to say, but there are better choices of rims than Mavic which have a reputation for spoke hole cracks.
Last edited by Lombard; 10-25-22 at 11:45 AM.
10-25-22, 11:52 AM
#28
Senior Member
Wise adage: if you have the same number of spokes front and rear, then you either have too many spokes in the front, or too few in the rear.
Since the rear wheel takes >60% of rider weight, and the worst impacts, and the most flats, rear wheels should be built with heavier duty rims, more spokes and fatter and more robust tires. Selecting a front wheel with these same characteristics is sub-optimal in terms of weight.
Since the rear wheel takes >60% of rider weight, and the worst impacts, and the most flats, rear wheels should be built with heavier duty rims, more spokes and fatter and more robust tires. Selecting a front wheel with these same characteristics is sub-optimal in terms of weight.
10-25-22, 12:39 PM
#29
Sock Puppet
Join Date: Oct 2022
Location: Planet Earth
Posts: 1,701
Bikes: 2014 Cannondale Synapse Carbon, 2017 Jamis Renegade Exploit and too many others to mention.
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1031 Post(s)
Liked 863 Times
in
573 Posts
Wise adage: if you have the same number of spokes front and rear, then you either have too many spokes in the front, or too few in the rear.
Since the rear wheel takes >60% of rider weight, and the worst impacts, and the most flats, rear wheels should be built with heavier duty rims, more spokes and fatter and more robust tires. Selecting a front wheel with these same characteristics is sub-optimal in terms of weight.
Since the rear wheel takes >60% of rider weight, and the worst impacts, and the most flats, rear wheels should be built with heavier duty rims, more spokes and fatter and more robust tires. Selecting a front wheel with these same characteristics is sub-optimal in terms of weight.
10-26-22, 09:39 AM
#30
Ride, Wrench, Swap, Race
Join Date: Jan 2010
Location: Northern California
Posts: 9,194
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Mentioned: 132 Post(s)
Tagged: 0 Thread(s)
Quoted: 1565 Post(s)
Liked 1,296 Times
in
866 Posts
In the case of hitting a sharp bump or rock in the road, where the tread gets pushed dangerously toward the edge of the rim, a wider rim helps the tire to better support the load by spreading out the beads of the tire.
A narrow rim allows the tire's sidewalls to bulge outward so severely under impact that the rim intrudes further into the tire's volume, allowing road surface peaks or small rocks to strike the rim more easily.
As well, the flattening of the tread at the road surface by itself pushes the sidewalls outward closer to a horizontal disposition, which alone causes the rim to ride closer to the road surface (again increasing the chances of pinch-flatting and rim damage).
And a wider rim increases the tire's air volume, again helping to keep impacts from reaching up to the rim's edge.
I've come across a few bespoke builds that were in such good condition (and with matching spoke styles and rim vintages) that I found it easy to conclude that the wheels were probably built with a wider rear rim originally. The pairing of a Rigida narrow front with a wider Mod58 rear rim is one combination that I've seen more than once, though it's at least possible that the rear rim could have been a replacement.
No question however that any wheel builder from that era was fully aware that the Mod58 rim was much tougher than a same-period (narrow) Rigida 1319.
A narrow rim allows the tire's sidewalls to bulge outward so severely under impact that the rim intrudes further into the tire's volume, allowing road surface peaks or small rocks to strike the rim more easily.
As well, the flattening of the tread at the road surface by itself pushes the sidewalls outward closer to a horizontal disposition, which alone causes the rim to ride closer to the road surface (again increasing the chances of pinch-flatting and rim damage).
And a wider rim increases the tire's air volume, again helping to keep impacts from reaching up to the rim's edge.
I've come across a few bespoke builds that were in such good condition (and with matching spoke styles and rim vintages) that I found it easy to conclude that the wheels were probably built with a wider rear rim originally. The pairing of a Rigida narrow front with a wider Mod58 rear rim is one combination that I've seen more than once, though it's at least possible that the rear rim could have been a replacement.
No question however that any wheel builder from that era was fully aware that the Mod58 rim was much tougher than a same-period (narrow) Rigida 1319.
Last edited by dddd; 10-26-22 at 09:44 AM.
