Wider rims (inner measure) - how wide is "good"?

BugsBunny
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Wider rims (inner measure) - how wide is "good"?

Postby BugsBunny » Wed Sep 27, 2017 11:05 am

Cutting through much of the marketing BS, I do tend to believe that a wider INNER rim will give you: a more comfortable ride, and better handling if matched to a correspondingly wider tire. My Mavic R-SYS rims are 15mm inner and I'm on the look out now for something in the 17mm-21mm category. 21mm seems to be the upper limit for most road clincher/tubeless rims. But there are very few options. The bulk are at 17mm.

I'm struggling to see the worth in "upgrading" to something that is just 17-18mm wide given that the tires I want to run are 23mm/25mm. This being the case, is the upgrade only "worthwhile" if I go for the 20-21mm options? Or would I see obvious improvements with 17-18mm options?

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silentbutdeadly
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Re: Wider rims (inner measure) - how wide is "good"?

Postby silentbutdeadly » Wed Sep 27, 2017 11:35 am

I run 28 width tyres on 17 mm inner width rims, 35 width tyres on 19 mm inner width rims and 57 mm tyres on 24.5 mm inner width rims. But I'm not sure this helps you...

I wouldn't bother upgrading if you are only going to run 23/25 mm tyres unless your current rims are toasty...
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BugsBunny
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Re: Wider rims (inner measure) - how wide is "good"?

Postby BugsBunny » Wed Sep 27, 2017 12:19 pm

Thanks SilentBD.

I once tried 28mm Conti GP4000 tires on 15mm inner rims and it ballooned waaaay too much. I reckon its almost dangerous as its gets "floppy" (imagine left and right flex of the tire out of the saddle or when cornering hard) unless you run very high pressures (which I don't) to keep the tire stiff.

Don't you find 28mm tires on 17 inner too wide? Or moreso the 35mm on 19mm too wide? I would love to run 28/30mm tires but my understanding is that there is a practical limit based on a corresponding rim width. From my limited experience, that does seem outside of the boundaries of what is practical even though it does fit. Thanks for sharing.

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MichaelB
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Re: Wider rims (inner measure) - how wide is "good"?

Postby MichaelB » Wed Sep 27, 2017 12:25 pm

For the last 4 years +, I've been running 25C tyres on a set of MTB (chinese even !!) carbon rims with a 19mm inner width.

Work a treat, and the 19mm is probably a sweet spot in terms of width :-)

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hamishm
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Re: Wider rims (inner measure) - how wide is "good"?

Postby hamishm » Wed Sep 27, 2017 2:01 pm

BugsBunny wrote:I once tried 28mm Conti GP4000 tires on 15mm inner rims and it ballooned waaaay too much. I reckon its almost dangerous as its gets "floppy" (imagine left and right flex of the tire out of the saddle or when cornering hard) unless you run very high pressures (which I don't) to keep the tire stiff.

I've been running 28mm 4000sIIs on Open Pros (15mm) for nearly a year without any issues. I've settled on 75 psi. I'm not cornering hard though.

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Thoglette
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Postby Thoglette » Wed Sep 27, 2017 2:06 pm

Image (from VelosterTurbo.org)

This has been discussed lots of times, like here and here

I usually end up posting this chart from Mavic Image

Note that modern rims are all C (crochet or hooked). Others note that the above is a conservative guideline.
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Nate
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Re: Wider rims (inner measure) - how wide is "good"?

Postby Nate » Thu Sep 28, 2017 3:23 pm

I run 19mm inners from bdop in my alloy's.

with 25's & now 28's & will definitely stick with them - allow for more volume of air & less chance of pinch flats.
I'd go up to 19mm, but above that its questionable if it will seat - so be a little careful

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rodneycc
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Re: Wider rims (inner measure) - how wide is "good"?

Postby rodneycc » Thu Sep 28, 2017 4:20 pm

I like this article which I seem to always google and come back to.

https://intheknowcycling.com/2016/04/03 ... heel-sizes

The basics of it are:

A 23C tire on a 15C wheel – this is the likely stock or alloy upgrade wheel and tire combination you have as a baseline on bikes made before 2016. You know how this rides. This is still a perfectly good width combination in my view. What follows are your options.

A 25C tire on a 15C wheel – somewhat improved comfort over a 23C tire but worsened speed and handling for reasons described above. Better to reduce pressure 5psi or so on 23C tire for better comfort without losing handling performance. Neither combination is going to be an aero star.

A 25C tire on a 17C wheel – better comfort but no better speed or handling than a 23C tire on a 15C wheel. 23C tire on 17C wheel at right pressure will get you somewhat improved comfort with improved aero if the rim has at least a rounded nose rather than box or V profile, is >35-40mm, and you are riding at 18mph/29kph or faster.

A 25C tire on 19C or wider wheel – best comfort, improved speed and handling over options above. A nice set-up for long endurance rides at a good average speed (18mph/29kph or higher) especially on deeper (>35-40mm) and preferably rounded profile wheels. But, most alloy wheels aren’t going to be that deep or have a rounded rim profiles where the spokes join the rim.
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BugsBunny
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Re: Wider rims (inner measure) - how wide is "good"?

Postby BugsBunny » Fri Sep 29, 2017 11:46 am

Happy Friday! And thanks all for your inputs.

I've spent the last year or so mulling over this wide rim concept - more so than the wide TIRE concept and have come across and read most of the marketing and manufacturer recommended pairings for rims/tires. I had put 28mm Contis on my 15mm Mavics purely based on the official recommendation by Mavic that it was within its specifications. But my real life experience wasn't so good. Hence, I take them with a grain of salt.

What I cannot find much info on is regular folks experience using wide inner rims - especially those in the 19-21 mm inner rim range. Or those who have tried and switched from 15mm to 17mm - whether it made any real difference to comfort, braking, handling?

The bottom line is, if I go wide, then is it worth while going the hog hog and get the widest 20-21mm? I think the jury is still out as most manufacturers have settled on 17mm as the new norm, but I reckon that is done moreso from weight / marketing reasons rather than what is the "best" which I *think* should be 20-21 given that most ride 25mm tires.

Cheers!

Bugs

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Re: Wider rims (inner measure) - how wide is "good"?

Postby minhyy » Fri Sep 29, 2017 7:27 pm

something to consider about going wider rims is that the tires may become substantially "larger" too - so it is worthwhile ensuring there is adequate frame and/or brake caliper clearance
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eeksll
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Re: Wider rims (inner measure) - how wide is "good"?

Postby eeksll » Fri Sep 29, 2017 9:15 pm

accompanying the text following the chart which Thoglette pasted above

http://engineerstalk.mavic.com/en/the-r ... rim-width/
Example of reading: a 23mm tyre can be safely mounted on traditional rims of 13mm to 16mm (internal width). On any rim wider than 16mm, it is not possible to use a 23mm tyre safely.

On the other hand, a rim that is 21mm wide internally, can only accept tyres from 35mm and above.


and also to point out, its a recent-ish article where they are presenting the view that a wider tyre is better for comfort and rolling resistance. Not an article based on "common knowledge" from the ye old days :mrgreen: .

I haven't checked, but I would think Mavic would sell rims at the 21mm inner width as well so I don't think its complete marketing BS.

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Nate
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Re: Wider rims (inner measure) - how wide is "good"?

Postby Nate » Tue Oct 03, 2017 1:30 pm

eeksll wrote:accompanying the text following the chart which Thoglette pasted above

http://engineerstalk.mavic.com/en/the-r ... rim-width/
Example of reading: a 23mm tyre can be safely mounted on traditional rims of 13mm to 16mm (internal width). On any rim wider than 16mm, it is not possible to use a 23mm tyre safely.

On the other hand, a rim that is 21mm wide internally, can only accept tyres from 35mm and above.



its also coming down to the profile of the rim inside & around the bead area.
The profiles can be very different & affect "safety".

On my bdop wheels (using Kinlin rims) the cross section isnt a perfect U shape, so its really tricky to get the tyre on/off - except when the tyre is in the MIDDLE of the rim. As near the bead hook - its a larger diameter, helping to hold it on better.

When i did my looking around most places recognised the need for more research & data - as rim profiles had changed significantly in recent times.

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Re: Wider rims (inner measure) - how wide is "good"?

Postby BugsBunny » Wed Oct 04, 2017 2:51 pm

Thanks all.

I've decided to make the jump and have put in an order in for some wheels with a 20.7mm inner rim. That's wider that the external width of my Mavic R-SYS!

I'll share how they ride once I get them.

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