Tech Rim width and tire width

Apr 3, 2012
401
98
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Tama Center <-> Otemachi
#1
So my search skills are failing me and I turn to the wisdom here at TCC!

What are the recommendations for tire width for to rim width? Example, with a 24mm rim width, would tire choice be limited to 25mm and up? Or would 23mm still work?

Other gotchas?
 
Apr 3, 2012
401
98
48
Tama Center <-> Otemachi
#3
I'm looking at picking up this wheel being offered used. The specification is 24mm width, which I suspect means the outside measure. From other similar profiles, the inside rim is likely 18mm... So according to the chart, minimum tire width is 25mm. All my stock is 23mm... is putting 23mm tire on an inside rim 18mm a bad idea?
 

Sikochi

Maximum Pace
Sep 13, 2010
1,147
45
68
Kochi
#4

Sikochi

Maximum Pace
Sep 13, 2010
1,147
45
68
Kochi
#5
From the previously listed article.

Note that there is a distinct cutoff that we should all be concerned with – between 15c and 17c rims. As mentioned, 15c tends to be on the wide-end of old traditional road rims. For example, the ubiquitous Mavic Open Pro is a 15c rim. According to the rules, the narrowest tire you should use with this is a 23mm. You will notice that many of the newer wide rim manufacturers fail to mention the ETRTO size; they only tell you the outside-to-outside measurement of the rim. I can tell you with a high level of certainty that any 23mm wide rim is at least 17c ETRTO. Most of these rim manufacturers recommend a minimum of a 23mm tire… but that technically doesn’t fit the chart…>insert screeching halt<

Huh?! Are you at a risk of system failure, and perhaps a crash? The late bicycle genius, Sheldon Brown, suggested that the ETRTO chart is on the conservative side in its prescriptions. It is common knowledge in the mountain bike world that you can get away with a much wider tire than recommended. We also know that folks have used 18-20mm tires for years on many standard rims, including the technically-too-wide 15c standard. What does this all really mean?

The real take-home is that we should all educate ourselves on the topic, and understand that if we choose to go outside of the standards, it is at-your-own risk. As well, we should continue to push manufacturers for full-disclosure of their rim ETRTO sizes. Perhaps they will tell you if you call them up, but none currently publish this information of their new wide clincher rims. While I wouldn’t recommend using anything less than a 23mm tire on a rim that is ETRTO 17c (or 23mm outside-to-outside), it appears that many people are using this combination today without issue.

***

For reference, my new wheels are 23mm wide - internal width not listed - and I ran them with a 22mm conti attack for my hill climb on sunday with no probs. Actually, the biggest problem was getting the bugger on the wheel - damaged one inner tube during installation - really can`t see the tyre coming off that.
 
Apr 3, 2012
401
98
48
Tama Center <-> Otemachi
#6
So a bit more about my use case - Mainly this is for "fast" commuting about 37km each way through the Tokyo suburbs and metro areas. The worst road conditions is typically what's found in Roppongi doori and the Shibuya area (246). Other is along the Tamagawa and those speed bumps. I'm comfortable riding out of saddle, lightly weighted in the saddle, bunny hopping over the worst bits, and going a bit off road.

Inclement weather is avoided. Or I would switch to by current budget alloys.

According to the recent health check, I'm currently at 69kg. Add a few more to accommodate backpack stuffed with the $dayjob costume.

I'm fine with harsh rides.

Currently the budget alloys have 23mm Schwalbe Ultremo clinchers pumped to about 100psi up front and anywhere between 110psi to 120psi in the rear. With the pack, this pressure seems to give the tire a bit of deflection.


I have a stock of 23mm tires I'd like to continue using. Hence the question, what's the minimum tire width I can use with reasonable safety. This is unusual since everyone seems to be asking the opposite, what's the widest and lowest inflation possible.

Thanks.
 

Sikochi

Maximum Pace
Sep 13, 2010
1,147
45
68
Kochi
#8
I thought the post above answered the question re:what is safe.

Inclement weather is avoided. Or I would switch to by current budget alloys.
Anyway, if your plan is to swap from carbon rims to alloy rims you would have to swap brake pads all the time. Apologies for the unsolicited advice, but if I was going to use carbon clinchers for commuting, safety issues re: tyre size would be the least of my worries.
 
Apr 3, 2012
401
98
48
Tama Center <-> Otemachi
#9
Fair enough and advice appreciated. If something is absolutely a bone head idea, I do want to be warned off.

Ack'd that 23mm tires is risky for this width.

Carbon specific brake pads for carbon wheels.

Acknowledged that carbon rims and other things light weight are a risk trade off. This particular build of a wheel seems robust and it's a good oppurtunity to satiate the wheel envy I'm having.

I haven't been #9 for a while. It's too much time to clean up after a messy ride during work days. The past two weeks has been terrible for me with no riding... And too much demand for my time this week to even sneak in a ride during this nice cooler days.
 

TCC

Tokyo Cycling Club
Jun 30, 2013
2,362
1,291
133
#11
The only issue you will have with carbon clinchers is with steep, technical descents, in the mountains where you need to be hard on the brakes for extended periods of time; this WILL melt them, no matter what anyone says and no matter what they claim the layup / resin, etc to be like. Everyone who has carbon clinchers and has ridden them in the mountains will have melted a set at some point, and if they haven't, then they were not riding hard.

Don't worry about 23mm / 25mm tyre width. If you are just commuting to work, you are not descending like an eagle, and you are unlikely to be doing much more than 40kmph for any extended period, especially in Tokyo. You are making an issue out of a non-issue.
 

TCC

Tokyo Cycling Club
Jun 30, 2013
2,362
1,291
133
#12
Oh yeah, and there is another slightly related issue with carbon clinchers; when you put the tyre on and pump it up, the spokes lose a lot of tension, due to the required tightness of the tyre on the rim in a clincher system, and the tube pressure. This does not cause too much of an issue on the front, due to both sides being evenly tensioned (if built properly!), so the tension reduction will be fairly even around the whole wheel (with +/- given for variations in the material build). The tension reduction on the front can be uniformly dealt with in a few ways which I won't bore you all with here.

On the rear, however, if the non-drive side is not laced to deal with this tension reduction, you might get problems with tensions dropping below acceptable levels, meaning the wheel is likely to go out of true, or spokes start snapping. This is compounded when you are limited to relatively low tensions by the components used in the wheel. This can be got around with 2:1 lacing, or by using lacing patterns designed to cope with this (ie, radial, heads out lacing). You can also re-tension to bring the wheel back to what it should be, taking into account for the expected reduction induced by the tyre and tube, but that is a dangerous game, for reason that I can go into, but will bore most of you.

Obviously this is an aside to your 'issue', however, but is perhaps interesting non-the less. Getting a spoke tension metre and measuring the before and after tyre mounting and inflation tension on wheels made with carbon clinchers reveals some shocking results, I can tell you!
 

Sikochi

Maximum Pace
Sep 13, 2010
1,147
45
68
Kochi
#13
The only issue you will have with carbon clinchers
Indeed the only real issue, but for day to day commuting, you have a lot of extra hassle involved with CC`s. Very regular cleaning of rim / brake pads required that alu rims are much more forgiving of. Cost of brake pads, plus more likely to wear quicker. Attractiveness to thieves. And if you aren`t gifted with strong thumbs, and tyre installation is a PITA, alu rims will be a lot more forgiving of tyre levers. And then there`s always that one day when a sudden unnanounced downpour occurs and the arse of a taxi driver decides at that exact moment to veer left for a passenger. In such a scenario, I`d rather have alu rims underneath me...unless of course, you have disc brakes. But saying that, one of the local bike shop owners commutes on a set of Lightweights.

Don't worry about 23mm / 25mm tyre width.
That was the point I was trying to make.