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Need help understanding rim/tyre standards

Old 06-19-21, 09:44 PM
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Plainsman
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Need help understanding rim/tyre standards

I知 trying to buy a second rear wheel so I can run gravel tires on my hybrid bike. The new tires I bought are 700x38c. My goal is to keep to sets of wheels with tires mounted - one for road and one for gravel. I知 looking at a wheel that is listed as an ISO 622. All I know about the rim is that it is an Alex DC19. How can I tell if the 38c tire will seat on that rim? I tried the tire on an old and seemingly narrow road rim I had sitting around, and it would not stay seated once inflated (bulged at the valve stem).

https://alexrims.com/products/dc19/
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Old 06-19-21, 10:25 PM
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Measure the internal width of that old road rim - it's probably 15mm ??
That Alex rim seems to have a 16mm internal rim width, if I'm reading the specs correctly.
Internet recommendations vary, but most say a 17 mm rim width is needed to mount a 38 mm tire.
(It probably depends on the tire as well? Casing flexibility?)



About the bulge at the valve - are you sure the tube was pushed 'up' inside the tire? I've learned to make sure the tube is freely moving at the valve by pushing the stem 'up' into the tire before inflating. This seems to prevent getting the tube stuck under the tire bead.
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Old 06-19-21, 11:08 PM
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I don’t see an issue with running a 38mm (1-1/2”) tire on a 16mm internal width.

If you are running 2 sets of wheels, rim brake, I would think you would want to duplicate the same wheelset you have now. Same rim, or at least same outside width, and same hub.

You’ll want to set it up so you don’t need any adjustments going from one to the other.

John
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Old 06-19-21, 11:16 PM
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Originally Posted by 70sSanO View Post
I don稚 see an issue with running a 38mm (1-1/2) tire on a 16mm internal width.
I'm running 44mm RH Snoqualmie Pass tires in 17 mm internal rims with no problems.
Originally Posted by 70sSanO View Post
If you are running 2 sets of wheels, rim brake, I would think you would want to duplicate the same wheelset you have now. Same rim, or at least same outside width, and same hub.
Good advice.
With rim brakes, getting the tire past the pads can be a squeeze even if the brake has a release lever. I found that when I moved from 23mm to 28mm tires on the road bike.
My bike with the 44mm tires has disc brakes, so not an issue there.
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Old 06-20-21, 12:25 AM
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It'll probably work OK, but a wider rim would be more ideal if you're already buying a new wheel.
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Old 06-20-21, 05:34 AM
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Originally Posted by VicBC_Biker View Post
I'm running 44mm RH Snoqualmie Pass tires in 17 mm internal rims with no problems.

Good advice.
With rim brakes, getting the tire past the pads can be a squeeze even if the brake has a release lever. I found that when I moved from 23mm to 28mm tires on the road bike.
My bike with the 44mm tires has disc brakes, so not an issue there.
Thanks! These are V brakes and not caliper, so no issue with clearing pads to mount the wheel.
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Old 06-20-21, 05:36 AM
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Originally Posted by 70sSanO View Post
I don稚 see an issue with running a 38mm (1-1/2) tire on a 16mm internal width.

If you are running 2 sets of wheels, rim brake, I would think you would want to duplicate the same wheelset you have now. Same rim, or at least same outside width, and same hub.

You値l want to set it up so you don稚 need any adjustments going from one to the other.

John
Agreed and and I would if I could. The wheels on my old Cannondale Quick (2017) are pretty generic, I知 not sure how/where to find a match.
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Old 06-20-21, 10:56 AM
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Originally Posted by Plainsman View Post
Agreed and and I would if I could. The wheels on my old Cannondale Quick (2017) are pretty generic, I知 not sure how/where to find a match.
Measure the old rims?
Do you have calipers that measure mm?
They are very useful, and not expensive.
Stainless or cheap plastic:
https://www.amazon.com/Stainless-Micrometer-Measuring-Precision-Measurements/dp/B074HZ8S21



https://www.amazon.com/Caliper-Plastic-Vernier-Jewelry-Measuring/dp/B01N0N3Z7N/
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Old 06-20-21, 11:16 AM
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Originally Posted by VicBC_Biker View Post
Measure the old rims?
Do you have calipers that measure mm?
They are very useful, and not expensive.
Stainless or cheap plastic:
https://www.amazon.com/Stainless-Micrometer-Measuring-Precision-Measurements/dp/B074HZ8S21



https://www.amazon.com/Caliper-Plastic-Vernier-Jewelry-Measuring/dp/B01N0N3Z7N/
I do. Figure all I can do is measure between the hooks though, don稚 know what to use to measure between where the beads seat.
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Old 06-20-21, 11:24 AM
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Originally Posted by Plainsman View Post
I do. Figure all I can do is measure between the hooks though, don稚 know what to use to measure between where the beads seat.
I just measure the inside width of the rim at 'the lip' (outer edge). I wouldn't worry about +/- part of a mm.
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Old 06-20-21, 11:25 AM
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Originally Posted by Plainsman View Post
Agreed and and I would if I could. The wheels on my old Cannondale Quick (2017) are pretty generic, I知 not sure how/where to find a match.
Since your bike has rim brakes, it is better to keep the same rim width for a second wheel set. If the widths are too different, you値l have to adjust the brakes each time you swapped the wheels.

Originally Posted by cpach View Post
It'll probably work OK, but a wider rim would be more ideal if you're already buying a new wheel.
In what respect is a wider rim 妬deal? Wider rims are just heavier. Using a narrow rim with a wide tire creates no problems with regard to handling but they are lighter.


Originally Posted by VicBC_Biker View Post
Measure the internal width of that old road rim - it's probably 15mm ??
That Alex rim seems to have a 16mm internal rim width, if I'm reading the specs correctly.
Internet recommendations vary, but most say a 17 mm rim width is needed to mount a 38 mm tire.
(It probably depends on the tire as well? Casing flexibility?)



About the bulge at the valve - are you sure the tube was pushed 'up' inside the tire? I've learned to make sure the tube is freely moving at the valve by pushing the stem 'up' into the tire before inflating. This seems to prevent getting the tube stuck under the tire bead.
That chart is less conservative than many I致e seen but I often run tires widths that are way outside even that chart. My touring bike has Velocity Deep Vs which have a 13mm inner width. I run 38mm tires on them without issue. I have 17mm rims on any number of mountain bikes in my garage with 2.1 to 2.3 (54mm to 60mm) tires without issue. I致e been running them since about the time the universe started.
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Old 06-20-21, 11:53 AM
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Originally Posted by cyccommute View Post
Since your bike has rim brakes, it is better to keep the same rim width for a second wheel set. If the widths are too different, you値l have to adjust the brakes each time you swapped the wheels.



In what respect is a wider rim 妬deal? Wider rims are just heavier. Using a narrow rim with a wide tire creates no problems with regard to handling but they are lighter.




That chart is less conservative than many I致e seen but I often run tires widths that are way outside even that chart. My touring bike has Velocity Deep Vs which have a 13mm inner width. I run 38mm tires on them without issue. I have 17mm rims on any number of mountain bikes in my garage with 2.1 to 2.3 (54mm to 60mm) tires without issue. I致e been running them since about the time the universe started.
I知 not too worried about adjusting brakes. Running V brakes on a hybrid bike, so pretty easy to adjust.
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Old 06-20-21, 04:45 PM
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V-brakes eliminate the tire width issue with caliper brakes.

I’d still look for a rim with the same external width that you have now. While some, I’m not one of them, are concerned with internal width, your brakes make contact with the external surface.

Yes v-brakes are easy to adjust, and if the rims are close in width a turn of the adjuster at the lever might work, but if they are not you don’t want to have to re-set the cable every time. That will just cause it to break and fray over time.

You also want to get the cassette located the same distance from the dropout. If it is close you can use very washers washers on the axle, or behind the cassette (depending on which way it needs to move) to keep the limit screws and barrel adjuster the same.

John
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Old 06-20-21, 05:06 PM
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Originally Posted by Plainsman View Post
I知 not too worried about adjusting brakes. Running V brakes on a hybrid bike, so pretty easy to adjust.
You say that now. Just wait until about the 4th or 5th time you have to do it. It痴 a pain and one of the reasons so few people actually have two wheel sets.
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Old 06-20-21, 09:03 PM
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Not to be too rude, but why? There are plenty of gravel tires that will move fast anywhere that bike is meant to go. Pick a good all-around tire like the Donnelly X'Plor USH, there are other tires just like it, and it will do wonderfully on pavement and any rail trail. I've tested mine out on the Prince Edward Island confederation trail, the Erie Canal trail, several sections of rail trail in PA, and the gravel roads around my parents. Also had no problems riding the gravel bike on the roads and maintaining speeds close to the road bike, road bike is lighter, geared differently and more aero so some difference is to be expected but often only about 2mph slower. Just never had to worry about road conditions getting to the fast part of the ride. Found them to be a great install and just go ride tire without a need to swap something else on. I know Vittoria makes something similar as does Challenge, I'm sure other brands do as well. Personally, if I need to swap tires I found it was only worth it if I needed a significantly different tire, not just a slight size change.
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Old 07-07-21, 05:01 PM
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Just to follow up - I wound up taking the 30s off of my bike and installing the 38s on my existing wheelset. Thanks for all of the good advice. I may still look for that second set, but for now I知 going to see how it rolls on asphalt with Maxxis Ramblers.
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Old 07-07-21, 09:16 PM
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The rambler has enough center tread it should roll decently, the more continuous the center tread the easier they tend to roll on pavement, and its a decent all around size. Hope it works well for you.
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