Proper tube size for 21 inch wheel

[hard_y_rd]

Just wondering the proper tube size for a 1.6 X 21 inch wheel. I have an Avon speedmaster on it now. The tube i bought seemed pretty wide for that narrow rim. I think the guy at the shop didn't really know and just gave me whatever he had. I got it in the tire but pinched it in the process. I'm thinking a skinnier tube would be better in there. Anyone know the size i need?

 

[mick71b]

I've always used 90/90-21.

 

[hard_y_rd]

Thanks mick, I'll have to see what size is in there now.

 

[TwoManyXS1Bs]

On my 1.6 rim I run 3.00-3.25 tube...

 

[XSLeo]

On any tube it should match the size of the tire. The rim width has very little to do with it.
Leo

 

[fredintoon]

Just wondering the proper tube size for a 1.6 X 21 inch wheel. I have an Avon speedmaster on it now. The tube i bought seemed pretty wide for that narrow rim. I think the guy at the shop didn't really know and just gave me whatever he had. I got it in the tire but pinched it in the process. I'm thinking a skinnier tube would be better in there. Anyone know the size i need?

Hi hard_y_rd,
pinched tubes! Another hateful memory of times past.
Like XSLeo sez, it's the tube that's the same size as the tire.
What I do with tubes these days is the same as I do for tubeless,
I pay the bike shop guys to do the work for me.
Best $30 you'll ever spend.
Hey, I'm not a total wimp, I do pull the wheel and take it in,
not drive the entire bike to the store like some of the Goldwing owners I know.

 

[Fndirtygreaser]

Yes changing inner tubes sucks. Especially with 21" rim. I usually go to cycle gear and get the only 21" tube they carry.

 

[hard_y_rd]

The 21 was harder to mount than the 5.00 x16 Firestone.

 

[TwoManyXS1Bs]

A 1.6" rim is a bit narrow, best run with tires less than 3.25. Your pic looks like 3.00. Maybe choose a 2.75-3.00 tube...

View attachment 40788

 

[hard_y_rd]

The tube that was in there was an 80/100/21. What does 80/100 convert to.

 

[member3480]

275/300/21 is a 80/100/21
http://www.cb450stuff.com/tires/ CONVERSION CHART

 

[hard_y_rd]

Chart seems pretty random.

 

[fredintoon]

The tube that was in there was an 80/100/21. What does 80/100 convert to.

Hi hard_y_rd,
Canada has been officially metric since 1974 and you are still in denial, eh?
OK then, these days, tire numbers are kinda bi or even tri lingual
The first number is the tire width in mm (80mm = ~3")
The second number is the tire width to height %age (which seems kinda meaningless on an innertube)
The 21 is the tire rim diameter in inches.
So, I'd say the tube was right but your install technique needs work.

 

[hard_y_rd]

I swear this tire went flat on me at least 3 times over the summer. I didn't have any way of putting air in my tube till this morning. I pulled it out last night in haste. I didn't care if I nipped the fucker again. Figured there was a hole anyway. Got some air in it now it won't leak. Tried soapy water, nothing, no hole. WTF. Gonna let it sit for the night. All I can figure is it may have twisted or something in the tire. Anybody experience this.

 

[XSLeo]

Fred your kinda right on the tire sizes, first is tire section width, the second is aspect ratio. Those are the proper terms.
On an inner tube the sizes are just width.
And as I have mentioned before there are 25.4 mm to the inch. So to convert from mm to inch divide the mm by 25.4. in this case 80 = 3.14 Or in tire size a 3.10, 100 = 3.93 or 4.00 So a 80/100 21 fits a tire from 3.10 to 4.00.
If you can't find a leak in the tube itself it may be a bad valve stem core. You can get them most anywhere, even Wal Mart. Look where they sell air compressors and tire pressure gauges, They often have car valve stems too.
A few bucks for a pack.
I always save the ones I take out old tubes and the valve stems I replace when I replace them on car tires I replace. I mount all my own tires. Bike car, van, truck, trailers, boat and flat bed for hauling bikes and such.
Leo