Inner tubes

[Derek]

hi - I just got some new Coker tires (26x2.50) and thought I'd put some new tubes in while I am at it. I bought a pair of 26x2.125-2.75 heavy duty tubes but they are way too big (diameter). What size should I be getting?

[Ricks]

hi - I just got some new Coker tires (26x2.50) and thought I'd put some new tubes in while I am at it. I bought a pair of 26x2.125-2.75 heavy duty tubes but they are way too big (diameter). What size should I be getting?

Are they bicycle tubes? If so, they are not too big.  That is what 99% of the Simplex bikes out there run.

 I prefer the motorcycle tubes with the screw in valve stems.  I use the 21 x 2.50-2.75 size.  Check my thread on my 1955 restoration for a picture of the tubes that I use.

[Derek]

I assumed they were bicycle tubes, bought off ebay, they look like they'd fit a 29" wheel.

[Ricks]

I assumed they were bicycle tubes, bought off ebay, they look like they'd fit a 29" wheel.

Without a picture of the box to verify, I'd say you have he correct tubes.

I don't know if you are aware, but a Simplex rim is the same size as a 26" bike rim.  Bike rims are measured by the tire size, whereas a motorcycle rim is measured at the rim.

[Derek]

They were supposedly bicycle tubes. Maybe I can return them.

[Ricks]

They were supposedly bicycle tubes. Maybe I can return them.

26 x 2.125-2.75 bicycle tubes are correct.

[Derek]

I am not sure what I am doing wrong, I ordered another pair of tubes 26x2.25-2.50 and they are way too big (diameter) for the rims too. I got them through Amazon, they were described as bicycle tubes as did the boxes. The tires are 26x2.50. What is going on?

[ndian22]

Derek are you just eyeballing tube to rim or are are you actually installing and airing up tube, tire, rim strip and wheel as a complete unit?

[Derek]

I have installed it on the rim, with strip, aired it up. No tire. It looks like it would fit a rim 2 inches bigger. I can put my fist in the gap between the tube and the rim. I used enough air to bring it to shape, not overfilled.

[Ricks]

I have installed it on the rim, with strip, aired it up. No tire. It looks like it would fit a rim 2 inches bigger. I can put my fist in the gap between the tube and the rim. I used enough air to bring it to shape, not overfilled.

1st Install rim strip
2nd Install one bead of tire
3rd Install Tube
4th Install second bead of tire
5th Air the tire to 35psi
Done!  You have the right tube.  The tire keeps the tube from expanding outward, but will expand inward until the rim stops it. Don't overthink it.

If you think those bicycle tubes look big, try the motorcycle ones I use.

[Derek]

I have installed bicycle and motorcycle tires but have never seen this big of gap between the tube and rim, but I will say that I never looked at a tube on a rim. I would usually stuff them in the tire and go with it.

[kartjockey]

Just re-reading these posts.  Just a thought to add to the mounting process. I like to sprinkle talcum powder in side the tire and around the tube.  This will help it to slide as needed as the tube inflates and prevent it from maybe doubling itself over.

[carryall]

Never thought of doing that.  I've wet the tube before with water.

[Ricks]

I like that idea!  I use the motorcycle tubes, and they can bunch up a little, as they are much heavier than the bicycle tubes.  I also like to leave the schrader valve out, and air them up and down a couple of cycles before reinstalling the schrader valve.  This seems to help them unwrinkled themselves.

[pd]

Along the same lines : dish soapy water seems to do much the same . I put it in a spray bottle , which makes application very easy .

Pete .