Inner tube for 405 rim

[Yvonne Goldsmith]

Suddenly can't seem to find a 20" x 1.75" inner tube with presta valve for my 405 rims (2008 Gnu).  There's plenty with schrader valves, which I can use.  Schwalbe has one labeled "PV7" for 406 rims.  Can anyone confirm for me that those WiLL NOT work?  Weird, since I've never had this problem before.  Thank you.

Yvonne Goldsmith

Anchorage

[Walter Lapchynski]

You can get spare tubes of any kind from us, as you have many times before in the past. However, there should be plenty of other places you can find them. Outside of folders, 406 is mostly used for BMX street/park, kids bikes, and the occasional application on recumbents, cargo bikes, and trailers. By and large, that tends to mean Schraeder valves with the exception of perhaps the recumbents. If you can find a recumbent shop, you can probably find exactly what you're looking for.

If you're specifically looking for Schwalbe, you do want a 7 for your approximately 45mm tires (that tube item is rated for 40-62mm), but you confusingly want what Schwalbe calls a SV ("standard" valve i.e. Presta) and not the alternative AV ("American" valve i.e. Schraeder).

More generally, you could go with a slightly narrower tube and be fine. A larger one than recommended is much more problematic as it will be difficult to stuff it in the tire and it might get crumpled up and cause problems simply for that reason.

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Walter Lapchynski
Sales Consultant | Information Services Assistant

Green Gear Cycling dba Bike Friday

direct line +1 541-234-5126

[Scott McMahon]

Hi Yvonne,

In light of Walter's response, I'm not sure if I understood your question correctly, but just in case you were asking about the difference between 405 and 406, that's nothing to worry about.  

You probably already know this, but 405 and 406 are Bead Seat Diameter (BSD) measurements.  BSD is the diameter of the rim at the ridge on the inside of the rim where the edges of the tire will sit, when it's pumped up and seated.  Rims, tires and tubes labeled 405 and 406 are essentially the same.  Any tire or tube labeled 405 will fit a rim labeled 406, and vice versa.

Additionally, tubes, in particular are quite stretchy, and will often work in a tire they weren't designed for (as Walter mentions.)  For instance, I've used 405 tubes in a 451 rim and tire, although it's a little trickier to keep them from getting pinched under the edge of the tire somewhere.

Scott McMahon