Folding Bikes - I accidentally bought 451 tubes

I'm trying to get my Downtube sorted and in racing shape for the Smithfield Nocturne. I'm just cabling her up with her new drop bars and barend shifter, lacing on the elkhide bar tape, and fitting my new 100 psi Marathons. I had not anticipated how hard it would be to find 20 x 1 3/8 tubes locally, so I was very pleased when I found one bike shop had a whole box of them, and only wanted £1 for each cos they'd been there forever and nobody wanted them. They are Bontrager tubes, and they're not marked with the ERTO size. The fact that they are Presta valves should've clued me in, but it didn't, and when I went to put them on, I discovered they were wrong. I've ordered some 406 x 1 3/8 tubes online, and they'll arrive on time, but I'm not going to get any proper test riding in. I'll get the cabling etc done so that I can commute on it on Tues, but it'll be on the old tyres. Oh well!

Just buy 103 bikes and rent them.

oh thought the 406 were all quite wide
and 451 was tall and skinny

You can get skinny 406's. I have some! Generally, you're right though. 406 = bmx, 451 = recumbent

Tubes can be quite tolerant of size differences. Someone might put me straight, but a couple of weeks ago I replaced an inner tube in my SLO (305) with one for my Merc (349). It has a tuck in it, but it is not detectable through the tyre. So far so good. The tyre is hard and performing normally.

I got a big box of 18" tubes from ebay for very little
got a pair in my 20" wheels on my city folding bike
there ok
have had 2 punctures in the rear
but that was on glass on the paths I rode
and my tyres are worn out

I have Conti tubes that are marked 406/451, so I think you can use them without too much trouble.

They were significantly too big! I've had enough blowouts to be nervous. Some 406 x 1 3/8ths tubes are in the post now.

They were significantly too big! I've had enough blowouts to be nervous. Some 406 x 1 3/8ths tubes are in the post now.

I agree with Sammyboy here. I have a *cough, cough* friend who made the same mix-up. Got several blowouts. :o

Ha! I just did the same mistake. I bought a pair of 20 x 1.25 thinking they were for 406 rims since they were not written as a fraction and there was no mention of 406 or 451. $10 bucks gone there. Maybe I will build some 451, but I don't really see an advantage.

Luckily, because the guy was just happy to get rid of them, I only paid £1 per tube. Unfortunately, on that basis I bought 5! Oh well.

Ha! I just did the same mistake. I bought a pair of 20 x 1.25 thinking they were for 406 rims since they were not written as a fraction and there was no mention of 406 or 451. $10 bucks gone there. Maybe I will build some 451, but I don't really see an advantage.


From personal experience and a technical viewpoint 451s are a better size for performance riding.

I have a friend like yours Sesame that accidentally fitted 406 WHEELS to his R20 because he did not know that there was more than one 20" size... :)