19" wheel

[taehome]

Ok what is a 19" wheel? I know there on the back of mod bikes, but how are they different than a 20"? Diffferent iso? does anyone know what the iso is?

[jak442]

Just a 19" rim laced to a regular BMX hub.... 116mm?

[taehome]

I don't believe that is really correct. bmx hubs have 110mm spacing not 116. Maybey I should have specified that the question regarding the iso sort of relates to tire size also. Webcyclery advertises the tyres as 20x2.5 but will not fit a normal 20" rim. So what gives, anybody know?

[Redneck]

i think they just say 20X2.5 because the mod bikes with the 20" front and 19" rear tires are commonly referred to as a 20". i think they are just trying to make it simple.

[durkie]

the 19" is actually smaller. the alex dx32 mod rim claims on its label that it's 381mm bead seat diameter, while sheldonbrown.com has the smallest 20" wheel size at 419mm.

as far as i know, it's a relic from when monty was calling the shots on trials bikes and were still designing them as miniature mototrials bikes without motors, since motorcycles have smaller rear rims and fatter tires. they tried to do the same thing with 25" rear stock trials rims, but it didn't really work.

[Marino]

Hmmm... TryAll sells some 19'' rims, too:

http://www.k-124house.com/TRIAL/rims/all (scroll down to the bottom).

I thought these were the BMX standard... A little more reinforcement, stronger, etc. Now I'm curious, too

[taehome]

Ok here's what I figured out. The 19" has a iso number of 387, that is also referred as the bead seat diameter. Should be the actual diameter at the bead in mm's. So it is smaller in size than a normal 20", which on your bmx or freestyle bikes is 406. Oh and there is also 20x1 1/8 which has an iso of 451 which is used on bmx race bikes, folding bikes and some recumbents. I would guess the 20" sizing does simplify it for advertising reasons ( if your shopping for it you should know shouldn't you?). My initial questioning was a resault of impatiance will wating for my new to me mod bike. So thats what a 19" wheel is to me, FWIW.

[saylor]

so is a 'trials rim' just a rim? - like an alex dx32 or whatever everyone talks about , , thats a 20" rim?

[[BMF] Chris]

the added amount of tire around the rim is about an inch more since its so fat. therefor, a 19 inch rim is used instead of a 20 inch rim. but the 2 wheels side by side will be equal height when they have tires on them. if you think about it, its only a 1/2 inch all the way around, but when you add the top and bottom thats an extra inch of tires difference, 19 +.5 +.5= 20

[saylor]

well, I was planning on taking some chrome 48spoke alex triple walls (supra J pros)

and throwing them on there. Is that a not cool thing to do? They are a little skinner on the width , ,but they are like 3x thick instead of lo profile or whatever.

my idea no good?

- Saylor