Wheel size bungle?

[Horseye]

Hi ,

I picked up a pair of 20 x 1 3/8 Araya 7x for my Hutch build project. I'm surprised to see the diameter is considerably bigger than a "normal" 20x1.75 BMX wheel. I haven't got brakes etc yet but it looks like it might be difficult to make them fit because the wheels are so much taller.

Can anyone shed any light on this? Have I goofed in my naivety?!

Dan

[GavinDavis]

What do thy measure?  Are you sure its not just an optical illusion due to how thin they are?

[pkripster]

He's got horse eyes lol

[Jon The Bassist]

Wheels measured in fractions (eg 1&1/8, 1&3/8) are different diameter to those measured in decimals (eg 1.5, 1.75").
Sheldon was the guru and explained it here: http://sheldonbrown.com/tire-sizing.html

[AKGOFF]

It's something along the lines of:

The thinner the rim (1 3/8 & 1 1/8) the bigger the diameter but also the 'depth' of the tyre decreases to compensate.

I think.

Adam

[Horseye]

They're definitely bigger. Jon the bassist / Sheldon Brown has the answer.

These wheels will fit in the frame and forks but I don't know how/if I'll manage to get the brake blocks aligned to the rim, they're about 2cm further out...

Thanks for your help and any more advice/tips welcome!

Dan

[griff]

It's something along the lines of:

The thinner the rim (1 3/8 & 1 1/8) the bigger the diameter but also the 'depth' of the tyre decreases to compensate.

I think.

Adam

The master of theoretical bike building has spoken 

[GavinDavis]

They're definitely bigger. Jon the bassist / Sheldon Brown has the answer.

These wheels will fit in the frame and forks but I don't know how/if I'll manage to get the brake blocks aligned to the rim, they're about 2cm further out...

Thanks for your help and any more advice/tips welcome!

Dan

You need mini brakes bud......like the smallers dia compe calipers 

[Jon The Bassist]

My little bro no5, Hutch expert with 1 & 3/8 wheels:

[pkripster]

i know bungle he lives dwn my road

[Pooch]

i know bungle he lives dwn my road

zip it...!!!

[T WILD]

You need calipers off a racer/road bike

[Andy68]

It's all about the rolling diameter with tyre = 20''.     Little side wall on ya 3/8 tyres so rim diameter larger than ya 1.75 rims and so on.

You'll defo need shorter reach caliper, not sure which one tho, you'll have to measure. Plenty of Dia Compe, Weinmann 730's etc out there on ebay.