Powerlite question

[steve69]

Did Powerlite ever make a mini/micro with 18" wheels (1" threaded headset) OR an expert size frame with a 3" head tube??

reason for question is an odd size pair of Powerlite forks


Thanks and Happy New Year everyone

[HEYWOOD BMX]

  Could be wrong but I thought 18" wheel micros (like Redline,Haro) were a pretty recent creation.I can see a 3" headtubed expert frame being a reality .

[steve69]

Could be wrong but I thought 18" wheel micros (like Redline,Haro) were a pretty recent creation.I can see a 3" headtubed expert frame being a reality .

that being the case...

what is the diameter of a 20 x 1-1/8" wheel with a tyre fitted

[moley]

20" rims are not 20" in diameter

A 20" rim is around 406mm = approx 16" in diameter

A 20" diameter = 506mm which is actually around the size of an actual 24" cruiser rim diameter (507mm)

So if you had a 20" x 1 1/8 rim it will be thin and 16" diameter (406mm) and the tire would be thin too so maybe it would fit into an 18" fork (16" for the rim and upto 2 inch for the tire)

Thinner the rim width then smaller circumference fo the tyre.  Plus you have to add the tread depth on top so maybe 18" for forks is right! 

Plus because the rims are narrow.............I dont think many people would run super chunky tires with huge tread depths on them as they'd probably pop off the rims are make it wishy washy in the handling.

18" is about right.................but I'm no expert..........so dont hold me to it!! 

[moley]

All the above is on the assumption that a Micro/Mini Frame and Forks is not designed to fit normal Wheels/Tyres (i.e swapping parts from a Pro bike etc, etc).

I presume a Mini/Micro would be designed to fit narrower rims/tires etc, etc........

..............and if that is the case the forks would have a huge gap if they were running a thinner 1 1/8" tire instead of a 2.125 tyre which wouldn't make sense for a little 'un to push a 2.125" tyre.

[HEYWOOD BMX]

  Just measured a 20 x 1 1/8 rim with a  1 1/8 Tioga Comp 3 & the diameter is aprrox 550mm.

[Jon The Bassist]

Fractional rims (20 x 1 1/8, 20 x 1 3/8) have a larger outside diameter than metric rims (20 x 1.5, 10 x 1.75) etc. Sheldon Brown (RIP)'s website has loads of info on this: http://sheldonbrown.com/tire-sizing.html.

On junior/expert sized bikes, wheels of different diameters and widths were often swapped around eg 20x1 3/8, 20 x 1.5 etc

It'd be rare for a mini or midi sized frame to be used with anything other than 20 x 1 1/8 or 20 x 1 3/8, so those frames never had to fit in the much fatter tyres.

Hope this helps a bit.

[Jon The Bassist]

Just measured a 20 x 1 1/8 rim with a  1 1/8 Tioga Comp 3 & the diameter is aprrox 550mm.

We used to take a skinny rim and tyre to be about 21",  which is just under what James has measured 

[steve69]

Just measured a 20 x 1 1/8 rim with a  1 1/8 Tioga Comp 3 & the diameter is aprrox 550mm.

Are you sure you didn't mean 505mm Voivod   as 550mm is 30mm bigger than the 20 x 1-3/8" (with comp3) that i have.

Thanks for all the reply's 

The full story on this is... i've ended up with a set of Powerlite forks that were sold to me as mini forks, went to fit my 20 x 1-3/8" araya wheel with comp3 tyre and the tyre is hard up against the bottom of the steer tube with the hub spindle still 10-15mm away from the drop outs, so fork legs seem to be 25-30mm too short for this size wheel

So the main question is...  what the hell have i got? (need to know so i can sell them on with the correct description )

I don't want to simply just get smaller wheels as the only reason i started this build was that i had a nice set of wheels kicking around doing nothing.

[HEYWOOD BMX]

  Measured again Steve,come up with 510mm.Maybe you have regular forks for a 20 x1.75 wheel?
18" wheels for a micro are very hard to come by & would fook the geometry of your frame as they are 18"micro-frame specific.

[steve69]

Measured again Steve,come up with 510mm.Maybe you have regular forks for a 20 x1.75 wheel?
18" wheels for a micro are very hard to come by & would fook the geometry of your frame as they are 18"micro-frame specific.

That was the reason for the second part of the first question, the forks only have a steer tube length of 4-1/4", so mini size headtube (and they're NOS so not cut down)