Silly bike related question which can't go in road section!!

This would offend the purists if I asked in the road section and I can't think where else to put it so....

I want to buy a shopping bike and pimp it up. Is there anything to stop me putting 20" BMX wheels in it as it will inevitably have horrible steel wheels? And tyre choice would then be massive compared to 20" x 1 3/8" choice....would they fit in, what would the rear spacing be, etc, and how could I upgrade the brakes if this is possible?

And before you ask 'why' it's because it's an itch I just have to scratch, must be my age.... :roll:

Re: Silly bike related question which can't go in road secti

Something like this?:

http://www.cyclofiend.com/cc/2006/cc115 ... d0506.html

I was looking at 20" folders a while back and the Dawes Kingpin originally had 500A rim sizes, for which it's hard to find decent tyres and which have a ISO bead seat diameter of 440mm. Widely available 20" BMX wheels are 406mm ISO bead seat diameter. This means that the brake surface will be roughly 17mm lower, so you might need some very long reach brake callipers. Pedal clearance while cornering might also be an issue, but fatter tyres might make up for some of the lost wheel diameter. I thought fatter tyres might be a positive anyway, as small wheels give a harsher ride.

There's also a 20x1 1/8" wheel size, with a bead seat diameter of 451mm, which would mean that the brake surface is only 5mm higher than the originals, but there is less tyre choice available than the more common 406mm ISO bead seat diameter BMX wheels.

The Raleigh 20 had both 406 and 451mm rims, but had to use long reach callipers for 406mm rims: http://raleightwenty.webs.com/406or451.htm

Some info on rim sizes: http://sheldonbrown.com/rim-sizing.html

As for hub widths, I think the front is standard 100mm, but the rear may be 114mm, for use with a Sturmy Archer 3 speed. I was considering re-using the 3 speed hub with a new alloy rim, however, if you were going to use a different rear hub you could cold set the frame to widen the spacing: http://sheldonbrown.com/frame-spacing.html

It's also worth noting that Raleigh used an odd bottom bracket size with non standard threads, whereas the Dawes Kingpin has a standard 68mm BB width with English threads, so you can drop in a sealed cartridge square taper BB, or even an external BB if you wish together with modern cranks rather than the original cotter pin cranks.

http://raleightwenty.webs.com/thatbottombracket.htm

Re: Silly bike related question which can't go in road secti

Oh my god, that's absolutely brilliant, thank you! I was really hoping to find a Kingpin as that was my first 'proper' bike, though it would have to be brown then like the original....

Running late for work so will have a proper look again at this later, but this is this kind of info I knew would be out there but it's knowing where to even start or what exactly to type into google!! The Raleigh's I had thought may well have odd threads, etc, so that is useful to, just so I know to avoid for definite. Thanks again! Much to dwell on now in a boring job today!

Re: Silly bike related question which can't go in road secti

From the cult of old mtb's to the even stranger cult of twenty pimping. Nice bunch on Raleightwenty.webs, i've been a member for a while but still have not built my twenty up. I've got side tracked by a 16" wheeled bike.....temptress that it is..........oh wait is that another cult or fettish..............

Re: Silly bike related question which can't go in road secti

You know, I wouldn't have thought anyone else much would be mad enough to think this was a good idea! How wrong could I have been....there's a whole new world out there!

16" wheelers, you say, now there's another thought.... :facepalm:

Off to have another look at the local bikes on ebay, from a quick browse it seems old shoppers have increased in value lately :shock: perhaps they have wind of our idea....

Re: Silly bike related question which can't go in road secti

it seems old shoppers have increased in value lately

Click to expand...

I've been looking for a while and £50 to £80 seems to be the going rate. They vary quite a bit though, sometimes you'll see a really tidy one, at the other end of the country, go for £60, then a scruffy one just along the road will fetch £80. :?

If I ever get around to "pimpin' my Kingpin", I plan on ditching pretty much everything except the frame, forks, rear 3 speed hub and possibly the handlebar stem. Everything else I wanted to replace with better, lighter components. I keep looking for something cheap and local, but I'm not too worried if it's a bit scruffy, although it would be nice if the paint on the frame and forks was half decent.

Re: Silly bike related question which can't go in road secti

Raleigh's weird bottom bracket can be overcome with a sealed cartridge bb designed for bikes with knackered threads. They're about the same price as regular ones, I bought one by accident once. Being 3mm wider doesn't seem to be a problem.

Re: Silly bike related question which can't go in road secti

LikeClockwork":3uvkmumn said:

This would offend the purists if I asked in the road section and I can't think where else to put it so....

I want to buy a shopping bike and pimp it up. Is there anything to stop me putting 20" BMX wheels in it as it will inevitably have horrible steel wheels? And tyre choice would then be massive compared to 20" x 1 3/8" choice....would they fit in, what would the rear spacing be, etc, and how could I upgrade the brakes if this is possible?

And before you ask 'why' it's because it's an itch I just have to scratch, must be my age.... :roll:

Click to expand...

I'm telling!

Re: Silly bike related question which can't go in road secti

^ ^ ^ ^

lol!

I'm getting distracted now by old Moulton's...who knows what may happen next.... :facepalm:

Re: Silly bike related question which can't go in road secti

any one in luton? http://www.ebay.co.uk/itm/281258615460? ... 1423.l2649