folderfan550

I am planning to replace the stock steel rims with alloy ones on my recently acquired Raleigh Twenty. It currently has 406 (20x1.75) rims. Is it best to stick with this size or is there any benefit to converting to 451 (20 x 1 3/8) rims? I know that the brake calipers would have to be changed. I am thinking of using Sun-Ringle CR-18 rims but would consider others.

Thanks!

Sixty Fiver

CR18

Oh wait.

You have it covered.

stevegor

Pity you don't live near me in Oz.....I have a set of new 451 Velocity Aero rims laced to a NOS Sachs 3x7 R hub and a Deore F hub that I'm thinking of getting rid of...........

AEO

if you want any stopping power, then you'd probably want to replace the brakes as well.

451mm have lower rim and tire selection, but you can use a tektro R556 long arm caliper brake.
406mm have plentiful selection, but you'll need to use a drop bolt to make a modern caliper brake work.

EM42

ISO451 better[for looks? i believe] , less rolling resistance, brakes work better because of shorter brake reach downside would be the limited tire choices and widths as mentioned above[compared to the wide variety of choices of types and brands for a 406]

another benefit using ISO451 is increased ground clearance on the crank arms/pedals and ability to use common 170mm crank arms instead of the 165mm cranks. This was the primary reason for my upgade. Installing narrower tires on a 406 rim like continental 1.35 or primo coment 1.3 or schwalbe kojak/durano 1.3, dahon/schwalbe mango 1.1 tires will really put the pedals too low and you'll have problems with clearance on basic turns. you want to use at least a 1.5 or 1.75 tire[or wider] on a 406 and as AEO mentioned a drop bolt especially on the rear wheel is almost mandatory or do both F/R the better.

Sun Rims SL-1 Assault ISO451 28H semi-aero


here it is when the upgrade was done


another R20 that i upgraded with alloy rims from a BMX bike bought at a garage sale for cheaps


an all stock setup with the rims relaced with bargain BMX alloy rims. This one comes installed with Michelin 1.75" tyres

Sixty Fiver

I run 170's on my 20 and have never had a problem with pedal strikes and until recently rode the bike as a fixed gear.

Just got some Comet Primo's and will be running a pair of those.

NormanF

Stick with 406. And get them Schwalbe Big Apples!

Dynocoaster 

I have 451 stock steel rims on my Stowawayand I like the looks of them. Gaerlans sells 451 rims. I want change out mine in the future but they are in almost new condition which makes it hard to do so. I am waiting for the 2 speed Sturmey Archer hub and I will either have it installed on the Stowaway or get a MU uno.

stevegor

I have both sizes on my R20s, and I do like the look of the 451 better, but as I'm setting 2 R20s up as serious tourers I think the 406 size might be easier to find in out of the way places.
On one R20 I'm using 406 with 165 mm cranks with no strike problems and I also have a lovely set of 145 mm cranks waiting for the next project.

Sixty Fiver

Comet Primos... fast and smooth at 95 psi.

rhm

I know them well. Too well, in fact; they're on my "never again" list. They are smooth and fast, as you say, but the 16" ones on my commuter bike never lasted more than 700 miles or so. 20" one on the tandem lasted maybe 1200 miles.

Sixty Fiver

And they are also pretty light.

Seems to be the trade off for performance... same thing happens with high end road tyres and smaller wheels wear out 1.4 times faster than 700c tyres of the same design..

Have some 27 inch Avocet TT30's that weigh nothing, and are as fast as sin, but are probably only good for 500 miles.

Friend gave me half a dozen Primos the other day as he does not ride 20 inch bikes and have been running the front tyre for many hundreds and hundreds of miles and it still looks great but all the load is in the rear.

veloceleste

Hi. I run 451 CR-18's with Primo Comet tires. I changed the brakes out to a mid-sized Tektro caliper and Koolstop orange pads. The bike feels fairly quick and stops well.

Sixty Fiver

Took my Twenty and those Primos out for 100 km yesterday... ride quality was amazing and I had 30-35 pounds of gear and was fighting a nasty headwind the entire way.

folderfan550

Thanks for the info on the two rim sizes. Are the Kevlar Primo Comets decent at avoiding punctures? I have a pair on a cheap 16" wheel folder, but have have not ridden them long enough to have had any problems.

folder fanatic

My own little Twenty is now being sized up for it's new rims and tires, too. I decided to remain at the 406 level as the bike is already set up for that size with it's original rims & braking system geared for it. And I like the idea of the ease of getting parts in the future should I need them. The brakes & levers will stay with some nice Kool-stop pads added will be enough for me. The original 406 steel rims and hubs on both wheels will go as both are badly in need of a complete overhaul (too much trouble for parts that will be needed to be replaced eventually sooner than later anyway) or better yet modernization and upgrades are readily available with gently used parts from my "donor" bike ready for transfer. The tires will be transfered too but will be changed very soon when I decide what I want to try out on the bike. If they are good choice, then I will buy the Brompton the same ones-the Twenty is fast becoming my "guinea pig" bike.

The point here is the sky is the limit when you select parts for any given bike. It depends on your interest, budget and the bike's true worth.

stevegor

I think the beauty and frustration of the R20 can be described like this......

It's like a blank canvas, the sky is the limit if you want to upgrade and experiment with it's components...where do you stop?
From personal experience I've spent too much time, too much money and way too much thought about my R20s
I've even considered a Rohloff, and with the much anticipated Shimano 11 spd hub nearly here, I'm thinkin'...."Hmmm maybe I could"

Why do I do this?
Because I love the thought of such an ugly, maligned little bike doing what it does SO well, whatever guise it may be wearing.

Sixty Fiver

Thus far the investment I have made in my 20 has been pretty nominal unless you consider sweat equity... it helps to be able to build your own wheels.

The next leg of my shake down tour will take me out to the frame building shop and I might come home with a new handmade fork and stem and some rear braze ons for v / canti brakes.

A ten speed drive (2 x 5) is in the works too.

kraftwerk 

451 is my vote. I like to have the biggest small wheel possible on my 20.

AEO

I've done the measurements and I'm quite sure you can fit a 24" (ISO 520) on a R20.
at least for the rear it's possible.

gruffydd

It would seem many combinations work.

My R20 has alloy wheels with 406 Schwalbe Stelvio tyres (20 X1.10).

It rides very well, but I am careful on the corners due to 170 crank length.

stevegor

Check out LittlePixel's R24 in the archives, he used a 24" front fork from a Terry frame and moved the rear brake bridge up to fit 24" wheels.