rustystrings61 

I want to convert an older road bike that has geometry that works for my body to take puffier tires for use on mixed surfaces, including sand and dirt. I have a deal pending for the bike itself - a 1990 or 91 Diamondback Venture (or DBVenture, according to the decal) in my size, complete, for $50. I have priced out some surprisingly cheap brake calipers and wheel parts on the big auction site that would allow me to have acceptable quality parts for my purpose.

I started off thinking 650b, but I am not enamored of the rim-brake compatible rims in my price range. Then I ran into references to 650A/590/EA3, and did some research, and lo, I can go that route and actually save a few bucks.

So, some questions -

If anyone has Panaracer Col de la Vie tires in 590 size mounted on Sun CR-18s, just how fat are they, anyway? What is the wheel radius or diameter like? I know the radius is officially 3 mm longer than 584/650B, but what does that translate into, in real life and not on a screen?

If you have ridden this combo on fire roads and rail trails and pavement, how was it?

I mean, I know I am giving up the Gallic coolness of the 650B thing, but I think I can live with it if it will serve my purposes - and I already have an old Gitane in my stable, and that should be enough Gallic coolness for any lifetime.

What have your experiences been?

flypaca

We have a french made tandem that was to have had 650B but BITD they were the hen's teeth to find so I built it up with 590 (26 x1 3/8) Those tires and cr 18 rims have had a number of miles on them and now that size is getting rarer to find. Fashions come and go. I will stick with my 590's and the cantilevers adjusted easily to the minor rim diameter variance. The traditional pattern of those tires for randoniers(sp) and rough road use are great. light and a great ride.

ThermionicScott 

My Col de la Vie's ended up in the 36-37mm range on Sun AT-18s. (Single-walled version of the CR-18.)

Rollout was 81-3/8", which I converted to 2065mm for the benefit of my bike computer. That works out to a wheel roughly 25.9" in diameter.

bikemig 

I wish it was possible to buy a sun cr 18 in 650b. The only real downside is that you are limited in tires. I'd be loathe to do this conversion for that reason alone. I like the idea of saving a few bucks on the conversion, though. I find 650b conversions to be pricey.

You've seen this from an ebay seller, right?

https://www.ebay.com/i/252604585112?chn=ps&dispItem=1

Some of the posters here complain about tire seating on the rim but the price is certainly right.

rhm

I hear you, but be careful what you wish for! They actually did make that size for a while, but there were serious tire seating problems (as you describe, even if I took your words out of context). You may find them on eBay, but getting tires to seat will still be a problem.

smallpox champ

I tried this conversion and rode it for a while. The tires were a bit undersized, 35mm-38mm, the diameter was smaller than 700c wheels and dropped the bike a fair bit with the lower pressure. The max pressure was 45psi, not enough for the width. They felt comparable to pasela's except the tread pattern made the tire squirm a bit, not confidence inspiring.

Personally I'd get some $40 650b rims like the Velocity Twin Hollow, or Weinmann ZAC-19, and get some Panaracer Pari-Moto tires.

rustystrings61 

Thank you all for the information - now I have some ideas to mull over as I gather parts ...

kroozer 

The nice thing about 590 is that it's mainly for old 3-speeds, of which there are still millions around in the US. So high-quality vintage-looking rims (CR-18) and tires are easily available and at good prices. 650B availability is getting better but prices are still pretty high. I would think a CR-18 in 650B would be pretty popular.

JohnDThompson 

I have 650A Col de la Vie tires on CR-18 rims on my Raleigh Superbe. I measure them as 36mm wide and a radius of 343mm. HTH …

rustystrings61 

This is precisely the information I needed, and thank you very much!