B'stone RB2 650B Conversion?

[mikel...@juno.com]

I have a 1994 59cm RB 2 I'm thinking about converting. I would like to hear from folks who may have done so.

mike goldman
rhode island
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[David Cummings]

What would you like to hear? I find that Bridgestones make good candidates because they have better tire clearance than other contemporary frames. My ‘91 RB1 will likely never go back to 700c even though it only sees pavement or hero-gravel - supple 650b x 38 tires are just too much fun. 

David in MT

[pcb....@gmail.com]

David, wondering what your 650b-38 actual tire width is on your RB1/rims? I'd figure in general that if RB-1/RB-2 frames can clear 700c-28mm actual-width tires, with bb drops around 70mm, then 650b-36mm actual might clear OK, and possibly 38mm if lucky. Just spitballin', though.

Paul Brodek

Hillsdale, NJ USA 

[pcb....@gmail.com]

Also likely a fair amount of previous discussion online. Here's an RB/Conversion post/thread from a few years back:

https://groups.google.com/g/650b/c/QFuApsY9u8A

Paul Brodek

Hillsdale, NJ USA

[David Cummings]

Paul,

I'm running Panaracer Pari-Motos (designed by Pacenti?) on Pacenti SL23's and they are just a hair under 38mm.  Clearance is close at the chainstays, but not enough to worry about.

David in MT

[ThermionicScott]

I'm not David, and don't own an RB-x, but I do ride Pari-Motos on a set of the same generation Pacenti SL23s (18.5mm inner width) as him.  The tires start out around 37mm wide, but after a few years at 50psi in back, they end up at 40mm.  If I needed to stay within 36-38mm, I might choose a different tire.

- Scott in Cedar Rapids

[David Cummings]

Good point - I haven’t measured my tires in a couple years, so it’s entirely possible they have grown. ;)

David “not Scott” in MT

[satanas]

FWIW, GB's Écureil EL on Pacenti PL23 rims were 36.5mm the last time I measured, and are really comfy and fast. Conti's new GP5000S TR will be available in 32mm at some point, so should be a good option if the BB doesn't end up too low; I haven't seen any signs of availability yet, but hopefully in a few months...

Later,

Stephen

[Chris Cullum]

I seem to recall this being discussed a bit and remember it fitting >38mm. Bitd the Col de la Vie which was nominally 38mm but more like 36mm actual was common for conversions. I think that tire is a bit turd like however. I also seem to recall a few people going back 700C. There's lots of nice 700C x 28mm tires these days, way more so than the heyday of the RB-1. The Hutchinson 650B x 32 tires ends up about 34mm actual and is a good choice if things are tight for 38s or bigger. It will drop the BB a fair bit though.

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[pcb....@gmail.com]

Very cool machine! This to me is  the ideal-case scenario for tight-bike conversions, which I so seldom successfully pull off in my own bike life. Safe 700-28mm clearance to start, 70mm or shallower bb drop and absence of pesky pinch points allowing safe 650b-38mm clearance sounds like it shouldn't be hard. But I so often find one or two flies in the ointment that mean it just won't work for me. Usually I can't get to 38mm, with the lower wheel height making the bb too low.

David's got the clearance and the cush, and it looks great. Well done!

Paul Brodek

Hillsdale, NJ USA 

[John Speare]

i did this conversion on a couple RB-1s: one was standard long-reach brake situation. 

the other was a total re-hack with canti breaks after a bottom bracket cracked... one of the most fun bikes i've owned, for sure -- a prehistoric blogpost is here:  Cycling Spokane: Resurrecto

[David Cummings]

Super cool conversion with the canti’s, John! Handy having Glenn to do the work! 😁

I love my RB-1 for any road. Not to toot my own horn, but it’s fun to ride a fast pace and catch the look on people’s faces when they see my “fat tires.” Some people just won’t believe that tires wider than 25mm can be as fast or faster. 🙄

Just because I could, I built that wheel set with a 7s DA uniglide cassette hub. On the road, I often wonder why we need more than 7 speeds, if not just 6...

David “but I digress” in MT

[Stephen Poole]

Sigh. Not this again....

If n=(>whatever) is too many then you can always go fixed or SS, or else the ultimate solution:

http://www.wot.latrottineuse.com/en/world-tour-push-scooter/

Personally, I could always use either closer ratios or more range - or both. If survival is your only goal then one gear is enough - one can always walk after all. At present 12 is the limit for road use, and I suspect it will stay that way for a while. For 1x off-road drivetrains at least 13 is achievable given large enough cogs, and I expect SRAM and Shimano will get there in due course - anyone care to bet on when?

However, small cogs can only get so small before they become too inefficient and the correspondingly smaller chainwheels wear too fast, and larger cogs will eventually cause ground clearance problems with derailleurs, while wider cassettes will at some point cause chainline, Q factor and heel strike issues. There's no sign as yet of the efficient CVT people sometimes suggest should happen, and I don't expect to see such a thing.

If anyone had asked me 40 years ago when more rear cogs would appear I would have had no idea how to answer, but nowadays the interesting thing is to try to predict when the next one will appear. My guess is that GRX will go to 12 either this year or next, but after that who knows?

Later,

Stephen

On Thu, 6 Jan. 2022, 15:10 David Cummings, <flath...@gmail.com> wrote:

...On the road, I often wonder why we need more than 7 speeds, if not just 6...

[David Cummings]

Oh come on, Stephen, I was just thinking out loud about what works for myself, not what other people should run. 😉 I don’t have a superiority complex about gears - I support whatever setup makes people happy. I do have a superiority complex, not just about gears. We all have to be a little crazy to be doing 650b conversions, right? 🤪

Sent from Dave's rockin' iPhone

On Jan 5, 2022, at 10:28 PM, Stephen Poole <nsc.e...@gmail.com> wrote:



Sigh. Not this again....

[Stephen Poole]

@ David: I think riding bicycles is probably a pretty good indication of craziness - 650b conversions might be confirmation though.  ;-)

Later,

Stephen (who has a conversion in the pipeline if suitable shift levers can be found)

[David Cummings]

I’m pretty sure my coworkers think I’m certifiable for riding bikes today: single digit temps and snowing all day. I thought it was lovely. 

Sent from Dave's rockin' iPhone

On Jan 5, 2022, at 10:51 PM, Stephen Poole <nsc.e...@gmail.com> wrote:



[Stephen Poole]

That's much nicer than 82°F, windy and raining which is what's happening here today; I hate summer and wish I could hibernate. Only 155 days till our ski season officially starts now...

Later,

Stephen

[David Cummings]

The grass is always greener (or snowier) 😉

[ThermionicScott]

We not only ride bikes, we spend additional free time talking about them on the Internet -- that definitely puts us in a different category than "normal." :^D

- Scott in Cedar Rapids

[Anthony Pappalardo]

But the "norm" is a variable.

TonyP

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From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of ThermionicScott <thermio...@gmail.com>
Sent: Sunday, January 9, 2022 11:15 AM
To: 650b <65...@googlegroups.com>
Subject: Re: [650B] Re: B'stone RB2 650B Conversion?

 

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