narrow 650b rims in Europe?

[Eric Hounshell]

Hi, I'm New to the group -- an American living in Europe building up a vintage Pinarello frame and thinking of going 650b to get a little more clearance.

I am having trouble finding relatively narrow rim-brake 650b rims. Looking for something like the Velocity A23 in 18mm interior width, which will fit tires 23mm to 35mm.

Best I've found so far, which isn't really so helpful, are Mavic OpenPros, which will only take up to 28mm. I don't think there's a point in going 650b unless I am able to get some slightly thicccer tires on there.

Any help appreciated. Also feel free to tell me that putting 650bs on an old italian road bike is dumb. (Keep in mind I don't have any brakes yet, so there is no sunk cost.)

-e

[Fred Blasdel]

Here is the european-market option with a brake track:

https://www.xxcycle.com/rim-ambrosio-keba-650b-silver-confreriale,,en.php

They have a matching narrow-ish tire as well for traditional french bikes:

https://www.xxcycle.com/tyre-hutchinson-confrerie-des-650b-275-650-b-ts,,en.php

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[Greg Achtem]

Why not go with the Open Pros? We (well not me personally) used to run ~2 inch wide mtb tires on the famously Keith Bontrager rolled down Mavic MA40 rims, a set of which I found online to be 13.5 mm internal width. Open Pros seem to be 19.5 mm. You  should be okay with wider than 28 mm.

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[Harry Travis]

Here, too, confusion of internal and external dimensions. The open pro had an EXTERNAL dinension of 19.5mm. Internal is 15mm, which was wide compared to the 13mm internal width for go-fast look alike bikes.

On tire width, it suits mfgs to quote suitabilities reenforced by aerodynamics which ‘dictate’ by current dicta tires fitting like low-profile slicks on street racing cars.

Here’s a reality check: The Pacenti rims had about the same 19mm internal width as A23 rims. The Pacenti branded tires came in 37, 42, and 49mm widths.

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Harry P Travis

14.4

On Feb 19, 2021, at 1:20 PM, Eric Hounshell <ehoun...@gmail.com> wrote:

35mm.

[Brad]

The Keba rims build up nicely.  I order from XXCycle and get stuff faster than ordering from Oregon or California. 

With my calipers the outside measures 24 mm.

[Ian A]

SJS Cycles in the UK (no longer Europe, sadly) have the Thorn branded 650b silver rims with brake track. 32 holes only, weight 480g. https://www.sjscycles.co.uk/rims-tape/32-thorn-275-650b-584-rim-polished/?geoc=CA

Never tried these particular rims, but in my experience SJS/Thorn are reliable in their product recommendations. SJS is a great bike shop.

They also carry some profoundly beefy 650b V brake rims (~750g!) if you decide to take your conversion expedition touring.

Ian A (Remainer), Alberta Canada

[Ray Varella]

Eric,

Are you sure the Magic Open Pros are 650B and not 650C?

The last generation of Magic 650B (584) that I was aware of were Module 3 and those predated Open Pros. 

You may want to double check with your supplier. 

You don’t want to get your wheels all built up just to find out your tires don’t fit. 

Ray 

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Ray Varella

IAABC Parrot Division

Supporting Member

[pcb....@gmail.com]

Lots to chew on here...I guess I'll start from the big picture?

Trying to convert an old Italian 700c-designed road bike to 650b isn't dumb at all, IMHO. It's not always possible/practical, but converting older narrow-clearance 700c frames to 650b use is kinda what supercharged the 650b resurgence.

That said, and I'm not meaning to pick on your word choice here, I think we usually look at doing conversions not to just "get a little more clearance," we're usually looking for significantly more clearance. Because of all the issues involved, and depending of course on many frame geometry/dimensional factors, if your frame fits 28-622/700c, you're generally not looking at the hassle of conversion to just go to 32-584/650b.  It's more like hoping to get 32mm/650b for the frame that only fits 23mm/700c, or 38mm/650b for 28mm/700c frame. Etc.

IME the biggest issue is always potential 650b tire clearance, not only because it may not seem worth it if you can't get at least 32mm tires squeezed in, but because 700c road bikes can have lowish bottom bracket heights, and narrower 650b tires can drop the bb too far, leading to frequent pedal strikes when cornering. Part of the 650b conversion reasoning is the fatter tire on the 650b rim makes the wheel taller, and if it works splendidly your converted frame/bb height is hardly changed. But if you can't fit a wide-enough 650b tire to come close to the effective maximum 700c wheel height, then your bb height is going to drop, and you need to figure out, case by case, what that means.

I'm thinking/remembering 68-70mm of bb drop is kinda the dividing line. Drop >70mm spells trouble unless you can get some fat rubber in there, like 38mm+. You can find more exacting info online, including effective wheel/tire diameter comparison charts/graphs. And useful conversion guides, including how far from axle center to measure for 650b clearance.

If you have enough bb height and tire clearance to make a conversion worthwhile, I wonder why you're specifically looking for narrower rims. Unless it's to preserve a visual vintage vibe, no reason not to look at wider rims. At least as long as you can get a decent width tire in there.

And then, it's been said already, but just to emphasize, no reason you couldn't use tires wider than 28mm on the Open Pros, if in fact they are available in 650b. There's a number for this, too, don't know what it is offhand, but in practical terms you don't have to worry much about wider tires on a specific rim until you're getting at multiples of rim width. Plenty of us running tire widths more than double the internal the rim width. 

All rules/guidelines are subject to constructive violation. One of my favorite road frame conversions was an '84 Marinoni Special, which was a little tight at 28-622, but with a shallow 64mm bb drop I could go to 38-584 without much bb trouble, and the extra 10mm width made for a nicer ride. I similarly managed an extra 10mm on an '80s Mikkelsen road frame, which had a 67mm bb drop. My most successful/fave conversion is a '71 Raleigh Pro Track frame, that was tight with 26-622, and also has fairly steep and unforgiving geometry for road riding. But with a very track-specific shallow bb drop of only 53mm, I could go to 32-584 without worrying much about the lower bb height. That extra 6-8mm or tire width made a noticeable difference in smoothing out the ride, and the lower stance is nice as well, but it's still a track bike, with track angles, and "floaty" it ain't.

Paul Brodek

Hillsdale, NJ USA

[Orc]

What's the IW of the Open Pro?   15mm?  You could fit Hutchinson Confreries (34mm) on them though you'd have to keep the tire pressure reasonably high so the bicycle won't slosh back and forth across them.

(And where did you find 650b Open Pros?  Mavic's US website is pretending that such a thing does not exist.)

-david parsons

[Eric Hounshell]

Sorry all, false alarm on the Open Pros. They are indeed 650C, not B, upon closer inspection. Mavic has some 650b rims, the A1025 model, but it doesn't look made for rim braking.

Thanks especially to Paul for a thorough consideration of my planned build and explanation of the factors involved. There is not much hassle to build this bike up to 650b beyond what I'd be doing to build 700c anyway. I don't have any components, no accumulated parts bin b/c I have moved overseas, etc. I am likely going to have to lace a vintage 126mm rear hub onto a rim anyway. I'm not so experienced in wheelbuilding, but I'm not afraid of it either. Really the only hassle in this regard is that I have to relearn where to acquire my parts in the European market. So even if I "just" get from 28mm to 32mm, it is maybe "worth" it.

So I suppose my issue is that I do not expect to get enough clearance in that Pinarello frame and fork for a truly thicc 650b tire. That is why I was hoping for the Velocity A23s b/c I likely can't fit anything beyond 35mm (but I can't say this until I get the frame in my hands this evening) and yes I might as well preserve the classic look. (Suddenly I have the urge to ride the original Eroica while I am living not so far away.) That extra tire width will not make up for the drop in the bottom bracket. I am fine with using shorter cranks--my fixie has 165mm cranks--but I may regret the different ride quality.

Questions: So maybe the "easiest" way to figure this out is to find someone who will lend me 650b wheels for long enough to do some BB height measurements. Or can one calculate it with rim size, tire size, and (hopefully) specs one can find on the interwebz? Is a tire the same "height" as it is "wide" (and yes I know the specs are often not reliable or variable according to your exact rim, air pressure, etc.)?

Ultimately if I go 650b and the tips on European products here don't pan out, I might order from Harris Cyclery and get a friend to mail them to me. I've shipped a rear wheel from Germany to Los Angeles and it only cost like $35 or so. 2 rims wouldn't be so expensive.

[Eric Hounshell]

OMG WOW XXCycle is a nice shop. They have other "old technology" components that my Swiss and other European ecommerce sites won't even bother with -- downtube shifters, freewheels, etc. I was already starting despair about finding all this stuff efficiently.

-e

[David Cummings]

It’s good to know the Ambrosio Keba rims build up nicely. How do tires mount on them? It’s a real bummer to build up a set of wheels only to discover you can’t get the bead to seat properly and you’ve got a hop, or it can only be mounted with soapy water and high pressure (ie not roadside serviceable). 

David in MT

[Peter Adler]

Yes, thanks to Fred for the tip. I've been searching for an off-topic 700c Mavic touring rim to do a rim swap for the T520 generator wheel I dented severely just before Christmas, in a crash that totaled my 1971 Raleigh International (my pack mule for the last 12 years). With Mavic in receivership, the US distributor seems to have closed up shop; none of the US LBSes can get them to answer the phone, and everyone's out of inventory on everything. I ended up buying a pair of rims from an eBay seller in the UK, feeling lucky to get them for about $70 each shipped; but it turns out that XXCycle in Toulouse has the same rims in stock for US$27.35 each, with an estimated $20.68 shipping. Definitely where I'm going for spares.

Beck on topic. Don't be so sure you're limited to 32-35mm. For what it's worth, the senior wrench/wheelbuilder at my LBS showed me a 650B conversion he's been riding around for a few years: a late 70s/early 80s Pinarello, on which he's running Pacenti/Panaracer Pari-Motos at 584x38 with acceptable clearance. You'll have to give up on fenders or knobby tires at that width, and you'll need to keep your wheels pretty well trued to avoid rub on the chainstays, but it's feasible in principle.

Have you measured between the chainstays at the approximate maximum width point of the tires, about 300mm from the dropouts? At one point, Bicycle Quarterly had some article about tire width for various wheel formats yielding the same effective outside wheel diameter from tread to tread. As I recall, a 584x42 tire/wheel was the same effective diameter as a 700x32; it decreases the rim diameter while increasing the tire diameter. At least in theory then, a frame that can fit a 700x28 should also be able to fit a 584x38.

Peter Adler

Berkeley, CA/USA

[Harry Travis]

The potential for lingering rub - pun - is from two or three decades (at least) of mislabeling those racy 622 tires, building them on underwidth casings so they could by advertised as lighter.

Someone could have a bike with Specialized Turbo 622-28 tires (made by Panaracer) which measure just 23mm on 14mm rims. Fast 28mm Schwalbes I stocked up on all measure 25mm. 

But, yes, there are plenty of online resources for likely tire fit if one will only measure and calculate. For example for extra thick tread (add 2mm) and shoulder knobs (so, measure width at the tire circumference top, not at the side bulge).

I understand this sanguine take is not for those with 175mm crank arms on wide triples.

--

Harry P Travis

14.4

On Feb 20, 2021, at 2:04 PM, Peter Adler <divis...@gmail.com> wrote:

Yes, thanks to Fred for the tip. I've been searching for an off-topic 700c Mavic touring rim to do a rim swap for the T520 generator wheel I dented severely just before Christmas, in a crash that totaled my 1971 Raleigh International (my pack mule for the last 12 years). With Mavic in receivership, the US distributor seems to have closed up shop; none of the US LBSes can get them to answer the phone, and everyone's out of inventory on everything. I ended up buying a pair of rims from an eBay seller in the UK, feeling lucky to get them for about $70 each shipped; but it turns out that XXCycle in Toulouse has the same rims in stock for US$27.35 each, with an estimated $20.68 shipping. Definitely where I'm going for spares.

To view this discussion on the web visit https://groups.google.com/d/msgid/650b/5699043e-9280-4d52-a3f2-1dca333ae718n%40googlegroups.com.

[Eric Hounshell]

Peter, thanks so much for your input both anecdotal and calculated -- both of them promising. Wouldn't expect less from a Berkeley dweller (I lived there for 6 years, the decisive ones in which I became a bicycle lover as an adult).

I picked up the frame today (it's a beaut, not sure yet what vintage) and did a rather slap-dash measurement with some measuring tape (my calipers are in storage on the other side of the planet). 300mm from the drops it looks like I have a scant 42mm of clearance!

Assuming that the bike was designed for something rather skinny -- maybe 23 or 25 -- I wouldn't even need to get anything as big as 584x38 on there, so that is also encouraging regarding BB height. I need to do the calculation or find a chart for what 650b would be equiv to 700cx23ish.

Or what say you Harry, Paul, and Peter?

Next quandary will be which 650b x 35 (or whatever I calculate is likely possible) tire to pick for road and short stints of gravel...

[Chris Cullum]

On Sat., Feb. 20, 2021, 15:03 Eric Hounshell, <ehoun...@gmail.com> wrote:

Peter, thanks so much for your input both anecdotal and calculated -- both of them promising. Wouldn't expect less from a Berkeley dweller (I lived there for 6 years, the decisive ones in which I became a bicycle lover as an adult).

I picked up the frame today (it's a beaut, not sure yet what vintage) and did a rather slap-dash measurement with some measuring tape (my calipers are in storage on the other side of the planet). 300mm from the drops it looks like I have a scant 42mm of clearance!

Assuming that the bike was designed for something rather skinny -- maybe 23 or 25 -- I wouldn't even need to get anything as big as 584x38 on there, so that is also encouraging regarding BB height. I need to do the calculation or find a chart for what 650b would be equiv to 700cx23ish.

Or what say you Harry, Paul, and Peter?

Next quandary will be which 650b x 35 (or whatever I calculate is likely possible) tire to pick for road and short stints of gravel...

Pacenti rims have UK distributer now. I think the Brevet is great rim, and they seem to have sorted out the reliability issues with previous rims. I think the Hutchinson Confrerie tire at 32mm nominal but more like 34mm actual on modern wide rims would be a nice sporty choice. Both are not terribly expensive either, and are easily attainable in Europe.

To view this discussion on the web visit https://groups.google.com/d/msgid/650b/c5bf6a6c-6a1c-494b-a900-e1533410f60dn%40googlegroups.com.

[pcb....@gmail.com]

Simple math (the only kind I do) says a 584 rim sits 19mm lower than a 622 rim.

The first chart on this page shows a 21mm tire width increase required for a 584 wheel/tire to have the same height as a 622 wheel/tire:

https://bikecounterculture.com/2017/08/17/bike-wheel-diameter-calculator/

So if your Pinarello truly maxes out at 25-622, you'd need almost 48-584 to not lower the bb at all. Not very likely to fit 48s. If you can fit 38-584, your bb should be about 12mm lower. Whether that's a problem or not depends on the bb drop measurement.

If you've got 42mm clearance at 300mm, and you're comfy with 5mm/side, 32-584 should fit between the stays. If you jump up to 38s, now you're down to only 3mm/side. With vertical drops and care, maybe doable. With horizontals I'd want a seriously locking rear qr skewer, like a DT RWS.

Keep in mind you've got potentially 7 potential pinch points on any frame: between chainstays, between seatstays, behind chainstay bridge, under brake/seatstay bridge, behind seat tube, under fork crown, between fork blades. About the only one I can't recall every experiencing is behind the chainstay bridge. I've met all the others.

So just knowing your chainstay clearance helps, but it's not the full story. 

On all the vintage-ish/road-ish frames I've tried converting, I've found 10mm or so to be the max width advantage I've been able to get going to 650b, which would also imply lowering the bb 10mm or so. I'm not including touring/sport-tour frames that already cleared 32-622, or modern disc allroad/gravel/cross/yaddayaddayadda frames design to fit really wide tired of any flavor.    

I think you're not going to know how it'll work without trying.

I'd start with measuring the bb drop. If it's 70mm or less, better chances. If >70mm, chances may not be as good.

Next step if you forge ahead is getting a 650b wheelset and a pair of 32-584s. If you want to stay around 32mm, use narrower rims. Wider rims might get you out to 34mm, depending on the tire.

Narrower 584mm tire choices are kinda limited, choices start opening up at 38mm & wider.

Conti makes the GP5k in a 28-584, maybe easier to find in Europe? I have a just-in-case pair, if I wind up with some lovely track frame with a 50mm bb drop that barely fits 19-622s. Not likely to ever get used.

At 32mm you've got the Hutchinson and the Grand Bois Cypres. I have the Cypres on my Raleigh, and I've used the Hutchinson in the past.

There's knobbies in 35-584, but not much in a road-ish tread. There was a Schwalbe Kojak slick in 35-584, but I don't see it on their website any more. Some retailers still have stock. 32mm road basically jumps to 38mm.

38mm gets you Rene Herse, Soma and others.

Don't forget to have fun!

Paul Brodek

Hillsdale, NJ USA

[Hahn Rossman]

Eroc-

You don't mention where you are in the EU. There are a bunch of good shops that could help out.

Also to shamelessly toot my own horn:

https://www.rossmancycles.com/parts/tire-fit-guage

I designed and made this tire fit gauge for exactly these reasons. It's important to be able to check the tire clearance with the chainstays, seatstays and fork crown.I can ship one to you, once we know where you are.

Hahn Rossman

To view this discussion on the web visit https://groups.google.com/d/msgid/650b/93e4e1df-88ce-4c1e-9c6a-fafb69f2a86an%40googlegroups.com.

[Orc]

On Saturday, February 20, 2021 at 6:49:27 PM UTC-8 pcb....@gmail.com wrote:

There was a Schwalbe Kojak slick in 35-584, but I don't see it on their website any more.

Be aware that that Kojak is a pretty stiff and slippery tire -- you're not going to get any sort of supple life out of it, and it's going to need to be run at a fairly high pressure if you don't want to feel like your pedalling through mud.   (And I had a pretty nasty wipeout with them on one of my bicycles; once it started sliding it didn't stop until I used my left side as an emergency brake.)

-david parsons

[Harry Travis]

OP already stipulated going to 165mm crank arms. There’s 7.5mm to 10mm picked up in clearance to ground  over the 172.5 to 175mm cranks than regular frames allows for. 

YMMV; you may be pushing hard through turns. Blessings.

--

Harry P Travis

14.4

On Feb 20, 2021, at 11:06 PM, Orc <grr.g...@gmail.com> wrote:



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[Eric Hounshell]

Thanks everyone for the various tire recs. I am saving them all in my build spec sheet.

And big thanks to Paul for another thorough bit of advice. I just measured the BB drop by tying a string between the dropouts and measuring the distance between it and the center of the cranks. Bad news. BB drop looks rather clearly to be about 80mm (albeit with this somewhat wonky measurement method).

I suppose the next step would be to figure out more precisely what max tire clearance I could get in there (maybe by picking up one of Hahn's tools!) and then make a calculated decision.

-EH

[pcb....@gmail.com]

Assuming a level/horizontal top tube, as long as the dropout string was at the center of the slots, closely approximating axle centers, you should have a pretty accurate measurement.

The bad news for 650b conversion is an 80mm bb drop is pretty solidly no-go territory.

The good news for 700c handling is an 80mm bb drop should give a very planted ride.

I'd set me sights on maximizing 700c width clearance.

If you're lucky and you don't weigh a lot, and the frame fits 28-622s, you'll find that nice light, supple 28s should ride really well.

If you're slightly less lucky, but your main pinch point is between the chainstays, increasing chainstay clearance by increasing the inner dimpling isn't major framework. As long as the frame isn't built from ultrathin heat-treated tubing, where post-build framework is mostly verboten, bumping the stays isn't a major job. Google a bit and you'll find home mechanics (more adventurous than me) do it themselves with vise grips and round chunks of metal. Or a bench vise with wooden forms to maintain outer stay profiles. You might have local shops/builders who can do it for you.

If you're unlucky and have multiple pinch points and can't go wider than 23-25mm, then there you are. Either learn to like it, or tolerate it, or keep it as a thing of beauty that rarely gets ridden, or move it on. I don't mean that to sound harsh or dismissive or etc, digital communication bugaboo fears here, but, ya know, either you can fit wider tires or you can't. If you can't, you either live with that, or find somebody else who wants it. We're not talking about living/breathing things, and unless the Pinarello has some kind of additional/intangible personal meaning to you, if it doesn't fit your needs, there are plenty of bicycle frames out there in the world that will.

This is coming from someone who mostly gave up the 650b conversion route and sold all the frames that wouldn't fit at least 28-622s, then in a second wave upped that keeper line to a minimum 30mm clearance. I recently let the Raleigh Pro Track sneak in, because it made my knees wobble, but I'm pretty adamant about not bringing in frames that lack the clearance I want.

YMMV.

Paul Brodek

Hillsdale, NJ USA

[pcb....@gmail.com]

Oh, and I'll also echo David P's take on the Kojaks, they are not light/supple tires at all. I only rode 'em briefly, didn't have any sliding issues, but I only rode them briefly.

I mentioned them primarily because I don't see any other 35-584s that try to be road-ish. The Schwalbe G-One is/was available in 35-584, but those have knobs, and I saw a Schwalbe Marathon, I think, touring tire that looked a lot heavier/nastier than even the Kojak.

Not much at all out there until you get to 38-584. But I've ridden the GB Cypres for many years now, and it's a great tire. I briefly rode the Hutchinsons, didn't like them as much, but they're still a good choice. The weird thing about the Hutchinsons is that, not sure if I can explain this well, it's like a 30mm casing with a thicker 32mm-tire tread glued on top, with the tread going 2/3 of the way around the tire, wrapping over the sides. The 32mm width I measure includes at least 2mm or tread cap that stands proud of the casing, which in my experience is kinda weird. I don't think I have any other tires in-house built like that.

I think it'd be really cool if Conti went wider with the GP5k, and gave us a 32-584 & 35-584.

Paul Brodek

Hillsdale, NJ USA

[Eric Hounshell]

Thanks again Paul. I am not ultimately unwilling to ride a 28mm tire. That's what I've ridden for years as a fixed gear on a wonderful early 2000s Bianchi Volpe frame. (Let's not get into the reasons why I am not rebuilding that now. Short answer is that it's on the other side of the planet in a storage unit.) And before it got stolen I also rode a sweet Centurion Ironman, ca. 1987(?) on 25mm Vittoria Rubinos for rides similar to what I'm intending with the Pinarello--weekend pleasure rides on country roads.

I thought getting the bike set up on some 650b x 35s or so would make a wonderful classy ride. But it sounds like it may be best for me to shelve those 650b plans for now and look around for a decent 700c wheelset so i can do the most important thing about this beautiful bike, which is ride it!

I almost picked up a vintage Motobecane frame from a seller claiming it was built for 650bs. But it was one of the bottom of the line models made of a lower quality steel and I figured it would not be worth the money invested in the frame, shipping, and build up.

e

[Eric Daume]

 Paul, what made you (mostly) give up on the 650b conversions?

I've done a handful of these, none currently, but I have two frames in the garage that are candidates (old Trek 710 and Raleigh Technium). I'm hesitating, because while I like the big tires, the weak brakes and minimal rim selection is making me hesitate. It would be nice to fit something bigger than a 28mm tire with a fender, though.

Thanks,

Eric

To view this discussion on the web visit https://groups.google.com/d/msgid/650b/8de45648-e098-42bf-93a7-39a53cf353fcn%40googlegroups.com.

[Andrew L]

After you digest all the encouragement to try for the widest comfortable tyres in your frame, if you are going to put 650B wheels on, then I'd strongly recommend Pacenti Brevet over Ambrosio Kebas.  I've got both, and while both built up nicely and the Kebas are both a bit cheaper on postage in the EU than for us on other continents and a bit easier to put tyres on, the Kebas are relatively ugly and won't suit a nice older Italian road bike, but the Brevet rims will look more "right".  Also, the Kebas only come in 36H but the Brevets are available in 28, 32 and 36H.

Andrew

[Michael Mann]

While 650b conversions are fun and a good entry point into the world of 650b, it seems to me that everyone who goes down that rabbit hole eventually either commits to finding a purpose-built 650b bike, or decides that plush 26-inch tires are actually better than skinny 650b. Or just gives up.

Mike M

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Michael Mann

[Hahn Rossman]

Eric-

I did some lovely rides out of Geneva in the summer of 2019, right before PBP. I can't remember the name of the shop that let me use their bench vise  and some other stuff to tweak my bike for the Concour des Machines. They were super nice and suggested going up the Salève instead of slogging around the lake. If you are on the french side, I envy you your access to the Vercours. The ride from Geneva to St Jean de royans was awesome. 

Hahn Rossman

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[pcb....@gmail.com]

More often than not the 650b conversions just didn't work out for me. I could rarely get more than 10mm in additional tire width, which meant a 10mm lower bottom bracket. Most of the frames I was looking to convert had bb drops of 70-80mm, and with me riding mostly 172.5/175mm cranks the post-conversion bb heights were just too low. I tried a couple with higher bbs, but they started off with clearance so narrow I could barely fit 32-584s.

Best I can recollect I've tried conversions on about a dozen bikes, and out of those only 3-4 worked out OK, and I only kept 2 of those. This stretches back more than 15yrs now? If I had Hahn's nifty tubular guage, and paid more attention to the bb drop numbers I could've saved myself a fair amount of trial-and-error work. But I'd need to McGyver some 28-30-32mm discs for Hahn's tool, though.

I do have two disc-equipped cyclocross-type frames that work fine with both 584/622s. And I did try a low-trail 650b-centric rando frame, which showed me I'm not a low-trail dude---definitely not a fan.

You brought up braking, which prompts me to say that I like really good, solid braking, and the only rim calipers with 60mm+ of reach that I'm happy with are Paul Racer centerpulls. Which meant most of the conversions I tried needed $250 worth of Paul goodness, plus additional bolt-on cable stops, transverse cable yokes, and all the additional general fussiness of centerpulls.

I'm not much of a rim hound, I suppose, so I don't have much of an issue with less availability of 650b rims. I can get HED rims, and I like the Pacenti Brevets. My Raleigh Pro Track has the Brevets in 650b.

Paul Brodek

Hillsdale, NJ USA

[satanas]

Re BBH/drop: FWIW & YMMV, I've found that with 172.5mm cranks and small pedals (various Speedplay) I'm pretty well okay with 260mm BBH, 257 at a push; however, I don't usually pedal around low speed corners. So, with 80mm drop that means 28-622 will give ~260mm, and 25mm will give ~257mm. At 257mm I've occasionally clipped pedals on high speed sweepers, but things would be much worse with flat pedals, tight bends or if you habitually pedal around corners. Lower might be okay with shorter cranks, and/or if you're very careful.

Also FWIW, one of the more recent Specialized Diverges had 85mm drop and they said it was good with 700c or else 47-584 only - which would give ~257mm BBH.

Very, very few normal road frames with short reach brakes will clear 700c tyres with a nominal width of more than 28mm, but in practice many of these are closer to 26mm on anything other than very wide rims. On the frames I have lurking about:

1. Tony Oliver 531 Pro road will clear ~32-622 at the fork, but not at the chainstays or behind the seat tube; the limit there is 28-30mm. 32-584 might barely turn at the rear, but 38-584 (really 36.5mm) rubs on the chainstays. (This frame was built for 57mm reach brakes in error.)

2. Casati Gold Line SLX (circa 1986) will clear 38-584, though not by a huge amount; the chainstays are seriously ovalised

3. Alan Competition will clear 28-622 or ~32-584

4. Two different local brand UJB/UTB road frames will clear 38-584, one by enough (just), but the other needs some indenting

5. Lemond Victoire 2008 CF will clear 38-584 at the fork, but nothing wider than 28mm at the chainstays, in either 650b or 700c. Larger than 28-622 would rub on the fork crown too

6. Bianchi 928 Monocoque CF will clear 28-622 (dim possibility of 30mm at the fork), but I doubt even 32-584 would clear the chainstays

7. Felt F5 CF circa 2012 will clear 28-622, and maybe 32-584 at the chainstays

8. Heavy gauge steel local brand road frame with ovalized and indented stays will easily clear 38-584, and probably 42-584 too

It's rare that road frames have much chainstay clearance, given they're all intended for 700cwheels and typically the brake reach (49-51mm) is such that larger tyres wouldn't turn as they'd hit the brake bridge, chainstay bridge and/or fork crown; that clearance assumes the pads are towards the bottom of the slot, but often they're near the middle. Unless the builder has made allowance for seriously bent wheels to turn the chances of getting in anything larger than 28-622 (at best) or 32-584 are generally poor. Touring bikes, or older bikes intended for 27"/630mm BSD wheels will generally have excessive brake reach, and/or too much BB drop. There are exceptions, but not so many.

YMMV!

Later,

Stephen

[daxo potato]

@paul  fortunately, i haven't had as many problems doing 650b conversation as you apparently have. i think it speaks to the frames being converted and possibly to the intention of the conversion. i want wider tyres. I've found the more a frame is built as a "racing bike" (ie, super tight clearances, low bottom bracket, etc), the more difficult it is to do anything with it other than racing (ie, wider tyres, fenders, racks, generator lighting etc).

and the other way around, the more the bike is an "all around recreational bike" the more likely that modifications will work out. my favorites are 80's steel Japanese bikes. the ones designed for 27" i can change to 700c and put 35's with fenders. they just work. 650b is sometimes trickier but usually they work too. i think most people on this list would find the ride quality unacceptable, but fortunately i don't know any better and don't have the finances to sample up. i do have one bike that is probably in the ball park of the custom "planing" bikes i read about, but it suffers from exactly what i described above: 700x23 max without fenders, low bottom bracket, narrow chainstays, etc. I've tried half a dozen builds and it still won't work. o well.

maybe some day I'll get to ride a lightning bolt or some super custom steed that costs as much as the roof my haus needs, but until then: my praise for the cheap old bikes!

-dave "I've never raced a day in my life" in NY

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[pcb....@gmail.com]

Looks like I fell off the back on this thread.

I think what Stephen says about tight 700c tire clearance on road frames with short-reach rim brakes is especially true when you look at production frames. But it is possible to design a short-reach road frame to fit 32-622 actual-width tires. It takes a degree of design finesse and production precision that most volume mfrs can't profitably handle. Component selection can play a part as well, you generally need calipers that don't have much overhang beneath the underside of the rear brake bridge and fork crown. 

I've got a few short-reach frames that max out at 30mm actual, and a few that'll go to 32mm. They're all low-volume handbuilts, some stock, some custom. The two oldest are '78/'82, than there's a gap till you hit a custom Riv in '98. The rest are from this century, Waterford RS-series (Road-Sport) and a DiNucci-designed Specialized Allez. If later-'80s production bikes kept the tire clearance of my '78 Kvale, Grant wouldn't have had to start Riv. Or would have had to start it very differently. I don't know what the Old Norwegian was thinking back then, but his '78 Road Standard is a lot like a 1st-gen Riv Road, minus the creature comforts. Those 28mm Panaracers plump out to just over 30mm on wider rims.

I also had several short-reach frames that fit 28-622 tires fine, but they got sold off as I purged, and the only short-reach frames I kept had to fit at least 30-622 tires.

I guess my progression was having short-reach frames and riding 23-25x700c tires, where they maxed out, then trying some 650b conversions when I couldn't go any wider with 700c. Most of those conversions didn't work so well, so I went looking for short-reach frames that fit wider 700c tires, and long-reach frames, and canti frames, and etc.

Paul Brodek

Hillsdale, NJ USA

Stephen wrote (snips):

Very, very few normal road frames with short reach brakes will clear 700c tyres with a nominal width of more than 28mm, but in practice many of these are closer to 26mm on anything other than very wide rims...

It's rare that road frames have much chainstay clearance, given they're all intended for 700cwheels and typically the brake reach (49-51mm) is such that larger tyres wouldn't turn as they'd hit the brake bridge, chainstay bridge and/or fork crown; that clearance assumes the pads are towards the bottom of the slot, but often they're near the middle. Unless the builder has made allowance for seriously bent wheels to turn the chances of getting in anything larger than 28-622 (at best) or 32-584 are generally poor. Touring bikes, or older bikes intended for 27"/630mm BSD wheels will generally have excessive brake reach, and/or too much BB drop. There are exceptions, but not so many.

[wg ws]

Stephen rightly notes that "Very, very few normal road frames with short reach brakes will clear 700c tyres with a nominal width of more than 28mm". FWIW, the current rim brake version of the Ritchey Road Logic frameset will clear 32 mm tires on 19mm internal width rims using SRAM Rival brakes. Ritchey indented the rear chainstays a couple of years back, and increased the clearance for its carbon fork. Given that they generated the rear clearance by indenting the chainstays, I don't think it will buy much in terms of a 650b conversion, but then again, for someone looking for a current production road fast bike road frame, the 32mm 700c clearance could be attractive enough. Out of stock now, but a sales rep from Ritchey I spoke to said they were on order and should come in late April, early May.

geoff s

arlington, ma