USAZorro

The radius is what matters - not the diameter. It might still be too much, but only half as bad as you thought.

lonesomesteve

Rear spacing and alignment come to mind as things that could, and most likely would go wrong.

As @Tim_Iowa said, there are many examples of "proper" ways to do this only a quick Google search away. This isn't one of them.

noglider 

You raise good points. The actual quote was something like, "What could go wrong?" It was not, "Nothing could possibly go wrong."

nlerner

rhm

I am not sure whether I remember all the details now... but this is what I did with my Lambert a few years ago.

The stay spacing was a little tight for the tire, which was either 700x28c or 700x32c. I'm not sure, now, what I used; probably the head of a pretty big ball peen hammer, the end of which measures about 35 mm. I placed it where the additional space was desired, but it did not fit. So I took another hammer and applied one persuasive blow in the direction of the bottom bracket. Now it fit snugly, right where the tire was supposed to fit.

When I removed the hammer, I found a matching pair of round dents on the inner sides of the chain stays. The paint was scratched on the drive side, but there was no paint on the non-drive side (the tire had already removed it). The spacing of the dropouts had not changed, so I concluded the alignment had not changed either. The fatter tire now fit perfectly.

So... what could possibly go wrong? Well, obviously, many things could have gone wrong. Fortunately, they didn't.

Sir_Name 

Another possible source of inspiration and ideas:

https://www.bikeforums.net/classic-vi...ear-sport.html

gugie 

Don't give up on a 650b conversion just because it's an International. My BB height is higher than most, and chainstays are longer - 42mm Hetres on this one.



When I originally bought this frame I posted to the 650b google group about converting to 650b and was talked out of it, and ended up with a JP Weigle'ized 73 Raleigh Competition, and rode the International as a "gentleman's bike":



I took Admiral Grace Hopper's advice, and found out that the common knowledge was wrong in this case:

noglider 

@gugie, that Competition is a gorgeous machine. What does it weigh configured as pictured? I've decided I want to keep mine as light as possible, and I'll put on as few fenders and racks as I can manage.

gugie 

Thanks! To be clear, the green bike (pictured above) is an International and weighs 28 lbs as shown. My Competition is 29 lbs with similar config:

Machine Age

Just curious, did you grease the hammer head? Wonder if doing so could help avoid splitting the tube as in those photos above.

rhm

I don't think I did! Would have been a good idea, though.

I don't think there's such a great danger of splitting a 531 or chrome molybdenum tube, provided you don't introduce a sharp crease. Don't do it to 753, aluminum, or carbon fiber.

noglider 

What could possibly go wrong?

kalash74

Ran across these Raleigh conversions today. Just beautiful. Any idea which model/year they are? There is a Raleigh Professional 1973 on ebay right now. Any idea how much it's worth?
1973 Raleigh Professional 50cm Reynolds 531 Campagnolo Blue Mink Carleton | eBay

Road Fan

Taking this number, the radius is then 334 mm. BTW, I assume it will not drop significantly more with a fatter tire.

First, many roadie bikes have used 21 mm tubulars, and for them the diameter is 666 mm, for a radius of 333 mm. So it is possible (odd comparison, I know!) to have a 700c wheel that is about the same diameter as a 650b wheel. 650b is not necessarily lower than 700c.

What are some other wheel radii?

700x28, 340 mm
700x21 tubular, 333 mm
630x28, 343 mm
584x38, 333 mm.

My Trek 610 has BB drop of 70mm. The max BB height is with the stock tire, 273 mm. With the 21 mm tubular, the BBH is 263 mm. When I tried the bike with tubulars, many years ago, I did not have any pedal strikes.

I have trouble seeing how a few mm reduction is BB height is a major issue. While 650b is usually lower than 700c, I'm sure it's not always significant.

Whether your pedals will hit ground is also a function of road roughness, crank length, crank Q factor, and pedal design. Not to mention the elephant in the room, do you need to pedal through corners on a 650b rando bike?

Sir_Name 

Those Raleighs are lovely.

The bike in the auction you linked to is gorgeous and very high quality (though dented, doesn't appear bad). It's at the top of your budget, but you could sell the wheels, brakes and drivetrain for some good money and find replacements to fit your build. I suspect you could still end up over budget.

Plus:

I was was all but ready to tell you that the Raleigh Professional you linked more than likely would not take 650x42, but found this thing while trying to confirm:

Raleigh Professional 650B conversion | Velo Finds

I believe the fastback seat stays point to this being earlier than the one you linked to (no comment on the build, 'accessories', or cable length...). Whoever built the bike I linked claimed to fit 650x42, but who knows if any work on the frame was required (dimpling chainstays) and how much clearance there really is. I am certainly not 'a Raleigh guy', but I'd still be surprised if the one in the auction you linked fit 42s. I believe the Raleigh International and Competition are more frequent conversions. There should be some significant differences in geometry between those and the Pro, too. One of the other posters here knows quite a bit about that. Also do a search for JP Weigle and Raleigh conversion for some top of the line eye candy (are the ones in your pic some of his work?).

Keep in mind what was said about Raleighs a page or two ago, "There are Internationals, then there are Internationals. And there are also Internationals." Or something like that. Point being, there can be a lot of variety in any one model of bike between years and perhaps even within the same year. And I get the sense that's especially true for some Raleighs.

If I were in your shoes I'd want to purchase in person to take measurements (plus I just like buying in person better, and shipping won't eat into the budget). I'd also consider finding some 650b wheels and 42mm tires if you're really set on that size so you could bring them with you to check. You'll need to buy wheels anyways if you're buying used unless you really luck out. It'll probably take some time to find the right bike, but it's out there somewhere. 650b x 38mm is great, and may open up used options a bit.

If if you post your general location and size range you might get some help with possible candidates in your market.

mountaindave 

Lots of great advice here. You can estimate tire spacing - one of the early 650b conversion links has a great way of showing you how before you even invest in anything.

My suggestion is to look into Bicycle Quartely and prepare to think that 700x28 is ridiculously narrow... and to "need" a custom lightweight randonneuring frame hand built to your personal specs. It's a slippery slope my friend...

I can attest to the cheap-but-functional 650b wheel sets off eBay. Not ideal, but a good tentative step into the 650b world. It let me begin experimenting. But tires are a b!tch to mount properly. 650b on my old 80's steel frames Japanese and Taiwanese frames was great.

kalash74

Does anyone have any thoughts about the Velo Orange 650B wheelsets?

Grand Cru Diagonale Rear Wheel (Touring Hub 130mm, 650b) - 650b - Complete Wheels - Wheels, Rims, Hubs & Accessories - Components

Harris Cyclery used to sell an entire wheelset for less than $300 with Velocity A23 rims, but these are long out of stock.

Do you think I'd be best purchasing a complete wheelset from Velo Orange or somewhere else, or just buying the rims and re-using the old hubs the bike came with? I suppose the advantage of the latter is not having to cold set the rear triangle. From what I understand, old spacing (70s-80s) is 126mm. Am I correct?

bikinbruce

Spacing in the 70s would be 120mm
Spacing changed to 126mm when full width 6 speed freewheels came along, this spacing was also used for 7 speed road bikes.

gugie 

Going from 23 to 32 is a huge improvement. Going from 32 to 42 is sublime. 50? Wouldn't know.

gugie 

That photo is from Peter Weigle's flickr site. The one in the front is almost exactly like mine, pre-paint. Those are all Raleigh Competitions, around 1973. The one in the back is "Miss Rene", a guy here in Portland now owns it. Amongst the 650b, low trail cult (I'm a member), that bike has almost mythical status.

gugie 

The rims are fine. The hubs are high quality. You couldn't go wrong with one.

kalash74

Nice to know. Is there a near guarantee that a Raleigh Competition will be a good fit for a 650b conversion? Or did they vary from year to year?

mountaindave 

No offense, but are you following this thread closely? Multiple suggestions of how to get into a conversion.

If you can't measure a bike in person or get a seller to do the measurements for you, there's no guarantee that a certain bike will work. As you can see here, there are lists of conversions, but nothing is a guarantee. I can guarantee that you will be amazed by how fun they are to ride if you do a 650b conversion.

To be honest, I would just go get yourself a cheap bike-boom frame or complete bike and start building it up - those are about as close to a guarantee of a successful 650b conversion as you can get. If you aren't totally committed, get the cheapo ebay 650b wheels for ~$100 and get started. Buy some Pari Motos on ebay and prepare to be amazed at how you float over gravel roads. You need to stop asking people if the water is warm enough and just jump in! You will invest about $200 max (wheels, tires, tubes and long-reach brakes), but recoup most of that if you are completely turned off and decide to sell because other fools like us will want your cast-offs. If you love it, you will build higher quality wheels for it and find another bike soon to put the cheapo wheels on. I already have plans to get friends into "gravel grinders" with old steel frames and 650b wheels. It's addictive, but that's why you're here in the first place.

All the cool kids are doing it.

gugie 

@mountaindave is pretty much correct. There are some bike boom frames that you might have to go narrower than 42 to get it to work. Just throw a dart at a list of 70's to mid-80's "sport touring" bikes and you're probably ok. Many that aren't even "sport touring" will work as well. Find something you're interested in, go ahead and double check here, and if you get a good feeling from the replies, fire away!

nlerner

@gugie would know better than I, but I believe that Weigle repositions the brake bridge and dimples the chain stays in his Raleigh conversions.