Conversion candidate frames

[Jason Mansey]

I've been considering a Lightning Bolt for some time but being in Canada it's pretty expensive to import. 

Noticed they sell a stand alone Randonneur fork and it has me thinking I should just do a conversion.

https://crustbikes.com/collections/forks/products/crust-650b-canti-rando-fork

Thinking I could have canti bosses brazed on.

Is this a good candidate frame, believe it's Tange 1? Would a 27" wheel frame play nice with this fork?

[Ian A]

It could be good, but with buying the fork, having cantis brazed on the frame (although you could probably have good results with long reach sidepulls) you might be spending more than anticipated. Plus it would be an experiment which might not be as good as you hope.

What about combing Pinkbike? This could be an option https://www.pinkbike.com/buysell/4091279/

IanA Kitimat BC

[Brad]

Dia Compe 750 or Mafac Raid brakes, 650B wheels (might require getting frame spread or wheels built on 120 spaced rear hub) and your done.   Braze ons are a convenience not a necessity.  Tange tubing is first rate.  The fork appears to have enough rake to now be classified as low trail.  

[Michael Goetinck]

I found this helpful when I started doing conversions.

https://www.bikeman.com/blog/guidelines-for-650b-conversions.html?srsltid=AfmBOoqSEJKOKmRGRpjTlnGmYdNfoMm2pD_khw0iciJ9MOui0eoJwCDF

 

I’ve also found some forks on eBay that had a wide enough crown to accept the bigger tires I wanted to run.

 

Have fun,

Michael H. Goetinck

Snowdog Construction

(802) 649-3605

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/650b/CAC4Z95m-tfmSHoQiLEmhC%2Bu5VQ%2BjC9ke%3DabJxpAr%2BycXPjbuQg%40mail.gmail.com.

[andrewd...@gmail.com]

If you're using a 27" frame with a 650B fork, it'll tilt forward a bit.  For each cm shorter it is from axle to crown, the angle of the headstem will increase by roughly a degree.  And thereby your trail will increase.  There are calculators online for those who want low trail.

[satanas]

The calculators will also help you avoid low trail, or just to figure out what it wil be:

http://yojimg.net/bike/web_tools/trailcalc_dual.php

Later,

Stephen

[Cameron White]

Before digging any new pits to burn monies, first confirm that:

1. Bike handles well to your desired needs.  Up/down hills, carving, flats, carrying a load.

2. It fits you.

3. Does not have any significant frame build quality issues as is so common with old frames.  70s japanese bikes...in my opinion their QA/QC is lacking compared to 80s.  Guessing mid '70s on this Nishiki.  Maybe later, like '77?

4. Has clearance at the chainstays and fork for tire + fender width.

5. You are aware that a bike may/will handle differently once converted to 650b, and you might not like it.

Agreed with the others that the original fork should have enough rake to be considered low trail.  Nishiki made a lot of low trail bikes in the 70s, into the 80s a bit as well.

You're on the money you'd probably need to braze canti bosses on there.  27" >> 650b usually is too far of a brake reach change for long reach calipers.  

[fordb...@gmail.com]

It looks like it might have room for 700 x 38s if it won't work for 650b. 

Ford

Ghent, NY

[Mark in Beacon]

One other parameter to check is your bottom bracket height. A 27" bike will drop further than a 700C, bb drop being equal. 27" x 1 1/4" or 3/8" are also bigger that a 25-30mm tire.

[Jason Mansey]

This is something I've wondered about. 

Your saying bottom bracket height is better maintained when using a 700C frame? 

Are there any favorite frames for conversions?

--

You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/93c80052-f451-4a9c-8a61-68932e3ba761n%40googlegroups.com.

[Mark in Beacon]

Bottom bracket drop is a frame attribute that is set, no matter the wheel and tire size. I'm saying if the drop was designed with 27" wheels with x 1 1/4" wide tires to be, say, 10 3/4" height, and another frame was designed with  
700 x 25mm to be 10 3/4" height, when you put 650b wheels on both, the bb height of the 27" frame will be lower than the 700 frame. Hope that makes sense.

[Mark in Beacon]

There is a ton of good information on 650b conversions here on the internets, along with potentially good frames to try.

[Stephen Poole]

BB drop (and thus BB height) is very much a personal preference thing, and will depend on crank length, Q factor, pedal size, one's tendency to pedal around corners (or avoid doing so), etc.

I like low BBs (~260-265mm for road use), but plenty don't; YMMV, depending on the factors above.

Later,

Stephen

[Brad]

Actually, the ERTRO for a 27 x 1/1/4 tire is ....32 x 630.   Bottom bracket height change is another place where research and math can help.  The circumference or the radius for a given wheel can be helpful in a comparison.

622 (the bead seat diamter) for a 700 c wheel yields a radius of 311.

Typically race bikes are designed for a 700 x 23 tire.

So we add 23 to 311 to get the tire shod diameter of 334.

Now subtracting from 334 will get us the comparison.

584 is the bead seat diameter for a 650B tire.

Half of 584 yields 292 as the radius to the tire bead.

 We can add tire sizes to 292 to get comparison numbers on drop.

For a 38 tire we get 330.  

A 14 gauge spoke is 2mm.

330 will be a bottom bracket drop of two spoke widths or 4mm.

For a 42 x 584 tire magically we have the same radius as 700c wheel with a 23 mm tire.

Space between fork blades is now the controlling factor.  A cheap pair of calipers like the ones from Harbor Freight will come in handy here if you don't have a tire shod wheel to shove in there.

[Bernard Duhon]

 

Has anyone tried these v-brake extensions to convert a 700 v-brake bike to 650b  

700c touring bikes always have more tire clearance than the 70-80’s road bikes your posts discuss.  I am thinking instead of squeezing the 38mm 650b you could get ample clearance for 42mm 650b.

 

Box Two V-Brake Post Extender (Black) - Dan's Comp

 

 

 

Yours sincerely,

 

Bernard F. Duhon

Bernard F. Duhon, Ltd.
A Professional Law Corporation
111 Concord Street, Suite B
P.O. Box 1169
Abbeville, LA 70511-1169
Telephone - (337) 893-5066
Fax - (337) 893-0030
E-mail - ber...@bernardduhon.com

 

 Attorneys:  Pursuant to the new LA. C.C.P. art. 1313 (c), please serve ber...@bernardduhon.com  and ad...@bernardduhon.com if you are attempting to serve a rule date.  I will respond in order to facilitate proof of delivery.

******************* Internet Email Confidentiality *******************
The information contained in this E-mail message is legally protected by the attorney-client privilege.  It is intended only for the individual or company named above.  If the recipient of this e-mail is not the person to whom it was sent, his employee or agent, this e-mail should not be distributed, copied or given to any other person or entity.  Distribution or copying of this communication is prohibited.  If you have received this communication in error, please call this office by telephone immediately. Please return the original message to me at the address indicated above.

 

 

 

 

 

From: 65...@googlegroups.com <65...@googlegroups.com> On Behalf Of Brad

Sent: Saturday, April 4, 2026 8:32 AM
To: 650b <65...@googlegroups.com>

--

You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/347efaa8-054f-4c58-8af3-9df150cb4005n%40googlegroups.com.

[Brad]

My mistake.  I did the math for a 700c wheel, not a 27" wheel.

700c is 622 in diameter and 311 in radius.

27 inch rims have a 630 bead seat diameter and a 315mm radius.

In ancient times the switch to 700c wheels from 27 inch wheels required a brake with four or more mm of room to adjust the pads down.

[Jason Mansey]

90% sure I'll be picking up a Raleigh International next week. 

I read that the tire clearance over the years hasn't been super consistent. Not sure if the fork can accommodate 42c with fenders.

For my riding 38c is enough. My concern is really related to pedal strike.

Pretty excited about this find!

--

You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/ec316caf-d56d-42e7-b18b-73f19924c7dcn%40googlegroups.com.

[Stephen Poole]

According to Grand Bois' website, their 650b tyres have the following ODs - others (like RH, etc) are likely to be similar:

1. Cypres (32mm nominal width), 652mm OD, so 326mm radius

2. Hetre (older, nominal 42mm width), 669mm OD, 334.5mm radius

3. Hetre Forestiere (current), 672mm OD, 336mm radius

(4. And, FWIW, WTB's Horizon (47mm nominal) was said to have a radius of 342.5mm)

Nominal widths (and radii calculated from them) are likely to be out by a few mm, so will not be reliable - one must measure things on the intended rim; actual tyre width will vary by ~0.4mm for every mm in internal rim width, so WAM (Width As Measured) is only helpful if the rim's IW is specified too.

In practice, 700x23 tyres are likely to have a radius of 336-338mm, provided they're actually close to being true to size, not labelled 23mm but actually  smaller - not uncommon, especially in the 80s.

The radius of the tyre will affect the BBH, but is rarely the limiting factor in whether a wider 650b tyre will fit. That's usually the (nominal) width, which can be a problem at the  seatstays (less likely), fork blades (somewhat more likely, especially if >38mm), and the chainstays (very likely if >32mm). YMMV depending on what frame and fork you have - one must *always* measure, never assume or guesstimate!

Later,

Stephen

On Sun, 5 Apr 2026, 00:58 Bernard Duhon, <ber...@bernardduhon.com> wrote:

 

Has anyone tried these v-brake extensions to convert a 700 v-brake bike to 650b  

700c touring bikes always have more tire clearance than the 70-80’s road bikes your posts discuss.  I am thinking instead of squeezing the 38mm 650b you could get ample clearance for 42mm 650b.

 

Box Two V-Brake Post Extender (Black) - Dan's.

[daxo potato]

these extenders only work on (removable?) canti posts that thread into the frame. I've never seen such posts, I'm told it's a bmx thing. 

if you don't believe me, i have a set I'd sell cheaply 😜 

Dave in NY 

On Sun, 5 Apr 2026, 00:58 Bernard Duhon, <ber...@bernardduhon.com> wrote:

 

Has anyone tried these v-brake extensions to convert a 700 v-brake bike to 650b  

700c touring bikes always have more tire clearance than the 70-80’s road bikes your posts discuss.  I am thinking instead of squeezing the 38mm 650b you could get ample clearance for 42mm 650b.

 

Box Two V-Brake Post Extender (Black) - Dan's.

--

You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/CAEqY5rcFE0hAL9FWAHJhHfoFuP%2BhGnttXO3BbkVUEp%3Dw_arg-A%40mail.gmail.com.

[Bernard Duhon]

thank you👍

Get Outlook for iOS

---

From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of daxo potato <daxo...@gmail.com>
Sent: Sunday, April 5, 2026 5:54:36 AM
To: 650b <65...@googlegroups.com>
Subject: Re: [650B] Conversion candidate frames v brake extentions

 

To view this discussion visit https://groups.google.com/d/msgid/650b/CAKihenqKBm1AM0dqguvQz27ANn%2BRNaAteLEc%2BcxE5bXb4tJrLw%40mail.gmail.com.

[David Cummings]

If that Raleigh International is the one you're considering buying, go check it out and see how it rides.  If it fits you well and you like how it rides, proceed!  Ii looks like a great candidate and, as you have probably read, many an International has undergone the same 650b treatment.

I have a '77 Austro-Daimler Inter-10 that can fit 700x38 tires - no conversion! (But also no room for fenders.). Pretty wild what could fit in some of those old steel frames!

David in MT

[fordb...@gmail.com]

That's a gorgeous bike ! I have seen Internationals with 42s and fenders, but it would be a great riding bike with fat 700c tires, too.

Best of luck !

Ford

Ghent, NY

[Andy Beichler]

I have a 71 Raleigh International that I converted to 650b. I had the fork rake adjusted to 65mm for a trail of around 35 or 36 with 650bx42 tires.  I love how it rides.  I have a second 71 International that has the stock fork rake with 700cX38 tires (actual 36) without fenders.  I can get 700cx35 tires and fenders on it.  Both ride exceedingly well.  

According to everything I have read, all years of the International ride very nicely. You should know that the one you are looking at is later than a 71 and probably has shorter chainstays.  You may not get 42's in there but I am sure you can 38's with chainstay clearance being the limiting factor.  The Classic and Vintage section of Bike Forums is full of us International fans.  You can get some great info over there.  

I don't think you will regret it if you get it.  

[Jason Mansey]

Any, have to have any photos you can share of your projects?! 

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/0f60e38f-3934-487f-8f7a-fb48adeb267en%40googlegroups.com.

[Ford Bailey]

Here are three of my 650b projects, one with flat bars.

The Raleigh Competition has 650b x 42s, the Gran Sport has 700c x 38s,

the Follis has 650b x 48s.

I think the difference between these tire sizes is quite small.

Ford

Ghent, NY

You received this message because you are subscribed to a topic in the Google Groups "650b" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/650b/E_CIOL31cOk/unsubscribe.
To unsubscribe from this group and all its topics, send an email to 650b+uns...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/650b/CAC4Z95nbmZ4utgddY3RxNo6NCKU%2B9VP9yVa%3DDM%2BVrkLYYx7Ctw%40mail.gmail.com.

[Adam Komosinski]

Ford,

That’s encouraging to hear about the tire size similarity. I just finished building a 1982 Woodrup Giro-Touring with 650B x 43 GKSKs

(labeled and actual width) and I was very disappointed that I couldn’t clear 48s in the fork. I thought about commissioning a new fork, but that feels like I’d be getting into a low return-on-investment scenario, especially considering how expensive this whole thing ended up being 😳 

I’ll try to get a decent picture of it later. Still haven’t had a proper photo shoot.

Adam K

Northampton, MA

To view this discussion visit https://groups.google.com/d/msgid/650b/CAKcX8kwS2cmg30QdOvisRgqkw%2B_0HrMpRJKkkRvYE2RrDMPJ-A%40mail.gmail.com.

[David Hays]

I converted three Mercians to 650B before having them build me one specific to that size.

My first is a green 1983 KOM that fits 650B x38’s Ecureuil tires.

The second is a black 1984 Olympiad that fits 650Bx 42’s Light Hetres.

And third is a 1987 red KOM that I have my brother which fits 650B x 38’s Loup Loup Pass’s

Love the ride

Cheers

David Hays

Williamsville, New York

 

To view this discussion visit https://groups.google.com/d/msgid/650b/CAFmsfxXp%3DpOoazOJJ8RjSRKbXgotws8J554trLjkbu4-njWMUA%40mail.gmail.com.

[Adam Komosinski]

Here's my new 1982 Woodrup Giro-Touring after a couple good long rides and some rain. David and Ford, I took some inspiration from your black frames while waffling on silver vs black fenders. It fits 650B x 43 GKSKs on Pacenti Brevet rims and rides like a dream. Rear has plenty of clearance, though the fork is pretty tight. The wee hairs on the edge of the tire tread brush the dents on the fender ever so slightly, so I'll be filing that back one of these days.

Adam K

Northampton, MA

On Tuesday, April 28, 2026 at 6:09:29 PM UTC-4 bead...@gmail.com wrote:

I converted three Mercians to 650B before having them build me one specific to that size.

My first is a green 1983 KOM that fits 650B x38’s Ecureuil tires.

The second is a black 1984 Olympiad that fits 650Bx 42’s Light Hetres.

And third is a 1987 red KOM that I have my brother which fits 650B x 38’s Loup Loup Pass’s

Love the ride

Cheers

David Hays

Williamsville, New York

 

[Jason Mansey]

I believe my frame is a '74. Certain both 38 and 42 will require some dimpling. There isn't presently any ok the inside of the stays, just the outside for the crankset clearance.

My concern recording tire size is the fork.. which leans me to 38.. and opens up my fears of pedal strike. I'll be running 170mm cranks anyhow. Maybe this isn't a real concern idk. 

On Wed, Apr 8, 2026, 8:13 a.m. Andy Beichler <andybe...@gmail.com> wrote:

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/0f60e38f-3934-487f-8f7a-fb48adeb267en%40googlegroups.com.

[Adam Komosinski]

My Woodrup has 65 mm BB drop and a BB height of 273 mm with 650B x 43. Cranks are 170 mm and pedals are SimWorks Bubbly, which are pretty thick and wide. I’m pretty careful and mind my pedal positions while turning hard & fast. The only times I’ve had pedal strike was on rocks while riding light single track.

650Bx43 and 700Cx23 (and 26”x2.1”) should theoretically be the same OD of about 668 mm. Your International, which was likely designed for 27”x28 or 32, might lose about 10 mm of BB height with 43s, but you could confirm that by measuring your current tire OD and BB height. Once you have that projected BB height you can decide on 170 or 165 mm cranks.

Regarding tire clearance in the fork, the casing on my GKSK is widest at 320 mm from the axle center, and the tread is widest at 325 mm. And this is all on a Pacenti Brevet rim. 

If you don’t own a vernier caliper, go buy a cheap one, it’s the perfect tool for measuring tire clearance. If you want to get nuts you can put masking tape on the inside of the fork blade and mark 320 or 325 mm on it with a marker. Makes it easier to be certain of where you’re measuring. In my case, the Woodrup has about 47 mm clearance, so I had to make my wheel perfectly trued and dished to take full advantage of that 4 mm of clearance. Yikes! 

Use the same masking tape measuring technique on the chainstays and you can get a range based on how long your dropouts are.

Where in the world are you? There’s probably a bike shop somewhere near you that can dimple the chainstays. And of course you can manage that at home, too. Plenty of threads on the iBOB list about that.

Adam K

Northampton, MA

You received this message because you are subscribed to a topic in the Google Groups "650b" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/650b/E_CIOL31cOk/unsubscribe.
To unsubscribe from this group and all its topics, send an email to 650b+uns...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/650b/CAC4Z95n3zvfMxQMMG8pLxXpF20gvG%3D%3DxhUFHx_mJQt7-eu6cRg%40mail.gmail.com.

[Andy Beichler]

Sorry for the delay in responding. A combo of sickness, the end of the semester writing crunch and the fact that I can't seem to figure out how to reply from my phone (where my pictures live) has got me lagging. I will get something posted in the next few days.  

[Andy Beichler]

I had a 1991 Mercian KOM in that same green color. It had cantilever bosses so it could not be easily converted but I did put a set of 650b wheels on it. It easily accepted 42's.  I ended trading it for my second Raleigh International frame.  Both of us felt like we did well in that trade.  

On Tuesday, April 28, 2026 at 6:09:29 PM UTC-4 bead...@gmail.com wrote:

[fordb...@gmail.com]

What size tires fit in the Nishiki ?  Without going to 650b. With wide 700c tires, good brakes, lower gearing that bike looks like it would be a lot of fun. I would keep the stock fork.

Ford

Ghent, NY

On Friday, March 27, 2026 at 6:02:47 PM UTC-4 jason....@gmail.com wrote:

I've been considering a Lightning Bolt for some time but being in Canada it's pretty expensive to import. 

Noticed they sell a stand alone Randonneur fork and it has me thinking I should just do a conversion.

https://crustbikes.com/collections/forks/products/crust-650b-canti-rando-fork

Thinking I could have canti bosses brazed on.

Is this a good candidate frame, believe it's Tange 1? Would a 27" wheel frame play nice with this fork?

[Jason Mansey]

Oh, I didn't bother with the nishiki. Grabbed a 74 international.

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/650b/67fd02ee-24ea-4f37-bf78-87256e67c330n%40googlegroups.com.

[Mark in Beacon]

Here's another conversion with a black frame--Tange Prestige Panasonic DX5000. It has 38mm Pacentis that measure out to 40mm. Could probably get away with 42mm; no interest in fenders on this bike. (I do have a slightly less jarring bar tape on standby, this one is brighter than I thought when I bought it online.)