polymorphself 

I've been looking for Fuji S12-S frames as I've seen that they take to 650b with no fuss and easily take 42mm tires with fenders. Aside from those I see that the International/Super Course/Competition is a popular choice as well as some Trek models, although it seems like treks are more prone to needing frame work done and won’t be as low trail as the others.

Paramaters are:

23" frame
42mm with fenders minimum
No frame mods needed
Lower trail as I like a front load

I'd love a 1979 S12-S LTD and have begun the search for one, but am interested in what others think about the various Raleigh models with the above parameters?

Thanks in advance. Hoping to make a nice,
long project out of this.

bark_eater 

Well I kind kind of stopped looking after I found a Fuji S12-S, but if an LTD pops up with in a 100 miles...
The Raleigh Competition and Internationals are also hens teeth, and among those tiny teeth are vintages that are better or NSG for conversion.

The early 70's Super Courses have a low trail fork but all ready use long drop brakes with 27" wheels, so your into BMX and Beach Cruiser caliper brakes. Also the Super Courses I've seen from this generation do not have a lot of extra chainstay clearance, so I'm not sure you'd get 42 mm tires in the back.

I'm sure someone has a list they will post of bikes that fit your criteria, but it might be kind short.

The Plan B I can suggest, is to find a 27" frame that has the tire clearance in the chainstays. The Bridgestone 200-500 come to mind, but there are a lot of "fatties fit fine" threads here, mostly focused on 700c conversion gravel grinders. If you can find one of these 27" frames with rear spacing and swap in a 700c fork with 55mm of rake, you can at least have solid braking in the front, even if you need BMX calipers in the rear. The shorter fork will also increase the head tube angle a bit, and help reduce the trail. Bottom bracket height will get double whammies, so 165m cranks might be necessary.

nlerner

42mm with fenders could be tough unless you’re willing to do some chainstay dimpling. I have that on my Gugified ‘71 Intl but couldn’t fit that on my ‘74 Intl without some dimpling. Early 70s Raleighs originally designed around 700c wheels are all possibilities. Another is a Motobecane Grand Record from that era. Tons of room.

jamesdak 

Well for sure the S12-s will work as that's the one I converted to 650b with no real issues. It rode very plush after the conversion and yet could still really fly when I got on it.

Here's a gallery of pics I took of it.

https://pbase.com/jhuddle/fuji_s12-s

I sold it a couple of years ago to a local guy who is still loving it and sends me texts about how much he's enjoying it.



The only real "mod" I remember having to make was triming away a bit of the rear fender to fit it between the chainstays for attachment. There also wasn't enough room by the rear break bridge to get the fender line visually correct. Plenty of clearance from the tire though. Everything else bolted on just fine. I had originally planned on upgrading the components but the pantographed Fuji stuff worked great and looked right on this to me. After these pictures were taken I did degrease and clean the components better and then polished them up. The wheels were handbuilt by Velocity.

bear_a_bug 

Had a '79 Fuji S12-S LTD which was my introduction to 650B. Wonderful bike for conversion - everything fits just so. I'd also keep my eye open for a Fuji America from that time, pretty sure they fit similarly.

bikemig 

I second nlerner 's suggestion of a 70s Motobecane GR. They have a remarkable amount of clearance and would be easy to mod. They came with 27 inch wheels but if you run 700c wheels on them, they can take a 700 x38c tire which gets you into gravel bike territory.

If you don't mind a more "modern" vintage bike, look for Bridgestone XO series. The 1 is expensive but the 2 and the 3 often came with road bike geometry built around 26 inch wheels. BITD if you wanted a gravel bike, 26 inch was the way to go. My 1993 XO 2 is a terrific gravel bike. I'm running 26 x 1.75 tires and there is plenty of room for fenders.

noobinsf 

The only thing to be mindful of with the Moto GR is that the rear brake reach is long if you're using center-mounted centerpulls. I use every mm of the MAFAC Raid back there, and I even had to tilt the shoes downward. It brakes just fine, but even the DC750 I tried would have needed some filing on the brake shoe mounting slot. That being said, I love it as a 650b.

bikemig 

Cool bike. What size tire? Did you have to mod the chainstays?
I may talk myself into doing this for my Moto GR. The paint is crackled which means its perfect for rough stuff. Good to know about the brake reach. The Raid has a max reach of 80; Weinmann 750 75. The Tektro 810 goes to 81 and with a modern brake lever would likely work well.

For a vintage bike, the Moto GR has an impressive amount of room for a fat tire.

fettsvenska 

One alternative to these options that I had good luck with is the Trek Singletrack 930/950/970 series bikes from the early 90s that had the lugged steel frames. Obviously, these are very different frames from the road oriented frames that have been listed previously in this thread but the conversion was easy and there was plenty of clearance for the typical 650b tires and fenders. I added a dirt drop stem with Nitto drop bars and bar-end shifters and Tektro CR720 cantilevers for the brakes and that is about all I had to do to accommodate the conversion.

noobinsf 

I’m running 38mm Pari-Motos with 50mm fenders. No mods to the chainstays, but I did spread them to 128mm from the original 120mm. I doubt that had an effect on tire clearance, but mentioning it nevertheless. The chainstay gap at the widest point of the tire is 45mm, so 42s ought to just work. Here is a view of that gap.

gugie 

Ah, I see you've been warned.



The Fuji S12-S is the ideal. Early 70's Raleigh Competitions and Super Tourers aren't often what I'd call low trail, but they're certainly "lower trail". They both always (almost) have 57cm top tubes. Motobecane Grand Sports have shorter top tubes and chain stays, and fit 42's easily because of the factory dimpling. Some model Treks work as well.

polymorphself 

Looking like it's S12S or early 70s Raleigh. The Moto GR and XO series suggestions are good ones too, will look into this. May have to throw up some WTB posts in the sales forum soon! 79 S12S LTD still seems like what I want, the color is a huge plus for me, geometry is closest to what I'd like and it's plug and play.

bikemig 

What about 70s Fuji Finest? Aren't they pretty good for this conversion as well? Or do the stays need to be modded?

gugie 

If the OP can find an early 70's Fuji Finest, even better! Nicer frame, natural low trail.

nazcalines

If you want to make this a *real* long term project, consider taking some brazing and/or machining classes. If you're lucky enough to have access to a good maker space or community college it can be hugely rewarding.

On the Treks, my 83 600 series has room for 42mm tires and fender in the rear without any crimping, but the front fender would probably need to be crimped to fit around the blades. I have no idea about the brake reach tho, it's pretty far, maybe too far for any standard bolt on brake.

polymorphself 

Those were nicer frames?

bikemig 

The S10s has a chrome moly main triangle. The 70 s Finest were full chrome moly and chromed underneath the paint.

gugie 

The dude abides.

gugie 

Oh, MAFAC RAIDs and modern equivalents reach plenty far.

gugie 

Chainstays are already dented, and if you wanted to use modern gearing on it, spread them to 130mm, which is well within the reach of an ambitious DIYer.

OutnBack

Has anyone done a Moto Grand Jubile? I have my eye on a minty 1979 built w/ Vitus tubing & center pull brakes.

Vintage_Cyclist

Food for thought.

https://www.bikeforums.net/classic-v...nversions.html

gugie 

Calling @Andy_K

polymorphself 

Yep, I’ve perused the entirety of that thread at least three times. Now here I am