carfreefamily

I have a 1978 Schwinn Super Le Tour that we bought at a garage sale as a single speed conversion that had 700cc wheels when we bought it. (I believe it was originally equipped with 27" wheels. I ended up converting it to a 3-speed, and it has become my go-to commuter bike. My only complaint about it is that I cannot fit tires bigger than 25mm without the front one rubbing on the fender at the fork crown.

I've long thought about doing a 650b conversion of it, and yesterday I ordered some Tektro 559 brakes from Rivendell, (I noticed they finally had the bolt-on version back in).

I'm messing around on the internet this morning - instead of diving into my work like I should be doing - trying to see if that 73mm brake reach is long enough for a 650b wheel, (rather than doing the actual work of putting the bike on the stand and measuring, etc.).

From some things I've seen, it looks like they might not be long enough. But I'm wondering if the slightly larger 650a would fit those brakes and allow me to use a larger tire.

Ultimately, I'll just put the brakes on the bike when they come, and see if the reach works with the wheels from my old Raleigh, but I thought I would go ahead and dip into the collective wisdom of Bike Forums to see if anyone else has done a conversion on a '78 Super Le Tour.

There are a few pictures on my largely neglected blog, though they are mostly of the 1952 Raleigh.

Here's a recent photo of me and the bike as it now exists:

daverup 

My 78 Super Le Tour is still on original 27" rims, and the clearances don't seem that close.
It could be that those fenders won't work with your conversion.

abshipp 

I have a 1977 SLT running 700c wheels. I looked in to a 650b conversion with R559s as well, but determined that the reach was not long enough. It was within a few mm IIRC, but just wasn't going to work.

Surprised you can only fit 25mm with fenders, I run 28mm with fenders and there's a decent amount of room. Wouldn't want to go any larger, though.

bark_eater 

It always seemed to me that there weren't any 650a tires available, that would make the conversion worthwhile.

nlerner

The Panaracer Col de la vie in 650A/590/EA3 is a pretty decent tire.

52telecaster

If the bike was meant for 27", it almost certainly won't work with the tektros. You might get by with the long weinmann center pulls. When doing a conversion I almost always go 27-700c or 700c-650b. You can get 650a rims and I have built those wheels but you won't find 38s or 42s in them I don't think. The panaracer 650a tires are nice but are pretty flat prone in my experience.

ironwood

73mm probably isn't long enough. Weinmann or Dia Compe 750s probably are. . Soma fab has some long reach dual pivot brakes with an 80mm reach. They work, but I like the centerpulls better