650b front/700c rear?

[Brad L]

Hi, I have an old Wester Ross touring bike that I believe was a 27" originally.  I am trying to max out tire size and with Tektro 559s, 650b will work in front -- looks like with fender I might be able to get a 650b 48mm in there, but in the rear, the 650b rim is just too small and the 559 won't reach.  I think I can get a 700x38 in the rear.  The result will of course be a smaller outside diameter tire in front.  I know this will slightly mess with the bike's geometry, but maybe not that much?  

Any thoughts?

Is anyone aware of spacers, tall fork races, taller headseats etc. I might be able to use to lift the head tube a little?  

I can of course experiment but would rather not spend the coin on a tire I can't use.  

Alt of course is just to keep 700c front/back.  

Thanks for any thoughts!

I am otherwise a very happy Gitane TdF 650b conversion rider and have been so for many years.  

[etorg...@yahoo.com]

Hi Brad. 

The answer to this problem is a brake drop bolt.  (Especially because, we are, after all, the 650b group.) Sheldon has a page on it here.  I recently (last year) made one for my Merlin Extralight CX.  The bike started with cantilever brakes.  I first drilled the rear bridge and used the Tektro 559s for maybe 10 years.  I never really liked the rear braking that much (probably because I was at the extreme of the adjustment) so finally, one day I made my own drop bolt and then added a Velo Orange Gran Cru brake.  It works great.  I actually think it looks pretty good too. Here is mine.

Good luck.

Eli

In Albuquerque

[etorg...@yahoo.com]

I should add that the fenders will make it a little trickier, but there are workarounds, including one cited by Sheldon.  (That one doesn't look so nice though.)

Eli

In Albuqueerque

[etorg...@yahoo.com]

Another option to to keep the 650b rear wheel is using a set of offset brake pads like these from Blue Lug.  They give you 10mm additional reach.  

Eli

In Albuquerque

[etorg...@yahoo.com]

Sorry for all the advice.  I also used these brakes for this very problem.  However, the long arms made for pretty flexy braking in my opinion which is why I eventually went with the brake drop.  

Eli

In Albuquerque

[Brad L]

Eli, all super helpful.  Worked on the bike today with my nephew and he suggested some type of drop plate.  I showed him my Campy drop bolt.  And here you are suggesting the same thing.  

Those drop brake shoes though might be the easy button.  Smart.  I'm gonna try them.  

I wish someone would just make some decent quality dual pivots with even longer arms, I would think there would be some demand.  

[etorg...@yahoo.com]

Great to hear, Brad.  

Tell us what you decide.  

To round things out, I will add that Moots Mounts plus a set of canti or V brakes would allow you to run the wheel of your choice.  Unfortunately, Moots Mounts are as rare as Hen's Teeth.  

Eli 

In Albuquerque