Classic & Vintage - 650b conversion from 27 " Miyata one- ten
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12-19-07, 06:30 PM
I've picked up a nice Miyata one- ten bike - I'd like to convert it to 650B,
Currently the brakes have a reach of about 60mm - I'll need 80mm i THINK?!
Is this achievable?
The only other concern is the expected reduction is bottom bracket height. From a 27" with a 1/1/4 " tyre can anyone advise what the reduction in BB height would likely be ?
Am I wasting my time thinking about this frame as a conversion project?
12-19-07, 07:06 PM
Going from 27" to 650B wheels is a reduction of 23mm (630-584 / 2), and that's a lot of brake reach! Bottom bracket height might certainly be an issue unless you can go with relatively short crank arms and promise not to pedal through turns.
Check out this site for lots of good advise: http://www.freewebs.com/650b/conversions.htm
12-20-07, 04:18 AM
You can minimize the difference between the current and 650B tire drop (slightly) by using the fattest tires you can find (kind of the concept of 650B anyway, right?). But a 650 x 40 versus 27" x 32 would only diminish the difference by 8 mm out of 23 [thanks, Neal]... plus, that is just the theoretical (unloaded) difference. With lower pressure tires, you don't get even that much abatement.
Shorter crank arms can help. Also, narrow width pedals... for example, SPD clipless rather than wide touring pedals like the MKS Road or Touring models, for toeclips. And, mainly just don't pedal into slow turns and you shouldn't have a real issue with the lower BB. :o
As for EXTRA-long brakes... Good Luck! This may be your primary consideration before you proceed on the project. Rivendell has some 750s in both center-pull and now in dual pivot side-pulls, but, you'll probably need more length - as you assumed. So, this leaves mostly cheap BMX side-pulls, they'd probably work fine with decent brake pads... they're just not very pretty. :rolleyes:
Here is one alternative, but not easily found. These are MAFAC "Raid" calipers which I used for a similar application. Nothing fancy, just think of them as simply the big brothers of the "Racer" model. Their reach is up to 85 mm and the spacing between the pivot bolts is a bit wider. As you can see, on this bike they used up all the additional length. What makes use of these center-pulls convenient is I can easily revert the bike back to 27" or 700c by simply replacing these calipers with the original Weinmanns (or Mafac Racers), I'd already have the center-pull hangers in place, and there is still plenty of clearance beneath the mudguards for the taller wheels. :)
12-24-07, 07:49 AM
I'm a huge 650b fan (Bleriot, fixed 650b conv, and soon a Kogswell P/R if Matthew can come up with 2 53cm frames for Anthony of Trinity Cycles) and I own a Miyata 110 so I have a pretty informed opinion on your situation. I converted my Miyata 110 to 700c and I couldn't be more pleased...think A. Homer Hilsen. It feels similar to my other 650b bicycles. 650b conversions shine when there is not currently room for wide tires and fenders, and especially when dealing with smaller frame sizes. I think you would be asking a little much from this conversion and would be begging for pedal strike. Just my 2 cents!
12-24-07, 08:03 AM
Not only that, but longer reach calipers = less braking power. :eek:
12-24-07, 11:57 AM
I'm a huge 650b fan (Bleriot, fixed 650b conv, and soon a Kogswell P/R if Matthew can come up with 2 53cm frames for Anthony of Trinity Cycles)
We sell them direct, you know.
12-25-07, 07:03 PM
We sell them direct, you know.
I do know that, however, you sent me to Anthony, and I've already pre-paid with him. He thought that with him being the biggest Kogswell dealer, he could get his hands on at least two 53cm frames. Maybe that's too much to ask? Who knows? I'm sure we can come up with something if the P/R thing doesn't work out.
12-25-07, 07:32 PM
You would gain a little extra clearance by going to 700c wheels but without having to get super-long reach brakes. And I doubt bottom bracket drop would even be an issue. I've done it on two of my bikes with great results.
12-27-07, 01:58 PM
those diacompe 750s (also available from universal (http://www.universalcycles.com/shopping/product_details.php?id=9533&category=525)) are supposed to reach 62-78mm which is close enough you might be able to get away with modifying (shaving) the pad if you needed to.
you could also have a builder throw some canti posts on the front, but I'm not sure if the seatstays could handle it.
12-28-07, 07:18 AM
here is some 650B conversion info: BIkeman's 650B Blog (http://www.bikeman.com/content/view/1018/33/)
AS I crawl thru my winter commute (on a modified Peugeot US Express w/3 speed hub), my mind wanders more towards the idea of a 650B rig... but I'd like to do it with some old skool steel stock before I drop good bucks on a Kogswell (okay... I'd love to go Kogswell... just don't have that kinda do-re-mi right now). So the Craigslist hunt for a frame goes on...
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