mudboy

I'm building a commuter frame for my 5'4" wife. I intended on basing it on the frame I just built for myself, which was built around 650b wheels. I got what turned out to be a great deal on the set of wheels ($100 shipped for new wheels with Deore hubs and ZAC 19 rims), so it all came together pretty well.

Well, now I'm looking for a similar deal on 650b wheels for my wife, and the least inexpensive wheels I'm finding are $240 from Riv. Knowing that she'll benefit from the reduced design compromises that 650b wheels would have for a frame her size over a 700c wheeled frame that would accept 35mm tires and fenders, I got to thinking that I should just save myself the wheel search hassle by just building her frame around 26"/559 wheels. Rims are definitely not a problem, nor are tires....but I like how 650b wheels with Fatty Rumpkins roll. Wifey would benefit from more standover.

So my question is this...should I modify my design to accomodate the different (and more available) 26" wheels? Or should I stick with my original plan? Have any of you ever made design changes based upon factors like this?

Thanks

Pete

unterhausen

there are some really nice 26" tires, so I think on a budget build it's a no-brainer to go with 26"

It doesn't seem to me that 650b is appropriate for the budget-minded.

mudboy

Thanks. I liked 650b on my bike, because, as an experiment (I had never ridden 650b before), if it failed I had also designed the frame to work fine with 700c wheels. My wife probably won't care, so long as it works.

Now to figure out the max size tire that I should accomodate, and how much room to leave for fenders. I think it's going to have to be built for cantilevers.

Pete

unterhausen

you should be able to go with long reach brakes if you want. I'm not sure I would subject my wife to cantis, v-brakes maybe. I'd probably design for 40-50mm w/fenders.

mudboy

I asked her what she would prefer, and she said, with confidence, "cantilevers".

unterhausen

cool, it's her fault now

mudboy

LOL no, it'll end up being mine

It's OK, though, she takes good care of me.

mudboy

OK, so I'm playing around in Rattlecad, and using 559 rims with a 37mm nominal tire diameter, I have to bump up to a 55mm BB drop to bring the ground to BB center into a reasonable distance (261.5mm, and she'll be running 170mm cranks...that's still a 10.3" BB height, which seems a shade low, but she's not a "pedal through the corners" girl). I've built for 700c (and a 700/650 convertible) before, and this seems pretty high...I know I should be thinking spatially rather than being fixated on dimension, but are there any other dimensions that I am going to need to tweak in order to accommodate the smaller 26" wheels? I also reduced rake from where I normally am (45mm w/73 HTA) to 40mm (again, w/73 HTA) to arrive at a mid-50's trail, and brought the chainstays in to 410mm from where I originally was at 425mm.

repechage

On the BB height, I would consider what pedals she will be using, if more modern stuff then the cornering clearance will be no problemo. If she wants a wide touring pedal with a full length axle, then maybe bump it up a bit. No one mentioned if you guys ride together and if the ability to swap wheels should play a part.

mudboy

She'll have the SPD's that have clipless on one side and cages on the other, but again, she's not one to pedal through corners. We don't swap wheels all that much, but I'd rather have 2 wheels size in the house (700c and 650b) than 3...I probably need to rethink the budget, it might be worth a couple of extra bucks overall to go 650b that will also be able to run 700c...

Pete

nfmisso

just to throw in another wrench in the works: have you consider 650a (ISO 590); Sun offers the CR18 rim in 32, 36 & 40H in that size, and there are tons of tires available. It is still one of the most popular sizes outside of the USA.

26" is generally ISO 559. There is also 650c - ISO 571; almost all really skinny rims and tires now.

Given your current ride is convertible from 650b (ISO 584) to 700c (ISO 622); it should also accept 590 with no issues........