jimmuller 

I'm considering a frame on ebay for a smaller bike for my sweetie. It is described as requiring 26 inch wheels. As I read the tire specs, that could mean many things. But it strikes me that as long as the brakes can be made to reach then any wheel would do, so maybe the variatoins between the different kinds of "26 inch" wheel/tire are insignificant.

I can build the wheels so finding them complete isn't the issue. I just need to know what kind of rim it would require.

Tanks.

jimmuller 

Thanks. I already looked at that page, wihch is why I asked here. The frame in question is a small road frame. I would not want to mount true mtb tires on the bike, but if equivalent road tires are available they would do nicely. I know there are some 650B enthusiasts here.

The other half of the problem is brake reach. I thinking there isn't so much difference between the various nominal 26" wheels that I couldn't find something. But is always better to know than to not know.

curbtender

I'd say your biggest issue would be brake type. Side pull, canti?

ThermionicScott 

I would ask the seller to measure the distance from the dropout to the fork crown.

sailorbenjamin 

And rear dropout to brake bridge. It's got calipers, right? Canti posts sort of dictate your rim size but if it's calipers then you just measure the distance from the dropout to the brake bolt hole and subtract the rim diameter to determine brake reach (minus a little cause you have to reach all the way to the braking surface, not just the bead seat).
There's also the issue of width. If you're going to use skinny tires then no problem. Balloon tires don't always work on a middleweight frame, though.
you can get really skinny 559s these days and there's an odd size tire that goes on a 571 rim, it's not the Schwinn middleweight tire, though it's the same BSD. It would be intereting to find one of those.

jimmuller 

Thank you all. (I see dphilips removed his reply.)

Brakes would be side-pull. I got a reply from the seller that the wheels were marked "600". I have no idea what that means.

However it turns out I won't be buying it. The TT length was listed as 51cm, exactly the same as the bike I'd be replacing. Which means it wouldn't decrease the reach, the main thing I'd be hoping to improve. Bummer.

GrayJay

If the bike is a nicer 26" road bike it likely uses 571 BSD, aslo called 650c the clincher equivalent of 26" road tubulars. Max tire width available for these is a 28mm Terry tire, most 571 tires are more like 21-25mm. The 571 BSD is close enough to 559 mtb wheels that the brakes can usually adjust reach to adjust for the 6mm difference in radius if you want to try wider, stouter MTB wheels. Difficulty is that there may not be frame clearance for larger diameter of fat 559 tires and availability of nice 559 tires for road riding that much less than 32mm wide is fairly minimal.

Out in the garage recently, I tried interchanging a 26" mtb rim into a 650c road fork & frame, works fine. The 6mm difference in rim radius is miniscule, almost dont even need to adjust the brake pads for the rim diameter change and the 105 road calipers on the fork had plenty of adjustment range. It is really pretty stupid that the industry has kept both 559mm and 571mm rim standards alive, they both should have been consolidated together long ago. I would probably have picked 559mm as the surviving standard since there is already a slightly larger 584mm/650B/27.5" offroad and fat road tire standard and because for thier purpose, small wheel road bikes would probably benefit more from using an even smaller size, the jump from 700c to 650c is not really all that big. All 26" wheel riders would all benefit if MTB owners had access to light, fast road rims & tire (including tubulars) and if small road riders had access to tires wider than 28mm and could get more aggressive CX/offroad tread patterns. Same sort of mutual compatibility between 29er MTBs and 700c road wheel size parts has certainly been good for CX.


584mm bsd 650B tires (27.5" mtb) are almost certainly too large of diameter to fit a road frame designed for narrower, smaller diameter 650c.

GrayJay

While the 650c bike may have similar TT length, it probably has no toe-overlap. A 700c bike built with a 51cm TT likely does compromise toe-tire clearance to get that short. To get a 650c bike much shorter than 51cm TT length, you need to design it around cranks shorter than 165mm and/or be willing to accept toe-tire overlap. ( I just recently got my daughter non-vintage 47cm Jamis with 650c wheels, similar 51cm TT length).

jimmuller 

Whether it is a nicer road bike I can only guess.
https://www.ebay.com/itm/Vintage-Kuwa...-/130846612703
The frame appears like it should be decent. You tell me.

Sharon already rides with 140mm cranks so toe/wheel clearance is not really a problem. But she really doesn't like too much reach, never liked it when we were riding solo bikes together. I've tried replacing her stem and drop bar with a short-reach upright stem and urban-type bar with a small amount of sweep-back but still with lateral grip sections. It didn't make her any happier.

T-Mar

I think the seller has made an error. A 44cm frame with a horizontal top tube would not accommodate 26"/650 wheels. I believe this frame requires 24" wheels. If the wheels were marked 600, that equates to 24".

The question is, which 24/600 bead seat diameter? A "600" marking with no suffix would imply 540 BSD. Given the Japanese origin of the frame, the rims are probably Araya and they typically marked the suffix. However, to be sure, you should get the seller to take rim measurements and the previously suggested frame measurements.

Tange 900 typically indicates a mid-1980s model of upper entry level to lower mid-range quality. It was a seamed, butted, CrMO tubeset. In this case the presence of stamped dropouts indicates it is almost certainly Tange 900 only in the main triangle, with hi-tensile stays and forks. If so, I would classify it as upper entry level for the period. Normally, I wouldn't offer anywhere near that amount for a frame of this level, but the very small size does command a premium.

Edit: D'oh! Screwed about doing the conversion in my head! 44cm could handle 26" wheels. I was thinking 44cm =13", not 16"! Still, if the matching wheels are 600, that's 24"

T-Mar

I tried scaling some measurements off the frame using the seat tube dimension as a reference. Things came out a tad tight for 26"/650c, even if it was racing frame, which it isn't. However, it would be just about right for 24" wheels with fender clearance. Given the dropout eyelets, I still believe it is designed for 24"/600 wheels with fender clearance.

jimmuller 

Thanks, T-mar.

I wasn't thinking that would be a superb road bike, and the weight the seller quoted seemed quite high. But for a casual cruiser it would have been okay. However the TT length makes it no better than the nice road frame she already has. So I'm not going to make an offer.

Thanks again.

rhm

Okay I understand you are not buying the bike. So the question is no longer active.

Still, let us be clear. "26 inch" tells us approximately nothing. It rules out 700c and 27" but we still don't know what size the wheels are.

"650" tells us more, but only just barely. 650a is bigger than 650b and they're both bigger than 650c and they're all "26 inch" but there are still other '26 inch" sizes both bigger and smaller than that.

Jim, I think you should look at some folding bikes with 20" wheels. There are many, and their geometry varies (as does the wheel size-- there are two "twenty inch" rims ). If you found a bike that allows you to adjust handlebar height (some do, some don't) you might get lucky.