Bicycle Mechanics - Difference between 29 and 700c

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ncscott
11-06-11, 05:45 AM
I am hopefully going to have a road frame with disk brakes soon. I need wheels now. So I need a hub that is disk compatible and rims that will fit 28mm slick tread tires.
I've noticed that I can get complete wheels sold for 29 inch mt bikes. Would a 28mm road tire fit on a 29'er mt bike wheel?
Scott
MichaelW
11-06-11, 06:05 AM
29" wheels use MTB hubs with a width of 135mm.
Road bikes usually use road hubs which are 130mm wide.
Touring and hybrid bikes use 700c rims on MTB hubs.
Most disk hubs are sized for MTB so you may be OK.
29" wheels have wide rims to accommodate knobbly tyres. They may be too wide for 28mm tyres.
You can always select the hub and rim and get a wheel built up by a bike shop.
ncscott
11-06-11, 06:32 AM
So I guess the real questions is... How narrow/wide does the rim need to be to accept a 28mm rim? I've noticed the rim manufactures call them "touring/29er" rims.
reptilezs
11-06-11, 06:44 AM
most road type rims are 15mm internal width. you can find some xc oriented 29er wheels with 17-18mm width and that will be fine with 28 tires
Cyclesafe
11-06-11, 06:58 AM
Velocity Dyad rims with ~19mm internal width use 28mm tires as a conservative minmum. With a wider rim than than that (most - maybe all - commercially built "29er" rims) you take your chances.
So I guess the real questions is... How narrow/wide does the rim need to be to accept a 28mm rim? I've noticed the rim manufactures call them "touring/29er" rims.
Roughly grouped, rims with 17-18 mm inside width will work with 25 mm wide, and wider, tires. 13-15 mm width rims are generally good for up to a 28 mm tire. Variables are the rim's bead depth and how 'true' the tire's size is.
Brad
dsbrantjr
11-06-11, 08:54 AM
ncscott: Here is a Sheldon Brown article on tire sizing. Scroll down for a chart of recommended tire widths vs rim width. These are conservative suggestions, not engraved in stone, and recent practice is to use wider tire widths than recommended on this particular chart. http://sheldonbrown.com/tire-sizing.html
cyccommute
11-06-11, 09:05 AM
29" wheels use MTB hubs with a width of 135mm.
Road bikes usually use road hubs which are 130mm wide.
Touring and hybrid bikes use 700c rims on MTB hubs.
Most disk hubs are sized for MTB so you may be OK.
29" wheels have wide rims to accommodate knobbly tyres. They may be too wide for 28mm tyres.
You can always select the hub and rim and get a wheel built up by a bike shop.
To go more basic, a "29er" rim and a 700C rim are both ISO 622 or have a bead diameter of 622mm. A "29er" tire will fit on any 700C rim and a 700C tire will fit on "29er" rim. The only issue to worry about is width. As reptilezs points out, there are lots of XC wheels that are close to the same width as road rims (15 to 18 mm) but there are also lots of wider rims out there that a 28mm tire couldn't fit on. It depends on the width of the rim. Sheldon Brown says (http://sheldonbrown.com/tire-sizing.html) that a 28mm tire will fit a 15-19mm wide rim. I'd probably push it a little to a 21mm rim. If you used a 32mm or 35mm tire, you could get them onto something as wide as a 23mm or 25mm rim, respectively.
How the wheel is built and what components it uses are irrelevant.
mrrabbit
11-06-11, 09:58 AM
29 = 700c
29 is simply a marketing term invention....
As noted already - just watch your tire widths - and compatibility with frame for given tire widths.
=8-)
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