Bicycle Mechanics - 27 vs 700, how much difference?

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View Full Version : 27 vs 700, how much difference?


ben trim
08-26-04, 11:54 PM
I'm new here so I hope this is not a dumb or faq. I didn't find it by search except 7/22/04 hook rim discussion.
I have a road bike with 27" wheels. One rim is bent beyond fixing by LBS. I'd like to try wheelbuilding. Can I replace the 27 w a 700 rim, new spokes and my old hub? Shopping online I don't see any 27 rims. Any problem with brakes or frame fit? Thanks


Raiyn
08-26-04, 11:58 PM
http://www.bikeforums.net/showthread.php?t=59535&highlight=internal+rim
To answer your question no you can't replace the rim with a 700c your brakes won't reach

ben trim
08-27-04, 01:02 AM
Thanks. I see here http://www.sheldonbrown.com/tire_sizing.html that the ISO bead seat diameter is 8 mm smaller for a 700C vs 27" . Like you said.
I don't like the shape of the replacement 27" wheelset I got at the LBS. The 27x1 1/8 tire is close for the chainstay space but narrow for the rim. Know of a source for 27" rims?
Thanks again.


shecky
08-27-04, 01:10 AM
Nashbar sells a inexpensive single wall 27" rim. I've used one for a long time with no problems.

Bikeman (http://www.bikemannetwork.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=BIKEMAN&Category_Code=COMPRMOTRD27) also has Sun CR-18 rims in 27".

capsicum
08-27-04, 05:48 AM
http://www.bikeforums.net/showthread.php?t=59535&highlight=internal+rim
To answer your question no you can't replace the rim with a 700c your brakes won't reach
Actualy it depends on that particular bike's brakes. It is only a 4mm difference from the axle/fork tip.

sydney
08-27-04, 07:06 AM
http://www.bikeforums.net/showthread.php?t=59535&highlight=internal+rim
To answer your question no you can't replace the rim with a 700c your brakes won't reach Sometomes they will.It depends on how much adjustment there is in the pads.

halfspeed
08-27-04, 12:37 PM
Thanks. I see here http://www.sheldonbrown.com/tire_sizing.html that the ISO bead seat diameter is 8 mm smaller for a 700C vs 27" . Like you said.
I don't like the shape of the replacement 27" wheelset I got at the LBS. The 27x1 1/8 tire is close for the chainstay space but narrow for the rim. Know of a source for 27" rims?
Thanks again.

Sun's CR18 is readily available as a 27" rim. If you want a narrower rim, Sun's M13 II is available at bikepartsusa. The 27" Nashbar rim is a rebranded Alex x404 which Alex sells as an OEM rim for cheap hybrids. It's really not very good and hard to get tensioned correctly when building, partly because it doesn't have nipple eyelets.

bluesref
08-27-04, 02:06 PM
I just swapped out a 27" with 700 on my old Lotus. OK I guess the Old Weinnman's are Long reach. I dropped the shoes down to gee alomost half way down in the calipers.

So it may fit depening on the rim height and the brake reach.

Good luck.

little5guy
08-27-04, 03:40 PM
I'm new here so I hope this is not a dumb or faq. I didn't find it by search except 7/22/04 hook rim discussion.
I have a road bike with 27" wheels. One rim is bent beyond fixing by LBS. I'd like to try wheelbuilding. Can I replace the 27 w a 700 rim, new spokes and my old hub? Shopping online I don't see any 27 rims. Any problem with brakes or frame fit? Thanks


700c rims (standard road rims for modern bikes) are slightly smaller in diamater than 27 inch rims, so I would not recommend having one 27 inch and the other 700c. Also, because of the smaller diameter wheel, you will need to be sure your brakes reach down to the 700c wheels. On an older road bike this is likely to be a problem; older bikes require brakes with a longer reach. Your best bet would be to take the bike to a bike shop and have them test out the brakes with 700c wheels. I recently bought some brakes on ebay I cannot use because they do not reach far enough.

Finally, your old hub with properly sized spokes will work on a 700c rim, but still you will have mis-matched wheels on the bike. And as I understand you need some specialized (read: expensive) tools to build a wheel, so you may want to chat with your LBS about that--perhaps you can borrow their shop for a modest fee. And you may want to ask your LBS or look more on the web for 27 inch wheels because I have seen some. The selection is not as great as for 700c, but they are out there.

good luck.

PGZX3
08-27-04, 10:03 PM
wheel building for me always has and always will consist of the proper spoke wrench, proper spokes and guage correct nipples, and starting off with no brakes on whatever dropout the wheel is going into and using the frame and brakes as a stand. Has worked for dozens of wheels for me, worth a shot and FAR from expensive on the tool side (only a spoke wrench need apply!!)

TechJD
08-28-04, 01:17 AM
http://www.bikepartsusa.com
they carrie some 27's including Weinnman