Bicycle Mechanics - 630mm 27 1/4 wheels and tires
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10-19-10, 12:04 AM
hi, i have some old mp(made in italy wheels) laced onto some campagnolo record hubs. i would like to use what i have. on the harris cyclery website, sheldon says that the newer 27 1/4 tires they sell with a steel belt, will work on the straight wheels versus the hooked newer ones, just at lower pressure. does anyone know if this is true from experience.
here is the link to the page http://sheldonbrown.com/harris/tires/630.html
here is what he says
"Traditional 630 mm (27 inch) rims were straight side design, but in the late '70s they evolved to a "hook edge" design which would permit the use of higher pressures.
These days, many 630 mm (27 inch) tires are marked "For hook edge rims only" (some companies use the term "crochet type" instead of "hook edge"...this is the result of poor translation.)
The fact is that modern 630 mm (27 inch) tires will work on older straight-side rims, but they won't handle as much pressure as they are capable of with hook edge rims.
Generally, the "rule of thumb" for traditional 630 mm (27 inch) tires is that they should be inflated to 70-75 psi. This shouldn't be a problem with any tire, despite whatever disclaimer the manufacturer puts on the sidewall. However, if you're restricted to this pressure range, you probably shouldn't be running tires narrower than 1 1/8, or preferably 1 1/4, unless you're a very lightweight rider."
if i was to upgrade to new wheels, would i be able to keep the campagnolo hubs?
what size wheels would i get? 700c? or 27 1/4 with a hook edge?
10-19-10, 12:41 AM
You can build up the Campy hubs to any rims you want (with the correct number of spokes of course.) If you go this route, I'd suggest the 700c size since you'll have a much larger choice for tires. 700c rims and 27" rims are virtually the same size so your brakes should reach unless the pads are already at the bottom of the calipers.
It's unfortunate your rims are straight side, because it would be much easier and cheaper to just search for some nice 27" tires. I have never used straight sided rims so I can't help you there, but if you're willing to run 70-75 psi I'd say give it a shot. IMO that's plenty of pressure for a 27 x 1 1/4 tire, but I am also a lightweight.
10-19-10, 12:43 AM
what psi do you normally run in road bike tires for around town riding? i've never had a road bike before, and is that high or low?
10-19-10, 03:17 AM
I second the other poster's recommendation. Go to 700C rims and you'll have a bigger selection of tires. Its the road standard these days.
10-19-10, 03:18 AM
Well, if you're used to 26" MTB tyres at 40-60psi, then 27x1-1/4" tyres at 70-80psi would be considered high. However, compared to 700x23c tyres @ 120psi, they would be considered low.
You want to set pressure based upon tyre-width and load (weight). Typically a 15% sink is desired for a good combination of various factors.
10-19-10, 09:08 AM
You should post in Classic & Vintage about this. Switching tires from 27" to 700c can be a hassle because brakes won't always reach. I've used straight rim 27" wheels, and Sheldon's correct--they work fine, as long as you keep the pressure a bit lower. There are quite a few of the wider (27 x 1 1/4) sized 27" tires that have recommended of 80-90 psi, so don't worry about "being out of the norm." The wider the tire, the lower the pressure you can run it "safely." You wouldn't want to be using these as "racing" road wheels because the low pressure would just create too much drag and rolling friction, but for a nice, comfy ride, they'll work fine.
If you want to upgrade the rims, then yes, you'd want to get hooked bead rims, and you could use either 27 x ___ or 700c. If you switch to 700c rims, be sure to make sure you can adjust your pads in the brake arms far enough down, i.e., towards the hub of the wheel--you'll need 4mm more for it to work. Note that 27" tires are plentiful and available, so if, as you say, you'd like to use what you've got, your cheapest option is just to get yourself some 27 x 1 1/4 tires. I use some from Performance Bicycle that are usually around $10-$15 and often on sale.
garage sale GT
10-19-10, 09:47 AM
what psi do you normally run in road bike tires for around town riding? i've never had a road bike before, and is that high or low?It sounds like going with your stock wheels and 75 psi would be great. You'd mainly need to use higher pressure with a narrower tire, and that would compromise your ability to comfortably ride over minor cracks or pavement joints in town.
There are plenty of touring and training tires available in 27. Switching rims might garner you a small benefit in rolling resistance which you would mostly notice at higher sustained speeds but may not be worth it.
I use 65psi in front with my 27x1-1/4 and 75 in back, even though my rims have a hook bead.
I'd say just go ahead and use what you have. The experiment will only cost you a set of tires. If you find you need to lower your rolling resistance that badly (and can afford to compromise on how rough of a road the bike can handle), then you can get the 700 rims. Make sure you get your wheels tensioned and trued especially if they don't run straight after you use them for a few dozen miles.
garage sale GT
10-19-10, 09:51 AM
I use some from Performance Bicycle that are usually around $10-$15 and often on sale.The Performance Fortes are pretty rugged, thick, hard wearing tires. I like the Nashbar Primas because they are grippier and the sidewall is a bit more supple which is important to low rolling resistance when used at moderate pressure. They are also a value "store brand" for an online firm. The bike just rides and rolls a bit nicer with them.
The C&V subforum would know if you can use Panaracer Paselas on non-hook-bead rims. Those are skinwalls just like race tires but I believe they have a touring tread which MAY have a harder wearing compound. They are thin, low resistance tires which have a great ride. They're a bit more than the others though. The 27" variant has a vintage-look tread unlike the ones you see pictured- diamond pattern on the tread cap with a center wear strip which has two zigzagging grooves, and light brown sidewalls. Skinwalls can be a bit fragile though; scrape the sidewall hard against some jagged pavement and you have to replace them.
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