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Old 07-09-07, 12:33 AM   #1
lhbernhardt
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New Project

Yeah, so Bike Tools Etc. was blowing out its old Rock Shox Metro suspension forks for around $45. These are set up for disk brakes, 700c wheels, and a 1" steerer. So I decided to get one to put on my fixed gear road bike (it's currently got an old Kestrel carbon fiber fork). I'm curious to see if front suspension makes any difference on the road. Some of the roads around here are getting pretty beat up, and with a fixie you can't really float over the bumps like you can with a freewheel. I'm also interested in how effective disk brakes will be, and how durable the rotor will be after the typical Pac Northwest winter. At least I will no longer have to worry about the rim's braking surface deteriorating and eventually cracking (leading to front tire blowing off fractured rim, which has happened before).

However, now I have to figure out what disk brakes to get, and I need to get a hub that will accept the rotor. Anybody have any suggestions? Thanx.

- Luis
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Old 07-09-07, 03:53 AM   #2
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If you are still using road brake levers then the Avid mechanical road disc is for you. The pull ratio matches properly to the brake levers.

If you are using MTB brake levers (which do not fit the diameter of road bars) then any MTB brakes will work.

Any MTB front disc hub will do the job. Remember, no extreme spoking (radial, 20/1.5 etc) as the brake loads are no longer applied to the rim but must travel from the hub to the rim via spokes. There are spoking methods (Zinn's Art of MTB repair has one) that make the front disc wheel have stronger leading spokes as opposed to trailing spokes.
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Old 07-09-07, 11:15 PM   #3
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Hmmm. Very useful info. Thanx. Ya learn new stuff, even after nearly 40 years of riding.

Building the front wheel will be a challenge. I normally build front wheels 3x with 28 spokes, and they probably don't build disk wheel hubs for 28 spokes. I will have to think about the dynamics of the stopping power coming from the hub instead of the rim.

- L.
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Old 07-10-07, 03:45 AM   #4
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I looked up the latest generation XT hub and you are correct, disc in 32 or 36 hole only. There may be other brands but I think there is a message here.

The crux of a disc wheel is that it is laced so that on the front, the leading spokes are on the outside of the hub flange which is opposit from a rim brake wheel. The rear has the drive side trailing spokes on the outside and the non-drive leading spokes on the outside for a 50/50 ballance between pedaling torque and braking torque.

I've seen disc wheels spoked normally, so I guess that you have to ask yourself how much difference it really makes to worry about the outside spokes taking the greatest strain.

As long as you are taking the time to handbuild a wheel, these details are the difference between ordinary and "just right".

It should be an interesting project, post pictures when done.
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Old 07-10-07, 01:37 PM   #5
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Here is an article by Zinn re: disc wheel spoking. Scroll down to "regarding wheelbuilding".

Zinn Article

Here is another article by a frequent (and controversial) contributor to Mtbr.com. The photos show the different types of lacing quite well.

PVD Article
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Old 07-10-07, 03:30 PM   #6
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Talking Tandems- so overbuild the wheel. That is all I am going to say but You can use a conventional Rim brake rim on a Disc wheel if you cannot find a Disc specific rim. Then again- On the Quick release. You will need a lot of pressure on a Tight QR to stop it stretching(As the Titaniums Ones Do ) and cheap ones have a tendency to break. The Best QR for a tandem wheel is the Shimano XT. This has been proven many times over here in the UK so don't skimp or go bling.

Hopefully you will not require it but Bolt through axles are best for Disc brake suspension forks.
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