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Old 09-27-11, 02:42 PM   #1
shelbyfv
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Velocity Synergy rims, OC?

I am thinking of building a 650b wheelset using these rims. There is an OC rim made for the rear. However, it's a retro sort of bike and I think I like the look of the regular rim better. I will use Ultegra hubs. Are the supposed benefits of the OC rim real enough to warrant using it, regardless of appearance? I weigh 180 and have not yet broken a spoke on a road bike. I have not purchased the rims. thanks!
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Old 09-27-11, 03:57 PM   #2
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Depends how many speeds you intend to cram into what frame spacing. If it's 7 speeds in a 135mm frame, I wouldn't bother. But if you're doing 8/9/10 speeds in a 130mm frame then it can have a real benefit by reducing the dish of the wheel.
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Old 09-27-11, 05:10 PM   #3
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9 speeds in 130
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Old 09-27-11, 08:02 PM   #4
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Basically, the OC rim gives you less dish creating a much stronger wheel. Millions of people don't use OC rear rims, and most of them are just fine. So it's not totally necessary. I've never used one, but would like to with my next wheel build. It's really your call.

How much worse would an OC rim look than a normal one?
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Old 09-27-11, 10:17 PM   #5
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Originally Posted by FastJake View Post
Basically, the OC rim gives you less dish creating a much stronger wheel. Millions of people don't use OC rear rims, and most of them are just fine. So it's not totally necessary. I've never used one, but would like to with my next wheel build. It's really your call.

How much worse would an OC rim look than a normal one?
Do you know what dish is?

=8-)

...perhaps you meant to say that it makes the dish slightly more symmetrical and allows slightly higher tension on the non-drive spokes?

=8-)
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Old 09-27-11, 10:23 PM   #6
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I think most people call it "less dish" even though that might not make much sense as far as actual dishes go. I really like OC rims, specifically the Synergys. It makes spoke clearance much better in 1st. And it makes the wheel feel a lot more solid to me while building it. It apparently doesn't do much for wheel strength, I had a Bontrager OC rim that lasted no more than 2000 miles. I couldn't keep it true.
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Old 09-27-11, 10:56 PM   #7
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Remember it isn't the amount of dish (used here to mean asymmetry) that's the issue, but the tension difference that the asymmetry imposes. The relative right/left tension is inversely proportional to the horizontal flange to rim hole distance (flange to center distance if the rim is drilled straight down the center.)

Assuming a typical rear hub with flange to center distances of 37 & 21, that would mean the left tension would be fixed at 56.7% of the right, or limited to 62kg max. with the right at 110kg.

Now lets offset the rim drills 3mm to the left. 37/21 becomes 34/24 allowing the left side tension to rise to 70.5% of the right flange, which is not an insignificant improvement.

For many or even most people, it isn't necessary, since we've proven that today's highly asymmetrical wheels hold up just fine. But for heavier riders, utility riders, and mtn bikers who's wheels get rough service, off center rims are definitely worth consideration.
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Old 09-28-11, 06:26 AM   #8
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I bought a pair of Synergy rims from my LBS (in Australia, Velocity's home) and originally ordered one normal and one OC - I use Campagnolo exclusively so dish is an issue.

The proprietor of the LBS talked me out of the OC rim - said he'd had nothing but trouble with them. His take was that the the offset holes are too close to the rim wall and the gains from reduced tension difference are lost by the difference in ability to absorb stress without cracking.

Of course having not tried them I can't say whether he's right but I built a Campy 10 speed rear with 2.0 / 1.8 DS and 2.0 / 1.5 NDS to equalize strain and so far all good.
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Old 09-28-11, 06:58 AM   #9
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I've heard other reports of cracking wrt the OC rims. I'll consider using smaller diameter spokes for the NDS. That sounds like a good idea for mitigating some of the tension difference.
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Old 09-28-11, 07:13 AM   #10
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Currently riding Synergy rims, 26" 36h with a 3x build. I went with a non-OC rim for the rear, and am running a 10sp cassette. Wheel has been totally bombproof in practice. Last time I had it in the stand for service, I tossed the wheel on a truing stand and was amazed how true it remains. I'd not heard anything bad about the OC rims, just more used to dealing with symmetrical rims and didn't want to get into something new for my commuter wheel build.
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Old 09-28-11, 07:18 AM   #11
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I think the rumors about cracking were from some of the early synergy rims and doesn't seem to be a problem with the one I have. My rear synergy has been abused badly and has no issues
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Old 09-28-11, 08:56 AM   #12
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Pretty much all OC rims are subject to a long circumferential crack on the drive side of the rim unless the rim is beefed up to compensate. Ritchey has been through this...Bontrager...and others as well. A little beef buys a lot more miles...Velocity has a teeny itsy bitsy more beef in theirs...it helps.

Does it mean they're not worthwhile? Course not...

Knowing I can improve the tension a tad on the non-drive means knowing that I can pretty much guarantee the use of the spokes over 2-3 sets of wheels.

Wheels are an investment - long as I can get 30,000-40,000 miles out of a wheel sans an accident or theft - in my opinion I've gotten a decent return on the investment. Toss the rim - reuse the spokes on a new one - makes the investment a little better results-wise.

Point is to go with the OC rim that has a good reputation. Don't go with the cheap superlight - that's like using an Open Pro as an everyday commuter rim.

=8-)
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4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
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Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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Old 09-28-11, 09:14 AM   #13
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I built a set of Velocity wheels used the oc for the rear and a fusion radial spoke front. Went together beautiful great wheels have about 1000 miles on them with nothing needing touch up. Trued up great and tension was as velocity recommended on the rear. The other good thing is you can use the same length spokes on the rear.
Both side
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Old 09-28-11, 03:18 PM   #14
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I prefer a rear hub w/ a high/low flange.
white industries H3, for example.
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Old 09-29-11, 01:05 PM   #15
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"Dish" isn't different, but the spoke angles are closer to the same making it look like there's less. I have a couple of Synergy OCs and like the way the spoke angles look better than those on symetrical rims. And, you wouldn't believe the number of comments I get because OC rims are foreign to most of the biking public, and it really shows on the Synergys. Oh yeah- there's the spoke tension thing too. I've only got about 2000 miles on one of them, but so far no troubles. I like them.
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