OCR Rear Rim - Really necesary?

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy. One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

thanks to all, Rick

Not half an hour ago, I laced up my second set of Aeroheads, with an
OC rear. On symmetrical rears, I usually get a NDS with half the
tension of the DS. With the OC rear, it has 3/4 the tension of the DS.
That's more lateral strength, and greater resistence to going out of
true. My other set that I built this summer have been completely
trouble-free, and I've ridden off a few curbs with them (I weigh 240).
Very, very tough wheels. I'm sold.

As for why a wheelbuilder won't build with them, I'd be curious to
hear his reason. Lack of eyelets? IRD's Cadence VSR has them, but
availability is spotty. I'd guess that his distributors deal mostly
with Mavic or DT, and getting Veolcity rims seems like too much
trouble.

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear?

Like for like, offset rear rims are stronger and more reliable than
symmetrical rims. If you are in the market for one of the few rim
styles that is offered in offset drillings (lightweight 700c and 26"
MTB rims in medium and low spoke counts), then I recommend that you
use them wherever your hub's flanges are offset.

I use heavy-duty rims, so I can't exploit the availability of off-
center rims which are all of lightweight and flimsy construction. If
wide and sturdy rims come available in off-center drilling, I will use
them.

Chalo

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy. One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

My limited experience says "better" for the Aerohead OC. Had one local
shop-built, 36h Campy hub: used for a year, heaviest weight about 240,
finally came out of true slightly. Used it that way and it didn't get
worse. Also, didn't loosen spokes while yanking the bulk up (fairly)
steep hills.

Just took delivery yesterday of a rebuilt 32h Veloce-hubbed wheel,
that had a Wolber Alpine rim (box section, 425-ish gram weight).
Changed to Aerohead OC rim. The old wheel "wallowed" in corners. First
thing I looked for in the new one, seems good so far, only tried a few
sharp corners; more today (since the rain has stopped finally) and if
it does the same I'll report back. The 36h Aerohead OC wheel always
seemed solid. Great service IME, plus (if you care) it's a light rim.

No eyelets, have heard of one rim cracking between spoke holes. Mine
sure didn't and it's been ridden hard over some rough road and taken a
few good hits. Same BTW with the Aerohead front rims, I've used two of
those, excellent results here. --D-y

On Dec 15, 7:02 am, Chalo <[email hidden]> wrote:
....

Quoted message said:

I use heavy-duty rims, so I can't exploit the availability of off-
center rims which are all of lightweight and flimsy construction. If
wide and sturdy rims come available in off-center drilling, I will use
them.

Is the Velocity Synergy OC rim not adequate?

Victor Kan said:

Chalo said:

I use heavy-duty rims, so I can't exploit the availability of off-
center rims which are all of lightweight and flimsy construction. If
wide and sturdy rims come available in off-center drilling, I will use
them.

Is the Velocity Synergy OC rim not adequate?

No, I am of such a weight that any rim which isn't suitable for a
tandem team is not suitable for me. I try to build 48 spoke wheels
whenever possible, and to my knowledge no such rims are available in
off-center drilling.

If I were to build a bike to use at the velodrome, the Velocity
Synergy might be adequate. But in that case I wouldn't need an off-
center rim.

Chalo

Hank Wirtz wrote (in part):

Quoted message said:

As for why a wheelbuilder won't build with them, I'd be curious to
hear his reason. Lack of eyelets? IRD's Cadence VSR has them, but
availability is spotty.

My personal experience with that IRD rim: I built a wheel with one of
these onto a latest-gen 32-hole Record hub. The rim joint wasn't
perfectly aligned, but not unrideable. It took some tweaking at the
final truing to get rid of a hop at the joint.

After about 4000 miles this year, two of the eyelets on the rim had
cracked and lost part of their interior flange. These two eyelets are
now kinda tilted up where they are damaged. This is not to say that
the rims are failing - to the contrary - there are not any cracks in
the surrounding rim material. We'll see how they do long-term.

I did have some issues with spoke breakage earlier but that appears to
be due to some personal failing.

D'ohBoy

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy.

I think that's because Campag rear hubs need more dish.

I use Campag hubs with ordinary symmetrical rims and have no problems
but YMMV-- there are other factors, mainly how much weight you're
carrying I suspect, and also whether you're too proud to use linseed or
threadlock on the spoke threads.

In article
<[email hidden]>,

Chalo said:

Victor Kan said:

Chalo said:

I use heavy-duty rims, so I can't exploit the availability of
off- center rims which are all of lightweight and flimsy
construction. If wide and sturdy rims come available in
off-center drilling, I will use them.

Is the Velocity Synergy OC rim not adequate?

No, I am of such a weight that any rim which isn't suitable for a
tandem team is not suitable for me. I try to build 48 spoke wheels
whenever possible, and to my knowledge no such rims are available in
off-center drilling.

If I were to build a bike to use at the velodrome, the Velocity
Synergy might be adequate. But in that case I wouldn't need an off-
center rim.

My Burley tandem came with 48 hole Bontrager Fairlane rims, the rear
being an off-center rim. The finish appears to be a brushed aluminum
rather than anodized, but my continuity tester is busted. Maybe that'd
be a suitable rim for you, if you can find them. Their Web site is
atrocious- like most in the bicycle industry- and it's impossible to
quickly find any information about their rims.

Tim McNamara said:

Chalo said:

I am of such a weight that any rim which isn't suitable for a
tandem team is not suitable for me. I try to build 48 spoke wheels
whenever possible, and to my knowledge no such rims are available in
off-center drilling.

My Burley tandem came with 48 hole Bontrager Fairlane rims, the rear
being an off-center rim. The finish appears to be a brushed aluminum
rather than anodized, but my continuity tester is busted. Maybe that'd
be a suitable rim for you, if you can find them.

Thanks for the tip-- I think that would be a usefully sturdy rim for
me, for the next time I build a 7 to 9 speed rear wheel or a disc
front wheel.

The last time I built either of those things, I used Bontrager Clyde
700c rims in 48 hole drilling (a lucky eBay find). Those appear to be
a resurrection of the old Matrix Titan Tour extrusion but without
eyelets in this incarnation. They are not elegant in their details,
but they look nice enough and seem to do the job.

Chalo

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy. One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

thanks to all, Rick

Velocity Aerohead and Synergy OC + AlexRims Crostini T1.1 all help the nondrive side rear spokes carry additional share of the loads and therefore make the rear wheel more durable than the same build with a symetrical rim of the same basic construction.
I have experienced more reliability with Velocity and AlexRims products than the current line of Mavic rims, including non OC models.

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy. One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

Yes, the Velocity Aerohead OC will usually outlast Mavic's OP. Perhaps
the fellow thought you meant Ritchey OCR rims? Those have some issues.

The differences among modern hubs are small, less difference between
them than to older hubs as a group.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Chalo said:

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear?

Like for like, offset rear rims are stronger and more reliable than
symmetrical rims. If you are in the market for one of the few rim
styles that is offered in offset drillings (lightweight 700c and 26"
MTB rims in medium and low spoke counts), then I recommend that you
use them wherever your hub's flanges are offset.

I use heavy-duty rims, so I can't exploit the availability of off-
center rims which are all of lightweight and flimsy construction. If
wide and sturdy rims come available in off-center drilling, I will use
them.

Velocity Synergy OC? 500g 23mm wide.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear?

Stronger? Certainly. The more even tension does make for a stronger
wheel. Better? Well, that gets at the real problem. Yes, OCR rims
allow you to build a stronger wheel. But you can build a strong-enough
wheel with symmetric rims, one that will last until something else goes
wrong. So, the question is really whether it's necessary.

If all else is equal, I'll use ORC rear rims. But usually it isn't,
since they are hard to find and pricy. OTOH, Open Pros and similar
wheels are dirt cheap at any swap meet.

I use Shimano,

Quoted message said:

some say the OCR is more necesary and/or a better idea when using
Campy.

I have Campy wheels and (now) symmetric rims. I wore out the braking
flats of an OCR rim, but could not find an affordable (that is, dirt
cheap) replacement, so now it's symmetric. No problem with it at all.

Quoted message said:

One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

Can't imagine why anyone would refuse to use them.

--

David L. Johnson

It is probable that television drama of high caliber and produced by
first-rate artists will materially raise the level of dramatic taste
in the nation.
-- David Sarnoff, 1939

A Muzi said:

Chalo said:

I use heavy-duty rims, so I can't exploit the availability of off-
center rims which are all of lightweight and flimsy construction. If
wide and sturdy rims come available in off-center drilling, I will use
them.

Velocity Synergy OC? 500g 23mm wide.

The width is OK, the weight is marginal, and the available spoke
counts don't cut it. I'd consider that rim for a "race day" rear
wheel, if I were fool enough to race. I could likely dominate the
over-325-lb class if there were such a thing.

48h Sun CR-18 rims are the lightweight 700c stuff in my stable. The
heavy duty 700c rims are Kris Holm 29er unicycle rims, nearly twice as
wide and heavy as CR-18s. In between are Sun Rhynos and Rhyno Lites,
Bontrager Clydes and some beautiful double eyeleted RIgidas. And one
Mavic T519 that hasn't yet herniated its intestine into its scrotum
like all its kin have.

A few years ago I got a small batch of 72h Velocity Deep-Vs, but so
far I have only built a pair up for a friend. I have a hard time
imagining myself anymore on tires that would be a good size match for
19mm wide rims.

Chalo

On Dec 15, 8:40 pm, "David L. Johnson" <[email hidden]>

Quoted message said:

If all else is equal, I'll use ORC rear rims. But usually it isn't,
since they are hard to find and pricy. OTOH, Open Pros and similar
wheels are dirt cheap at any swap meet.

You can buy all the Velocity Aerohead OC's you want, and get them
delivered fast, too. Retail price may vary but they tend to be (maybe
a lot) cheaper than Brand M.

If Mavic and non-OC work for you, no complaints here <g>, OK? From one
scrounger to another? --D-y

On Dec 15, 7:40 pm, "David L. Johnson" <[email hidden]>

Quoted message said:

Can't imagine why anyone would refuse to use them.

I've heard some reports recently of them having a tendency to crack on
the drive side... apparently because that side of the rim is not
beefed up enough for the loads involved. But it would be nice for the
OP to find out and tell us.

Chalo said:

And one
Mavic T519 that hasn't yet herniated its intestine into its scrotum
like all its kin have.

Which part of the rim is the intestine, and what happens?
(I'm just trying to understand what failure mode you are describing.)

Tom Ace

Tom Ace said:

Chalo said:

And one
Mavic T519 that hasn't yet herniated its intestine into its scrotum
like all its kin have.

Which part of the rim is the intestine, and what happens?
(I'm just trying to understand what failure mode you are describing.)

I was speaking figuratively, but this is how those rims (T519, T520,
A719) have failed for me: In short, they squish compressively in the
surprisingly soft heat-affected zone surrounding the weld. The
machined finish in this area becomes upset and dimpled in the
characteristic way for an aluminum alloy, and the rim's sidewalls both
bulge slightly outwards at the weld. Such failure causes the wheel to
develop a deep flailing lateral curvature that, because it is a
failure to resist spoke tension, becomes worse if any attempt is made
to true it by tightening spokes.

I am sure that my preferred spoke count of 48 contributes to this
failure mode by elevating the total compressive load on the rim
section in proportion to the number of spokes, but no other 48 spoke
rims I have used collapse by pooching out in a putty-soft heat-
affected zone like welded Mavics do. Other rims which I have
inadvertently overtensioned for their strength (48 hole Sun CR-18 in
the 700c size, 36 hole Sun M13 in 27"😉 display a generalized buckling
that calls to mind Euler column behavior. But not Salomon Mavics!
The most expensive rims I've ever bought are evidently not heat
treated after welding, and they therefore display compressive hoop
strength determined by their weakest heat-affected areas. Not
impressive.

Chalo

RS said:

I'm not a wheel builder. I had one set of wheels built with Velocity
Aerohead rims, OCR 32h in rear. Is this really a stonger and/or better
rim then a Mavic Open Pro or DT rim without OCR rear? I use Shimano,
some say the OCR is more necesary and/or a better idea when using
Campy. One quality wheelbuilder here in the SF/Bay Area will not build
with OCR so I'm just curious about all this.

thanks to all, Rick

I have had two of these rims and won't use them any more. Both of them
got dents in the more vertical side, perhaps from a glancing blow on
the edge of a 'cateye' road marker. I've never had this happen to
another rim. Nor have I had problems with 'normal' rims going out of
true, if well built. Billions of wheels with 'normal' rims have
performed just fine. I think OCR rims are a case of a solution in
search of a problem, and they bring their own problem, so why bother?

Donga