Velocity A23 - regular or off center rear wheel?

[cyclot...@gmail.com]

Getting to the point of building up a rear wheel. 32 spoke 130mm spacing using Hetres. 200lbs rider + bike. Mixed surface, will see plenty of dirt. Any recommendation on which way to go with the rim, symmetric or OC? Any problems with the OC A23 rims, or was that just a batch of Synergy rims?

Thanks! 

[CMR]

If building and both available, I don't see any reason not to go assymetric - builds a stronger wheel with more even spoke tension. The only thing is they look a bit strange to my eye haha

[Justin Hughes]

Agreed. If OC is available, use it. 

[rob perks]

The 700cx36hole asym. version has treated me and a couple other 230-250lb riders well for a couple of years now.  the seam is not as nice as something like a Mavic, but they have been working fine and doing what rims are supposed to.  If this is for your salsa with disk brakes, there are some much better choices out there though

- 

Rob Perks

oceanaircycles.com

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[cyclot...@gmail.com]

So no downside? I just remember the Synergy problem, so that stuck in my head a little.

I already have the front wheel, just want to build up a matching rear. It's for a conversion on my Riv Road, so not a disc bike.

[Steve Palincsar]

The "Synergy problem" was not a function of asymmetric drilling.  I have a Velocity Aerohead with off-center drilling that had been on my Spectrum for the past 10 years and that's now on the Longstaff and it's just fine, whereas the Synergies would crack in a couple of thousand miles or less.  And even the most recent Synergy replacements have been fine.  I think there was some kind of metallurgical problem that Velocity found and fixed, but by the time they did the Synergy brand had been irrevocably soiled.

[William Lindsay]

Jan thinks off center rims are worse, but I've never completely understood his justification for that opinion

[cyclot...@gmail.com]

Thanks for the clarification... I remembered it as being the OC rims cracking, not the entire line.

[cyclot...@gmail.com]

Worse in general? Recall what the specific criticisms were?

[William Lindsay]

Again, I couldn't completely understand his argument.  Something weird about the off center spokes would twist the rim in unusual ways, and that symmetric was always fine, so asymmetric at best would be equal, and at worst might be worse.  If you are eager to receive a dissenting opinion, you'd probably need to email Jan.  I like asym rear rims.  

[Ryan Watson]

Don't know what Jan's argument is, but to me it seems like a bad idea to have uneven force on the  rim like that. I have wheels built with offset rims that I bought second hand and never had an issue but I would personally never use one if building a wheel from scratch. 

Ryan

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[Nick Favicchio]

I've used both. Really can't tell the difference. I'm not an engineer and both are pretty.

[cyclotourist]

Ask a simple question... :-) :-)

On Thu, Sep 8, 2016 at 8:39 PM, Nick Favicchio <nickfa...@gmail.com> wrote:

I've used both.  Really can't tell the difference.  I'm not an engineer and both are pretty.

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Cheers,
David

Member, Supreme Council of Cyberspace

"it isn't a contest. Just enjoy the ride." - Seth Vidal

[Jeff Bertolet]

As with many things, opinions vary. I know Grant Peterson is a OC advocate, while Jan is not. I haven't seen Ric Hjertberg (of Wheelsmith, Mad Fiber and Wheel Fanatyk) weigh in on the topic.

I would want to know the hub flange offset and rim offset before I make a decision. From this you can calculate spoke length for OC and non OC rims and see what the benefit is (i.e. how even spoke tension will be with OC vs non OC). This spoke calculator will show the theoretical variation in tension of the drive vs. non-drive side.

Generally, the more the center-flange distance on the hub differs between left/right, the more you would benefit from OC rims. Not such an issue with 126 spaced 5sp freewheel hubs, but a major issue with 11speed cassette 130 spaced hubs.

Many manufacturers pre-built wheels come with offset spoke beds or they have very stiff rims to compensate for the uneven tension, or they have 2:1 lacing (2 drive-side spokes for every non-drive) to even out tension.

On Thursday, September 8, 2016 at 3:24:43 PM UTC-4, cyclot...@gmail.com wrote:

[Tim Gavin]

I went with OC because it made for a nearly dish-less wheel.  I used a Phil Wood FSA freewheel hub (130 OLD), which has 5 mm of offset.  The OC rim gave me back 4 mm, leaving only 1 mm of dish.  I was able to use the exact same spoke length on both sides of both wheels.

Tim

[Joe Broach]

​I hope Jan will have a chance to expand on his argument some day. Like Bill, I took note but don't fully follow.​ I've had great success with O/C rims (Velocity Aerohead), but I don't have the counterfactual!

Jobst seems at least not to object, and that's something:

"Konstantin Shemyak writes:

> An asymmetric rim on the rear allows for a smaller dish, or even no dish at all.

> Why are they not used very widely? Is an asymmetric rim in some respect weaker by itself, than a
> symmetric rim of comparable weight and quality?

> Or, put it this way. Imagine a |_| -shaped rim and two options. First, drill holes in the middle
> and build a strongly dished wheel. Second, drill holes offset to the left and build it
> less-dished. Will the second option be superior to the first one in any aspect, or (as I guess)
> the rim itself will get noticeably weaker?

It means you need to stock two kinds of rims for a bicycle with the "same" rim front and rear. Spoke
pull-out from a rim is dependent on two factors, maximum spoke tension (when wheel is unloaded) and
varying spoke tension (the cyclic untensioning of spokes with each wheel rotation due to rider
weight). You can't do much about the dynamic load but lowering spoke preload reduces incidence of
rim cracking around spokes, something that happens around right side rear spokes more often.

Therefore, reducing dish, or spoke tension disparity from left to right is the main bonus, and it is
worth doing in some of the more severe cases of asymmetric rear wheels. As long as I can get away
with it, I am going to use symmetric rims, but then I run 120mm dropout spacing and fewer gears than
are considered necessary these days.

Jobst Brandt jobst....@stanfordalumni.org Palo Alto CA

​"​ (source)

Best,

joe

pdx or

On Thu, Sep 8, 2016 at 2:56 PM, William Lindsay <tape...@gmail.com> wrote:

Jan thinks off center rims are worse, but I've never completely understood his justification for that opinion

[Eric Keller]

On Fri, Sep 9, 2016 at 3:32 PM, Joe Broach <joeb...@gmail.com> wrote:
> I hope Jan will have a chance to expand on his argument some day. Like Bill,
> I took note but don't fully follow. I've had great success with O/C rims
> (Velocity Aerohead), but I don't have the counterfactual!

I had one of the synergy OC rims blow out when I hit a pothole. It
ripped right at the corner at the inside of the brake track where the
rim was made too thin. I contemplated getting a warranty replacement,
but didn't. I'm not sure that I believe that there is an issue with
OC rims. There isn't a lot of difference, and it does even out the
spoke tension quite a bit. The problems that they had were a lack of
material in the right places.

I really like building with them and it's nice that the derailleur
doesn't get as close to the spokes.
Eric Keller
Boalsburg, Pennsylvania

[Benz Ouyang]

Can you please explain what you mean by "uneven force"? If anything, asymmetric rims make spoke tension more even.

[Joe Broach]

Hey Benz,

Since Jan's not in this thread, I'll hazard a guess and say that he means the spokes aren't pulling from a point centered on the rim structure, but instead from a point a few millimeters left of center. I'd imagine it takes a little more thought (or computer modeling) to design an extrusion to handle that off-center force, given that the bead seats have to stay symmetric. I haven't heard of unusual problems with any asym rim except those cursed Synergies.

Best,

joe

pdx or

On Fri, Sep 9, 2016 at 4:55 PM, Benz Ouyang <benzo...@gmail.com> wrote:

Can you please explain what you mean by "uneven force"? If anything, asymmetric rims make spoke tension more even.

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[Jim L]

I assume most of you have already seen this?

https://www.youtube.com/watch?v=22B579FrfjQ

[cyclotourist]

Thanks, Jim. That's a great video! 

tl;dr version: No negatives to OC, several positives!

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[satanas]

FWIW, I have a set of Velomax 18/24° wheels which use an older version of the Aerohead/Aerohead OC rims, and have had no issues with them. Not that I've had many wheel problems, the rear 32° 650b PL23 excepted; this was helpfully bent a bit on a flight and has been a bit more touchy since.

As others have said, many of the low spoke count wheels out there use asymmetrical rear rims or spoking, and this has to help with 11 speed road wheels, especially if 130mm.

If we're talking about 135mm MTB wheels, then IME they're pretty bullet-proof even with lightweight standard rims, for me anyway.

Later,
Stephen