Off set rims

GaryGkn
GaryGkn Posts: 1,199
edited May 2008 in Workshop
I have been looking in to getting the Velocity O/S rims Aerohead or Synergy. The only problem is that living in the UK they seem to be unavailable.

Does anyone know of another off set rim?

Or where I can get the Velocity ones from?

Thanks Gary

Comments

  • acorn_user
    acorn_user Posts: 1,137
    Alex and Ritchey have them too. No idea on a UK source, sorry.
  • GaryGkn
    GaryGkn Posts: 1,199
    Thanks they seem rare in Europe but a good idea.
  • dennisn
    dennisn Posts: 10,601
    GaryGkn wrote:
    I have been looking in to getting the Velocity O/S rims Aerohead or Synergy. The only problem is that living in the UK they seem to be unavailable.

    Does anyone know of another off set rim?

    Or where I can get the Velocity ones from?

    Thanks Gary

    The USA web site is www.velocityusa.com
    I built up a set of areohead rims(off center rear) 32 spoke. Working just fine for me. Have
    been using them daily on less than perfect roads with no problems. And I'm not the
    lightest guy out there.

    Dennis Noward
  • GaryGkn
    GaryGkn Posts: 1,199
    That is encouraging news!

    Although I will have to have my wheels built.

    Did you order them direct from the USA?
  • dennisn
    dennisn Posts: 10,601
    GaryGkn wrote:
    That is encouraging news!

    Although I will have to have my wheels built.

    Did you order them direct from the USA?

    I am from the USA, so not a problem for me. Can't say what problems you would have
    in getting them sent over the big pond.

    dennis noward
  • graham_g
    graham_g Posts: 652
    You need to speak to these guys:

    http://www.53-12.com/bike/bike_index.htm

    Prices are very reasonable (i.e. probably a bit cheaper than ordering from the US and paying all the duty/vat/postage costs) and they order stuff in on a regular basis.
  • GaryGkn
    GaryGkn Posts: 1,199
    OK I will find someone who will import!

    Thanks Gary
  • geoff_ss
    geoff_ss Posts: 1,201
    Educate me. What exactly are offset rims? Are they designed to minimise the effects of dishing?

    thanks

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • dennisn
    dennisn Posts: 10,601
    Geoff_SS wrote:
    Educate me. What exactly are offset rims? Are they designed to minimise the effects of dishing?

    thanks

    Geoff

    You've got it. The spoke holes are offcenter or offset to one side of the rim and effectively eliminates rear wheel dish. Whether this is a great advancement in cycling
    or just, not a bad idea, is kind of up in the air. My rear wheel that I built hasn't needed
    much if any truing work and I don't consider myself a "master wheel builder" in any way shape or form. I have also seen hubs with a larger diameter flange on the drive side
    to help even the spoke angles out.

    Dennis Noward
  • aracer
    aracer Posts: 1,649
    dennisn wrote:
    I have also seen hubs with a larger diameter flange on the drive side
    to help even the spoke angles out.
    If you're using tangential spoking (as you almost certainly are on rear drive side) then that doesn't actually make any difference. I can explain further, but would encourage you to look at how the spokes leave the hub on a rear wheel to try and work it out first.
  • geoff_ss
    geoff_ss Posts: 1,201
    Thanks for the explanation, gents. I've never seen any rims like that - just ones with the holes offset to each side slightly.

    I believe Maxicar made hubs with different diameter flanges which were claimed to help with different spoke tensions on dished wheels. At first thought, that would seem to help but I'll have a think about it as aracer suggests.

    I don't claim to be a master wheelbuilder either but the wheels I've built for myself seem to work OK on solos (bikes and trikes) and tandems.

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • dennisn
    dennisn Posts: 10,601
    Geoff_SS wrote:
    Thanks for the explanation, gents. I've never seen any rims like that - just ones with the holes offset to each side slightly.

    I believe Maxicar made hubs with different diameter flanges which were claimed to help with different spoke tensions on dished wheels. At first thought, that would seem to help but I'll have a think about it as aracer suggests.

    I don't claim to be a master wheelbuilder either but the wheels I've built for myself seem to work OK on solos (bikes and trikes) and tandems.

    Geoff

    I've only got one rear off set wheel and have been riding it pretty much daily for a year or so. I'm to lazy to switch. Works just fine for me although not any "better" than my other,
    so called, regular rear wheels. So, it being the greatest thing since sliced bread is a bit
    of a stretch. I like building wheels and it was more of a "let's try this" kind of a thing than
    for any specific reason(i.e. areo, light weight, strength, etc.).

    aracer- am thinking about your statement but can't quite get my mind wrapped around it yet.

    Dennis Noward
  • DavidBelcher
    DavidBelcher Posts: 2,684
    Geoff_SS wrote:
    .

    I believe Maxicar made hubs with different diameter flanges which were claimed to help with different spoke tensions on dished wheels.

    Geoff

    Rear hubs with unequal flanges are still to be seen on some factory-built wheels. I was looking at just such a rear wheel (Mavic R-SYS or Ksyrium ES??) in a catalogue yesterday lunchtime.

    David
    "It is not enough merely to win; others must lose." - Gore Vidal
  • aracer
    aracer Posts: 1,649
    Just thinking about it will be kind of hard. You're much better going and looking at a wheel and considering where the spokes would meet the hub if it had a larger flange (or if you have large flanges, where they would meet with small flanges - or better yet compare one of each). Consider what difference that would actually make to spoke angle.
  • geoff_ss
    geoff_ss Posts: 1,201
    aracer wrote:
    Just thinking about it will be kind of hard. You're much better going and looking at a wheel and considering where the spokes would meet the hub if it had a larger flange (or if you have large flanges, where they would meet with small flanges - or better yet compare one of each). Consider what difference that would actually make to spoke angle.

    Of course, angle isn't the problem. It's the different tension needed to achieve the dish. I suppose they're directly proportional though but perhaps not linearly. I have an excuse for not understanding - I may be an engineer (retd) but my discipline is more concerned with amps, volts 'n' stuff :)

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • aracer
    aracer Posts: 1,649
    Geoff_SS wrote:
    Of course, angle isn't the problem. It's the different tension needed to achieve the dish. I suppose they're directly proportional though but perhaps not linearly.
    Well only not linear because you have a sine in the equation - tension required is proportional to 1/sin(angle) (where angle is from directly vertical). The point though is that if the angle doesn't change, then neither does the tension.
    I have an excuse for not understanding - I may be an engineer (retd) but my discipline is more concerned with amps, volts 'n' stuff :)
    I'm not letting you off that lightly, as supposedly so is mine (kind of - I'm mostly more concerned with radio waves and 1s and 0s). 8)

    Just to give you a bit of a help, I'll point out that in order for the spoke angle to change, given that the lateral distance between the centre line of the rim and the hub flange is fixed (you can't move the flange further right as the cogs get in the way), then you must reduce the radial distance between the point the spoke attaches to the hub and the point the same spoke attaches to the rim. Given tangential spoking, increasing the hub flange size moves the spoke attachment point perpendicular to the line of the spoke, therefore not changing the radial distance.
  • dennisn
    dennisn Posts: 10,601
    aracer wrote:
    Geoff_SS wrote:
    Of course, angle isn't the problem. It's the different tension needed to achieve the dish. I suppose they're directly proportional though but perhaps not linearly.
    Well only not linear because you have a sine in the equation - tension required is proportional to 1/sin(angle) (where angle is from directly vertical). The point though is that if the angle doesn't change, then neither does the tension.
    I have an excuse for not understanding - I may be an engineer (retd) but my discipline is more concerned with amps, volts 'n' stuff :)
    I'm not letting you off that lightly, as supposedly so is mine (kind of - I'm mostly more concerned with radio waves and 1s and 0s). 8)

    Just to give you a bit of a help, I'll point out that in order for the spoke angle to change, given that the lateral distance between the centre line of the rim and the hub flange is fixed (you can't move the flange further right as the cogs get in the way), then you must reduce the radial distance between the point the spoke attaches to the hub and the point the same spoke attaches to the rim. Given tangential spoking, increasing the hub flange size moves the spoke attachment point perpendicular to the line of the spoke, therefore not changing the radial distance.

    I'm thinking "a" that we are talking about two different angles. I'm looking at the rear wheel from the rear of the bike. The hub flange on the drive side is pretty much directly
    under the rim centerline or a bit to the right. The non drive side flange is much further left
    of the rim centerline than the drive side is to the right of it. Looking at the spokes(from the rear) the drive sides are almost vertical as they run toward the top of the rim whereas
    the non drive side are at more of an angle(more like both sides of the front wheel). If the
    drive side flange were made larger in diameter then the spokes on that side would be a
    little less vertical and at more of an angle thereby evening out the spoke tensions on each side somewhat. Sort of like the front wheel. Am I making any sense?? Can I
    ramble on any more???

    Dennis Noward
  • aracer
    aracer Posts: 1,649
    I'm obviously going to have to draw some diagrams. On the left a small flange hub with tangential spoking. On the right a large flange hub with tangential spoking. Note how much the spoke angle changes.

    wheel1.pngwheel2.png
  • dennisn
    dennisn Posts: 10,601
    aracer wrote:
    I'm obviously going to have to draw some diagrams. On the left a small flange hub with tangential spoking. On the right a large flange hub with tangential spoking. Note how much the spoke angle changes.

    wheel1.pngwheel2.png

    What I meant was that the spoke hole diameter is bigger on the drive side flange thereby
    changing the angle of the spoke. How does that sound???

    Dennis Noward
  • aracer
    aracer Posts: 1,649
    Yes Dennis, I've shown the effect of a larger spoke hole diameter in my diagram. The spoke head in the right diagram has moved toward you out of the page. Note how much that changes the spoke angle.
  • dennisn
    dennisn Posts: 10,601
    aracer wrote:
    Yes Dennis, I've shown the effect of a larger spoke hole diameter in my diagram. The spoke head in the right diagram has moved toward you out of the page. Note how much that changes the spoke angle.


    hang in there. I'm going downstairs to study this.

    Dennis Noward
  • dennisn
    dennisn Posts: 10,601
    aracer wrote:
    Yes Dennis, I've shown the effect of a larger spoke hole diameter in my diagram. The spoke head in the right diagram has moved toward you out of the page. Note how much that changes the spoke angle.

    After retreating into the basement for a extended period(about 5 seconds) of intensive
    study of one of my wheels I have realized(rather quickly) that you are absolutely
    correct in your thinking. I always thought I was pretty sharp with geometry but I'm
    going to have to re-evaluate that idea. I just wasn't thinking tangential, probably thinking
    more along the lines of radial lacing with a larger flange. In any case, as we say here in the states, "I'm not worthy".

    Dennis Noward
  • aracer
    aracer Posts: 1,649
    So all it took was for you to follow my first suggestion and actually look at one of your wheels? :roll:

    I was worried I was going to have to muddy the waters even more there with some equations! To be fair, it is also something I learnt from reading Jobst Brandt's book, and it made me think "huh, that's not right" when I first read it!
  • dennisn
    dennisn Posts: 10,601
    aracer wrote:
    So all it took was for you to follow my first suggestion and actually look at one of your wheels? :roll:

    I was worried I was going to have to muddy the waters even more there with some equations! To be fair, it is also something I learnt from reading Jobst Brandt's book, and it made me think "huh, that's not right" when I first read it!


    Amazing what actually looking can do.

    Dennis Noward

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