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  1. #1
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    Question Rear Wheel Alignment

    Hi. I'm new here but will stay and contribute for sure from the forum topics that I've read! All are awesome Q and A's.

    I received a free set of Mavic Cosmos wheels where the rear wheel has a 9 cog cassette. My previous wheel was a much older 7 cog screw-on cog set. The lesser width chain that I have employed works perfectly with the 9 cog cassette and chainrings.

    The axle width and/or the dish of the new Cosmos rear wheel causes the rim/tire to not be centered under the rear brake's 'center post.' Plus, the wheel is slightly non-perpendicular to the ground plane.

    I really do love these new wheels on this older frame for their torque transfer. Their transfer is much greater than my older Araya wheels.

    But, there are many concerns (three): do I risk cracking the frame (steel Cro-Moly) at the horizontal rear brake bracket due to having to expand the dropouts 5mm to accommodate the wider Cosmos axle, do I lose straight-line power transfer if the rear wheel isn't in the exact same forward plane as the front wheel, and do I lose power transfer if the rear wheel isn't exactly perpendicular to the ground (i.e. it appears slightly slanted from a behind view)?

    Thanks from the newbie here!!!!
    Joe
    Last edited by PelotonCyclist; 12-06-2009 at 01:20 AM.

  2. #2
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    A steel frame can be be cold set (bent) to accept the wider hub. You can "do-it-yourself" like this: http://www.sheldonbrown.com/frame-spacing.html or take it to someone who will use jigs to maintain/reset all the alignments (aka a bike shop like Yellow Jersey in Madison Wi, etc.) Some guys just cram the wheel in without cold setting the frame. . .as long as the alignment is ok after cramming the wheel - it works. Having someone who knows what they are doing minimizes the risk of breaking something. At the very least they can eval the frame and let you know if they see a risk.

    The wheel dish is another matter. If the wheel was properly dished to begin with it should be centered once the frame is spread to accept the axle width. If not then one of 2 things: A) the frame is out of alignment (one side spread more than the other) or B) the wheel is not dished right.

    Either way you need to fix the dish issue. If you run the wheel out of plane (front-to-back) it won't track with the front wheel and screws with handling. If you run it out of vertical plane you compromise the structural integrity of the wheel. Think of an extreme example: wheel running at a 45deg vertical angle/riding a straight line. Uneven side load plus one good bump and the wheel goes taco.

    Take the wheel to a LBS, they can check dish for you really quick. Use the method in the Sheldon link to check frame alignment (use dental floss rather than string when you check the frame.) Just me but I wouldn't ride that wheel until it's properly aligned

  3. #3
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    I had exactly the same issue right down to the old Araya rims!

    My chromoly frame had a 126mm spacing and the 9sp required 130mm. I was fortuate enough to be able to just "cram it in there" and it works fine. You do have to make sure you that you preserve alignment but there was enough play once I got the wheels in the drop that by using the brakes as a guide that I could center the wheel properly.

    I was going to cold set the frame and maybe I still will but since I was able to get it to work with a little effort I'm just being lazy.

  4. #4
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    You can can very easily determine if the wheel is out of dish or the frame out of allignment by installing the wheel in the frame backwards. If out of allignment switches with the wheel, you need to redish the wheel, else you have a frame allignment issue.

    There is no issue permanently cold setting a steel frame, or temporarily spreading the stay to force a wider hub in on an as needed basis. If you are not planning to use the narrower hubs again with the bike, I'd suggest permanently cold setting the frame for the wider 130mm hubs, then get the dropouts (particularly the drive side) realligned so indexing works perfectly.

  5. #5
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    Ride it in

    Quote Originally Posted by PelotonCyclist
    Hi. I'm new here but will stay and contribute for sure from the forum topics that I've read! All are awesome Q and A's.

    I received a free set of Mavic Cosmos wheels where the rear wheel has a 9 cog cassette. My previous wheel was a much older 7 cog screw-on cog set. The lesser width chain that I have employed works perfectly with the 9 cog cassette and chainrings.

    The axle width and/or the dish of the new Cosmos rear wheel causes the rim/tire to not be centered under the rear brake's 'center post.' Plus, the wheel is slightly non-perpendicular to the ground plane.

    I really do love these new wheels on this older frame for their torque transfer. Their transfer is much greater than my older Araya wheels.

    But, there are many concerns (three): do I risk cracking the frame (steel Cro-Moly) at the horizontal rear brake bracket due to having to expand the dropouts 5mm to accommodate the wider Cosmos axle, do I lose straight-line power transfer if the rear wheel isn't in the exact same forward plane as the front wheel, and do I lose power transfer if the rear wheel isn't exactly perpendicular to the ground (i.e. it appears slightly slanted from a behind view)?
    Others have noted how to determine if the wheel is not correctly dished, so sort that out first. Rather than cold setting the frame, you might consider just riding it. I did this with a high quality steel frame, and after a few thousand miles, the wheel went right in without having to spread it. It seems as though the frame cold set itself over time.

    BTW, I have no idea what you are talking about when you say the new wheels have better "torque transfer." This makes no sense.

  6. #6
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    Hi all. First, thanks for all the great advice and I'll follow the recommended steps and procedures. I really appreciate the help!! I may just get the frame 'permanently adjusted' to the newer style wider axle that must be common on all bikes nowadays. One mentioned doing that as an option and I don't see why I shouldn't when I can run all of the 'new' wheels 9 rear cogs on both chainrings without too much front derailleur rubbing (only those 'shouldn't use' combos like the 42-12 or 54-27 cause some chain-on-derailleur light friction, heh).

    Regarding my mention of better torque transfer, compared to my circa 1987 original wheels, these Cosmos ones just feel much more responsive if I begin to increase my pedaling torque through harder spinning or out of the saddle stomping. As if the bike accelerates faster and I'm not a light guy (6'1" and 225 lbs). I was just trying to convey that I think the Cosmos wheels seem to better transmit power to the pavement. I could be wrong, I admit that. But, perhaps my 1987 wheels do actually 'twist a bit' when the hub's torque will try and transfer its rotating motion to the rim but the spokes are bending a bit with each hard crank on the pedals? Like some of my pedaling energy is wasted into twisting the wheel spokes instead of a better (stronger) hub-to-rim link via stronger a spoke and lacing attachment? Like I said, these Cosmos wheels just seem snappier in response to heavy acceleration. I'm not a physics expert, heh. Also, when the pedaling torque is lessened for the instant through the crank pedaling cycle, I'm kind of sure that the 'untwisting' of the spokes doesn't provide any 'elastic' effect of helping to propel the bike (i.e. again, wasted effort spent on bending metal). Anyone done an analysis on that? Thanks again all!

    And, I just realized that I upgraded to 175mm cranks from the bike's original 170's. It was bought for me many many years ago (like I said, back in the late 1980's). So, perhaps that too is contributing to quicker/easier acceleration?

    Thanks again all. I'm glad the frame is steel because I bet 'widening' the frame if it were aluminum, titanium, or carbon would be very risky due to possibly cracking it?
    Last edited by PelotonCyclist; 12-07-2009 at 09:03 AM.

  7. #7
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    If there is a weight difference between the wheel sets, new being lighter, that is where the resposiveness discovery is found. If components were "bending", you would also feel the spring as they returned to normal state. I doubt there is enough deflection to notice or have an impact to responsiveness. And yes, going from 170 to 175 has an impact.

  8. #8
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    I know what you mean by superior "torque transfer" of your new wheels. Back when those Arayas were standard, I bought a set of new wheels from Colorado Cyclists, 36 stainless steel spokes hand tensioned on Campy hubs and Wolber Super Champion rims. Man, were they great! I noticed right away how stiff they were and how well they transferred pedaling efforts to the road. I was amazed how much difference a nice set of stiff wheels could make in overall handling! The spokes on the old wheels weren't tensioned evenly, and when climbing out of the saddle the bike would go all over the place. The rims couldn't stay aligned with the hubs under torque. With the new wheels, the bike would effortlessly shoot straight up the road. A tremendous amount of energy was being lost with the old wheels, all on account of the slightly loose spoke tensioning.

    If the rear wheel isn't perpendicular to the ground, the dropouts aren't the same height. (?) That's a weird alignment problem. Any LBSs or frame builders in the area that could accurately check frame alignment and cold set the dropouts to 130mm? Then, if the wheel is properly dished, which they aren't always, and the front fork and headtube are aligned, the two wheels should track the same line. I've successfully used taut string or a long straight edge to check this. If the edge touches both wheels in two places, they're aligned. If they aren't, you're crabbing down the road. That doesn't have anything to do with transferring energy from the crank to the road, though. The latter's pretty much a function of drive train efficiency, stiff wheels being the last link in that.
    Last edited by Fredrico; 12-07-2009 at 06:18 PM.

  9. #9
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    Some heat treated steels cannot be cold set and will crack if you try. Check with your manufacturer or post on a forum where some frame builders visit, to get an answer.

  10. #10
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    Will do on all of the excellent suggestions! Thanks again to all for your expertise. The bike may 'only' be a late 80's Schwinn Peloton (from which I derived my alias) but I received it from my father (brand-new back then, the bike - not him, haha) so it has a very high sentimental value to me. Not to mention riding it everywhere in Minnesota, Colorado, and Wyoming over the years. While I do a twice yearly near full teardown and reassembly (spring and fall), I'd like to get this 'rear Cosmos wheel with 9 cog freewheel alignment problem' fixed and properly aligning this rear wheel is technically beyond my capabilities so I'll have a local expert shop (one used by racers) give it a thorough analysis. On a funny and memorable note, the flexibility of the frame causes a bit of instability (wobbly headset area) when high speed downhilling mountainous Colorado roads, haha. But, it most certainly is FUN.

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