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  1. #1
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    True and Repair extensive wheel lateral damage

    I am somewhat new to bicycling and rode a hybrid bicycle from bikesdirect.com without truing the wheels first. I rode lightly, a daily commute of about 4 miles. A couple rides later I bumped a curb causing rear wheel lateral damage. The wheel still spin through the fork, but I had to unhook the brakes.

    Since then I've learned a lot about truing. The wheel now looks true but the spoke tension is very uneven. I know I could just get a new wheel, however, the wheel uses an in-hub gear shift and is pricey to replace.

    I'm thinking about undoing all the spokes of the wheel and trying to bend the rim straight with hand force. Then lace it back into the spokes. This should work, right? I haven't seen this technique mentioned before, I'm guessing this is because in-hub gear shifts are uncommon?

  2. #2
    coprolite fietsbob's Avatar
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    you could hire the services of the bike shop you skipped , before.

    another fix , buy an identical rim, tape it to the bent one , and transfer all the spokes,
    one at a time without un doing the lacing pattern.

    but that may also be outside of your skill level. ,
    and might still need a shop to finish the tensioning and truing.

  3. #3
    You gonna eat that? Doohickie's Avatar
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    I did exactly that- I transferred the spokes, one at a time, from an old, damaged rim to a new one. No problems.
    I stop for people / whose right of way I honor / but not for no one.



    Originally Posted by bragi "However, it's never a good idea to overgeneralize."

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    fietsbob & Doohickie, thank you! I didn't think of buying just the new rim. I'll do some research on getting a new rim.

    The rim sticker says ETRTO 622x19, but I noticed most wheels or rims available online seem to be based off tire sizes. Bit confusing, I think I'll go to the local Performance Bicycle shop to have them help me order just the rim.

  5. #5
    coprolite fietsbob's Avatar
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    the rim has to be identical in the part where the spoke nipples set, inner rim diameter.

    Or things get complicated by needing a different spoke length.

    ETRO is about T=tires, R=rims , getting the rims and tires compatible.
    has nothing to do with spoke length.

  6. #6
    Ride, Wrench, Swap, Race dddd's Avatar
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    Fixing it on the cheap, but still good

    OK, here's what I always do. It sometimes consumes considerable time, but often goes swimmingly and restores a very strong wheel.

    After attempting to true the wheel, and with tensions building un-evenly (usually already more than un-even), I will mark the HIGH spots of the rim where maximum lateral deflection is centered. I put a sharpie letter A, B, C.., and so on on the opposite brake track, i.e. the side of the rim opposite where the brake pad (or trueing stand indicator) that rubs.
    I then lay a foot-long piece of lumber (2X2 or 2X4) on the ground pointing away from me, and lay the rim on the cross-section of the lumber. The Sharpie letter will be at 12-O-Clock, looking at the wheel.
    Using my hands to either side of the bent spot, 2 hours away from the 12-O-Clock position (i.e. @ 10 and 2 O'Clock) I push down with force. This force can be greatly variable, from gentle to all-out (I weigh only 160). I then return to the truing stand and once again try to true the rim while evening the spoke tensions. <<<A doublewall 26" rim can require huge effort>>>

    That's it, it's an iterative process, often taking several "rounds" between bending bar and truing stand, but I usually get even the badly tacoed wheels evened out to within +/- 10% tension.
    Often, the first try or two doesn't go well, but perseverence just as often creates a sudden, dramatic improvement. Seldom do I resort to a re-lace (by taping the new rim to the old wheel as fietsbob mentioned) unless the rim seam gets ugly or the rim is too strong for my weight/strength to re-bend.

    Note further that if the spokes were pre-stressed and evenly tensioned prior to the traumatizing impact, the wheel can and should first be trued using the 2X4 "bending bar"!
    This will straighten the rim and even out the tensions at the same time, needing only mild fine tuning with the spoke wrench. I've done this during a CX race, laying the rim on a discarded coffee can, and was able to quickly re-join the race after one go.

    Note also that any bending done near a pinned or sleeved (not welded) rim seam tends to disrupt the even mating of the ends of the rim extrusion. A purely later disruption can usually be tapped into alignment using the 2X4 as a hammer, or better yet using 2X4 as a sort of drift punch, hitting it with a real hammer.

    Do not resort to explosives in any case.
    Last edited by dddd; 10-17-11 at 04:46 PM. Reason: spelling

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    That's awesome, dddd. This method sounds even better. Trying to match rim sizes wasn't fun in a previous attempt.

    Quote Originally Posted by dddd View Post
    ... Note also that any bending done near a pinned or sleeved (not welded) rim seam tends to disrupt the even mating of the ends of the rim extrusion. A purely later disruption can usually be tapped into alignment using the 2X4 as a hammer, or better yet using 2X4 as a sort of drift punch, hitting it with a real hammer. ...
    The rim seam is where the spokes seat up against the inner tube? Does leaving the tire on and inner tube in while bending the rim against the 2x4 help the seam stay in place, or would it just lead to a spoke popped inner tube?

  8. #8
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    Quote Originally Posted by Feddas View Post
    Trying to match rim sizes wasn't fun in a previous attempt.
    Look at your rim. Is there any label that has an ERD listing? Or what is the model of the rim? These will probably only help is the rim manufacturer makes the rim itself available for sale if the rims are only sold in a complete wheel that information will be harder to find.

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    Quote Originally Posted by Bezalel View Post
    Look at your rim. Is there any label that has an ERD listing? Or what is the model of the rim? These will probably only help is the rim manufacturer makes the rim itself available for sale if the rims are only sold in a complete wheel that information will be harder to find.
    No ERD but there is an ETRTO. I'll attach a picture. I think the big X 202 (that's partially cropped out on this picture) is the model or brand.
    X202bikeRim.jpg

  10. #10
    Senior Member gyozadude's Avatar
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    Alex X202 in ISO 622x19 size is a fairly common 700 x 35c hybrid rim, single wall, and they have an 605.1 ERD (Effective Rim Diameter). Get something plus/minus 1 mm ERD and around 22 - 24mm outside width that's also 700c, and you're in business. A direct replacement is online for $10 - $15. The Alex ZC1000, Alex Adventurer rims are also available for a little more cost.
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  11. #11
    Ride, Wrench, Swap, Race dddd's Avatar
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    "The rim seam is where the spokes seat up against the inner tube?"

    Yikes, no, the seam is where the two ends of the rim are joined to form a hoop. Most good ones today are welded, then machined smooth all the way around for the brake pad region of the rim side.
    Rims that don't have the two ends welded together will dis-join unevenly if bending forces are applied there, making for uneven braking (pulsation). It is also easy to brake the sleeve insert that way.
    Last edited by dddd; 10-17-11 at 07:44 PM.

  12. #12
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    Quote Originally Posted by gyozadude View Post
    Alex X202 in ISO 622x19 size is a fairly common 700 x 35c hybrid rim, single wall, and they have an 605.1 ERD (Effective Rim Diameter). Get something plus/minus 1 mm ERD and around 22 - 24mm outside width that's also 700c, and you're in business. A direct replacement is online for $10 - $15. The Alex ZC1000, Alex Adventurer rims are also available for a little more cost.
    Thank you gyozadude. Good to have these numbers incase the 2x4 wheel bending goes awry. Where'd you find the rims for $10-15? The lowest I found online was $40.

  13. #13
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    Quote Originally Posted by dddd View Post
    "The rim seam is where the spokes seat up against the inner tube?"

    Yikes, no, the seam is where the two ends of the rim are joined to form a hoop. Most good ones today are welded, then machined smooth all the way around for the brake pad region of the rim side.
    Rims that don't have the two ends welded together will dis-join unevenly if bending forces are applied there, making for uneven braking (pulsation). It is also easy to brake the sleeve insert that way.
    Ah, thank you for clarifying that. Never thought about how they manufacturer the rims.

    So, I don't have to worry about the spoke pushing through the rim?

  14. #14
    Ride, Wrench, Swap, Race dddd's Avatar
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    Quote Originally Posted by Feddas View Post
    So, I don't have to worry about the spoke pushing through the rim?
    Spokes are just pieces of wire. They can pull hundreds of pounds, but can't really push at all, and remain in a state of elastic tension even as the rim is stressed.

    Only a spoke that's too long for the chosen rim and spoking pattern will intrude on the inner tube.

    A rim that is highly bent in different directions at each 90-degrees around the rim is said to be taco'd, "(double) folded" or full "potato chip". In this state, the tension on all spokes is uneven and minimal, as the spokes have new-found leverage against the rim's cross-section.
    Such rims usually can be (somewhat wildly) sprung back in the opposite directions all at once and will recover to a fully-tensioned state in a decent condition to be trued.
    A full snap in the opposite direction MAY be needed and involes a noticeably high exchange of energy "bump-bump" between rim flexure and spoke tension as one goes from a taco to a reverse-taco followed by allowing the rim to snap back to an on-center, fully-tensioned state. This usually happens in an instant, the panicked mechanic instantly releasing the reverse-"sprung" wheel (first bump)which then instantly snaps back into tension (second bump). Slightly exciting.

    Singlewall rims will taco at low levels of force and similarly can be sprung back much more easily, as their "flat stock" cross-section allows the rim to twist along it's length without much resisting force and without taking much of a set.
    Singlewall rims and rims with higher spoke counts, larger diameters and lower weight also need to be built with lower spoke tension ceilings or may taco by themselves during tensioning!

    I prefer to do all wheel work with the tire removed, except during an emergency.
    And, it's best to reduce any crazy-high spoke tensions that have been torqued into the spoke nipples AFTER any wheel trauma.
    Last edited by dddd; 10-17-11 at 09:15 PM. Reason: for fun

  15. #15
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    Been a while, but finished fixing my bicycle earlier today. Want to thank everyone that helped me both learn a bunch about bicycles and saved me cash from the bicycle shop.

    I used the info from fietsbob and gyozadude to try to buy the Alex X202 (I didn't realize that was the wheel name until gyozadude said it) rim at 2 different places, both turned out to not really have the rim in stock. So I bought a whole wheel set for $39.99 (Evidently, got the last one) and extracted the rim. then transferred it using the "tape to the broken wheel method".

    If something goes awry with the new rim I'm going to try bending as suggested by dddd since his info on how to bend is awesome and according to this site it's possible, but very tricky, with a alloy rim.
    Last edited by Feddas; 02-06-12 at 02:15 AM. Reason: sentence fixes

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