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  1. #1
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    rookie swap rim question- velocity blunt sl's on giant xtc2 29er wheels

    So I'm riding a 2011 XTC2 29er and want to put my tax money to good use - wheels.

    I found this set of rims on Ebay
    http://item.mobileweb.ebay.com/viewi...id=64670098442

    And if it's possible to switch my hubs/spokes over, I'll save about $200 and get to reuse almost brand new parts. 2 questions present themselves:

    1. If my current setup is 28 spoke (like the rim) and i have access to a truing stand, is this an easy operation?

    2. Are these weight savings going to be good? I don't have specs on current wheels/hubs but can you guys speculate? Both are giant I'm pretty sure, and i know it's better to shed weight at a far radius than a near one. I like my hubs and will search for the weights when i get home.

  2. #2
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by enerj View Post
    So I'm riding a 2011 XTC2 29er and want to put my tax money to good use - wheels.

    I found this set of rims on Ebay
    http://item.mobileweb.ebay.com/viewi...id=64670098442

    And if it's possible to switch my hubs/spokes over, I'll save about $200 and get to reuse almost brand new parts. 2 questions present themselves:

    1. If my current setup is 28 spoke (like the rim) and i have access to a truing stand, is this an easy operation?

    2. Are these weight savings going to be good? I don't have specs on current wheels/hubs but can you guys speculate? Both are giant I'm pretty sure, and i know it's better to shed weight at a far radius than a near one. I like my hubs and will search for the weights when i get home.
    You have at least two issues.

    1. It is unlikely the Blunt has the same effective rim diameter (ERD) as your Giant rims, so you may need new spokes.

    2. It appears the Giant wheels are 32 spoke. You can not lace 28 hole rims to 32 hole hubs.

    Weight difference? Who knows? have not seen anyone you has disassembled their wheels to weight the Giant rims.
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  3. #3
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    The rims are Giant SXC2, indeed 32 spokes. It says

    ETRO: 622x19 ERD: 597

    Now that I know more about how the wheel works, I see a huge variety of 32h rims on ebay. How big of a variation can I go with the ERD? I see the blunts are 598, which I'm pretty sure would work as this is only a 0.5mm variation in the radius (spoke length) and can probably be adjusted out.

    However some Sun rims are 608 which would probably require a longer spoke.

    Now I guess its a game of looking at cost, weight and reviews. Open to suggestions from the pros!

  4. #4
    Fat-tired Roadie
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    +/- 1mm is usually okay.

    If the dimensions for both rims are correct (not always the case, be warned) at worst, you'll have a little more trouble lacing the last few spoke nipples.

    I reused spoke nipples the last time I did it. A lot of people advising getting new nipples. Professional wheelbuilders frequently won't reuse spokes, but that has more to do with not knowing if the spoke's been abused in the past, and not wanting to risk it on something that carries their name.

    Make sure you want to reuse your hubs before you commit to this. Your rear hub is a Formula. They make both well-regarded hubs and complete trash. I see their loose-ball hub as being garbage. If that's what you've got, consider new complete wheels, or at least a new hub. (Probably blow away any savings from not replacing the hubs if you need one new one.)
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  5. #5
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    dude, get a book on lacing wheels... it's not a really difficult thing to do, but can be confusing as all h3ll to figure out the way the spokes run. then you have to have a good idea on tension, spoke lengths truing and centering. and honestly I'd think the hub would be a better thing to replace as the bearings aren't going to be the greatest thing... get a whole new wheel before bothering with relacing any of those components.

    if you want to save some rotational weight, try converting them to tubless.. will save you from flats and save weight at the same time.
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  6. #6
    Fat-tired Roadie
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    Actually, swapping rims is pretty easy.


    wheel build 1 012 by Andrew183, on Flickr

    Tape them together with the spoke holes lined up. Detension the spokes on the old wheel evenly, a little bit at a time. Move them over one set at a time. I took this picture after moving the third set; follow the link back if you want to see all the steps for one wheel. Then tension and true your new wheel. No unlacing or relacing required.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  7. #7
    Trail Tire TV on blogger
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    Quote Originally Posted by AndrwSwitch View Post
    Actually, swapping rims is pretty easy.

    Tape them together with the spoke holes lined up. Detension the spokes on the old wheel evenly, a little bit at a time. Move them over one set at a time. I took this picture after moving the third set; follow the link back if you want to see all the steps for one wheel. Then tension and true your new wheel. No unlacing or relacing required.
    dude, that a friggin awesomely simple idea!!! as long as everything's the same sizes...
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  8. #8
    Fat-tired Roadie
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    LOL. Wish it was my idea, but I read about it somewhere. Probably here. Probably from one of the posters that really knows wheel building.

    If things aren't the same size, I don't think there are any short cuts. Just have to fully disassemble the old wheel and start from zero.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  9. #9
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    Quote Originally Posted by AndrwSwitch View Post
    Your rear hub is a Formula. They make both well-regarded hubs and complete trash. I see their loose-ball hub as being garbage. If that's what you've got, consider new complete wheels, or at least a new hub.
    You're spot on about the hubs, here's the specs from the spec sheet

    [F] Giant Tracker Sealed w/ 15mm Axle, [R] Formula, 32h

    In another thread I found these specs for weight

    1. S-XC2 profile inner bead width is also 19mm with a pinned joint. The rim weights are: 460g (26") and 520g (29"), also give or take 10g. A slightly shorter profile is not nearly as radially stiff which does allow for slightly greater vertical compliance.

    2. Front: 860 gm
    Rear: 1160 gm

    this is bare wheels - no rotors, strips, etc.

    So these rims are looking pretty good actually, maybe I'll keep my eye on decent rear hubs and just go tubeless in the mean time for some lower pressure goodness, especially since one of my local trails is pretty rocky and this is a hard tail.

    How do people get their bikes so damn light? Should I turn my eyes to stem, seat and seat post?

  10. #10
    Fat-tired Roadie
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    Quote Originally Posted by enerj View Post
    How do people get their bikes so damn light? Should I turn my eyes to stem, seat and seat post?
    Obsession. Money. Spreadsheets. Loss of perspective.

    I was starting to write way too much about the dynamics behind why it's mostly pointless when you're talking about trying to make a 30 lb bike into a 25 lb bike, let alone a 27 lb bike into a 26 lb bike. But it's all over the internet already anyway. Look up "rolling resistance coefficient" and "bicycle power loss" or maybe "mountain bike power loss." Something like that. Most of the numbers are going to be fairly general. Humans have very inconsistent performance, compared to machines. But it can give you an idea as to where the power you're developing on your bike is going.

    Something that's going to be conspicuously absent is anything that reports the weight of the bike separately from the weight of the rider.

    There are a couple things that are "magic" about wheel weight. I got lighter wheels last summer, and I think my bike has marginally lower handling effort. It doesn't make as much of a difference as tires, IME. Actually the black rims in my picture are also a little lighter than the red rims they replaced, and I could swear that bike handles a little lighter. I still miss the red wheels, though, they looked really good on that bike. I did the swap because I'd worn out the brake tracks.

    Tubeless isn't a bad suggestion. There's an easy experiment you can do that's supposed to show that there's a lot of work being performed by friction between the tube and tire. Translation being, power loss. Put a business card between the two and go riding. Take it out afterwards. I haven't tried it myself; supposedly it will have been shredded by the tube and tire sliding against each other. This proves that you're losing at least enough power to shred a business card at that interface.

    Also, tread pattern and rubber compound matter. I have a racing tire on the back of my bike. While I can't prove it's done anything, it certainly feels like I don't have to work as hard. I ended up sticking a Nevegal on the front, though. Not worth it to me to have trouble keeping it together on a descent.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  11. #11
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    thanks for the input Andrew, gonna put this one on the back burner and play with a Stan's flow tape and a bottle of sealant, that should keep my hands occupied and my brain satisfied. Tricked him again

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