$/g of going disk over XT v-brakes- Mtbr.com
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  1. #1
    goes well with tea
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    $/g of going disk over XT v-brakes

    Let me just say that this is the outcome of my own analysis of ditching v-brakes and trying to buy a disk brake system without adding too much weight to the bike. I don't want to get into arguments about performance, since where I live, v-brakes are pretty ok. I would *like* to go disk...

    Basically it seems irrationally expensive to switch to disks, someone correct me if I'm wrong but...

    Current
    my current system is: '08 Shimano XT M770s (350g), generic levers (155g) , generic housing/cable (150g?).
    Total: 655g

    BB7
    If I go budget and switch to BB7s, I can pick up a set of 160mm (660g) with Avid SD 7 levers (180g) for $140. Keeping housing and cable, I end up with:
    Total: 990g for $140 (355g added to bike)

    Hope Mini's
    Expensive, but light. at 375g per brakeset, I get
    Total: 750g for $400 (95g added to bike)

    Forumula Oro Puros
    Almost all out. Really expensive, very light weight. I found 340g F, and 360g R claims.
    Total: 700g for $500 (45g added to bike)

    BB7 Ultralight
    I found a nice discussion for lightening the BB7s in http://forums.mtbr.com/showthread.php?t=343181 Also quite an expensive route.
    Total: 666g for $496 (11g added to bike)

    I I take a look at the options, I can easily and cheaply go disk with the BB7's, but I'm going to add 355g (.7 lbs) to the bike. It doesn't seem that attractive, since I'm working towards lightening the thing, not make it heavier. The other 3 options don't add any weight, but they all are basically more than 1 $/g in weight savings over the BB7. Which is to say the difference in price vs. the BB7, and the difference in weight vs. the BB7 comes out to something in the range of $1.08-$1.24. That seems like an excessive amount of money to pay.

    Is this normal for weight weenie stuff? Do I have any other options?

  2. #2
    himom!
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    This is why I went from a cheap disc (BB5) setup to V-brakes.....much better bang for the buck. I'm not really noticing much of a performance difference - except when the rims get wet. Then it's a squeaky for a few minutes. I can use just one finger and control the bike well.

  3. #3
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    Hope Mono Mini Pros are ~100gr lighter, for $100 more, than the standard Hopes. $1 for each gram saved is pretty cheap by weight weenie standards, I'd be looking at $2-3/gr to make my bike any lighter.

    What about wheels? Are your current wheels disc compatible?
    www.yourtrails.net/weights/ - Kick ass weights listing
    racing.thylacinecycles.com - Racing silliness

  4. #4
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    Quote Originally Posted by Some Guy
    What about wheels? Are your current wheels disc compatible?
    Nope.

    I can get a pretty good deal on Mavic STs though, which would actually be a bit of an upgrade from my current wheelset that I use for training and racing (so doubly cool). I don't know if I have the money to drop on an ultralight disc setup right now though... and if I can't figure out a cheaper alternative than the hope minis/formula puros then I may opt to just stick it out for another season on the V's and see what happens next year.

  5. #5
    CB2
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    Sorry to vent but...
    This Winter I had one too many snowy, icy, brake robbing, rides, so I finally bit the bullet and bought disc brakes.
    Yes, their Winter performance was significantly better than my V's, but damn they were noisy.
    Sometimes they'd squeal when wet, sometimes not; temperature seemed to have some effect on this. When ever they'd get wet, I'd hear and feel a grinding, that although I doubt was robbing me of any momentum, would drive me nuts.
    Now that the snow's gone, the performance isn't any better, so they came off my main bike, and will go on a Winter specific bike for next season.
    ...vent over.
    One reason I believe the performance isn't any better is Koolstop Tectonic pads and holders I've been using on my V's. They perform great!

    Maybe just try them instead of discs?

  6. #6
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    Can't you save 4 to 6 ounces with these rotors (~1/4 lb) ?
    I'm going to try them on my next build on my avid mech. (I love the mechanicals) It's hard to be a weight weenie on the cheap. But this is pretty big bang for the buck isn't it ?
    http://www.gramslightbikes.com/2007/...-serrated.html

  7. #7
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    Quote Originally Posted by ghawk
    Can't you save 4 to 6 ounces with these rotors (~1/4 lb)
    25 grams per rotor vs standard steel 160mm rotors. A lot of light brakes come with rotors lighter than that though, Hope standard rotors are the same weight as Alligators without the pulsing issues, and the Pros are even lighter.
    www.yourtrails.net/weights/ - Kick ass weights listing
    racing.thylacinecycles.com - Racing silliness

  8. #8
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    Quote Originally Posted by Some Guy
    25 grams per rotor vs standard steel 160mm rotors. A lot of light brakes come with rotors lighter than that though, Hope standard rotors are the same weight as Alligators without the pulsing issues, and the Pros are even lighter.
    Oh, I was comparing this listing.
    http://www.rei.com/product/737159?cm...m_cat=datafeed
    I've got a couple of these on a bike.

  9. #9
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    I just replying 'cause I'm interested in where this thread goes.

  10. #10
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    Quote Originally Posted by ghawk
    Oh, I was comparing this listing.
    http://www.rei.com/product/737159?cm...m_cat=datafeed
    I've got a couple of these on a bike.
    That weight is way off, real weight is 115gr: http://www.yourtrails.net/weights/li...t=22&subcat=81

    Quote Originally Posted by limba
    I just replying 'cause I'm interested in where this thread goes.
    You can subscribe to a thread without posting, it in the 'thread tools' menu above the first post.
    www.yourtrails.net/weights/ - Kick ass weights listing
    racing.thylacinecycles.com - Racing silliness

  11. #11
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    I didn't know that. Thanks.

  12. #12
    Rod
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    Now because of this thread I want to remove my rotors and weigh them. They're the stock rotors and saving rotating weight is always a good idea.

  13. #13
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    Quote Originally Posted by CB2
    Sorry to vent but...


    Maybe just try them instead of discs?
    Where did you pick those up at?

    I'm still a v-brake holdover also.

  14. #14
    CB2
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    Quote Originally Posted by Toff
    Where did you pick those up at?

    I'm still a v-brake holdover also.
    Any LBS can order them thru Quality Bicycle Products.

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