Failed (bike) Geometry 101, please help...- Mtbr.com
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  1. #1
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    New question here. 29"er Frame Spec's Geometry Comparison

    Neither of these two 29"er frames are technically mountain HTs, more along the lines of cross/ long tour or fireroads. Both are 58cm and made of steal. I am trying to determine how similar they'll ride. One is very expensive, the other is not, and both are made overseas, 1 by hand & 1 by production line. How do you think they'll compare ride wise?

    Frame 1 - 58cm, 700c wheels - Rivendell
    tubing - custom mix from Reynolds, True Temper, and tubes from Japan and Taiwan. The seat tubes, down tubes, and chainstays are heat-treated, because they?re the only tubes that ever break on any bikes, and we wanted added toughness. The top tube and seat stays are standard CrMo steel
    geometry
    Frame Size 58, Wheel Size 700c, Seat Tube angle 72.0, Head Tube angle 72.0 , Top Tube lengeth 58.5, Fork Rake 4.5, BB Drop 8.0, Chain Stay 45.5, Stand Over* 83.2/84.6
    Notes - Frame1 has a 2.5-degree upsloping top tube, and the top tube measurement is taken on the theoretical horizontal. Rear spacing is 135mm.

    Frame 2 - 58cm, 700c wheels - Surly
    tubing 4130 cro-moly steel. Main triangle double-butted. TIG-welded
    Geometry
    Rear drop Semi-horizontal w/adjusters 135mm spacing, ST (C-T) Inches 22.8 mm 580.0, TT (C-C) Inches 22.8 mm 580.0 TT (Effec.) Inches 22.8/580.0 mm, HT Angle degrees 72.0?, ST Angle degrees 72.5?, BB Drop Inches 2.6/66.0 mm, CS Length Inches 16.7/425.0 mm, Wheel Base inchess 40.6/ 1030.00mm, Stand Over ht 32.7"/829.9mm, Head Tube length 5.6"/141mm, Fork Length 15.7"/400mm, Fork Rake 1.7"/44mm

    Basically, I can't afford the expensive one & am looking for cheap but similar riding economy version for a winter project build. Thanks.

    Scott in NJ
    Last edited by Scott_in_Jersey; 01-20-2005 at 11:49 PM. Reason: stupid title, not interesting enough

  2. #2

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    Quote Originally Posted by Scott
    Basically, I can't afford the expensive one & am looking for cheap but similar riding economy version for a winter project build. Thanks.
    Well that answers your question no?

    Sure, the Rivendell (Atlantis?) will be a bit nicer ride -and I love those lugs! The Surlys (is it a Crosscheck you're asking about?) are a well thought out package though, and you'll find a lot of posts on here raving about how well their Surlys ride.

    If it is the Atlantis and Crosscheck you're comparing, be aware the Cross check doesn't take full size 29" tyres, and while the Atlantis will, it's not really ideal for technical MTBing.

    Sam

  3. #3
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    also....

    The Surly is not 135mm spacing, it's actually 132.5. This may sound insignificant, but it's not. To get a decent chainline on a crosscheck is like pulling teeth. You have to mix a mountain rear hub with a roadie/cross crank to get a good line. If you put mountain cranks on the front, even with a 108/107bb your chainline will be way off. I experimented with a Race Face isis bb up front which has an adjustable chain line but ended up with my crank arms totally different distances from the stays, and when that happens you're not centered on the bike. Trust me, I went through this exact issue with these exact bikes, and if you want a 29er, then get a 29er. If you want some sort of super "do it all" bike - give it up. There's no such thing. The Riv and the Monkey aren't woods bikes. They're heavy, and your position on the bike will be high and forward, which will put you in constant danger of going over the bars. Remember that you can use a true 29er on the road, or for cyclocross with great success.

  4. #4
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    If the rear spacing really is 135mm on teh Surly, I was guessing perhaps he meant the Long Haul trucker. I can only say that my Cross-Check rides just great. It's fork has an old fashioned shatter when you do serious braking, but that belongs to the retro design I guess. Ride quality is just fine.
    Klok - XC - Skate - Ski

  5. #5
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    The long haul does indeed have 135mm spacing, so that would be easier to set up a chainline. But a cross check will never handle a mountain ride as well as a mountain bike, or everyone would be riding cross bikes on the mountain.

  6. #6

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    Quote Originally Posted by new kelly
    your position on the bike will be high and forward
    How so? Particularly the Rivendell with such a low BB, I would think endo factor would be similar to others (and better than any 26").

    Sam

  7. #7
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    WOW, Kolo you Nailed it, Atlantis Vs. Cross Check

    I was comparing the geometry of the two, trying to find a affordable platform to build up a ride like the Rivendell Atlantis. Though I am sure the Surly Cross Check has a fine ride, probably considerably more forgiving than my AL Jake the Snake, using the Cross Check frame & fork to attempt a Atlantis wannabe bike would indeed be a mistake. Other than my cx bike, I tried my hand at the big wheeling with this 56cm 2004 Kona Dew project as well which is obviously not done yet. Here's the geometry...

    https://konaworld.com/2k4_catalog/16...alog_54-55.jpg



  8. #8
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    because

    Quote Originally Posted by Kolo
    How so? Particularly the Rivendell with such a low BB, I would think endo factor would be similar to others (and better than any 26").

    Sam
    It's simple really..The handlebars on a crosscheck or riv are lower with reference to the seat which - unless you use a dozen spacers - puts your hands down and forward and your ass up, therefore placing a disproportional amount of your bodyweight forward. When the bars and the seat are at roughly the same height, and your technique is sound, your body weight is equally distributed over both wheels thereby maximizing traction and handling.

  9. #9
    Master of the Obvious
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    Go Monkey

    Why not try a Karate Monkey? this is truly Surly's Holy Grail when it comes to big wheels, this bike does it all! I am planning on building a brown roadie this year.

    P.S. I grew up on the Jersey Shore, where are you ?
    Check out my Blog!
    Yes ! I am posting on my Blog again! come visit!

  10. #10
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    Thanks for the suggestion

    I'll keep an eye out for monkey frames. I am in Cranford, NJ (GSP exit 137). Faminly shore place is in LBI. Thanks.

    Quote Originally Posted by Angus
    Why not try a Karate Monkey? this is truly Surly's Holy Grail when it comes to big wheels, this bike does it all! I am planning on building a brown roadie this year.

    P.S. I grew up on the Jersey Shore, where are you ?

  11. #11

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    Quote Originally Posted by new kelly
    The handlebars on a crosscheck or riv are lower with reference to the seat which - unless you use a dozen spacers - puts your hands down and forward and your ass up, therefore placing a disproportional amount of your bodyweight forward.
    Well, that need not be the case. I don't think you'll find that much of a difference in headtube length. Moreover, with particular reference to the Atlantis, it has a threaded steerer and a quill stem doesn't require a stack of spacers to be set nice and high. If you see how most people have their Atlantises set up they run the bars pretty high a la the Petersen school of bike fitting... Either way, I think your comments about endo factor are unwarranted - if a bike is well sized and fitted to the rider, the weight is evenly distributed between the wheels and the hands are where they are comfortable. I don't see why you think either of these bikes would have a higher endo factor than any other bike one might be considering.

    Scott, if you're looking for a "budget Atlantis" I'd say the Crosscheck is a pretty good way to go. As you can see from your original post the crucial numbers are very similar. Surlys are well thought out and well put together. If you're looking for an all-round nice riding bike they're pretty hard to beat. If you're looking for a genuine 29" wheeled MTB that can be set up to do a variety of other duties, the Karate Monkey is well worth having a look at.

    Let us know what you go with in the end.

    Sam

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