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  1. #1
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    Fantom DS 26er BB height and ETT measurements.

    Looking for a cheap 4" FS frame to replace a broken one and am considering a Fantom DS frame and fork only from BikeIsland, but the specs don't look right. The BB height shows as 11.75 inches which is quite low for an MTB and I'm not a fan of pedal strikes, so is this right?
    Also the top tube measurement for an 18" frame shows as 22.5 inches which is also short if it is an ETT mesurement (it doesn't clarify on the bikeisland spec, but on motobecane site it claims this is ETT measurement but shows an even shorter measurement). Based on that , I'd be looking at their 20 inch frame, but I've had a bunch of mtbs over the years and they've all been 18 to 19 inch frames (I'm 5' 10")

    I don't mind buying online, but I'd like to know for sure what I am getting before I order.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  2. #2
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    Yes, the BB height on my Motobecane Fantom Team is 11.75" with a 120mm travel fork and no weight on the bike. I strike rocks and roots all the time. It's only 3/4" lower than my previous bike, and I constantly hit things that I didn't with my old bike. For the trails that I ride in Colorado West of Denver, I would prefer at least 13" BBH.

    I barely breach 5'10", and I have the medium (47cm=18.5") frame. The large would definitely be too big for me. It feels just right in the cockpit with a 110mm stem, BUT, the stand over height is 772mm=30.4". My legs are a little on the shorter side for my height (31.5" inseam to floor), and when I hop off the saddle, there's not much room for error. No pain yet in 1,300 miles of riding this bike (from the top tube anyway), but I'd feel better with another inch of clearance like most frames built these days have.

    Another issue that I have with the frame is the head tube angle. It's 71.5 degrees, which is great for climbing and accelerating on the flats, but on steep downhills I feel like I'm going to go over the handlebars. I actually did once this year and once last year in places that I didn't think I'd ever endo (there was pain involved). Also for fast descents it feels twitchy, sketchy and dangerous. I'm always the last to the bottom of the mountain on this bike. I would prefer a head tube angle of about 67-68 degrees.

    Yet another thing that I don't like about this bike is the short wheel base of 1013mm=39.9". It contributes to the feeling of a lack of control on fast descents. I think I would prefer a wheelbase of about 44" (like they build them today).

    The seat tube angle is also relatively steep, but I don't know too much about that, and I think I've said enough already.

    Love how it climbs and accelerates on the flats. Don't love how my pedals hit everything, I endo and descend-o-so-slow. If you're riding railroad grades with no rocky descents, this frame could work for you. But for what we ride here in the Rockies, there are many better alternatives.

  3. #3
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    I contacted BikeIsland and they confirmed the 11.75 BB height measurement as well. Did you measure to the center of the bb spindle or the bottom of the BB?

    A low BB height is a deal-breaker for me, and that is really low. I built up a hardtail about 5 years or so ago that had a BB height only about 1/4 inch lower than my other hardtails, and I noticed more pedal strikes immediately and hated it.

    As to the wheelbase measurement, did you measure your bike or take the measurement they have online? I'm having a hard time believing that is right. In fact, depending on how you get to the geometry chart, there area 2 different charts with different measurements. It's really hard to buy a bike online when you can't figure out what the measurements are.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  4. #4
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    I measured from the bottom of the BB...pardon my ignorance. When I measure from the center of the BB, I get 12 3/4". I guess it's important to mention that I'm running 26"x2.35" Maxxis Ignitor tires, which are bigger than the 26"x1.95" tires that came with the bike (I never used them as they would be worthless around here). That's awfully close to the 13"+ that I said that I would prefer. I remeasured my trusty old Cannondale, and it came in at 13 5/16". Its BB is only 9/16" higher than my Moto, but now that I think of it, there are two more variables that come into play: the Headshok had only 60mm of travel compared to 120mm on my Moto and the rear shock travel on the Super V is maybe a few inches max, I'm guessing, compared the 5" setting I'm using on my Moto (am I the only one using the 5" setting...I'm old and life's short so why not?). So, with my weight on my Moto, the BB sinks much lower than on my Cannondale, and I constantly hit rocks that I never hit with my old bike.

    Yes, you caught me trusting the BikesDirect and/or Motobecane geometry tables for wheelbase. When I measure skewer to skewer, I actually get 42", which is a couple inches longer than the 39.9" the geometry table says. Could adding 20mm of fork travel add 2" to the wheelbase? That doesn't seem right. Also, the geometry chart says that the medium and large have the exact same wheelbase, and that also doesn't seem right.

    Another thing about Moto and BikesDirect is that I think this bike was designed around a 100mm travel fork (when did this frame actually come out?), but apparently they didn't update the geometry chart when they started putting 120mm travel forks on them. A longer fork would slightly slacken the head tube angle (I'm guessing by a half a degree to a degree. Get the trig books out and correct me). A longer fork would also raise the BB a scosche. If you push down on the fork 2cm, the BBH is about 12 1/4" with the bigger tires on. Maybe the stock tires are 1/2" less tall than what I have on now, and that's how they got 11 3/4" BBH back when they had the 100mm travel fork. But if you look at the chart for the Team with 1.95 tires and the Comp with the 2.1 tires, they both say BBH is 280mm=11.02".

    The Team description at BD says to add 3/4" to stand over height. Now, when I click on geometry chart, it sends me to the MB site, where it does not mention to add 3/4" to stand over height. If I'm measuring correctly, the stand over height of my bike is 31" just over the BB. That only gives me 1/2" of clearance at that point of the TT, and it gets higher as you move forward. Some bike manufacturers (Like Titus) show different geometry with different travel forks on them. I would expect a bike manufacturer to update their geometry table when they add 20mm of travel, but after years of selling this frame with a 120mm travel fork, MB and BD apparently haven't gotten around to that. The more I look, the less impressed I am. I'm not going to give them a grade...I'll just give them an "incomplete."

  5. #5
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    As I mentioned before, a slightly lower BB can be very noticeable depending on how and what you ride. My trails have a lot of short but very steep uphills in very narrow winding singletrack that doesn't give you a nice straight approach to the uphill. So I tend to hammer real hard into the these uphills (through the transition at the bottom), and that's where I'll immediately notice a lower BB.

    As to the other measurements, Bicycle manufacturers and component manufacturers frequently post incorrect, incomplete, or misleading specs. But the really crazy thing is that I noticed the online bicycle and frame manufacturers/sellers (not just BD) tend to be even worse then the others. They should be the ones making more of an effort to provide correct information about their products since their customers don't have an opportunity to see the product in person before buying.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

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