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Thread: Moto-Style 650b

  1. #1
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    Moto-Style 650b

    I know a lot of people are running 650b in the front and 26 in the rear what I call Moto-style as off road motorcycles pretty much all do it but with a 21" front and 19" rear wheel. Having tried a full 650b rig I went back to Moto style because it seemed to me that I kept that great roll over anything feel in the front yet kept the quick acceleration and quick handling of a 26" rear wheel while still keeping the BB low which I like for better handling. I think the motorcycle guys have it nailed after riding my current bike for 3 months. Anybody else feel the same?
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  2. #2
    TNC
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    Same boat...pretty much

    I like long travel AM bikes...nothing less than 5.5". I've had a 650B on my Nomad for about a year and have loved it for all types of riding. I tend to lean toward keeping my AM bikes with 650B/26" for the reasons you mentioned. My Nomad won't accept a 650B rear anyway. I have a 650B ready to build for the rear on a trail Bullit that I have that already has a 650B front. I've had a lack of inspiration to do so. I believe this is going to be a very preferential issue or at least very bike and terrain specific with no clear answer. Two other guys at our shop are running front/rear 650Bs on their Epics, but those are different bikes with perhaps different goals and setup preferences.

    Edit: Hey, no one seemed to notice that the first pic I posted was a 26/26 setup. Here's the corrected pic.
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    Last edited by TNC; 12-29-2008 at 05:29 PM. Reason: Wrong pic

  3. #3
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    I ran 650b front only for about 6 months before fitting 650b in the rear of the same bike for the last 6 months.

    If you want slacker angled fork handling, then the 650b front-only a better way to do it than a 20mm longer travel fork staying with 26 inch front wheel. The 650b front wheel is lighter and better rolling than longer travel fork with 26" wheel, and the 650b front-only can be done at a much lower cost too.

    For my uses, having many tight switchbacks and much pedaling over rough trail, the original quick steering frame angles using 650b front and rear works better at slower tight trail speeds with improved rolling, and the added pedal clearance was a huge improvement for maintaining power without fear of the frequent pedal strikes previously with 26" or 650b front-only. I raise my 130 to 160mm travel fork above the designed 140mm height to slow steering for higher speed and extraordinarily rowdy trail riding.

    Low BB’s are for sure more stable, but handling a higher BB is easy to adapt to.
    Last edited by derby; 12-29-2008 at 12:59 PM.

  4. #4
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    All very interesting. Some food for thought: Many years ago I had a Yamaha Big Wheel 350 (I think thats what it was called). It had the lowest center of gravity of any dirt bike I tried. It was designed for sand. Extra wide, small diameter tires (thats partly how COG got low) and what I can only guess was a slightly slack HT angle. This thing was by far the most stable bike in a power slide I ever tried. I raced motocross so could do standing and sitting power slides on a MX bike. But this thing was effortless. So I can relate to what you are saying about:

    "Low BB’s are for sure more stable, but handling a higher BB is easy to adapt to."

  5. #5
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    I alternate regularly between 26"/650B and 650B/650B on my Mojo.

    For me, it depends on the trails and type of riding i'm going to be doing. The 650B *always* stays on the front end though, as it has too many advantages over a 26" wheel size to give up.
    As far as running 650B on the rear, i'm undecided, really. If I had more clearance on the Mojo I would probably prefer to run the larger wheel, but when the mud gets thick and sticky, I need to be on the 26" rear for the mud clearance.
    Overall, I think I prefer the 650B front 26" rear currently. It works very well, and the huge selection of rear tires for 26" is a real bonus.


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  6. #6
    Uncle
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    Bike is in but the jury is out

    I just built this up last night. And since I sacrificed my only good 26" wheelset to make it happen, I really hope this fits the bill.

    It's a Blur XC with a Stan's Olympic 26" rear / ztr355-650b up front. I just measured the wheel diameter: With my little Michelin 2.0 on the rear, the diameter is ~25.5" (sounds really small to me), while the front wheel is 27.5". With two 26'" wheels, the bike climbed like a goat but was a hair twitchy on descents. With the suspension unloaded, the BB sits just a hair below 13". I'm really hoping the 1" rise in the front with the new wheel isn't too much. But to be safe, I'm thinking I'll run the fork with a little extra sag to keep the rake effect from being too severe.

    Since the new wheels will need to be retentioned soon, I'm running tubes for now. Will stretch the tires a bit and let the spokes settle, and after retentioning, I'll switch it to Stan's tubeless.

    Hope to have a few rides on it by next week. Input before then completely welcome.
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  7. #7
    Mr.650b - Mr.27-5
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    Set up is key...

    Quote Originally Posted by 105millimetersofpleasure
    I just built this up last night. And since I sacrificed my only good 26" wheelset to make it happen, I really hope this fits the bill.

    It's a Blur XC with a Stan's Olympic 26" rear / ztr355-650b up front. I just measured the wheel diameter: With my little Michelin 2.0 on the rear, the diameter is ~25.5" (sounds really small to me), while the front wheel is 27.5". With two 26'" wheels, the bike climbed like a goat but was a hair twitchy on descents. With the suspension unloaded, the BB sits just a hair below 13". I'm really hoping the 1" rise in the front with the new wheel isn't too much. But to be safe, I'm thinking I'll run the fork with a little extra sag to keep the rake effect from being too severe.

    Since the new wheels will need to be retentioned soon, I'm running tubes for now. Will stretch the tires a bit and let the spokes settle, and after retentioning, I'll switch it to Stan's tubeless.

    Hope to have a few rides on it by next week. Input before then completely welcome.
    You will need to adjust your position relative to the ground, and more importantly the BB, to ensure that the bike performs well.

    Take some measurements off the bike with the 26" front wheel on; bars to ground, top of saddle to ground, nose of saddle behind BB.

    What you will likely find with the 650B wheel installed is that your bars will have to come down 13mm and the saddle will need to go up 6mm and forward 3mm. This should get you roughly in the same position over the bike as you had with the 26" wheel.

    Only then will you be able to accurately asses the performance of the wheel. Fwiw, if you do this, I am pretty sure you're going to really like the way the bike performs with a 650B wheel up front. Good luck!

    Cheers,

    KP

    PS: Do not run more sag in the fork to compensate for the additional ride height. This will certainly compromise the performance of the bike. Keep the fork set to your normal / preferred settings.
    “Those that say it can’t be done should get out of the way of those doing it.”

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  8. #8
    TNC
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    Kirk, I'm not so sure he's going to have to do as much geometry tweaking from the looks of his setup in the pic. He looks like a guy who either by his physical size or setup preference already runs his saddle well above the bar...for reason of his size, I'm guessing. I think he may end up liking the setup he's got now with the 650B. That guy at our shop, texheckler, who had the 650B Heckler and now the 650B Epic, is a very tall person. His bikes all look like this...refer back to the current 650B Epic thread for a pic. I don't think these types of riders who require such tall saddle to bar setups get a negative feedback with raising the front end a bit. In fact it usually makes such a setup a better all-around handling bike IMO and observation. People are different though, so the OP's preference will tell the tale, I guess.

  9. #9
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    I have the same bike

    I have the exact same frame; same size, even same color.

    I also have what would be viewed as a significantly higher saddle relate to bar position, but that may be because I have a lot of time on the road.
    I am 5'11", 32 inseam, and ride aggressive XC on typical Eastcoast rocks, roots.

    I agree w/ TNC that Kirk's recommendations may be too much, based on the starting point and my experience. Definitely move the saddle forward a bit, and up as mentioned.
    With the bars, move one or two spacers from below to above the stem. Ride it and adjust as needed. I did one, then another, and think I am now just a hair high.

    On fast, rough descents, drops, and log piles, there is a definite increase in stability. I think it a a combination of both the rolll over and the slacker angle, since the BXC HA is a bit steep. (Thx Cpt. Obvious!)
    There have been several cases where I think the 650B front was the difference in keeping me from going over the bars.
    On the other hand, I rode at a place that had extremely tight, twisty singletrack (tight to the point of having to have an eye on each end of the bar to make sure it fit between the trees) and the front seemed a little less manuverable.
    I am not sure how the guys on the ride w/ 29ers were managing it...they were behind me

    Anyway, until that ride, I had ONE instance when trying to get around a tight rocky switchback that I wished I had the 26" wheel on the front. As my friend pointed out - if it is a significant improvement 99.44% of the time, well that is a no-brainer.

    Good luck. Report back on how it goes.

  10. #10
    Mr.650b - Mr.27-5
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    TNC & RR,

    All good points and a valid approach. The point i was trying to address was 105's apparent apprehension over whether the bike would perform as he hoped.

    My feeling is that when changing any piece of equipment on your bike you should strive to eliminate as many variables as possible to gauge what's really happening to the bike. By recreating his old position he could reduce some of those variables and better isolate what impact the front wheel has on the bikes handling / performance. After that he could tweak other aspects of the bike's set up to suit his preferences.

    Cheers,

    KP

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  11. #11
    Uncle
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    Hey guys, thanks for the feedback. Reformed Roadie, thanks as well for the detailed report. I'm a tad under 6', and with the 26" front wheel, my top grip surface was ~2" below the bottom of the saddle's contour. While I've grown used to riding this way, I've been making moves over the last 1.5 years to bring my bars up on my bikes to 1" below, and have had good results with this change. Happily, the 650b wheel has brought the bars up an inch, so it's right in my target size. The two adjustments I've made since bolting on the 650b was moving the saddle (forward and tilt downward a smidge), and rolling the bars forward a bit -- all with the intention of getting my original position over the BB again. I have not yet raised the saddle, but I will as needed when I get it out on the trail.

    As for fork sag: When I first rode the bike, I liked how plush it felt, but the geometry seemed a bit aggro, so I ran the fork on the firmer side. The Float R ProPedal in the back works fine as is, so I didn't mess with setting. I think with the bigger wheel, I'll be able to run a bit more sag -- 15% instead of 10% in the front. Kirk & anyone else, do you think this is too much sag for this fork? As long as brake dive doesn't come in to play, I think it'll be ideal. I guess I won't know until I try; looking forward to it.

    Thanks again.
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  12. #12
    Uncle
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    Thoughts after a first ride on the BXCB

    Quote Originally Posted by 105millimetersofpleasure
    I just built this up last night. And since I sacrificed my only good 26" wheelset to make it happen, I really hope this fits the bill.

    It's a Blur XC with a Stan's Olympic 26" rear / ztr355-650b up front. I just measured the wheel diameter: With my little Michelin 2.0 on the rear, the diameter is ~25.5" (sounds really small to me), while the front wheel is 27.5". With two 26'" wheels, the bike climbed like a goat but was a hair twitchy on descents. With the suspension unloaded, the BB sits just a hair below 13". I'm really hoping the 1" rise in the front with the new wheel isn't too much. But to be safe, I'm thinking I'll run the fork with a little extra sag to keep the rake effect from being too severe.

    Since the new wheels will need to be retentioned soon, I'm running tubes for now. Will stretch the tires a bit and let the spokes settle, and after retentioning, I'll switch it to Stan's tubeless.

    Hope to have a few rides on it by next week. Input before then completely welcome.
    I spent Saturday morning pedaling up to and around Camp Tamarancho in Marin. I moved the seat forward a bit more and up 1/4" or so. The connector trail is somewhat rooty wiith switchbacks; the mud was pretty greasy. It pedaled well. The first switchback threw me off a bit, since I'd been riding a fully rigid bike while waiting for my wheels. It certainly feels taller than before. On level and descending rocky sections, the bike feels like a dream. The bigger wheel tracks really well and the NeoMoto tire is plenty grippy, and the whole bike makes easy work of the rocks and roots.

    My hope with going bigger in the front was to make the front end of my previously twitchy bike a bit more stable. The 650B wheel certainly did that, but brought vertical lift to the front end. I might lower the stem 10mm and see how it handles then, but in the back of my mind, I'm thinking about a potential handling improvement that might come from reducing the fork travel from 100mm to 90mm -- that 1cm might just make it perfect. I have reservations about this though because the rear travel is a claimed 115mm, and the difference from front to rear might make the bike feel uberwonky.

    Has anyone here reduced their fork travel to offset geometry changes when going to a 650B front wheel?
    Thanks again all.
    105mmop
    Last edited by Entrenador; 01-04-2009 at 07:22 PM.
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  13. #13
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    That's exactly what I do with my Blur LT. I run a Fox Talas in the front and have tried everything from 90mm to 130mm. The older forks are adjustable in 3mm increments. I like it best right about 115mm. It still climbs well and has enough travel for the rough stuff especially with the 650B up front.

  14. #14
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    Quote Originally Posted by 105millimetersofpleasure
    I might lower the stem 10mm and see how it handles then, but in the back of my mind, I'm thinking about a potential handling improvement that might come from reducing the fork travel from 100mm to 90mm -- that 1cm might just make it perfect. I have reservations about this though because the rear travel is a claimed 115mm, and the difference from front to rear might make the bike feel uberwonky.

    Has anyone here reduced their fork travel to offset geometry changes when going to a 650B front wheel?
    Thanks again all.
    105mmop

    I would move two spacers from below to above the stem and do a few rides. You need to adapt a little to how to how it feels before making a sound judgement, and going to the trouble of taking apart your fork (assuming it's not a Talas).
    If you shorten the fork, you are taking away half the improvement in stability by returning to the steeper HA.

    Another way to look at it is that most people never get full travel from their Fox Fork. If you can reduce the length and still get the same travel, say by shortening the spring side rod to make it more linear, that could work.

    I think once you get the position dialed, you'll forget all about tweaking the fork.

  15. #15
    Mr.650b - Mr.27-5
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    Quote Originally Posted by reformed roadie
    I would move two spacers from below to above the stem and do a few rides. You need to adapt a little to how to how it feels before making a sound judgement, and going to the trouble of taking apart your fork (assuming it's not a Talas).
    If you shorten the fork, you are taking away half the improvement in stability by returning to the steeper HA.

    Another way to look at it is that most people never get full travel from their Fox Fork. If you can reduce the length and still get the same travel, say by shortening the spring side rod to make it more linear, that could work.

    I think once you get the position dialed, you'll forget all about tweaking the fork.

    I am with RR on this one. Sort out your position first, my guess is that you will not need to touch the fork.

    Cheers,

    KP
    “Those that say it can’t be done should get out of the way of those doing it.”

    PacentiCycleDesign

  16. #16
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    When going to 650b front only I ended up doing all three position adjustments for mostly slower and smoother singletrack conditions (Tamarancho is my "backyard" loop too, a good area to test many trail conditions including some faster or very steep downhills that can be connected nearby).

    1. moved the seat forward about 6mm and up slightly to say over the pedals as before and maintain leg reach.
    2. lowered handlebars 1/2 inch.
    3. I had a Pike U-turn fork with infinite adjust and combined with the other two adjustments, I found that lowering travel about 5 - 7 mm returned turning response to very close to the exact same feel as before with a 26" front wheel and full travel, except better rolling and corner traction with the 650b front wheel. I did often raise travel backup to original height for faster sections and downhill to regain the more plush travel and slacker handling feel.

    Enjoy your rides!

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