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Thread: 650b Mojo

  1. #1
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    650b Mojo

    I got my first ride with 650b tires front and rear on my 2 year old Mojo. Thanks again Kirk Pacenti for bringing 650b wheel size and your very high quality tires to mountain bikes.

    Iíve run 6 months with the AM trail tread neo-moto with 26x2.3 size tires in the rear. The 650b front improved the ride very noticeably. Adding the 650b rear was a more subtle additional improvement, also noticeably smoother and easier to roll over rocks.

    The Pacenti quas-moto 2.0 tire fits the rear of the Mojo with at least ľ inch clearance, not enough for mud but enough for dry conditions. I had to put a shim the thickness of a quarter dollar coin under my PUSHíd Ď02 Vanilla RC bottom-bumper to limit travel and avoid rubbing the seat tube at bottom out. So the rear wheel travel is ľ inch less at only 5.25 inch travel now and uses the bottom bumper more on the occasions of full travel landing some of the jumps on my local trail. (PUSH makes shims for the air shocks they service if you decide to shorten travel. I donít know of a way to do it yourself for air shocks.)

    Overall the ride is smoother including the small travel loss. I actually reduced spring preload since I had added a turn or more to compensate for the 650b front only previously slackening the frame angles. I still have to tweak the damping and preload to fully optimize the taller wheel size.

    The quasi-moto hooks up surprisingly well for itís short and widely spaced knobs. It clearly rolled easier, smoother, and braked and cornered much better than the 26x2.3 Kenda Small Block 8ís I had been riding on the 26 rear wheel. Braking and corner grip is very close to the 26x2.3 Nevegal or Rampage tires, and of course the quasi-moto rolls much smoother and easier. The only fear is the knobs of the quasi-moto donít protrude wider than the side wall like the neo-motos using the same casing, so the sidewalls are rather unprotected from scrapes when brushing up against rock faces (Kirk it looks like the same knobs could be moved slightly outboard for better sidewall protection with no loss, if not greater cornering traction.)

    Gear ratios were all 5 - 6% higher than 26 inch rear wheel with the bigger 650b diameter. Itís noticeable and I had to find different gears than I was used to on the local trail I helped to build about 10 years ago and Iíve ridden at least 1500 times. The higher gear ratio and easier rolling inspired a faster pace, and the faster pace improved momentum and added up to being easier to do steady climbs faster. Steep climbs had great grip even in loose dirt and the slightly higher granny low made it easier to maintain traction.

    The adding the rear to match the axle height of the 650b front wheel returned the handling to the superb handling balance of the stock Mojo but much better pedaling clearance, curing my only minor disappointment with the stock Mojo. Having a low bottom bracket height at 13 inches, the Mojo with 26 inch wheels has occasionally poor pedaling clearance on rough trail. Using a 650bx2.3 neo-moto in front only with a 26x2.3 in back got the BB up to a decent 13.5 with a 140mm fork. With the 650b in back the BB is up to 13.65 inches with a 140 travel fork, ideal for a trail bike with 5.5 inch travel. Raising my Nixon 130-160 up to 160 makes 14 inch BB. I finally had a ride on the Mojo with no pedal strikes on my local favorite singletrack loop with rocky and gravelly fast fireroad downhill for the last mile.

    I ran with a tube in the rear using a temporary test wheel I built from my junk undersized Velocity and poor quality Hope Pro2 hub I canít stand for itís alarm-clock loud ratcheting and slow for 24-count engagement and noticeably high friction. I managed to pinch flat on some g-out stream crossings or jump landing in the fast rocky downhill at the end of the ride. Iíve been running Stanís tubeless convert for a couple years and so rarely have flats it was really disappointing to use tubes. Tubes require higher pressures than I like anywhere except where it so rocky every where that high pressures are required to avoid wheel damage and pressures higher than 32 psi blow Stanís converted tubeless tires off the rim. I look forward to running safer UST bead 650b tires tubeless in all conditions.

    Hereís some pictures:
    Attached Images Attached Images

  2. #2
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    Thanks for the report Derby - that thing looks fantastic!

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    Very interesting stuff. What fork is that? Is your rear shock the recommended stock i2i and stroke? I'm game when some proper UST or TR tires comes out.

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    NedwannaB
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    Familiar mountain......

    Quote Originally Posted by derby
    Here's some pictures:
    .....in backround of first pic! South side of CC or WWheel @ Tamarancho. Close?.....

  5. #5
    Mr.650b - Mr.27-5
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    Derby,

    Have you shown this to the boys and girls at Ibis?

    The beauty of that design is that with a slight drop out modification they could produce a 650B compatible bike with relative ease.
    ďThose that say it canít be done should get out of the way of those doing it.Ē

    Pacenti Cycle Design

  6. #6
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    Yeah, give them a hint. I already hinted at this on the other thread in the Ibis forum. They would probably have to redesign the swingarm for more tire clearance though- it is very close with a 650B/2.0 tire which is pretty skinny.

  7. #7
    mnt bike laws of physics
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    I had a strong feeling the Quasi would be a sweet tire.
    Cash along with the fear of sidewall damage keep me from going full 650b on my Rush. I'm glad your enjoying the full 650b experience on your Mojo. I really hope the quasi holds up to your trails - then you can go tubeless which as we know is the only way to go.

    I had heard the Hope Pro2 hubs were very nice except for the noise. Price and engagement are good at least, but you are saying even the engagement is not good? What would you use instead? I did not like the CK hub I had 11 years ago...and pricey.

  8. #8
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    Quote Originally Posted by Flyer
    Very interesting stuff. What fork is that? Is your rear shock the recommended stock i2i and stroke? I'm game when some proper UST or TR tires comes out.
    Fork is a discontinued '07 Nixon Elite RWDT 130-160 coil (Manitou still makes an í08 air version with very good reviews). It's kind of flexy compared to a Pike at 140mm travel or any 36 longer travel fork, but light weight and great damping well matching the PUSH'd '02 Vanilla RC. The RC is a 7.875x2.25 with spacer under the bottom bumper PUSH made to limit travel to 2.0 for 5.5 inch stock measured wheel travel without hitting the seat post. I had to piggyback another spacer to limit wheel travel to 5.25 for the bottom travel clearance for the taller 650b.

    I hear you on the UST/TR need for use in harsher conditions needing higher pressures than Stan's converted non-tubeless can tolerate safely - that goes for any size wheel. Hopefully Kirk can get them made up.

  9. #9
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    Quote Originally Posted by Kirk Pacenti
    Derby,

    Have you shown this to the boys and girls at Ibis?

    The beauty of that design is that with a slight drop out modification they could produce a 650B compatible bike with relative ease.
    In Ibis forum I posted a link to this post.

    Yes 6 months ago I asked Hans for modular dropouts for many uses, such as wheel sizes, BB height adjust, singlespeed, etc. The retooling for carbon fiber manufacturing is very costly and it didn't seem very feasible. I don't think it would take much to develop modular dropouts, using the same fitment points and change the dropouts to stubs that had bolt on brake mount and drop outs. I've considered designing some for the aftermarket myself. I hope it happens, but they probably have other priorities with greater market demand to cover first.

  10. #10
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    Quote Originally Posted by JMac47
    .....in backround of first pic! South side of CC or WWheel @ Tamarancho. Close?.....
    WW! Bingo!

  11. #11
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    Quote Originally Posted by yogiprophet
    I had a strong feeling the Quasi would be a sweet tire.
    Cash along with the fear of sidewall damage keep me from going full 650b on my Rush. I'm glad your enjoying the full 650b experience on your Mojo. I really hope the quasi holds up to your trails - then you can go tubeless which as we know is the only way to go.

    I had heard the Hope Pro2 hubs were very nice except for the noise. Price and engagement are good at least, but you are saying even the engagement is not good? What would you use instead? I did not like the CK hub I had 11 years ago...and pricey.
    About my dislike of the Hope Pro2, my opinion I think irritated someone about a year ago I won't mention who started a little hate-derby cult that still stalks and harasses a few of my posted opinions now and then, flaming lies and twisting words about my opinions. I was very disappointed at the Pro2's rear hub large backwards step in performance and frustrated with the lack of ease of maintenance compared to the earlier Hope Bulb model I used for many years with no issues having quick and quiet 32 point engagement. 24 point engagement is normally not very slow in engagement speed. But the Pro2ís 24 point engagement is slow because it has teeth which are saw-tooth shaped and the pawls backup or hesitate to seat into the teeth after engaging. It really engages about as quickly as a good 18 point hub, which is OK for downhill and higher gears but slow for middle ring and very slow for granny gear use. It required much brute force to pull apart the freewheel to maintain lube as I found out trying to quiet down the alarm-clock noisy ratcheting which is obnoxious to me and some friends who commented on the noise. The seal doesnít retain lube (Hope used a minimal amount of the stickiest lube I've ever seen in the new hub to avoid bleeding out all over the spokes, Phil's Tenacious Oil is nothing compared.) The hub is impossible to quiet to close to a normal noise. The unusual stiff pawl spring design produces noticeably more freewheel friction than most hubs, minor performance loss, but like a very lightly dragging brake. I won't ride it except like now for a short test before committing to buying a quality hub to build a wheel for long term use.

    I like any other hub better. My favorite is Hadley's. They are 72 point quick engaging, very quiet, easy to maintain, great customer help, not heavy but not extra light either, convertable from 5mmQR to 10 or 12mm solid through axle bolt on. Possibly Maxle compatible, but I'm not sure. Hadelys are about 50% more expensive comparing list prices than a Pro2, but less than CK.

    The new XT and XTR hubs are 32 point, and getting very good reviews too, there are converters from spline to 6 bolt rotor mounts available.

  12. #12
    NedwannaB
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    Thought so....

    Quote Originally Posted by derby
    WW! Bingo!
    We were accross from Pine Mtn. on Bolinas Ridge Sunday. What a perfect day, little warm but a breeze from the fog bank holding one ridge over above Stinson.

    I have a couple q's re: 650's. Check your PM.

    Thanks Jmac

  13. #13
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    Quote Originally Posted by derby
    Fork is a discontinued '07 Nixon Elite RWDT 130-160 coil (Manitou still makes an í08 air version with very good reviews). It's kind of flexy compared to a Pike at 140mm travel or any 36 longer travel fork, but light weight and great damping well matching the PUSH'd '02 Vanilla RC. The RC is a 7.875x2.25 with spacer under the bottom bumper PUSH made to limit travel to 2.0 for 5.5 inch stock measured wheel travel without hitting the seat post. I had to piggyback another spacer to limit wheel travel to 5.25 for the bottom travel clearance for the taller 650b.

    I hear you on the UST/TR need for use in harsher conditions needing higher pressures than Stan's converted non-tubeless can tolerate safely - that goes for any size wheel. Hopefully Kirk can get them made up.
    Thanks for the info! The tires are my main concern. I have seen quite a few of the regular tires burp badly enough to cause crashes on hard and fast turns. I used to do it myself till I saw my buddy go down hard in front of me. I consider it a major safety issue though many will probably think I'm a big ssisy for thinkig that way. That's fine- I'm happy with my sometimes paranoid ways when it comes to tires.

    Good to see you try this, Derby. I think the 650B wheelsize has huge potential but it really needs a couple of powerful catalysts- another 650B fork (from Fox or RS), one big (Specy/Trek) or 3-4 smaller manufacturers to jump on board with frames, and...well, that's about it. The rest (tires, rims, other frame manufacturers, etc.) will be a flurry of activity even in a year of slow bike sales.

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    Cool, thanks Derb I'm at 5/9 maybe a little short for a 29er, (long torso, short little legs) but this should be perfect for me to try. As far as the travel limiting on the air shock could I just run enough pressure to keep it from ever really going full travel maybe @ 8mm sag ?
    Thanks again.

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    Yes 6 months ago I asked Hans for modular dropouts for many uses, such as wheel sizes, BB height adjust, singlespeed, etc. The retooling for carbon fiber manufacturing is very costly and it didn't seem very feasible. I don't think it would take much to develop modular dropouts, using the same fitment points and change the dropouts to stubs that had bolt on brake mount and drop outs. I've considered designing some for the aftermarket myself. I hope it happens, but they probably have other priorities with greater market demand to cover first.
    Hmm, what if Ibis introduce the Tranny swap rear triangle concept to the Mojo? or they could just redesign the rear triangle and start selling em?
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  16. #16
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    Quote Originally Posted by glovemtb
    As far as the travel limiting on the air shock could I just run enough pressure to keep it from ever really going full travel maybe @ 8mm sag ?
    Thanks again.
    I wouldn't. You'd be limited in sag adjustment and screw up handling, and the tire might still scrape and damage the seat tube. A bike is not designed to take even a light hit to the back of the seat tube. It could be very dangerous if the frame collapsed at the same time you bottom travel.

    PUSH will do that shaft travel reduction at no extra cost when doing the minimum oil change service or any enhanced performance tune.

  17. #17
    Mr.650b - Mr.27-5
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    Quote Originally Posted by glovemtb
    Cool, thanks Derb I'm at 5/9 maybe a little short for a 29er, (long torso, short little legs) but this should be perfect for me to try. As far as the travel limiting on the air shock could I just run enough pressure to keep it from ever really going full travel maybe @ 8mm sag ?
    Thanks again.

    I will second Derby's thoughts here. Reducing the travel by upping air pressure in the shock is not a good idea. even if it prevented the tire from striking the ST, the ride would be altered considerably and certainly for the worse.

    Fwiw, I have been riding an Ibex Atlas (kinda like a Heckler) with 650B wheels installed for some time with good results. I have been running the shock on the soft side and with no modifications / limitations to the travel made. I have yet to get the tire to strike the ST. YMMV.
    ďThose that say it canít be done should get out of the way of those doing it.Ē

    Pacenti Cycle Design

  18. #18
    mnt bike laws of physics
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    Quote Originally Posted by derby
    I like any other hub better. My favorite is Hadley's. They are 72 point quick engaging, very quiet, easy to maintain, great customer help, not heavy but not extra light either, convertable from 5mmQR to 10 or 12mm solid through axle bolt on. Possibly Maxle compatible, but I'm not sure. Hadelys are about 50% more expensive comparing list prices than a Pro2, but less than CK.

    The new XT and XTR hubs are 32 point, and getting very good reviews too, there are converters from spline to 6 bolt rotor mounts available.
    Yea, dieselcruiserhead was talking about his new Hadleys. I think they now have 3 offset pawls for 108 point Engagement. Pretty serious huh? And they are not very loud. They make a 10mm aluminum QR through axle just like DT Swiss. Do you know if they do the same for the front with a 9mm?

  19. #19
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    Quote Originally Posted by yogiprophet
    Yea, dieselcruiserhead was talking about his new Hadleys. I think they now have 3 offset pawls for 108 point Engagement. Pretty serious huh? And they are not very loud. They make a 10mm aluminum QR through axle just like DT Swiss. Do you know if they do the same for the front with a 9mm?
    Hadley used to do 108 point engagement I had read about while doing research before buying my rear hub last fall, but now "only" 72 point. I don't know about the Hadley front hub. I'll buy one next time I need a front hub, but I have a Hope Bulb front hub (and a spare similar but slightly more flexy designed Pro2) now which has held up with a very slow rate of bearing wear compared to many other front hubs I've used previously.

  20. #20
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    This is very interesting.

    I have been debating if I should get a 29er to complement my Mojo.

    But the 29ers I have tried did not fully satisfy me, at only 5'10"/150lbs. But all my friends are moving to the 29er bandwagon, which appear to be a good fit for our local Texas trails. But they are bigger/taller guys.

    Derby, are you seriously considering this 650b conversion permanently?

    I am almost tempted to give it a try as a permanent setup.

    I would get:
    - WB Fluid-650b 130 (Can I stay with my 08 Talas 32 RLC fork instead?)
    - QuasiMoto Tires (The mud clearance is a non-issue for me)
    - NoTubes wheelset
    - Get my Fox RP23 tuned and limit travel as you recommended to 5.25"
    Last edited by flafonta; 08-07-2008 at 08:41 AM.

  21. #21
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    Derb
    I wouldn't. You'd be limited in sag adjustment and screw up handling, and the tire might still scrape and damage the seat tube. A bike is not designed to take even a light hit to the back of the seat tube. It could be very dangerous if the frame collapsed at the same time you bottom travel.

    PUSH will do that shaft travel reduction at no extra cost when doing the minimum oil change service or any enhanced performance tune.
    Kirk Pacenti
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    I will second Derby's thoughts here. Reducing the travel by upping air pressure in the shock is not a good idea. even if it prevented the tire from striking the ST, the ride would be altered considerably and certainly for the worse.
    Ok I'm excited about trying this easy as heck conversion for My Moj SL and pretty sure I would never go back to 26". But, I'm running RPL rear shock. Push does not work on them. I have not talked to Darren, but Jim said no.
    I would have to find someone to do the limit setting for me.
    You guys have any ideas on that ?

    Of course I have an RP23 medium compression tune sitting around I could send them.
    (Running a Talas in front.)
    So on to Wheels and Tires.

  22. #22
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    I need to test more conditions to verify exactly want the shock shaft travel limit shim should be. I did bottom travel on my first ride a few times and slightly scraped some tape I’ve got on the back of the seat tube. I’ve been too busy at work to ride more since that first test ride last weekend - hopefully I’ll be riding tonight.

    Another thing to consider is using a 650b wheel would very likely void your Mojo’s 3 year warranty, at least for the swingarm. Ibis is very reasonable but 650b is clearly not a stock option.

    I’ve got a proposal in with Ibis to finance a short run of reliable and warranteed 650b swing arms. If I or someone can contract that, it could be feasible to have them available in 3 – 6 months. But as you know the wait time can be much longer.

    Going to 650b front only is about 3/4’s of the noticeable gain in rolling and handling performance using a good 26 inch rear tire. All you need is a new front wheel and tire if using Fox, most RS and Manitou forks (I haven’t heard much about Marzocchi forks).

    Full 650b Mojo is very nice. My AM style of riding really needs the more durable neo-moto to fit in the rear and to reasonably clear mud also. I’m not going to be satisfied until I’m on a dw-link bike that fits them front and rear, hopefully the Mojo.

  23. #23
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    We should do a poll here on how many riders are willing and able to buy the new swingarm. I know I'm in but only with a full 650B setup so I'd invest in the new swingarm. I wonder how many they have to order for a single batch.

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    derby,

    A 2006 fox talas doesn't need a spacer to limit travel?

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    We should do a poll here on how many riders are willing and able to buy the new swingarm. I know I'm in but only with a full 650B setup so I'd invest in the new swingarm. I wonder how many they have to order for a single batch.
    New Moj toys ? I'm all in.

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