Building a CX commuter...- Mtbr.com
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  1. #1
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    Building a CX commuter...

    Hi all.

    Again, I come before you, hat in hand, trying to figure out what it is I'm actually doing.

    I'm looking to piece together a cyclocross bike. I have never built a bike before, and I'm just looking for a fun project to drop a little extra cash on here and there, while I get my fat ass in shape this year.

    I am planning to build off Nashbar's great 'cross frame. Components will be disc brakes (I know, I know, but I live and work in the wet PNW).

    What I specifically need is: What compnents are interchangeable from road and MTB? I ask because I can say " Okay, a bottom bracket is probably the same for both...." but I have no idea.

    I'm hopeful to build a 2x9, or maybe even a 1x9. The problem I'm having is looking at all the different components and seeing which is compatible. Price is not a HUGE issue, but this is a hobby bike. I would like it to be sturdy and reliable, without costing a huge chunk of change to build.

    So; Do I need a road specific deraileur? Road specific cranks? Or can I get away with MTB for both? Bottom bracket sizing? Threadless or threaded headset? Does it matter?

    I don't expect you all to just give me all the info, but pointing in the direction of resources that are NOT focused on racing would be fantastic.

    I really appreciate the help, apparently my search-fu is weak.

  2. #2
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    I apologize in advance, but I'm going to use this as another opportunity to post my bike:



    To answer some of your questions, the Bottom Bracket shell on the frame is 68mm. I can't tell you what legnth spindle you will need because it will mostly depend on the crank you use. Here are the frame's specs copy and pasted from Nashbar's web site:
    Frame Size: X-Small Small Medium Large X-Large
    Seat Tube*: 46cm 50cm 54cm 58cm 60cm
    Top Tube (act.): 50.0cm 51.3cm 53.7cm 56.5cm 59.5cm
    Top Tube (eff.): 52.0cm 53.5cm 56.0cm 58.0cm 59.5cm
    Head Tube: 11.5cm 12.5cm 13.5cm 15.5cm 16.5cm
    Head Angle: 70.5deg 70.5deg 70.5deg 70.5deg 70.5deg
    Seat Angle: 73.0deg 73.0deg 73.0deg 73.0deg 73.0deg
    Chainstay Length: 42.5cm 42.5cm 42.5cm 42.5cm 42.5cm
    Standover: 73.0cm 74.5cm 77.5cm 80.0cm 80.5cm
    Wheelbase: 986.9cm 1002.4cm 1017.9cm 1048.5cm 1064cm
    * measured center to top of seat tube
    Sample Weight (size small, by Tech): 3.63 lbs. 10/18/05 CNAP
    BB Drop (all sizes): 70 mm
    BB Width (all sizes): 68 mm (English)
    Rear Dropout Width (all sizes): 130 mm
    Seat Post Diameter (all sizes): 27.2 mm
    Front Derailleur clamp (all sizes): 1-1/4" (31.8 mm)

    You can use most of the MTB parts you already have. You may or may not need a road specific rear hub (I'm using a 29er wheelset, but it I had to do some squeezing to get it to fit). I have a few hundred miles on mine now and I haven't had any issues from using the wheelset, but to be safe you may want to get a road specific rear hub. Other than that, you should be okay to use whatever MTB parts you want. There are plenty of members on this board that have built up the Nashbar "X" frame. Take a look at their builds and maybe you will get some ideas from them. Good luck and make sure to post pictures when you are done.
    Last edited by Solomon76; 05-02-2010 at 09:04 PM.
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  3. #3
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    The Nashbar frame uses a 130mm (road) rear hub spacing which is very unfortunate because there are very few disc hubs that aren't 135mm (mountain bike). You might be able to get away with spreading the dropouts when inserting the rear wheel, but because this frame is aluminum, I would hesitate to do that.

    Compatibility between road and mountain bike components mainly rests on one issue - whether or not you are using drop bars. If you stick with mountain bike handlebars you will be able to use the most of the parts from a mountain bike (keeping in mind the hub problem). The bottom bracket is 68mm, so if your current ride has a 73mm bottom bracket you will need to add a spacer to each side (assuming an external bottom bracket).

    If you want to run drop bars, then you'll need to match the levers to the brakes (Avid BB7 Road brakes with any road lever or linear pull road brake levers with any mountain bike cable disc brake).

  4. #4
    I got nothin'
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    I built the Nashbar X into a commuter just a couple of months ago. I bought a set of Novatec hubs off ebay from a shop in China. They are 130mm rear and 100mm front spaced disc hubs. I built them up using Sun-Ringle Equalizer 23, 29er rims and Wheelsmith double butted spokes.

    I went with drop bars so I went with Avid BB7 road brake version. Although, I think Tektro now makes a road lever with a MTB brake pull length.

    As far as your other questions go: bottom brackets are generally universal between road and MTB's; derailleurs can go either way also, I am running a Deore RD with Shimano road shifters; and seats, seatposts, and stems can all be interchanged. The big difference is that road components are generally lighter weight. My only caution would be with crank sets, I would recommend a compact road set for appropriate gear ranges.

    Good luck and remember to post pictures when your done.
    I ride at ludicrous speed

  5. #5
    Ovaries on the Outside
    Reputation: umarth's Avatar
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    You have landed in the realm on opinion. I, were I to build up a CX commuter, would go after a drop bar, large clearance bike, as that cover bases pretty well. MTB or road BB7s, as both are easily accommodated. I would do a 38/48 crankset with a x by 30/32, etc. You will have the range to do anything.

    All you need then, are eyelets.

  6. #6
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    Seriously, that Novatec info might be the best thing I've heard all week. After being disappointed in bicycles all week (shop sold the LAST 21" GF XCal 15 minutes before I walked in with a large down payment... I guess the money I saved getting the Cobia will fund my Comucross, a term I just made up..Crossmuter? Cocrosser?) That's just awesome.

    Now I'm gonna start piecing it all together... I'll post up a thread when I get all the pieces. Thanks guys.

    One more question! BB's have different widths, right? I'm seeing 68mmx107mm, 68x110, etc... Does it matter?

  7. #7
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    The second measurement is the length of the spindle. If you are using an old style (seperate BB & Crank), it somewhat depends on the which crank you use as to what spindle length you will need (somewhat). If you are using the newer Hollowtech-II/GXP intergrated type BB/Crank, you should be okay with whichever crank you decide to get.
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  8. #8
    Bedwards Of The West
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    I'm just here to collect my commission for yet another commuter forum Nashbar X frame recruit.

    I've been riding the X frame as a commuter for a few years now. I've had it set up in a few different ways...a few points, maybe repetitive, sorry...

    I have never had an issue with road/mtn avid disc brake differences. I run Avid 'mountian' discs with time trial levers and bullhorn bars currently, before that I was using drop bars and tektro road levers. Never had an issue with lever pull being too much or too little...the difference is too small to matter in my opinion.

    You can use whatever cranks/gearing/derailleur you want. I currently have a Deore level mountain rear derailleur on there...for a while I had a vintage Suntour Pro road derailleur...before that I had a shimano XT. If it plays nice with your shifter, it will work.

    I have a FSA road double crankset on mine... but a mountain set up would work fine. On BB width, the different widths exist to avoid the crank or chainring (on big road chainrings) hitting the chainstay. Most will come with spacers that you can play with to avoid frame contact, while maintaining a decent chainline. Sometimes it's a compromise. I have a 50 tooth big ring (which nashbar says won't fit), and I have been able to get the chainline pretty good, but the right crank comes really close to the chainstay (it has worn a mark in my lizard skin chainstay protector). I'm running an mountain 8 speed rear cassette, which is a little more forgiving in terms of chainline than a 10 speed set up would be. I would choose the width of my 68mm bottom bracket based on the size of my big ring. The bigger the ring, the wider you'll need to go.
    Some of the new external BBs (like mine) are only one width, and you just add or subtract spacers to get your chainline right. Most of the external ones will come with the crankset, so don't double-buy on accident.

    Bottom line, just get the specs from the nashbar page and buy components with the same dimentions, and ignore the "road" or "mtb" title on various parts. It will all work.

    Oh, and just to rub salt in it... my rear hub spacing is 135. They changed it to 130 in the past couple of years apparently. I get to run pre-built 29er wheels and the options are endless. neener neener.

    Have fun with the build!
    You have no excuse for driving to work
    (unless you don't have studded tires)
    (no excuse for that either)

  9. #9
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    I'm more in the umarth camp: I'm running a Kona Jake that has been modified for commuting, long distance and road duties. It's got a triple 30-39-50 and I've since gone to Hope Pro III hubs with an 11-32 XT cassette and LX rear derailleur. The bike has lots of range for hills and the flats.

    If you've got a 130 rear, watch the spacings if you want to go for a mountain cassette....in a lot of cases, there isn't he clearance as the road cassettes are spaced a hair bit different. They are still 9 speed, but I found that a mountain cassette meant for 135 mm spacing has a little bit more space down in the 13T and 11 T cogs...don't fit well on the 130 mm spacing and often leads to contact
    As if four times wasn't enough-> Psycho Mike's 2013 Ride to Conquer Cancer Page

    Moran? Let your opinion be free -> F88me

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