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Conference noted::bicycle

Title: Bicycling
Notice:Bicycling for Fun
Moderator:JAMIN::WASSER
Created:Mon Apr 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3214
Total number of notes:31946

160.0. "Touring -> Dirt Bike Conversion" by KIRK::JOHNSON (Eminent Tautologist) Mon Oct 27 1986 18:11

    I rode a mountain bike for the first time this weekend.  It was
    fun, but not fun enough to plunk down $600 for a new one.  As
    I was talking to the owner of the bike I rode, I thought of 
    taking an existing frame of mine and modifying it into an
    off-roader.  
    
    Most frames wouldn't work, but I think I have half a chance with
    this one - a Fuji S10-S.  First of all, it's strong.  It also has 
    wide clearences around the wheels, a long wheelbase, and long trail,
    all in its favor.  It's a little on the tall side (25") and it 
    doesn't have the braze-ons for cantilever brakes, but I'm still under 
    the impression that it would work as a fire-roader ATB (as opposed 
    to a trials ATB). 

    I already have a seat, seatpost, bottom bracket, center-pull brakes,
    headset, and front derailleur.  I think I need wheels, tires, a
    crank, pedals, hite-rite, thumb shifters, rear derailleur, and 
    brake handles.
    
    Before I start building, does anyone have any advise on the 
    feasibility of pursuing this project?
    
    MATT
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160.1Alternatively, -> CylcocrossKIRK::JOHNSONEminent TautologistMon Oct 27 1986 18:145
    Another possibility is cyclo cross.  I know nothing about the
    sport or its equipment, but it sounds intriguing.  Any chance
    the Fuji would make a better Cyclocrosser than a mountaineer?
    
    MATT
160.2don't expect too muchAPOLLO::DEHAHNTue Oct 28 1986 10:5635
    
    The main differences between a cross bike and a mountain bike are:

    o Frame - the mountain bike uses oversized tubing, and is smaller
    in stature than a cross bike (you should be riding at least one
    frame size smaller on a MTB)
    
    o Wheels - The MTB uses 26 inch wheels, usually at least 1 3/4"
    wide tires. The cross bike is invariably 27" (700C) with cross
    tubular tires (32mm)
    
    o Gearing - Most MTB's have triple chainwheels (15-18-21 speed).
    Cross bikes use a single chainwheel (5-6-7 speed).
    
    Sure, you can hack your Fuji up, but you'll never make a $600
    mountain bike out of it. You'll spend $200 and probably not even get
    a $200 MTB out of it. The lower priced MTB's are really a bargain...
    I spent $260 for my Cycle Pro and have gotten 3X that in enjoyment
    out of it...and the main thing that seperates it from the $600 ones
    are the components, which can be upgraded later (as they break 8^)
    
    Your best bet for mod's is to attempt making a cross bike out of
    it, but remember, unless you're 6 foot 10 it's going to be too tall
    for you, too much frame for you to handle on rough roads. Be prepared
    to trash the paint job when installing braze-ons, like cantilever
    brake bosses. Also, expect it to ride very rough, as the frame geometry
    is too stiff/steep/long for off road. The best type of frame to
    attempt a cross conversion on is a small, strong touring or road
    racing frame.
    
    But if bucks are the bottom line, and your expectations match your
    budget, then what the heck.
    
    CdH
    
160.3Well, I've got this other frame...KIRK::JOHNSONEminent TautologistTue Oct 28 1986 11:5814
    On the other end of the scale, I also have an old Raleigh 
    Sports touring frame designed for 26" wheels.  It's only 
    about a 20" frame, though, so I was a little concerned that
    it might be too small.  Maybe it would be a better prospect
    for an MTB conversion.
    
    It sounds like the Fuji might not be all that bad for cyclocross,
    but what is cyclocross all about, anyway?  I've seen pictures
    of guys scrambling up mudslides with these bikes slung over
    their shoulders (sounds like fun! :~}), but I have no idea what
    else they do, how long races are, or how off-road performance of
    one of these compares to an MTB.  Any cyclocross racers out there?
    
    MATT
160.43 speed frame?APOLLO::DEHAHNWed Oct 29 1986 10:1214
    
    I don't race cross, but the rest of the team does. I'm just not
    that crazy about running up steep hills in the rain, slogging through
    knee deep mud, crashing 10-20 times per race, and destroying expensive
    equipment at an alarming pace.
    
    It's very popular in Europe, though, and the season is now in full
    swing. New England does have these events, there's one in Brimfield,
    a series in Plymouth and the championship is in New Jersey.
    
    Watching, for me, is much more enjoyable than participating.
    
    CdH
    
160.5KIRK::JOHNSONEminent TautologistWed Oct 29 1986 11:495
    Yeah, the Raleigh is a 3-speed.  I looked at it last night, and
    it's hopeless.  I'll continue scheming about things to with the
    Fuji...
    
    MATT
160.6APOLLO::DEHAHNWed Oct 29 1986 19:548
    
    What about you? How tall are you, what's your inseam length? Are
    you built stocky or lanky?
    
    Just trying to get some ideas.
    
    CdH
    
160.7Some SpecificsKIRK::JOHNSONEminent TautologistWed Oct 29 1986 20:0812
    I'm about 6'1", wear 33"/34" inseam pants, and weigh 185 or so.
    I ride a 58cm or 59cm Olmo racing bike these days for my primary
    recreation.  The 25" Fuji was just a little too big, but not
    bad for touring.  I'm definitely not worried about the frame's
    finish: it's already 8 years old.
    
    I inadvertantly saw a little off-road action on my Olmo today,
    when I got lost in Harvard, MA, and ended up having to ride it
    up a steep dirt road (being chased by a beagle, no less!).  Those
    115 PSI slicks don't spare you much in the dirt...
    
    MATT
160.8APOLLO::DEHAHNWed Oct 29 1986 20:2032
    
    Re: Olmo
    
    Nice bike. 58 cm. sounds like a great fit for racing.
    
    Re: Fuji
    
    25" (63 cm) is a bit too big for a cross frame for you, but not
    out of the ballpark. I was just concerned about being there. How
    many 5'6" guys have you seen riding 25" frames "because it's macho"?
    If you can do the conversion at minimal expense, what the heck,
    go for it. If you really like this type of riding then you can pick
    up a better quality used frame (Raleigh Pros are popular for this)
    to convert. If you need odd parts let me know, I'll check the basement.
    
    Re: dirt
    
    I love off road action on the racing bike. In the now-defunct Maine
    International, we used to race about 5 miles in dirt, part of it
    up a very steep climb. I always blew by others up that hill, because
    I used to train for it. Also, the Stowe road race has another dirt
    section that's somewhat difficult, but important, because it's a
    couple of miles before the finish. High speed dirt road bikehandling
    skills really help. We used to train on Pine street in Sherborn,
    about a two mile stretch of nasty dirt. We'd sprint for about a
    half mile before the start of the section, to make sure we were
    hitting it at a race pace. I always got beat on that stretch by
    my training partner.
    
    CdH
    
    
160.9Going for it!KIRK::JOHNSONEminent TautologistThu Oct 30 1986 14:1127
    Thanks for the tips.  I feel a lot more confident now about trying
    the conversion.  I don't care if the bike's world class: I just 
    want to get a taste of the action.

    From what you say, cross bikes have a particular 700c wheel,
    cantilever brakes (may I forgo these for now?), and cross tires.
    What kind of gears do they run?  What other special components
    should I be looking for?  I want to hang quality goods off of
    this frame, so that I can use them if I upgrade.  Feel free to
    name names of brands and shops were I can get them. 

    I currently have (and expect to be able to use): 
    seatpost, seat, bottom bracket, headset, center-pull brakes,
    brake levers, front and rear derailleurs (34-tooth shift range 
    on the rear, I believe), 13-28 six-speed gear cluster, 
    downtube-mounted indexed shift levers (is that where they go 
    on a crosser?), and a chain.  If I get wheels, tires, crank,
    handlebars and stem, I (naively) assume I'll be in business.
    
    I should correct something I said earlier about the Olmo.
    I claimed it was a form of recreation.  Actually, I think it 
    approaches something more like true love (WHY does it have
    to start getting cold NOW????)...

    Once again, thanks for your help.
    
    MATT
160.10NOVA::FISHERFri Oct 31 1986 10:0120
I saw a frame that was made for cyclo cross last winter. 

It was a 5 or 6 speed.  The chainwheel had guards on both sides to help
keep it from getting tangled or thrown.  I'd say that it was something like
a 42 to 45 toother. 

The shifter was a barcon.  There are times that you don't want your hands
to get far from the bars.  The shift cable traveled above the down tube and
over the bottom bracket also to help keep it from getting fouled. 

Paul at Category 1 Cyclegoods can give you more details about it. 

If you switch the Fuji to 700c wheels, your brakes may not reach. I'd say,
better to go with the 27's that you have and something like a specialized
tri-cross 27x1-3/8 tire (10.49 at Nashbar, if they have 'em).  Your rims
have to be able to handle a 1-1/4 tire, I think they do.

GO FOR IT.

ed
160.11long replyAPOLLO::DEHAHNMon Nov 03 1986 13:2357
    
    This is try #4 for entering this reply in here, I've gotten "ERROR
    WRITING RAINBO:" every other time. Anyone know how to recover lost
    replies?
    
    Anyway, Mr. Fisher gave you most of the info. I'll elaborate (ho
    hum)
    
    seatpost, seat, headset, bars & stem - nothing special.
    
    wheels - should be good strong tubulars, like Mavic GP4, 36 hole,
    14G straight spokes. Hutchinson makes a great cross tire. 4 cross
    is the lacing pattern. You can use clinchers, but they won't be
    as strong for the weight.
    
    bottom bracket, crank - you can't use your BB with a single chainwheel,
    the chainline will be off. Get a cheap track crankset with BB (Sugino
    makes a nice inexpensive one), and have the shop swap out the 1/8"
    sprint chainwheel to a 3/32" road chainwheel. Number of teeth is
    debateable, I'd start with a 44T. The crank must be set up with
    double chainguards, the kind you see on inexpensive bikes to keep
    your pants off the chain. They bolt onto the crank, either through
    the spider arms or as part of the chainwheels. They should look
    like this:
    
    			chainwheel--+
    				    V
    		     chainguard--->|X|<---chainguard
    				   |X|
    				   |X|--+
    				   |X|  |<---crankarm
    				   |X|  +-O<---pedal
    
    Pedal preference is towards regular road pedals with clips and straps,
    but there is a small faction that likes MTB/BMX pedals (with spikes)
    and no clips.
    
    brakes - your centerpulls should do ok for now, but see if tandem
    brake pads will fit. You may have to add extra spacers to your brake
    center bolts to accomodate them. If your centerpulls won't fit a
    700c wheel, let me know, I might have a set in the dungeon.
    
    derailleurs - the front is unnecessary, your rear should be ok.
    Shifter is almost always a single barcon on the RHS of the bars.
    Suntour makes a cheap set, maybe if you're nice the shopowner will
    sell you just one.
    
    cluster - 13-28 will get you started, but a 15-26 is better. You
    can add this later.
    
    bar tape is always cloth, some use foam underneath it.
    
    Enjoy!
    
    CdH
    
        
160.12now that I think of it...APOLLO::DEHAHNMon Nov 03 1986 13:298
    
    Your cranks should be ok. Just use the single chainwheel on the
    inside. You might have to get a set of chainwheel bolts for a triple
    crank, though, to fit the chainguards on (if they mount that way).
    
    CdH
    
    
160.13CESARE::GORRINOTue Nov 04 1986 11:148
    re 9:
    
    Matt,
    
    		forget Named Data and elope to Florida with your new
    love                                 
    
    						Mauro
160.14And have you gotten your SLX replacement yet?KIRK::JOHNSONSTS$VALUE = BSL$DO_WHAT_I_MEAN();Tue Nov 04 1986 12:197
    RE .13
    
        If I do, it'll be all your fault!

    (Mauro sold me the Olmo frame when he was visiting the U.S.)

    MATT
160.15A difficult choiseCESARE::GORRINOWed Nov 05 1986 06:401
    Is it better Olmo or Sannino ? This is my problem.