Conference noted::bicycle

    Hey David! Try note 860. There's a couple of cuts at the question.
    
    Chip

    May I add another question to this note?
    
    I just bought a TREK 1100 that has a triple chainring and for the
    mountians around here its terrific. My question is can I put this
    same gear arrangement on her Schwinn World Sport? I presume I'd
    have to buy the Chainring and freewheel as kind of a matched pair
    and I'd have to get a compatable derailer? Has anyone ever done
    this before?
    
    Fred Mudgett

    RE: .2
    
    Changing from a double to a triple could be an expensive proposition.
    Besides the obvious (swapping the crank), there are quite a few
    other parts involved.  Very few front derailleurs designed for doubles
    can handle the small ring of a triple.  The rear derailleur also
    has to be specially designed to take up the extra chain wrap.  Finally,
    you might need a new bottom bracket, if the new crank isn't compatible
    with the existing one.  
    
    Assuming that the freewheel already is a wide-ratio affair, you
    can keep that....
    
    All this adds up to $$$.
    
    MATT

    You will at least need a new axle as triple axles are usuallu longer
    than double axles.  Sometimes the easiest way to get the triple
    axle you need is to buy the bottom bracket, which includes an axle.
    
    It does add up.  That's why most of us stay with out 12 speeds
    instead of converting to 18 and raising the price. :-) :-)
    
    ed

    Fred,

	I just got a bike trailer (Burley Lite) for pulling my daughter around.
On the flats it's light and easy to pull, but a hill turns into a mountain
pass. With the gearing I have 42-52  13-26, I find I use only the three lowest
gears. I really could use a triple while pulling the trailer, but the trailer
set me back enough $. This is my solution...

Seeing how I don't want to go fast with the trailer I'm going to get a 39 tooth
inner chain ring with a 50 on the outside. This isn't a racing setup, but I'm
not racing anyone, I'm out having FUN.

Maybe this is what your friend could do to help on those hills.

Tom

A 172.5 gives you more tork without sacrificing spin.  I ride a 54cm. frame,
so I'm not exactly tall, but I use 172.5s.  One place where I noticed the 
difference was at Fitchburg Criterium, when I tried 170s one year, on the 
theory that you want more spin in a crit.  I had to work a good deal harder 
coming out of the corners, and went right back to 172.5s.

Another place I noticed it was Mt. Washington Hillclimb.  The first year I
did that after moving up to 172.5s, I knocked 5 minutes off my previous best
time.  Some of it psychological, I'm sure, but my lowest gear was a 42-26, and
I remember that I was really hurting in 42-28 during previous climbs using 
170s.

As for 53 teeth -- if you're racing seniors or older, at least 70% of the rest 
of the field will be using 53s.  If you accelerate like a track sprinter, you
can simply outspin the people on the 53s, if you have a 52.  Otherwise, you're 
better off with a 53.  

If you don't race, I think you'll find the 172.5s will still help you in the 
hills, or going into the wind.  

    I've been riding 53 (round)/42 (Bio-Pace) lately.  On the first
    lap of a recent race, I dropped the chain downshifting into a 
    corner.  As I tried to coax it back onto the chainring, I heard
    somebody in the pack mutter, "53".  It must be a fairly common
    problem....
    
    MATT

    I remember a couple years ago, when I ras racing with 52/42 (both
    BIOPACE) that the chain used to occasionally drop onto the BB when 
    shifting from 52 to 42. I always assumed that it was poor shifting 
    on my part.
    
    Last year I raced with a 54/39 (both ROUND), and never dropped a
    chain - in training or racing. I would expect that the 54 to 39
    shift, which drops the chain a long way to that 39, would be worse,
    but it was better than the 52/42 biopace.
    
    Could shifting onto a small biopace chainring be a problem in racing
    where one is moving & spinning fast?
    
    Mark
    
    

< Note 1115.8 by USMRM5::MREID >
                       -<  chainrings & dropped chains  >-

I have that problem occassionaly too, using either 52/42 and 53/42 combos, 
both BIOPACE.  I too assume(d) that it is basically my fault.  

Your hypothesis seems plausible: due to the shape, does chain tension vary on 
every revolution?  Seems like it would.  Maybe at high cadence the rear 
derailleur can't take up the slack fast enough, allowing the chain to bounce 
around a bit.  Shifting at the wrong time might then fling the chain, 
increasing the likelyhood that it will get dropped.  Sound reasonable?

Kevin

ps.  Mark, what freewheel are you using with that setup (I would guess close 
to a straight block) and how do you find that setup for racing in the hills 
(assuming you do).

    I ride a 53/42 both round Campy chainrings and have never had a
    problem. However, on the MTB that uses BioPace, I am always having
    problems with chain hopping off on bad terrain and missing during
    a shift.

    
          RE: .6
    
              Thanks for the input.....I was afraid I was going to hear
    something like that ?!? now I might just have to `bite the old
    proverbial bullet' and spend more money that I wasn't planning on
    ?!?  ..........anything to go faster huh ????  I did do a considerable
    amount of weight work this winter to include heavy squats, and I
    think longer cranks would take advantage of strong quads....then
    again....my own theories have been known to be wrong before....d:-)
    
             I will probably give them a try, all risks aside.....
    
    ...Dave