Conference noted::bicycle

    I have a Stumpjumper also....does your chain ride up around the
    brake and rub the braze-on that holds the brake?? I haven't had
    any trouble with the chain getting caught between the tire and the
    U-brake (is this what you were talking about??). How fat were the
    tires on your bike.....I have Ritchy Duro-K...2 inches. I'll check
    my bike just to be sure.
    
                                         Doug
    

Re: .1

I put on a pair of Specialized Ground Controls, 1.95" wide.  I was running
the standard 1.5" Hardpacks.  As a better description of the problem, the
U-brake shoes, when closed, rubbed on the sidewall of the rolling tire. I
adjusted the shoes so that they made contact just a little more on the inner
portion (toward the center of the wheel) of the rim.

Concerning chain snags, it has nothing to do with the tire: your description
is just what happened to me.  I only mentioned it as one more headache that
I've had with U-brakes.

.jim

    By the way, does your Stumpjumper have the Shimano Deore
    shifter/deraillers or does it have the Suntour xc stuff??
    I thought that this chain thing might be caused by the derailler
    not keeping the chain tight enough. I know of several bikes with
    U brakes that definitely do not have this problem. 
                                
    

    Is the Shimano Deore good or bad?  I'm considering a Trek 400T,
    and the Deore is standard on the rear.

    
    	I've seen this happen with the U brakes.    Stop to unhook
    the chain.    Bend the rim just a little, and before you know
    it the tire is trash.   They're hard to adjust, and collect
    lots of dirt.
    	I'll stick to the standard cantilevers, thanx.
    
    	Alan.

    Last year I had the problems with the U-brake.  I removed 2 links
    and added the Shimano Shark-fin on the chainstay.  I have had
    very little problems since then.  If it does happen, as soon as
    I feel it, I back peddle 1/2 turn and the chain re-engages on the
    small chainring.  
    
    re: 721.3  Shimano Deore on a touring bike is an excellent derailleur.
    
    steve

    I just killed a tire with cantilever brakes as well.  It seems the
    brake pad's were hitting on the tire slightly. (Mostly a problem
    with keeping the back wheel on straight with an imperfect frame)
    
    Robb

Re: .3

Mine's an '87 Stumpjumper with Suntour XC9000.  Has worked flawlessly: after
a full year of hard use, it has needed one minor adjustment which was done
with a quarter turn of the barrel adjuster.  I realize that I may be the
exception to the rule, however...

Re: .6

How does a chainstay protector (shark fin) help?  The chain snag problem 
happens below the chainstay, not above it.  I have seen the very recent 
shark *tooth*, which seems like it might help: it bolts onto the bottom
of the U-brake braze-on that's on the chain side.

.jim

    re:.8 
    The reason I asked is that mine is also the xc9000. I thought maybe
    the derailler is not holding the chain tight enough. After reading
    other notes (I have just started reading this notes file), Note
    441...Biopace chainrings....mentions the exact same problem. There,
    they believe it to be a result of the chain rings. I think it is
    a chainring-U brake-chain slack problem. The chain may be too long
    or the action of shifting down causes to much slack and the derailler
    cannot take up that much slack. First thing you know, the chain
    rides up above the U brake. The reason the Deore shark fin helps
    is that when you back pedal to keep the chain from rising, the chain
    can get caught in between the tire and the brake or chainstay.
    I think that the idea of taking a link or two out of the chain may
    help. Maybe switching to a derailler that will take up the slack
    will help. Maybe some kind of reverse shark fin that will prevent
    the chain from getting around the U-brake will help. Maybe switching
    to round chain rings will help. If you don't ride through a lot
    of mud (it hasn't rained here in a month), U-brakes are great. 
    They have excellent stopping power. I am going to upgrade to the
    Deore components this weekend (I have other reasons besides having
    this chain problem), and will tell you if it helps. 
    
                                       Doug
    

>    will help. Maybe some kind of reverse shark fin that will prevent
>    the chain from getting around the U-brake will help. Maybe switching

The "reverse shark fin" you hypothesized is exactly what I was describing
as the Deore Shark Tooth, and it already exists -- I've seen it on some
88 bikes.

.jim

Switching to all Deore components may be quite expensive and I don't really
think that it will help much.  I have an '87 Stumper as well and can't believe
some of the problems that I'm hearing.  I've ridden mine hard for about a year
and couldn't be more pleased.  I suspect that the XC9000 can wrap the chain
just as well as the Deore.  Also I love the Suntour brake lever/shifter
combination.  You'll have to give that up since I don't think that the shifters
are compatable.  The Deore has the same capacity as the XC9000 and both are
basically the same design.  I would also guess that the chain has a couple
extra links.  I'm not sure if this holds for a triple setup but a general rule
of thumb is to put it in the highest gear and the jocky wheels on the
derailluer should be perpendicular to the ground.  Remember that with such a
wide range any derailleur will have trouble keeping all the gears tight. 

I an still using the 1.5 inch tires but was going to switch to 1.9 or 2.0 this
winter (since there is no mud in Cal. in the summer the thinner 1.5 are ideal
for now).  Is Specialized the only bike with the tire rubbing problem? Road
bike brakes come in short or normal reach versions, but U-brakes?  If others
have made such changes and have no problems then let us know. 

    After thinking about this problem of the U-brake rubbing, the problem
    stems from frames with the standard dropout.  I have vertical dropouts
    on my Fisher, with 2.25" tires with no problem.  If you use standard
    dropouts and leave the wheel foreward, you may end up with the rubbing
    problem.  The solution:  Pull the wheel as far back in the dropout
    as possible then adjust your brake pads.
    
    steve

    re: .12
    
    	Yes, how far your wheel is back in the dropout can cause the
    tire rubbing problems, that end up by wasting the tire.
    
    	I, for one, prefer to keep my wheel forward in the dropout,
    to shorten the wheelbase a little bit.   I think it's a drag that
    the brake adjustment has to be changed if I move the wheel.
    A brake in the standard 'seat stay' position does not have this
    problem.   It'd be just one more thing I have to worry about at
    the time I adjust the brake shoes.
    
    	I have destroyed a tire with my standard cantelievers, too,
    but those U brakes by the bottom bracket seem to eat a *lot* of 
    tires.   I think the arc through which the brake shoes travel 
    makes this sort of thing much more likely with the U brake.
    
    	It is all to easy to knock a rim out of true in off road
    riding, or to get a flat and end up with the wheel moved a little
    bit.   All in all, I have decided that the U brake is not worth
    it, and I will stick to the seat stay cantelievers.
    
    	Alan.

    For those people who have purchased a bike with U-Brakes however
    don't have the option of going with Cantilever.  I was stating
    how to fix the problem, not decide which is better.
    
    steve

    Well, I switched to the Deore shifters because I already had 
    a freewheel and derailler from a previous bike. I bought the bike
    from a guy that road it is Chicago on a college campus. the largest
    rear ring was a 24...not good for someone who rides mountainous
    terrain. I had a choice of buying freewheel or shifters, and I chose
    shifters. The Deore transmission shifts much smoother. An interesting
    side note is that the spacing between the Shimano freewheel and
    the Suntour freewheel was exactly the same...I was able to swap
    the freewheel and ride the Suntour shifters with the Shimano
    freewheel!!  Anyway, I took several links out of the chain, and
    the chain still jumped up on the U-brake. I swapped deraillers,
    and the chain still jumped up on the U-brake. I put on the Shark
    tooth, and it stopped jumping up on the U-brake. I think that the
    problem is the Biopace chainrings, and the slack that is caused
    when shifting to the small chainring. Anyone who has this problem
    should invest $2.00 in a Sharktooth. It takes 5 minutes to install,
    and you'll never have the chain jump problem again. I have ridden
    15-20 miles since installation. Normally, my chain would have jumped
    10 times. It did not jump even once!! 
    
    re: 721.11
        I think that the xc9000 is good, but not as good. It does shift,
    but there is more lag time in the shift, the shift is not as smooth,
    and I can pull the shifters down one shift on a really heavy-duty
    uphill. My shifters have an annoying habit of skipping one of the
    high gears. I would not have done the upgrade if I did not already
    have a freewheel and derailler. The slightly better Deore transmission
    is not worth laying out very much more money. In fact, I plan to
    keep the Suntour components around in case I ever break something
    and need a backup SIS transmission in the short-run.
    
                                     Happy Stumpjumping...
    
                                            doug
    
    

    re: -.1 
    
    I've heard that several mountain bike builders have stopped using
    the BIOPACE small due to that problem.
    
    U-Brakes mounted by the cranks should also disappear from the market
    within a year or two as well, as some of the custom builders have
    cantilever brake mounts as a standard option.
    
    Robb

    Has anyone converted their bikes from U-brake to cantilever? Obviously
    this takes brazing on pegs and will wipe out the paint job in the
    brazed areas. I am getting desparate after getting a U-brake slash
    even with switching to the narrower kool-stops and keeping an eye
    on the adjustment. One of the problems of the U-brake is that it
    swings through a *large* tire approaching arc as the blocks wear
    versus the movement *away from* the tire of the cantilever.
    
    Assuming a do-it-yourself camoflauge paint touch-up :^) and Deore
    cantilevers and a midrange chrome-moly frame has anyone found any
    prices for the conversion or hidden expenses or problems??
    
    Thanks,
    Thom