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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

2179.0. "MTB Top Tube Clearance = ???" by POLAR::TANSLEY () Fri Jan 31 1992 13:22

    
    Does anyone out there have opinions (knowledgeable or otherwise) on the
    "correct" amount of top-tube clearance for a Mountain Bike? A sampling
    of various mags, books, etc. has offerred the following:
    
    	o 2 to 2 1/2 inches
    	o No, you should have 3 to 4 inches
    	o Almost 6 inches (from the latest issue of some Mountain Bike mag
    	  or other) 
    	o Go with whatever feels comfortable, and gives you good power
    
    I'm tempted to go with overall comfort, except I find that the amount
    of clearance can vary from one brand to another (I'm shopping for my
    first bike in close to 20 years).
    
    	All cards and letters welcome, folks! Help to lead this poor
        child out of the wilderness!
                                     
    By the way, many thanks to those who so kindly responded to my earlier
    note 2160-something ("Novice needs help"). I'm making progress in my
    search (meaning I keep looking at more expensive bikes!). My bike of
    choice at the moment is a GIANT ATX 760 (partly because the Canadian
    distributor only beefs up the price by about 14% over the U.S. price,
    compared with about 20% for TREK and close to 30% for Specialized and
    Bridgestone).
    
    If anyone out there has opinions on the GIANT (either that bike in
    particular, or the Company in general), I'd welcome them too!
    
    Thanks for your help and interest.
    
    Doug (who has a 17 year old mind in a 40+++ year old body) Tansley.
     
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2179.1Don't buy with price as #1 prority.WLDWST::SANTOS_EFri Jan 31 1992 14:1727
    The most important reason why you want 3" clearance is for your
    safety . If you are to fall between the top tube you'd want to plant
    your feet down before your jewels hit the tube.
    One thing you should know besides clearance is top tube lenght . This 
    when properly fitted you will not be crunched that your elbows hit
    your knees when pedaling, and alows plenty of room for your lungs to 
    expand. ( The handle bar should cover the front hub from your view
    while riding , Road fit Rule). This can however be corrected by a new
    longer stem at extra cost. Your head tube angle will be affected also,
    ( steeper angles 70degree has longer top tube than 68degree angle.)
    This in turn will affect your steering . Steep angles are good for
    single tracks where you need to pick a path . Relaxed angles are good
    for fire roads and fast decents. The smaller the frame size the less
    weight you will have to push up the hill, less flex (lost of comfort)
    Easier to manipulate during extreme handling or when throwing it side
    to side for climbing off the saddle.
     6" clearance is too much for me cause the cost will go up when I have
    to buy a super long seat post, handle bar stem, and posibly new crank
    arms cause they will be shorter than desired. Buying a good bike does
    not mean spending the most. Find the best one for you then find ways
    to save like mail order , cross the border , order from a shop in the 
    US. You'll need the money for a helmet a pair of shoes, shorts etc,etc.
    
     Regards
    Ed S.
    
    
2179.2Price is about #4.POLAR::TANSLEYFri Jan 31 1992 16:5428
    
    Ed, I like the GIANT ATX 760 on the basis of fit, feel and quality,
    with price being a secondary factor. However, I want to make sure of 
    the right amount of clearance, for me, and what concerns me is that
    I may ride quite differently after a few months than I do now (remember
    that I'm totally green at this). However, the GIANT, with an 18 inch
    frame, feels "right" with respect to arms, back, legs, everything, and
    gives me about 3.5 inches of clearance. It has quite a long stem, and
    I can't see the front hubs at all -- this is very comfortable for me
    because I have long arms (and can reach the bars easily), and because
    the seat is well back over the rear wheels without being uncomfortably
    high. The ride also feels good, but then I'm not really experienced
    enough to know what to look for -- I'm just going by feel. Some of the
    bikes I've tried feel kind of "wooden", even light ones. The GIANT
    feels livelier. The best analogy I can make is that with some of the
    bikes I feel like I'm driving my wife's Chevvie station wagon, and with
    the GIANT (and a couple of others) I feel like I'm driving my Acura.
    Even though the GIANT (at 27.5 lbs.) and the Acura are both heavier,
    they have more life, more power, better handling, are more FUN, and oddly 
    enough, give me a LOT more confidence. The confidence, as much as anything,
    tells me that that the GIANT is probably a good choice, for me.
    
    Any thoughts on the ATX 760, or on GIANT? Any alternate suggestions?
    
    Thanks for your interest Ed.
    
    Doug.
                                  
2179.3Clearance is not only for stand-overDECWET::BINGHAMJohn BinghamFri Jan 31 1992 18:089
The place I found clearance most critical was when climbing.  When climbing and
the surface gets too soft, or the wheel wedges against a rock, or the wheel
loses traction ... and it is necessary to put feet down the clearance needed is
more than stand-over on the flat, significantly more.

It goes something like the more radical you ride the more clearance you need.
It is much easier to get off a smaller frame when you have to --- not if, when.
Small, stiff, keeping the length needed in the frame --- look at observed trials
frames.