נושא: שמע גם אני התלבטתי בשאלה הזאת ולצערי תאריך: 7/17/2010 11:11:00 PM
מחבר/ת: איתן הדרי
קיבלתי כל מיני תשובות. תחושת הבטן שלי הייתה שהרוכבים לא ממש יודעים מה ההבדל ביניהם. מה עשיתי? כתבתי לסראם מה ההבדל בין הכלובים ולמה יש בכלל הבדלים? אני מעתיק לך את התשובה שקיבלתי מחברת סראם ומקווה שזה עונה על שאלתך.
Long/Medium/Short cages and TDC
How do you know what derailleur to put on a bike? Short cage works on any road bike, right? Why not a mountain bike? Why a downhill bike?
Here is the deal:
Before we go into what cage is appropriate, we´re going to cover something called Total Drivetrain Capacity or TDC. TDC is an easy thing to measure on your bike (you may be able to determine it without looking at your bike). It is the difference in teeth between the smallest and largest cog, added to the difference in teeth between the smallest and largest chainring. Here´s a couple examples:
Most XC bikes you sell on your floor have an 11-34 cassette and a 22/32/44 chainring combo. So that is (34 minus 11) added to (44 minus 22). 34-11=23 + 44-22=22 for a TDC of 45t. Now, how about one of the downhill bikes you love to work on? 12-26 cassette and one chainring. 26-12 is 14 so that is the TDC on your downhill bike.
How does that fit into determining what derailleur to use? Well, if you look in our tech manual, you´ll see the Total Drivetrain capacity for each derailleur specified. Since you´re here reading, I´ll tell you what they are:
Long: 45t capacity
Medium: 37t capacity
Short: 30t capacity
That is all there is to it. I hope you learned something new!
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