|   Hardtail Bobing | pahana
Nov 25, 2003 12:45 PM | | On my hardtail I start to bob up and down when I spin at 100rpm. What am I doing wrong? I like to pedal at 90 to 100rpm and I don't have this problem on my FS bike.I'm 5ft 4in. and I use an 175mm crank is this the cause too long a crank for my body type? I ride 175mm cranks on my FS bike and have no problem spinning fast.Both bikes have almost the same fit what's going on here? HELP |
| are u spinning on a smooth surface? | RVM
Nov 25, 2003 2:06 PM | | or is it bumpy? Maybe u just need to change to a different gear. |
| re: Hardtail Bobing | Damion
Nov 25, 2003 2:09 PM | | 1 of 2 things. I have found a timing resonance in a similar situation. Start with your spin. Are you pulling all the way through your pedal stroke? I try to train my spin by riding with knobbies on pavement and listening to the sound. The knobby growl faded and grew louder with my pedal strokes, and learned to spin circles that way.If it is not the spin... It is either the fork or the tires. Start with the tire pressure. I have found that a slightly firmer tire will help with this anomality. The second is harder to deal with, depending on the fork. Good luck. |
| try lowering your seat slightly, 5mm or so | FM or MF
Nov 25, 2003 2:36 PM | | If your seat is just a tiny bit high, it will cause your pelvis to rock on the saddle without causing knee pain. The pelvis rocking turns into bob as you are effectivly shifting your weight side to side every pedal stroke. try it. |
| re: Hardtail Bobing | jasonwa
Nov 26, 2003 7:03 AM | | Maybe a small hop in the rim but i am sure you have checked that. |
| re: rear wheel out-of-round... | thad(earthworm)thadthetroll
Nov 26, 2003 10:11 AM | | possibility... |
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