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#11
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Need stretch: stem or seat post?
Raptor wrote: I like my new Rockhopper Comp, but it's a bit cramped. On a trail that's Your thoughts and equipment suggestions? Set up your saddle position correctly first. Stand next to a wall and stick a narrow book between your legs and crotch. press it up there pretty good and mark a spot on the wall at the top of the book. measure this distance to the floor. This will be your inseam measurement. Multiply inseam times 0.883. That will give you center-of-BB to cusp of saddle measured along c-line of seat post. Next adjust your sadlle for/aft position by using a plumb line from knob on knees when the pedal spindle at 9-o'clock. the plumb should fall behind (1cm) the spindle for MTB. Next, When you're sitting on the bike, look ahead normally, then move your eyes down and look at where your bars are in relation to your front hub. If your bars are behind the hub then your center of gravity is back too far. I generally look for my bars to be in line with the hub to one inch in front. Buy a stem accordingly. |
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#12
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Need stretch: stem or seat post?
"Duncan" wrote:
"Raptor" wrote So I'm leaning towards moving the saddle back further instead of the bars forward. I'd like a seat post with some set back, maybe 2" worth. I'm not really advocating it but I ride with my seat right back and a short stem. I just ended up that way from lots of incremental changes and maybe the fact my legs are slightly short for my height. I like the quick steering of a short stem and tend to ride with a lot of weight on the rear wheel (quite often 100%). Disadvantages include front wheel washout, bent seat rails and bent seat posts. If you have short legs for your height, the last thing you want to do from a biomechanical efficiency perspective is to move the saddle way back. The handling effects of a short stem pale in comparison to having your weight balance wrong on the bike (as you mention above). The key is to always (always, always) start with a bike that fits. Trying to force fit the wrong bike means you'll spend all your riding time having less fun than you should. Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#13
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Need stretch: stem or seat post?
Mark Hickey wrote: The key is to always (always, always) start with a bike that fits. Trying to force fit the wrong bike means you'll spend all your riding time having less fun than you should. Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame Mark's right. A frame has a top tube length designed to obtain a certain center-of-gravity. When you go adjusting a saddle way back with a bent seat post you screw that center-of-gravity up. If you can't get your saddle back far enough with a regular post then you need to go and buy a larger frame with a longer top tube. |
#14
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Need stretch: stem or seat post?
"Mark Hickey" wrote in message
... snip If you have short legs for your height, the last thing you want to do from a biomechanical efficiency perspective is to move the saddle way back. The handling effects of a short stem pale in comparison to having your weight balance wrong on the bike (as you mention above). The key is to always (always, always) start with a bike that fits. Trying to force fit the wrong bike means you'll spend all your riding time having less fun than you should. I agree with what you say but I did spend a lot of time finding the right bike for me. I even wanted the smaller size but my LBS talked me into the next one up (19" frame I'm 6'). It's just what works for me, I'm quite flexable so I have no comfort issues with the bike even doing 12 hour enduros in a pair. As for weight balance, when it really matters I stand up and the saddle doesn't play a part anymore. So it is a little strange, but it does work well for me. I think there can be a fairly large margin for personal preference especialy when you ride a lot and try different things. Even off the seat I have a tendancy to weight the back wheel: http://www.ftf.com.au/racegalleries/...MG0640_JPG.jpg |
#15
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Need stretch: stem or seat post?
"Duncan" wrote:
"Mark Hickey" wrote in message .. . snip If you have short legs for your height, the last thing you want to do from a biomechanical efficiency perspective is to move the saddle way back. The handling effects of a short stem pale in comparison to having your weight balance wrong on the bike (as you mention above). The key is to always (always, always) start with a bike that fits. Trying to force fit the wrong bike means you'll spend all your riding time having less fun than you should. I agree with what you say but I did spend a lot of time finding the right bike for me. I even wanted the smaller size but my LBS talked me into the next one up (19" frame I'm 6'). Normally, a 19" frame would be in the range for your height (depending on a host of variables though - including how the builder measures "frame size"). It's just what works for me, I'm quite flexable so I have no comfort issues with the bike even doing 12 hour enduros in a pair. As for weight balance, when it really matters I stand up and the saddle doesn't play a part anymore. Your seated position does have a huge effect on your balance - Mr. Newton had a few things to say about that. If you're moving your butt way back, and compensating with a very short stem, your center of gravity WILL be further back, and that WILL affect handling. So it is a little strange, but it does work well for me. I think there can be a fairly large margin for personal preference especialy when you ride a lot and try different things. Or (as I've seen over and over), a rider can get used to a bad position on the bike. Yes, everyone is different, but the reason the "average position" works for most people is because the vast majority of us have physiologies within a very narrow range. Perhaps you're outside of this "normal range" - perhaps you've gotten used to riding with what for most of us would be an inefficient position. Even off the seat I have a tendancy to weight the back wheel: http://www.ftf.com.au/racegalleries/...MG0640_JPG.jpg That's an odd position. What can I say? ;-) Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#16
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Need stretch: stem or seat post?
"Duncan" wrote: Even off the seat I have a tendancy to weight the back wheel: http://www.ftf.com.au/racegalleries/...MG0640_JPG.jpg Are you sure that's a 19" frame? It looks too small for you. |
#17
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Need stretch: stem or seat post?
CowPunk wrote:
Mark Hickey wrote: The key is to always (always, always) start with a bike that fits. Trying to force fit the wrong bike means you'll spend all your riding time having less fun than you should. Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame Mark's right. A frame has a top tube length designed to obtain a certain center-of-gravity. When you go adjusting a saddle way back with a bent seat post you screw that center-of-gravity up. That's kind of silly when you realize that people are different. I have several pounds of weight above my waist that many mountain bikers don't. By bending or straightening my arms, I can move my COG instantly, on most any bike. Most high performance bikes are bought "small," the smallest frame that fits. My bike's seat tube is long enough. The top tube might actually be optimal for a different rider with my particular build. I've just become comfortable leaning forward with arms more outstretched than many riders. If you can't get your saddle back far enough with a regular post then you need to go and buy a larger frame with a longer top tube. Seat tube angle and length has more to do with "proper" saddle location than top tube length. -- Lynn Wallace http://www.xmission.com/~lawall I have nothing but contempt and anger for those who betray the trust by exposing the name of our sources. They are, in my view, the most insidious of traitors." George H.W. Bush, April 16, 1999, |
#18
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Need stretch: stem or seat post?
Raptor wrote: Seat tube angle and length has more to do with "proper" saddle location than top tube length. So, with your rear saddle position, can you drift both wheels in a corner, or does one break loose before the other? I bet your rear slides out first? |
#19
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Need stretch: stem or seat post?
"Mark Hickey" wrote in message
... It's just what works for me, I'm quite flexable so I have no comfort issues with the bike even doing 12 hour enduros in a pair. As for weight balance, when it really matters I stand up and the saddle doesn't play a part anymore. Your seated position does have a huge effect on your balance - Mr. Newton had a few things to say about that. If you're moving your butt way back, and compensating with a very short stem, your center of gravity WILL be further back, and that WILL affect handling. Absolutely, my arrangement was as much for handling as it was for comfort. I tend to ride the back wheel, I like to keep the front light and the rear planted. For downhills this lets me manual through dips and extend the legs to drop the rear wheel through after. For climbing it gives lots of rear wheel traction but I can still lean forward to weight the front as needed. As I said this is personal choice and I know there are pros and cons. Just this morning I did a flat track race with tonnes of 'pea gravel' and was constantly shifting my weight forward for the faster looser corners to prevent front wheel washout. On the upside it gives a lot of practice saving front wheel washout that absolutley saved my skin on the mtorobike the other day. So it is a little strange, but it does work well for me. I think there can be a fairly large margin for personal preference especialy when you ride a lot and try different things. Or (as I've seen over and over), a rider can get used to a bad position on the bike. Yes, everyone is different, but the reason the "average position" works for most people is because the vast majority of us have physiologies within a very narrow range. Perhaps you're outside of this "normal range" - perhaps you've gotten used to riding with what for most of us would be an inefficient position. Well you've definatly given me reason to rethink my setup which is exactly what a good newsgroup should do. I do occasionaly try something different so I may well give it a go. I do also have a 20" on-one frame that is very long and I also have the seat quite far back on that as well. |
#20
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Need stretch: stem or seat post?
"CowPunk" wrote in message
ups.com... "Duncan" wrote: Even off the seat I have a tendancy to weight the back wheel: http://www.ftf.com.au/racegalleries/...MG0640_JPG.jpg Are you sure that's a 19" frame? It looks too small for you. Yeah it's definatly a 19", brands vary a lot in shape and where they measure. Keep in mind the bike is a race bike where agility is quite important. Our local race courses have a tendency to by quite tight singletrack where quick steering pays off. |
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