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#1
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Thoughts about head tube
I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)? I really liked the front end of my former Specialized Allez. It seems from websites that many bikes have a short headtube. The Allez went much better than my old motobecane in handling. Why are so many designs of popular lines running with shortish head tubes? I gotta have an answer to this question. I know that a shorter wheelbase and short chainstays are supposed to help on ascents. Some bikes practically have the downtube joint right next to the toptube joint. Plus, not all websites mention actual numbers for this item. A fuji bike seems rather typical(plus the LBS has perceived these as a good value on componentry pricing). The head tube length is 189 mm. My old allez was in the 230 mm area. I think this quite a different. An inch and half to me is a huge, but I suppose others would disagree. The Fujis from the ads appears to have very little angle in the stem too. Another question in my ramblings pertains to the length of the stem. I am assuming that closest to the head tube equals more control. Isn't this correct? -- --- William O'Hara www.N1ey.com - Amateur Radio and Railfan Blog www.yahoogroups.com/group/illinoiscentral - premier discussion list ICRR |
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#2
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Thoughts about head tube
"William O'Hara" wrote:
I'm trying to figure this out. Is a taller head tube going to produce better handling(combined with less rake on fork)? I really liked the front end of my former Specialized Allez. It seems from websites that many bikes have a short headtube. The Allez went much better than my old motobecane in handling. Why are so many designs of popular lines running with shortish head tubes? I gotta have an answer to this question. I know that a shorter wheelbase and short chainstays are supposed to help on ascents. Some bikes practically have the downtube joint right next to the toptube joint. Plus, not all websites mention actual numbers for this item. A fuji bike seems rather typical(plus the LBS has perceived these as a good value on componentry pricing). The head tube length is 189 mm. My old allez was in the 230 mm area. I think this quite a different. An inch and half to me is a huge, but I suppose others would disagree. The Fujis from the ads appears to have very little angle in the stem too. Another question in my ramblings pertains to the length of the stem. I am assuming that closest to the head tube equals more control. Isn't this correct? It's a non-issue. You have to start from the assumption that the bars have to end up in the same position, no matter what the length of the head tube. Say you have two otherwise identical frame, one with a 12cm head tube and one with a 13cm head tube. You set up the latter with a 12cm stem and 1cm of spacers for the proper fit. To put the bars in the same position on the former, you'd simply use another cm of spacers, and the stem (and bars) would end up in precisely the same position. Hence, there's no effect on handling one way or the other. Other than that, the question becomes "does moving the bars up a couple inches change the handling", and the short answer is "yes". Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#3
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Thoughts about head tube
William O'Hara wrote:
I'm trying to figure this out. Is a taller head tube going to produce better handling(combined with less rake on fork)? if you mean "softer", yes. if you mean immediacy of response, no. longer tubes, anywhere on the bike, make for a more springy frame. obviously, you won't notice much between frames that only have a few mm difference between the top and down tube spacings on the head tube [the dimension that matters], but that's how the engineering principle works. I really liked the front end of my former Specialized Allez. It seems from websites that many bikes have a short headtube. The Allez went much better than my old motobecane in handling. Why are so many designs of popular lines running with shortish head tubes? see above. for aluminum frames, it makes for better fatigue properties too. I gotta have an answer to this question. I know that a shorter wheelbase and short chainstays are supposed to help on ascents. Some bikes practically have the downtube joint right next to the toptube joint. Plus, not all websites mention actual numbers for this item. A fuji bike seems rather typical(plus the LBS has perceived these as a good value on componentry pricing). The head tube length is 189 mm. My old allez was in the 230 mm area. I think this quite a different. An inch and half to me is a huge, but I suppose others would disagree. The Fujis from the ads appears to have very little angle in the stem too. Another question in my ramblings pertains to the length of the stem. I am assuming that closest to the head tube equals more control. Isn't this correct? |
#4
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Thoughts about head tube
Say you have two otherwise identical frame, one with a 12cm head tube
and one with a 13cm head tube. You set up the latter with a 12cm stem and 1cm of spacers for the proper fit. To put the bars in the same position on the former, you'd simply use another cm of spacers, and the stem (and bars) would end up in precisely the same position. Hence, there's no effect on handling one way or the other. Other than that, the question becomes "does moving the bars up a couple inches change the handling", and the short answer is "yes". What about ride quality? -- --- William O'Hara www.N1ey.com - Amateur Radio and Railfan Blog www.yahoogroups.com/group/illinoiscentral - premier discussion list ICRR |
#5
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Thoughts about head tube
jim beam wrote in
t: William O'Hara wrote: I'm trying to figure this out. Is a taller head tube going to produce better handling(combined with less rake on fork)? if you mean "softer", yes. if you mean immediacy of response, no. longer tubes, anywhere on the bike, make for a more springy frame. obviously, you won't notice much between frames that only have a few mm difference between the top and down tube spacings on the head tube [the dimension that matters], but that's how the engineering principle works. If this is case, then why don't more bikes go in this direction? Isn't this desired with the "comfort performance roadbikes?" -- --- William O'Hara www.N1ey.com - Amateur Radio and Railfan Blog www.yahoogroups.com/group/illinoiscentral - premier discussion list ICRR |
#6
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Thoughts about head tube
Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes". Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame I see there is a difference between your "team frame" and the regular road frame. You used a different downtube and you have the musucular chain stays. Why the design differences? The regular road looks pretty good to me. I'm actually thinking that perhaps I should get the 62 or 64 for a new bike. -- --- William O'Hara www.N1ey.com - Amateur Radio and Railfan Blog www.yahoogroups.com/group/illinoiscentral - premier discussion list ICRR |
#7
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Thoughts about head tube
William O'Hara wrote:
jim beam wrote in t: William O'Hara wrote: I'm trying to figure this out. Is a taller head tube going to produce better handling(combined with less rake on fork)? if you mean "softer", yes. if you mean immediacy of response, no. longer tubes, anywhere on the bike, make for a more springy frame. obviously, you won't notice much between frames that only have a few mm difference between the top and down tube spacings on the head tube [the dimension that matters], but that's how the engineering principle works. If this is case, then why don't more bikes go in this direction? Isn't this desired with the "comfort performance roadbikes?" you mean longer head tubes? because if the frame designed knows their business, they'll know the head tube [and attendant jointing] is highly stressed and therefore subject to substantial flex and fatigue. longer head tubes exacerbate the problem. |
#8
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Thoughts about head tube
"William O'Hara" wrote:
Say you have two otherwise identical frame, one with a 12cm head tube and one with a 13cm head tube. You set up the latter with a 12cm stem and 1cm of spacers for the proper fit. To put the bars in the same position on the former, you'd simply use another cm of spacers, and the stem (and bars) would end up in precisely the same position. Hence, there's no effect on handling one way or the other. Other than that, the question becomes "does moving the bars up a couple inches change the handling", and the short answer is "yes". What about ride quality? Depends on whether it makes the bike fit better or not. It's impossible to say otherwise, since it's an independent variable. Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#9
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Thoughts about head tube
"William O'Hara" wrote:
Other than that, the question becomes "does moving the bars up a couple inches change the handling", and the short answer is "yes". I see there is a difference between your "team frame" and the regular road frame. You used a different downtube and you have the musucular chain stays. Why the design differences? The regular road looks pretty good to me. I'm actually thinking that perhaps I should get the 62 or 64 for a new bike. The differences are the S-stays and the oversize oval down tube. That provides a bit more BB stiffness and better heel-to-stay clearance (which isn't an issue for most riders). There won't be any difference in "ride quality" however. Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#10
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Thoughts about head tube
"jim beam" wrote in message t... William O'Hara wrote: jim beam wrote in t: William O'Hara wrote: I'm trying to figure this out. Is a taller head tube going to produce better handling(combined with less rake on fork)? if you mean "softer", yes. if you mean immediacy of response, no. longer tubes, anywhere on the bike, make for a more springy frame. obviously, you won't notice much between frames that only have a few mm difference between the top and down tube spacings on the head tube [the dimension that matters], but that's how the engineering principle works. If this is case, then why don't more bikes go in this direction? Isn't this desired with the "comfort performance roadbikes?" you mean longer head tubes? because if the frame designed knows their business, they'll know the head tube [and attendant jointing] is highly stressed and therefore subject to substantial flex and fatigue. longer head tubes exacerbate the problem. I'm not so sure. A longer head tube is torsionally softer and will allow more out of plane/lateral deflection of the frame elements but I don't see how this translates to higher stresses/fatigue. It does however result in a poorer handling frame when cornering. Phil H |
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