Surly Pacer Frame Query
09-06-20, 09:13 AM
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Surly Pacer Frame Query
Hi !
Query : Surly Pacer 50cm
Pacer Geometry Chart
I had built this bicycle frame up, but somehow did not ride her much,. While doing some measurements, found that the wheelbase was 965mm instead of 985mm. Was pretty confused , however on closer inspection found that the Head tube angle was around 74 degrees which should have been 72 degrees.
From the geometry chart above 58cm to 62cm have this steep head tube angle
I had some queries with regards to this
1. Is this too steep of a head tube angle?
2. Is this bicycle safe to ride, since I am not too experienced.
2. Is there any issue on downhill or high speed turns that one should be concerned about ?
Any further advice that you'll could give me........
Query : Surly Pacer 50cm
Pacer Geometry Chart
I had built this bicycle frame up, but somehow did not ride her much,. While doing some measurements, found that the wheelbase was 965mm instead of 985mm. Was pretty confused , however on closer inspection found that the Head tube angle was around 74 degrees which should have been 72 degrees.
From the geometry chart above 58cm to 62cm have this steep head tube angle
I had some queries with regards to this
1. Is this too steep of a head tube angle?
2. Is this bicycle safe to ride, since I am not too experienced.
2. Is there any issue on downhill or high speed turns that one should be concerned about ?
Any further advice that you'll could give me........
09-06-20, 09:28 AM
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second 2- Your post suggests you have ridden this bike at least some. Was it stable enough for you to control it? If so then you have this question's answer already. If not then I suggest your post could have reflected the control issues you experienced.
first 2- See above.
1- See above again. The question of what's "too steep" is determined by how the rider deals with the bike's handling. Otherwise there's no too much or too little head angle, excepting stuff like toe clip clearances.
The last line on the geometry chart says it all. "All dimensions are preliminary and subject to change" This is one big reason why published charts are not a guaranty of what any one bike actually has, component or geometry wise. The second reason is that produced frames drift from intended specs all the time, production methods and care are not exactly the same every hour of any day. The third reason is that the person who established this chart is not the same person who designed the specs to begin, or the persons who set up the jigs, or who did the fabrication...
I feel the only answers to your questions will be found out by you, riding the bike in various conditions and see what happens. Humans and bike riders have an amazing ability to deal with widely varying bike designs, some designs are easier to ride and some less so. See this "classic" article for more about bike handling and being able to ride the bike, or not. Andy
https://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf
first 2- See above.
1- See above again. The question of what's "too steep" is determined by how the rider deals with the bike's handling. Otherwise there's no too much or too little head angle, excepting stuff like toe clip clearances.
The last line on the geometry chart says it all. "All dimensions are preliminary and subject to change" This is one big reason why published charts are not a guaranty of what any one bike actually has, component or geometry wise. The second reason is that produced frames drift from intended specs all the time, production methods and care are not exactly the same every hour of any day. The third reason is that the person who established this chart is not the same person who designed the specs to begin, or the persons who set up the jigs, or who did the fabrication...
I feel the only answers to your questions will be found out by you, riding the bike in various conditions and see what happens. Humans and bike riders have an amazing ability to deal with widely varying bike designs, some designs are easier to ride and some less so. See this "classic" article for more about bike handling and being able to ride the bike, or not. Andy
https://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf
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AndrewRStewart
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Last edited by Andrew R Stewart; 09-06-20 at 09:41 AM.
09-06-20, 11:40 AM
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A 74 degree head angle should be perfectly rideable. This used to be fairly normal on road frames but greater slackosity is in vogue now. You could make it a bit slacker by fitting a headset with a taller lower stack.
09-06-20, 01:57 PM
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sounds like it was in a head on crash. Do you have any pictures?
09-06-20, 02:09 PM
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09-06-20, 03:16 PM
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Yea, I guess I should assume the OP has left out all kinds of info. That would be par for this forum
Like getting the frame used instead of new. "I had built this bicycle frame up" Just seemed like the frame was new to me... Andy
Like getting the frame used instead of new. "I had built this bicycle frame up" Just seemed like the frame was new to me... Andy
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09-06-20, 06:55 PM
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That was my first impression too, but I don't think Surley is going to be that far off. It's weird that the tall bikes have 74 degree HTA.
09-06-20, 09:19 PM
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[QUOTE]sounds like it was in a head on crash[QUOTE]
Sorry, my bad ,should have mentioned the frame was purchased new and no crashes.
My other rides have wider tires and slightly taller head tubes, I am not too comfortable on road bikes, since I have a back issue and slight hip problem as well. However the Pacer could accommodate 32mm tires and I could keep the (uncut)steerer tube slightly longer than the average road bike, just to be upright, hence the purchase.
Thank you Andy for the detailed reply ! No per say, I haven't had any issues with handling, with what little I have ridden. I appreciate you explaining the pointers in detail , I am a bit OCD, and hence the query with 74 degree and lesser trail , but you have clarified that as well.
Life's a learning process , you just need someone to spell it out. I agree the build process is just not about geometry charts, but a lot more.
thanks for all your replies.
Sorry, my bad ,should have mentioned the frame was purchased new and no crashes.
Buy something else ? LHT? you act like you don't want a road bike..
second 2- Your post suggests you have ridden this bike at least some. Was it stable enough for you to control it? If so then you have this question's answer already. If not then I suggest your post could have reflected the control issues you experienced.
first 2- See above.
1- See above again. The question of what's "too steep" is determined by how the rider deals with the bike's handling. Otherwise there's no too much or too little head angle, excepting stuff like toe clip clearances.
The last line on the geometry chart says it all. "All dimensions are preliminary and subject to change" This is one big reason why published charts are not a guaranty of what any one bike actually has, component or geometry wise. The second reason is that produced frames drift from intended specs all the time, production methods and care are not exactly the same every hour of any day. The third reason is that the person who established this chart is not the same person who designed the specs to begin, or the persons who set up the jigs, or who did the fabrication...
I feel the only answers to your questions will be found out by you, riding the bike in various conditions and see what happens. Humans and bike riders have an amazing ability to deal with widely varying bike designs, some designs are easier to ride and some less so. See this "classic" article for more about bike handling and being able to ride the bike, or not. Andy
https://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf
first 2- See above.
1- See above again. The question of what's "too steep" is determined by how the rider deals with the bike's handling. Otherwise there's no too much or too little head angle, excepting stuff like toe clip clearances.
The last line on the geometry chart says it all. "All dimensions are preliminary and subject to change" This is one big reason why published charts are not a guaranty of what any one bike actually has, component or geometry wise. The second reason is that produced frames drift from intended specs all the time, production methods and care are not exactly the same every hour of any day. The third reason is that the person who established this chart is not the same person who designed the specs to begin, or the persons who set up the jigs, or who did the fabrication...
I feel the only answers to your questions will be found out by you, riding the bike in various conditions and see what happens. Humans and bike riders have an amazing ability to deal with widely varying bike designs, some designs are easier to ride and some less so. See this "classic" article for more about bike handling and being able to ride the bike, or not. Andy
https://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf
Life's a learning process , you just need someone to spell it out. I agree the build process is just not about geometry charts, but a lot more.
thanks for all your replies.
