When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Bike Geometry and Ride
- Thread starter Miq
- Start date
#eBayPartner Most Recent BUY IT NOW Items Listed on eBay
SKPC
Cruisin' on my Bluebird
I think that what John is pointing to is that no matter what #1 IS, it is a starting point. #2 applies to how and what you add to the frame and fork. These items help fit individuals to the fixed geometry and SIZE of the frame and fork you are building up. If you put a different fork on the frame that changes the frames' numbers, (longer, shorter, steeper or more lax with different offset), it will feel "different" with ride qualities changing no matter the parts mix. The chosen parts in #2 will affect how the old frame and fork end up "feeling" when rolling down the road. Frame geometry and fork offset is more noticeable when in Off-Road or in slower and tighter situations when you have to be more accurate in your line choices. These not-always-obvious riding qualities are even less noticeable when flying down the pavement going straight. No matter what the frame/fork numbers say, the person choosing the parts mix definately affects how the old fixed-number frame/fork will end up riding. That is just my experience after years of converting these old frames and forks to more "useable" riders. Variety is the spice of life I say when it comes to this. We also adjust and swap parts out over time on these old frames and forks, fine tuning them to our own personal preferences and based on the surfaces we are riding on. I feel that almost any old frame and fork, no matter the size, can be made to fit anyone. Just look at the tiny BMX bikes tall people set up to be "rideable"...
Being tall and heavier, frame/fork flex is also noticeable to me bike to bike. The Monarch Silver King duraluminum flex-master frame was a noodle I ended up busting. All of the frames & forks I end up building and keeping around are heavy guage, and pretty stiff, and all exhibit a different personality at the end of the day based on how they are set up. I will say though that the most surprising thing I found when I did the AMPS 7-bike test a few years ago, the Westfield Fattie single speed came out on top. It was the most enjoyable when blind-rating them post-ride based on the most noticeable basic things. It came out that simple, in-the-middle geometry with the ability to move around on the seat, bars and pedals made for the most highly rated bike, not the fancy parts. Wide steerhorn bars, the three-springer seat and flat Torrington pedals allowed for multiple hand, seat and foot positions that helped a TON on the longer rides I typically do...The Westfield was so user-freindly and nuetral-feeling, noticeably so. Sitting, standing, sprinting, steering, it just felt "spot on", but the ability to change hand, butt and foot positions at any time helped take it to the top spot in the "American Metal Performance Shootout"..
What bike did you ride today? | General Discussion About Old Bicycles
This one forgot phone again…
thecabe.com
Last edited:
Miq
Cruisin' on my Bluebird
Thanks for adding thoughts and ideas to this thread. I haven't stoked this topic in a while, it is nebulus, requires tedious measurements, and people tend to loose interest quickly. I brought it up again because I was able to measure a bike I have owned for over 30 years and wanted to compare it to my other bikes on the chart. This has been where this thread has been the most effective, comparisons of similar sized bikes set up by the same rider. Like @SKPC Pete's beautifully written AMPS, and @J-wagon 's descriptions of his bikes, there is real value in one person's evaluation of their bikes and their geometries. But it is not easy to generalize that riding experience to other bikes and riders.
I see a lot of parallels between biking and playing a musical instrument. I think people like @Tim the Skid @Mr. Monkeyarms @Bleecker @soddruntlestuntle and the other musicians reading this will relate. Your bike and your instrument become an extension of you. There is a feedback loop around your brain, body and the bike or instrument. You give it inputs from your body like moving your fingers, arms, legs, hips etc. and then interpret the results using your ears, eyes, sense of balance, body awareness and make quick adjustments to get the results you want. By wrapping the bike/instrument into this mental feedback loop you get an intimate understanding of how the device responds, especially after "practicing/riding" for hours and hours. But this understanding applies only to you, and the way that particular instrument/bike responds to you while you play that song or ride that terrain. It is hard to extend those experiences to another bike and rider. How does their body fit on their bike? How differently is their bike set up than your bike? How many times have they ridden that terrain? We know all that matters. This also leads to everyone customizing their bikes/instruments to fit them and the riding/songs they play and no one doing it exactly the same as anyone else. One of my favorite parts of being on the CABE is getting exposed to all the different bikes and terrain you post. Its a lot like listening to new music, certain combinations really connect with me, others don't, but I'm glad to be exposed to it. I feel like I'm getting a better appreciate for all of it.
Another thing I get from looking at this with you is what @J-wagon @Schwinn Sales West and @SKPC mentioned again above.
The numbers for the frame/fork geometry is only part of how a bike rides and those numbers change even within the same model. Some of the big contributors to this I see are handlebar and saddle position choice. My Klunkmaster and Cruiser frames and forks have somewhat similar numbers, but the handlebars and layback seatpost have a huge affect on how they ride. It's totally obvious when you look at the picture overlay and imagine how differently the rider's body weight is distributed over the frame. Sweeping the bars back and raising them leads to a much more upright riding position (aka a Cruiser)
The basic geometeries are similar but the ride is completely different. Tires, gearing, brakes etc also contribute to how different they feel.
This was why we added the "Handlebar" column. But its hard to capture things like using a layback seatpost, where I've intentionally altered the effective seat tube angle by using a non-straight post. It points to the bigger issue that makes this a difficult topic. You can't rely totally on the geometry numbers to give you the full picture, there's much more to it. Like buying a musical instrument, the best advice anyone can give you is to ride/play it before you buy it. Every instrument or bike is different, even the same model from the same maker. You need to see how it works with you before you buy it, or be confident you can adjust/modify to fit you.
Like @J-wagon mentioned above, the geometry numbers change even within the same model as the size of the bike changes. Here's a glimpse into the latest geometries Joe Breeze has been playing with for his Cr-Mo rigid Thunder off road bike:
Seat tube angle changes a degree from SM to XL within the same model to get the fit they way they want.
I also saw this overlay pic Joe Breeze created when he was seeing how far he could push the head tube angle (78 deg).
Nice to see a well executed overlay. Speaks a 1000 words. Hard to argue that the relationships between the seats, pedals, wheels, grips and trail were not the same. I love Joe's decription of riding it (practicing), getting good at riding it, then the shock of trying another more conventional bike in the brain - body - bike - body - brain feedback loop.
Comparisons between bikes that have focused single attribute differences, like only head tube angle, are not normal. You have to be a frame builder/designer to create that level of focus. When we try to compare bikes its not nearly as easy for all the reasons we have been talking about and more. We can't control all the variables to adjust just one.
But it is possble for us to make evaluations of how differences between similarly sized bike geometries contribute to differences in the ride. Increasing head tube angles leads to faster turning bikes, even slightly different bikes with significantly different heat tube angles will expose this difference. Shortening the rear triangle and moving weight further to the back of the bike will improve climbing, even if the two bikes being compared are not exactly the same. Its trends like these that we are really watching. How do the designers make tradeoffs to appeal to riders who want a certain performance on certain terrains? I'm starting to get a beginners feel for it from looking at it with you as we build, modify, evaluate the bikes we are designing.
I see a lot of parallels between biking and playing a musical instrument. I think people like @Tim the Skid @Mr. Monkeyarms @Bleecker @soddruntlestuntle and the other musicians reading this will relate. Your bike and your instrument become an extension of you. There is a feedback loop around your brain, body and the bike or instrument. You give it inputs from your body like moving your fingers, arms, legs, hips etc. and then interpret the results using your ears, eyes, sense of balance, body awareness and make quick adjustments to get the results you want. By wrapping the bike/instrument into this mental feedback loop you get an intimate understanding of how the device responds, especially after "practicing/riding" for hours and hours. But this understanding applies only to you, and the way that particular instrument/bike responds to you while you play that song or ride that terrain. It is hard to extend those experiences to another bike and rider. How does their body fit on their bike? How differently is their bike set up than your bike? How many times have they ridden that terrain? We know all that matters. This also leads to everyone customizing their bikes/instruments to fit them and the riding/songs they play and no one doing it exactly the same as anyone else. One of my favorite parts of being on the CABE is getting exposed to all the different bikes and terrain you post. Its a lot like listening to new music, certain combinations really connect with me, others don't, but I'm glad to be exposed to it. I feel like I'm getting a better appreciate for all of it.
Another thing I get from looking at this with you is what @J-wagon @Schwinn Sales West and @SKPC mentioned again above.
Nice addition to chartI guess maybe consider a column for frame size, esp for more modern mtb, as can affect wheelbase etc.
The numbers for the frame/fork geometry is only part of how a bike rides and those numbers change even within the same model. Some of the big contributors to this I see are handlebar and saddle position choice. My Klunkmaster and Cruiser frames and forks have somewhat similar numbers, but the handlebars and layback seatpost have a huge affect on how they ride. It's totally obvious when you look at the picture overlay and imagine how differently the rider's body weight is distributed over the frame. Sweeping the bars back and raising them leads to a much more upright riding position (aka a Cruiser)
The basic geometeries are similar but the ride is completely different. Tires, gearing, brakes etc also contribute to how different they feel.
This was why we added the "Handlebar" column. But its hard to capture things like using a layback seatpost, where I've intentionally altered the effective seat tube angle by using a non-straight post. It points to the bigger issue that makes this a difficult topic. You can't rely totally on the geometry numbers to give you the full picture, there's much more to it. Like buying a musical instrument, the best advice anyone can give you is to ride/play it before you buy it. Every instrument or bike is different, even the same model from the same maker. You need to see how it works with you before you buy it, or be confident you can adjust/modify to fit you.
Like @J-wagon mentioned above, the geometry numbers change even within the same model as the size of the bike changes. Here's a glimpse into the latest geometries Joe Breeze has been playing with for his Cr-Mo rigid Thunder off road bike:
Seat tube angle changes a degree from SM to XL within the same model to get the fit they way they want.
I also saw this overlay pic Joe Breeze created when he was seeing how far he could push the head tube angle (78 deg).
Nice to see a well executed overlay. Speaks a 1000 words. Hard to argue that the relationships between the seats, pedals, wheels, grips and trail were not the same. I love Joe's decription of riding it (practicing), getting good at riding it, then the shock of trying another more conventional bike in the brain - body - bike - body - brain feedback loop.
Comparisons between bikes that have focused single attribute differences, like only head tube angle, are not normal. You have to be a frame builder/designer to create that level of focus. When we try to compare bikes its not nearly as easy for all the reasons we have been talking about and more. We can't control all the variables to adjust just one.
But it is possble for us to make evaluations of how differences between similarly sized bike geometries contribute to differences in the ride. Increasing head tube angles leads to faster turning bikes, even slightly different bikes with significantly different heat tube angles will expose this difference. Shortening the rear triangle and moving weight further to the back of the bike will improve climbing, even if the two bikes being compared are not exactly the same. Its trends like these that we are really watching. How do the designers make tradeoffs to appeal to riders who want a certain performance on certain terrains? I'm starting to get a beginners feel for it from looking at it with you as we build, modify, evaluate the bikes we are designing.
Schwinn Sales West
Cruisin' on my Bluebird
Each night, I have been watching a little bit of the re-edited movie On Any Sunday II that was recorded from Mav TV. It's a great movie filmed in the 1960's and 70's. It's a Bruce Brown movie and they are always good. In my mind there's no difference between anything on two wheels, they are all just variations. Kids modifying their Sting Rays, into ramp jumpers and then the start of BMX, the Desert Racers, and Trials Riders, the evolution into Mountain Bike's, it's all connected. You cannot watch all of the action filmed in that movie and not see the same things we have been discussing in this thread about rider fit, geometries, different designs.
I agree with @Miq about how helpful the overlay shots are in analyzing the subtle differences between these bikes. It can be a $5 bike, or a $5,000 bike and the main geometry is very close, scary close to the same. We are about 125 years into this topic of the safety bicycle and very little has actually changed. Some things that changed have reverted back to almost the original ideas. Construction materials have changed and gotten better, and for sure bike/rider aero dynamics have improved. But bike geometry has to be tied to the ergonomics of the rider's body. Maybe that's why we keep coming back to the same general geometric triangle (feet/seat/grips). It has to fit the rider, be comfortable, before it can work for a long distance.
John
I agree with @Miq about how helpful the overlay shots are in analyzing the subtle differences between these bikes. It can be a $5 bike, or a $5,000 bike and the main geometry is very close, scary close to the same. We are about 125 years into this topic of the safety bicycle and very little has actually changed. Some things that changed have reverted back to almost the original ideas. Construction materials have changed and gotten better, and for sure bike/rider aero dynamics have improved. But bike geometry has to be tied to the ergonomics of the rider's body. Maybe that's why we keep coming back to the same general geometric triangle (feet/seat/grips). It has to fit the rider, be comfortable, before it can work for a long distance.
John
SKPC
Cruisin' on my Bluebird
Yes, very complicated. . The human form and factor delivers the unknown problem to solve, but individually, not necessarily one-fits-all dogma pinning it down....... individual to individual in terms of the many physical differences have a great affect. Well disected and thought through above @Miq @Schwinn Sales West
Edit: " Your bike and your instrument become an extension of you. There is a feedback loop around your brain, body and the bike or instrument." I thought long and hard about this universal truth @Miq The basic bicycle is one of these "instruments" you end up having an intimate relationship with. A machine that carries you smoothly along all under your own power with two spun up gyro-wheels keeping you upright and on track. When you think about this, there is no other instrument so perfectly matched to us that gives back so much. What other instrument or machine human powered compares?
Edit: " Your bike and your instrument become an extension of you. There is a feedback loop around your brain, body and the bike or instrument." I thought long and hard about this universal truth @Miq The basic bicycle is one of these "instruments" you end up having an intimate relationship with. A machine that carries you smoothly along all under your own power with two spun up gyro-wheels keeping you upright and on track. When you think about this, there is no other instrument so perfectly matched to us that gives back so much. What other instrument or machine human powered compares?
Last edited:
Similar threads
