There’s a reason the midpoint frames are built with angles around 73º - it works. Smaller frames typically steepen up in the STA and slacken off in the HTA and vice versa on larger frames to preserve the balance in handling. You can fine tune the trail using different rakes couple with slighter variations in the HTA, but STA is a function of femur to leg ratio. Stock geometry is tailored to the mean of the ratio. Companies like Deda offer 0, 15 & 25mm to allow this to be adjusted for outliers. As for cross geometry having a slacker STA, maybe check out Ridley. They don’t use a STA anywhere that low on any size. They have probably more experience in the game.
Really great video. I love my steel bikes and have built a few resto mods...... The most intersing one is a 'Carless' custom built for 80s time trialist Alan Roberts, the head angle is so steep, it's a large frame but the wheelbase is only 94cm! When I first rode it, I joined friends and almost came off doing slow speed in a car park, my feet overlapped the front wheel loads😂😂. It don't really notice it at speed, it's just a lovely bike to ride and an absolute beauty to look at😊
In the olden days, the street road bikes from Puch ran 72 degree angels and the more aggressive Austro-Daimler frames which looked basically identical had 74 degree angles for racing. You can see where 73 degrees make a pretty good middle ground. Seems sensible that the geometry is still in use today.
I used a few geometry tools when researching my new bike purchase, what I found really frustrating was trying to compare one frame against another was fairly straightforward, but trying to assess final positioning was a nightmare, different bar reach, stem length, seat post offset etc. I ended up with a Roadmachine but still had to shorten the stem by 10mm as 110 stock was too long. Bar width was also too wide, would love to know why manufacturers insist on 42cm being the standard.
Love the content @mapdec! One thing I would disagree on from this video. The seat tube angle that suits you best will not rely on your flexibility or even something like femur-to-tibia ratio alone. There are a multitude of factors that come into play. In order to achieve proper balance, GENERALLY, a high-functioning human with the ability to hinge at the hips well and extend their torso far forward will need more setback and therefore a slacker seat tube angle i.e 73 degrees. On the other hand, someone who “sits upright” and has poor flexibility, will project less weight over the front of the bike and will therefore generally be more comfortable and able to produce power with less setback (steeper seat tube angle). The correct “balance point” for each of these riders will also be where they achieve pelvic stability and engage both their posterior and anterior muscle chains evenly. Some pro’s and elite riders have the ability to run their seats further forward than the “balance point” while maintaining relative comfort over long periods. This comes down to core strength, time spent on bike, hip stability and other factors. You need to find that balance point first, then you can understand what angle of seat tube you need. As much as a steep seat tube angle can be a game-changer for some riders, it can cause a mountain of issues for others. (Assuming they cannot use different setback seatposts to achieve the desired saddle setback)
When Mike burrows took the industry from The double diamond frame to compact frames, manufacturers loved it because they didn't have to make so many sizes. They got around it by adjusting the fore and aft of the seat post and the length of the stem. That's the workaround for manufacturers only having four or five different carbon fiber sizes. What one needs to do is to work out their true size on something like Colnago or Tommasini steel bike and then find which manufacturer and model comes closest if you want carbon. But in the end, nothing beats having a custom-fitted and built steel or aluminum or titanium frame.
Fully agree. Why do we ride 73 bikes and then get zero offset seatposts with saddles slammed forward. Why don’t manufacturers build 77 bikes for example, so we could have normally positioned saddles. And you wouldn’t see that many pros riding the nose
Cause you want the seatpost back, so it doesn't rub your legs. I run a reverse offset post, (actually a Thomson 15mm lay back post turned around 180) so that I can avoid thigh rub. Especially if you have any accessories wrapped around the post.
The hip rotation actually works in reverse of what you describe: a steeper seat angle actually reduces the required hip mobility, which is why they do it on tt/tri, so they can get into an efficient pedaling aero position without requiring extreme hip flexion. It's a tricky subject to wrap your head around 😅
I'm not actually sure you watch my videos before commenting . My comment is pedal efficiency in extreme restriction. To get the most out of a bike with a steep seat angle you still need to rotate quite far.
In looking at the brands you mentioned, their frames don't get to a 73º seat tube until you get to a M/L or 58cm frame. But they all have different measurement ideas too. The mid point is 54/55cm. I'd venture to say 85% of the high end frames sold (are less than a size M/L 58cm) have 73º seat tubes . Maybe 2 MFGs make a small 73º seat tube road frame. Greg Lemond's book The Complete Book of Cycling page 132 Greg considers anything over 73º seat tube as steep/aggressive, hard to get proper position. 74º seat tubes don't allow a rider's physiology to be placed in the proper position to transfer core weight to the pedals. Especially for shorter riders. What matters is the relationship of the rider to the bottom bracket, to get CG over the pedals. It also depends on where they pivot the seat post. The main reason why they tilt seat tubes forward is to move the BB back, moving the crank, pedal, toe back in an attempt to prevent toe overlap. At a 66.5 cm saddle height, 1º is a 6 mm at the saddle rail (or more depending on the pivot point) difference. You can make up the difference sliding the saddle back but the rails have limits, there are saddles with longer rails. The other problem is with the seat tube at 74 the top tube is pushed forward, so it might be to long to get the saddle back. Why I think most people are on a bike too big for them, the top tube makes it impossible to move back. Too far forward and you have less of a power stroke and more weight on the bars. You'll have more power / comfort with your saddle center at 73º. 73º seat tubes also mean more shock absorbing, standing the seat tube up on an endurance bike doesn't make sense, carbon or not. MFG's build bikes for the masses, not for individuals. If you plan on buying a new bike get a fit from an independent fitter who doesn't sell bikes. Pick geometry over brand.
Moving saddle forward like on TT bikes will provide a stronger power phase and open hips. Yes. It moves weight onto the bars. Perfect for better handling. 6mm further forward is very welcome for many. Yes. Small and XL sizes have many design compromises. They really need correct size wheels.
Great info thank you im currently looking at a time ahdx frameset and wanted to do just this compared to a cervelo aspero and you came at the perfect time💪
This was very useful! Never considered those numbers, but thinking about what I would like, it is definitely something more like a 73 - 72/71 with maybe a longer reach than I currently have a the same stack! I can now confidently build my perfect bike. Thanks
Morning , unfortunately just caught the last few minutes of the live chat (2:20 am here) will have to look later. Your content is getting very interesting of late. There’s an incredibly knowledgeable guy on you tube ( pasatpit RUclips) that’s really into bike positioning. It would pay you to have a look and compare your views. Great job 👍👍
Cool, just been watching a little bit. I'm not in complete agreement, because I think we still need the handling to be the most important aspect. I think if we get too into precise biomechanics we can end up with a pig of a bike, with some crazy weight distribution. I guess in the triology of compromise I am more towards adaptation of the rider.
@@Mapdec agree with you in regard to mass produced bikes , there needs to be an average specification that can be adapted. Thus as you rightly say forever 73 degrees is pretty much on the money. I’m not sure of Pastapits background , however I’d say he was pretty much into producing bikes for extremely high level athletes such as Olympic / world record kilo riders or pursuit riders.Anway it’s interesting stuff, you may be interested in researching Shorter frames who built some beautiful bikes in the 70’s for a terrific rider named Alf Engers. Must try an visit your establishment if I get over there again. Take care 👍
I'm 5 ft 5 in. I ride a 50 cm center to center. Most stock frames put me on a 74 or 75 degree seat tube angle but I have really long femur bones and so I need a 72°. I can't get my saddle far back enough with a stock frame. The only ones that were like this where the Eddy merckx century geometry but they don't make those anymore. Carbon frames are made with cookie cutter manufacturing techniques. Also, just because you can design a frame on that website doesn't mean that the bike is going to be even rideable. A knowledgeable experience framebuilder will know what angles and what dimensions are possible.
Thank you for this explanation. I'm starting to dig in bike geometry and I find this video gives good basic references. I find road geometry a bit confusing because the manufacturers only play with few millimetres or degrees, so determining the category of a bike is more difficult than with a mtb. Maybe you can do other videos in a similar fashion to explain more points?
Thank you. If folk find my chats useful I will do more. I quite like doing Live vids. It’s a lot less formal and sometime you get audience feedback to stir discussion
Sorry I missed! I would have asked as I come down a my short list for a gravel bike here in the U.S./California if you have opinion on how Look Bikes fairs with their gravel bike? Their carbon as you've pointed out many x's is stunning but does it translate to an enhanced smoother experience out on gravel? Thus, far the Crux by specialized is topping my list. Cheers and thanks!
Compliance tuning is always very subjective. I think what you 'feel' with LOOK is a smoothness that comes from better alignment and precision of the fitted parts. Things don't rattle, creak and vibrate like other brands.
If you have a 74 angle seat post on a endurance geometry frame , and if you are inbetween frame sizes even with an offset seat post your saddle may have to be set all the way back if you choose the smaller frame, to fix this issue you can go up a size or choose an endurance frameset with 73 seat tube angle in the smaller size. Which one would you prefer?
The one that keeps my weight closest to the bottom bracket. When you start off setting saddles your weight distribution comes off the front wheel and your steering becomes light.
What are your thoughts on the allez sprint? If my budget is around the value of that bike, would you recommend the allez sprint as a race bike? Over, say, a carbon alternative in the same price bracket?
I've got a question: what about effective seat angle? With my body proportions and elasticity my effective seat angle is 76°, at least according to retul. Doesnt this negate this angle with all things being equal?
It depends. changing things like layback and saddle fore/aft to get a position can then change weight distribution and therefore handling characteristics. Some frames have a funky design that means they need to advertise an effective seat angle, rather than a true seat angle.
Bike geo has always been a bit of a black box to me. I understand the effect of individual geo numbers but predicting a bike’s handling characteristics based on the geo chart is still hit or miss. I once bought a bike blind that based on the bb drop and stack figures *should* have felt like being in the bike as opposed to on top of it. Turned out it felt exactly opposite, almost like being on stilts. I recall reading an interview with a frame builder who made a bike he thought would handle like shit, only to be one of the best he’d ever made despite looking terrible on paper. Guess it’s still a case of trial and error, at least on the mtb side of things.
@@Mapdec steeper seat angles aren't more efficient, they definitely don't stabilise the front of tt bikes, and they absolutely do not require more mobility
Lol. I think you need to rewatch that segment. Steeper seat angles on TT bikes with low stacks. Remember I was talking about the 78° angle. Not a 74° on an endurance bike. 😘. No designer would put a 78° on a bike without it being intended for a low TT position, and yes. That requires good hip mobility for a good glute extension in that position. Think pistol squat. The stabilising of TT bikes comes from the slacker head angles they tend to have. I don’t think you actually watched that video properly.
There’s a reason the midpoint frames are built with angles around 73º - it works. Smaller frames typically steepen up in the STA and slacken off in the HTA and vice versa on larger frames to preserve the balance in handling. You can fine tune the trail using different rakes couple with slighter variations in the HTA, but STA is a function of femur to leg ratio. Stock geometry is tailored to the mean of the ratio. Companies like Deda offer 0, 15 & 25mm to allow this to be adjusted for outliers. As for cross geometry having a slacker STA, maybe check out Ridley. They don’t use a STA anywhere that low on any size. They have probably more experience in the game.
Once again, I learned something from you Professor.
Awesome video.
Awesome, thank you!
As quite a new cyclist with my mechanical skill or know how on anything this content is outstanding for me. Good work buddy. Vkeep it up
🙏
Really great video.
I love my steel bikes and have built a few resto mods...... The most intersing one is a 'Carless' custom built for 80s time trialist Alan Roberts, the head angle is so steep, it's a large frame but the wheelbase is only 94cm! When I first rode it, I joined friends and almost came off doing slow speed in a car park, my feet overlapped the front wheel loads😂😂.
It don't really notice it at speed, it's just a lovely bike to ride and an absolute beauty to look at😊
In the olden days, the street road bikes from Puch ran 72 degree angels and the more aggressive Austro-Daimler frames which looked basically identical had 74 degree angles for racing. You can see where 73 degrees make a pretty good middle ground. Seems sensible that the geometry is still in use today.
I used a few geometry tools when researching my new bike purchase, what I found really frustrating was trying to compare one frame against another was fairly straightforward, but trying to assess final positioning was a nightmare, different bar reach, stem length, seat post offset etc. I ended up with a Roadmachine but still had to shorten the stem by 10mm as 110 stock was too long. Bar width was also too wide, would love to know why manufacturers insist on 42cm being the standard.
Love the content @mapdec!
One thing I would disagree on from this video.
The seat tube angle that suits you best will not rely on your flexibility or even something like femur-to-tibia ratio alone. There are a multitude of factors that come into play.
In order to achieve proper balance, GENERALLY, a high-functioning human with the ability to hinge at the hips well and extend their torso far forward will need more setback and therefore a slacker seat tube angle i.e 73 degrees. On the other hand, someone who “sits upright” and has poor flexibility, will project less weight over the front of the bike and will therefore generally be more comfortable and able to produce power with less setback (steeper seat tube angle).
The correct “balance point” for each of these riders will also be where they achieve pelvic stability and engage both their posterior and anterior muscle chains evenly.
Some pro’s and elite riders have the ability to run their seats further forward than the “balance point” while maintaining relative comfort over long periods. This comes down to core strength, time spent on bike, hip stability and other factors.
You need to find that balance point first, then you can understand what angle of seat tube you need. As much as a steep seat tube angle can be a game-changer for some riders, it can cause a mountain of issues for others. (Assuming they cannot use different setback seatposts to achieve the desired saddle setback)
Aye. And then there is aero.
I like the sloping down top tube because I’ve short legs but long torso for my height.
When Mike burrows took the industry from The double diamond frame to compact frames, manufacturers loved it because they didn't have to make so many sizes. They got around it by adjusting the fore and aft of the seat post and the length of the stem. That's the workaround for manufacturers only having four or five different carbon fiber sizes. What one needs to do is to work out their true size on something like Colnago or Tommasini steel bike and then find which manufacturer and model comes closest if you want carbon. But in the end, nothing beats having a custom-fitted and built steel or aluminum or titanium frame.
Or get a custom carbon frame made just like the likes of Ciocc, Colnago or De Rosa used to do. We still exist.
I completely forgot about this tool! It is hugely useful for sure - thanks for highlighting.
Glad it was helpful!
Fully agree. Why do we ride 73 bikes and then get zero offset seatposts with saddles slammed forward. Why don’t manufacturers build 77 bikes for example, so we could have normally positioned saddles. And you wouldn’t see that many pros riding the nose
Cause you want the seatpost back, so it doesn't rub your legs. I run a reverse offset post, (actually a Thomson 15mm lay back post turned around 180) so that I can avoid thigh rub. Especially if you have any accessories wrapped around the post.
Yes. I mean 77 is a bit extreme. But 74or even 75 would help a lot of folk find a bit more power from the legs.
The look blade rs is 75,9°, it's pretty heavy, but mostly an amazing bike
The hip rotation actually works in reverse of what you describe: a steeper seat angle actually reduces the required hip mobility, which is why they do it on tt/tri, so they can get into an efficient pedaling aero position without requiring extreme hip flexion.
It's a tricky subject to wrap your head around 😅
I'm not actually sure you watch my videos before commenting . My comment is pedal efficiency in extreme restriction. To get the most out of a bike with a steep seat angle you still need to rotate quite far.
In looking at the brands you mentioned, their frames don't get to a 73º seat tube until you get to a M/L or 58cm frame. But they all have different measurement ideas too.
The mid point is 54/55cm.
I'd venture to say 85% of the high end frames sold (are less than a size M/L 58cm) have 73º seat tubes . Maybe 2 MFGs make a small 73º seat tube road frame.
Greg Lemond's book The Complete Book of Cycling page 132 Greg considers anything over 73º seat tube as steep/aggressive, hard to get proper position.
74º seat tubes don't allow a rider's physiology to be placed in the proper position to transfer core weight to the pedals. Especially for shorter riders.
What matters is the relationship of the rider to the bottom bracket, to get CG over the pedals.
It also depends on where they pivot the seat post. The main reason why they tilt seat tubes forward is to move the BB back, moving the crank, pedal, toe back in an attempt to prevent toe overlap. At a 66.5 cm saddle height, 1º is a 6 mm at the saddle rail (or more depending on the pivot point) difference.
You can make up the difference sliding the saddle back but the rails have limits, there are saddles with longer rails.
The other problem is with the seat tube at 74 the top tube is pushed forward, so it might be to long to get the saddle back.
Why I think most people are on a bike too big for them, the top tube makes it impossible to move back.
Too far forward and you have less of a power stroke and more weight on the bars. You'll have more power / comfort with your saddle center at 73º.
73º seat tubes also mean more shock absorbing, standing the seat tube up on an endurance bike doesn't make sense, carbon or not.
MFG's build bikes for the masses, not for individuals. If you plan on buying a new bike get a fit from an independent fitter who doesn't sell bikes. Pick geometry over brand.
Moving saddle forward like on TT bikes will provide a stronger power phase and open hips. Yes. It moves weight onto the bars. Perfect for better handling. 6mm further forward is very welcome for many. Yes. Small and XL sizes have many design compromises. They really need correct size wheels.
Great info thank you im currently looking at a time ahdx frameset and wanted to do just this compared to a cervelo aspero and you came at the perfect time💪
Oh. I got my hands on an ADHX today.
@@Mapdec im looking forward to any real reviews i saw you made a short clip thank you for all you do for us regular cyclist
We have a bunch of Time frames on the way. As always there are pros and cons. I’m looking forward to it.
This was very useful! Never considered those numbers, but thinking about what I would like, it is definitely something more like a 73 - 72/71 with maybe a longer reach than I currently have a the same stack! I can now confidently build my perfect bike. Thanks
cool, thats CX and Gravel territory.
I’ve spent many hours playing with BikeGeoCalc. I use it to evaluate changes in equipment and when buying a new frame.
I’ve just been geeking on a yeti arc with a angle set 🫣. I have issues.
Morning , unfortunately just caught the last few minutes of the live chat (2:20 am here) will have to look later. Your content is getting very interesting of late. There’s an incredibly knowledgeable guy on you tube ( pasatpit RUclips) that’s really into bike positioning. It would pay you to have a look and compare your views. Great job 👍👍
Sorry pastapit youtube
Cool, just been watching a little bit. I'm not in complete agreement, because I think we still need the handling to be the most important aspect. I think if we get too into precise biomechanics we can end up with a pig of a bike, with some crazy weight distribution. I guess in the triology of compromise I am more towards adaptation of the rider.
@@Mapdec agree with you in regard to mass produced bikes , there needs to be an average specification that can be adapted. Thus as you rightly say forever 73 degrees is pretty much on the money. I’m not sure of Pastapits background , however I’d say he was pretty much into producing bikes for extremely high level athletes such as Olympic / world record kilo riders or pursuit riders.Anway it’s interesting stuff, you may be interested in researching Shorter frames who built some beautiful bikes in the 70’s for a terrific rider named Alf Engers. Must try an visit your establishment if I get over there again. Take care 👍
I'm 5 ft 5 in. I ride a 50 cm center to center. Most stock frames put me on a 74 or 75 degree seat tube angle but I have really long femur bones and so I need a 72°. I can't get my saddle far back enough with a stock frame. The only ones that were like this where the Eddy merckx century geometry but they don't make those anymore. Carbon frames are made with cookie cutter manufacturing techniques. Also, just because you can design a frame on that website doesn't mean that the bike is going to be even rideable. A knowledgeable experience framebuilder will know what angles and what dimensions are possible.
This is just a tool to help visualise differences
Thank you for this explanation. I'm starting to dig in bike geometry and I find this video gives good basic references. I find road geometry a bit confusing because the manufacturers only play with few millimetres or degrees, so determining the category of a bike is more difficult than with a mtb. Maybe you can do other videos in a similar fashion to explain more points?
Thank you. If folk find my chats useful I will do more. I quite like doing Live vids. It’s a lot less formal and sometime you get audience feedback to stir discussion
How long does it normally take you guys to build say a Campag 10spd ergo rim brake build ?
Sorry I missed! I would have asked as I come down a my short list for a gravel bike here in the U.S./California if you have opinion on how Look Bikes fairs with their gravel bike? Their carbon as you've pointed out many x's is stunning but does it translate to an enhanced smoother experience out on gravel? Thus, far the Crux by specialized is topping my list. Cheers and thanks!
Compliance tuning is always very subjective. I think what you 'feel' with LOOK is a smoothness that comes from better alignment and precision of the fitted parts. Things don't rattle, creak and vibrate like other brands.
Much appreciate! Cheers! @@Mapdec
If you have a 74 angle seat post on a endurance geometry frame , and if you are inbetween frame sizes even with an offset seat post your saddle may have to be set all the way back if you choose the smaller frame, to fix this issue you can go up a size or choose an endurance frameset with 73 seat tube angle in the smaller size. Which one would you prefer?
The one that keeps my weight closest to the bottom bracket. When you start off setting saddles your weight distribution comes off the front wheel and your steering becomes light.
What are your thoughts on the allez sprint? If my budget is around the value of that bike, would you recommend the allez sprint as a race bike? Over, say, a carbon alternative in the same price bracket?
We have some Alu bikes lined up. Did you see the vid on the BMC alu ?
I just got an email that Netflix will be shutting down their DVD by mail service in September. I’m stunned.
🤷♂️
Why didn't you use the shadowbike/2nd bike option specifically designed for comparing different bikes??
I don’t know. It was just a casual live chat.
So I'm a common 73/73 angled old tart.
haha. The New Madone is 73/73. Just covered in Lamborghini stying to cover it up.
@@Mapdec 🙂
I've got a question: what about effective seat angle? With my body proportions and elasticity my effective seat angle is 76°, at least according to retul. Doesnt this negate this angle with all things being equal?
It depends. changing things like layback and saddle fore/aft to get a position can then change weight distribution and therefore handling characteristics. Some frames have a funky design that means they need to advertise an effective seat angle, rather than a true seat angle.
Bike geo has always been a bit of a black box to me. I understand the effect of individual geo numbers but predicting a bike’s handling characteristics based on the geo chart is still hit or miss. I once bought a bike blind that based on the bb drop and stack figures *should* have felt like being in the bike as opposed to on top of it. Turned out it felt exactly opposite, almost like being on stilts. I recall reading an interview with a frame builder who made a bike he thought would handle like shit, only to be one of the best he’d ever made despite looking terrible on paper. Guess it’s still a case of trial and error, at least on the mtb side of things.
Ah yes. The F about and find out. It’s how we got to the 29er and geo like we see on the Pipedream Moxie and the Look 765… and the Niccolhi Geometron.
74-71 isn’t that radical when you’re a short arse and don’t have a great deal of choice 😢😂
Ah yes.
Customer just wants to buy a bicycle they don’t care about all that BS .
They care that we care.
@@Mapdec only how much does it cost ,I care deeply also.
Respectfully, this is all kinds of wrong.
Go on…
@@Mapdec steeper seat angles aren't more efficient, they definitely don't stabilise the front of tt bikes, and they absolutely do not require more mobility
Lol. I think you need to rewatch that segment. Steeper seat angles on TT bikes with low stacks. Remember I was talking about the 78° angle. Not a 74° on an endurance bike. 😘. No designer would put a 78° on a bike without it being intended for a low TT position, and yes. That requires good hip mobility for a good glute extension in that position. Think pistol squat. The stabilising of TT bikes comes from the slacker head angles they tend to have. I don’t think you actually watched that video properly.