Is bike geometry rubbish?
pbassred
Posts: 208
>I photographed my 2014 aluminum boardman CX bike next to my workmate's carbon fibre cervello S3. They look completely different. He calls the Boardman a hybrid. His is obviously more aero and its probably 3KG lighter. I wanted to know what the actual differences were, particularly with the number of dedicated; gravel, endurance and hill climbing bikes out there - all supposedly completely different. so i started measuring the photo. The wheel base is the same. The crank height is the same (surprising). The saddle are set the same distance from the stem. His stem is lower and his saddle is higher but those are just setup choices.
His steerer tube is one degree slacker, and his crank is 20 - 30 mm further back (which would help him get into an aero position) but that's all that I can find. He weighs 10kg less than me so he gets 13kg over all
Are all these divisions nonsense?
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Pretty much...0
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Yes! Marketing bullshit. Can anyone tell the difference between 1 degree at the head angle, or 10 mm more in stem height, or 1kg in total weight ? Or 25 and 28 mm tyres? 80 psi or 100 psi? I don't think so.0
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Of course it matters that's why it's made differently0
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No.
It is like Goldilocks and her housebreaking episode. I suspect she didn't know why she preferred one chair to the others, but prefer it she did. Her assessment was based in part on ergonomics, dimension and geometry.
I have done a road TT on a mountain bike. It was fun but not ideal. My usual mount is a standard road bike with drops... better but not ideal. Superfast fill use a TT bike.
The way some manufacturers reference geometry in their advertising copy is slightly odd, but it helps them to pry cash out of fingers. The cycling press are sometimes hard pressed to identify differences between what are, essentially, just bicycles.... and they too have to keep advertisers happy...
So you will read and hear a lot of blarney about geometry. But that does not mean it is all a lot of nonsense.0 -
Is this a thread for those with 15 plus or so bikes?0
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the only things I have found that make a massive difference to how the bike is used is Tyre clearance and wheel base length ... oh and shorter chain stays do make like easier when it comes to getting the front wheel off the floor0
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bike gepmetry affect evrything about how the bike feels and performs if the rider is the same.
head tube angle, fork rake/trail effect how the steering feels and how stable the bike is with the hands of the bars. seat tube angle will change weight distribution and your position. Every wondered why TT bikes are only god in a straight line?
Wheelbase affect more than just tyre clearance. is this a trolling thread? If not bike geometry is not rubbish it is the first thing I look at when buying a frame.http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
thecycleclinic wrote:If not bike geometry is not rubbish it is the first thing I look at when buying a frame.
In terms of certain measurements, then I'd probably agree. I tend to have a preferred HT and TT length, as do many others, I imagine. However, in terms of angles - I couldn't tell you the head or seat angle of any of my bikes and I couldn't tell the difference when riding them either.0 -
thecycleclinic wrote:bike gepmetry affect evrything about how the bike feels and performs if the rider is the same.
head tube angle, fork rake/trail effect how the steering feels and how stable the bike is with the hands of the bars. seat tube angle will change weight distribution and your position. Every wondered why TT bikes are only god in a straight line?
Wheelbase affect more than just tyre clearance. is this a trolling thread? If not bike geometry is not rubbish it is the first thing I look at when buying a frame.
This.0 -
Having just switched from 25 to 28mm tyres and dropped the pressure by 15 psi - yes, very much so. The "buzz" from the road that was causing my hands to go numb on 50 mile plus rides isn't there anymore.DaveP1 wrote:Yes! Marketing bullshit. Can anyone tell the difference between 1 degree at the head angle, or 10 mm more in stem height, or 1kg in total weight ? Or 25 and 28 mm tyres? 80 psi or 100 psi? I don't think so.0 -
My sannino for example has a steeper seat tube than other road bikes which puts more weight over the front wheel also it has a short wheel base and is two twitchier than my other bikes. I have made it fit me right . Head tube and seat tube angles change wheel base. I have a 1948 RRA and it has very relaxed geometry and is fine being ridden off road. My sannino is not nearly as composed off road. I have tried. MTBs have a bigger range of head tube and seat tube angles as well as BB heights. The kenesis ff29 has a geometry not far off a road bike but with a higher BB and longer forks legs extending the wheel base. Put drop s in it and it becomes a monster cross bike i.e a traditional xc bike that has good road manners. There are other MTBs with slacker angles and these bikes are better able to handle rocks and really rough terrain. My hill climb bike has the perfect geometry for steep climbs. The head tube is short enough and the top tube long enough that I have more weight over the front wheel which is ideal as I climb seated. I don't want the front wheel lifting up when putting power down on a 1n4. One rider at a recent hill climb found this out as his wheel lifted and over the back of the bike he went.http://www.thecycleclinic.co.uk -wheel building and other stuff.0
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Yes I can tell the difference in stem height, head tube angles and road tyre widths. If you can't any bike will obviously do. Nothing wrong with that but it may have more to do with how you ride that makes you less sensitive to differences.http://www.thecycleclinic.co.uk -wheel building and other stuff.0
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No, its not a trolling thread, but I wasn't specific enough with the title. It should have been "Is bike FRAME geometry rubbish. Obviously you can adjust the stem height and length, the seat position and change the tires, but for us mortals does 1 degree of head tube angle justify a completely different catagory? It makes me wonder is I would ever need to upgrade my bike - what could they possibly change that would make a difference?0
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catogaries of bikes are marketing. I ignore the catagory and look at the geometry and decide for myself what I would use it for. catagories are help people who dont understand bike geometry and to help sell a new bike.
if you are happy with what you have then dont buy another bike but if you get to understand how different factors in geometry affect how the bike feels then you may find like me that you get a bike for a specific purpose. this of course is a disease and one I suggest you dont catch. you need an understanding partner for starters or be and stay single.http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
Bike geometry is only rubbish if it's non-Euclidean.0
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Is this another one of those threads where people who have zero idea just say No?
A bike company will spend a fortune in R&D just to create an illusion. Ok0 -
If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape. A 59 Pista (ETT 575mm) has 75 degree seat and head tube angles, and 28mm fork rake. A 57 Etape (ETT 570) has 73 degree seat tube and 72 degree headtube angles and 45mm fork rake.
Set them up with the same effective stack and reach, use the same gearing, ride them for 10k on almost any route that has some corners in it, and then tell me geometry is irrelevant.
You could go further and compare the Pista to a properly slack "gravel" bike, or a mountain bike, but I don't have either of those, so wouldn't be speaking from experience.0 -
I've never seen a geometry table that tells me whether I can attach mudguards, how much tyre clearance there is or whether the bike has discs or not. Perhaps I don't understand.thecycleclinic wrote:catogaries of bikes are marketing. I ignore the catagory and look at the geometry and decide for myself what I would use it for. catagories are help people who dont understand bike geometry and to help sell a new bike.0 -
964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...0 -
Imposter wrote:964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...
In the confines of road bikes, the geometry can still differ a lot. Look at a Giant Propel compared to a Defy. The Propel wheelbase brings the rear closer to the crank (look at bikes with seatstay cut outs for the rear whee)l. with shorter chainstays which improve power transfer and is a lot stiffer. With a much lower front end and shorter head tube is makes the steering a lot more responsive and allows the rider to get lower and more aero. It is a lot longer and lower compared to the high up sloping geometry of the Defy. This is just two bikes from the same brand. Lots of bikes differ in many ways depending on their target discipline.0 -
Trivial poursuivant wrote:Imposter wrote:964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...
In the confines of road bikes, the geometry can still differ a lot. Look at a Giant Propel compared to a Defy. The Propel wheelbase brings the rear closer to the crank (look at bikes with seatstay cut outs for the rear whee)l. with shorter chainstays which improve power transfer and is a lot stiffer. With a much lower front end and shorter head tube is makes the steering a lot more responsive and allows the rider to get lower and more aero. It is a lot longer and lower compared to the high up sloping geometry of the Defy. This is just two bikes from the same brand. Lots of bikes differ in many ways depending on their target discipline.
I thought it was head angle and stem length that were the primary factors in the sense of steering responsiveness. My mountain bike feels super responsive, and the bars aren't much lower than the saddle. It does have a diddy stem though.
Some, but not all pro road riders choose a quite small size frame so that they can have a large saddle to bar drop, because they want to be very aero and they can actually function in such an extreme position. They have to combine this with a very long stem which actually deadens the steering characteristcs. Steve Cumming has commented on this.0 -
Alex99 wrote:Trivial poursuivant wrote:Imposter wrote:964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...
In the confines of road bikes, the geometry can still differ a lot. Look at a Giant Propel compared to a Defy. The Propel wheelbase brings the rear closer to the crank (look at bikes with seatstay cut outs for the rear whee)l. with shorter chainstays which improve power transfer and is a lot stiffer. With a much lower front end and shorter head tube is makes the steering a lot more responsive and allows the rider to get lower and more aero. It is a lot longer and lower compared to the high up sloping geometry of the Defy. This is just two bikes from the same brand. Lots of bikes differ in many ways depending on their target discipline.
I thought it was head angle and stem length that were the primary factors .
Yeah, and a shorter head tube will effect such angle. A taller head tube will bring the fork closer over the wheel for a given frame size. the wheel size remains the same so if you have a long low bike geometry with a short head tube the angle over the wheel is going to be a lot further back. you can counter it with stem length to prevent it getting too twitchy or make it more responsive if its quite dull.0 -
Look at the angle over the front wheel of the Venge Vias and how short the wheelbase is
Compare it to the Defy - much longer and stretched out. Offering a much more compliant riding position with comfort key, higher front end for a more relaxed sit up and beg ride. It may be comfortable to ride but it will be nowhere near a s responsive to sudden acceleration and sprinting than the Venge is. On the other side, the angle of the Venge means it won't be very comfortable to ride for long rides, lower back angle and more pressure on your arms and hands.
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Trivial poursuivant wrote:Imposter wrote:964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...
In the confines of road bikes, the geometry can still differ a lot. Look at a Giant Propel compared to a Defy. The Propel wheelbase brings the rear closer to the crank (look at bikes with seatstay cut outs for the rear whee)l. with shorter chainstays which improve power transfer and is a lot stiffer. With a much lower front end and shorter head tube is makes the steering a lot more responsive and allows the rider to get lower and more aero. It is a lot longer and lower compared to the high up sloping geometry of the Defy. This is just two bikes from the same brand. Lots of bikes differ in many ways depending on their target discipline.
Nobody is arguing that there are no differences in geometry - obviously there are. I suspect the argument is whether those differences actually have any real world impact, in which case I would argue the answer is 'no'. I've seen a Defy take the win in a 3/4 circuit race, and the guy had a perfectly good 'race' position on it. Like I say, the argument is not about whether there are differences - it is more about whether the differences actually matter as much as some people claim.0 -
Imposter wrote:Trivial poursuivant wrote:Imposter wrote:964Cup wrote:If you want to experience the difference geometry can make, get a track bike drilled for brakes, like a Bianchi Pista, and compare it to an endurance geometry road bike like an Enigma Etape.
Well obviously. You probably wouldn't want to ride a frame designed for downhill mtb around a velodrome, for the same reason.
But within the confines of road frames (which I'm assuming is the context for this discussion), then I think the point that frame geometry differences are subtle/marginal at best is a valid one...
In the confines of road bikes, the geometry can still differ a lot. Look at a Giant Propel compared to a Defy. The Propel wheelbase brings the rear closer to the crank (look at bikes with seatstay cut outs for the rear whee)l. with shorter chainstays which improve power transfer and is a lot stiffer. With a much lower front end and shorter head tube is makes the steering a lot more responsive and allows the rider to get lower and more aero. It is a lot longer and lower compared to the high up sloping geometry of the Defy. This is just two bikes from the same brand. Lots of bikes differ in many ways depending on their target discipline.
Nobody is arguing that there are no differences in geometry - obviously there are. I suspect the argument is whether those differences actually have any real world impact, in which case I would argue the answer is 'no'. I've seen a Defy take the win in a 3/4 circuit race, and the guy had a perfectly good 'race' position on it. Like I say, the argument is not about whether there are differences - it is more about whether the differences actually matter as much as some people claim.
Just because to you there is no difference it doesn't mean there isn't. IMO there is a huge difference. I read plenty of stuff about how aero is better than lightweight, etc. I never read anything to the contrary except from amateurs who are all too ready to just dismiss it. I cant remember hearing a pro, or a bike magazine or web page review suggest its all rubbish and there is little difference. If you are going on a 20 mile pootle around the countryside on a sunday, then any bike will feel the same. If you are racing and on the edge of its performance ther differences will be noticeable.0 -
Trivial poursuivant wrote:Look at the angle over the front wheel of the Venge Vias and how short the wheelbase is
Compare it to the Defy - much longer and stretched out. Offering a much more compliant riding position with comfort key, higher front end for a more relaxed sit up and beg ride. It may be comfortable to ride but it will be nowhere near a s responsive to sudden acceleration and sprinting than the Venge is. On the other side, the angle of the Venge means it won't be very comfortable to ride for long rides, lower back angle and more pressure on your arms and hands.
Head angle has a specific meaning. I do not doubt that in the two examples you show that the handlebars are in a different position relative to the front wheel. This doesn't particularly relate to head angle.0 -
Head angle on a Defy is 71 - 72.5 degrees (going smallest size to largest.
Head angle on a Venge is 72.5 to 74 (small to large)
The difference in stem length will effect handling and so will this angle. It may not sound a lot but then a few mm in stem length can effect steering just as much. A few mm seat height can make massive difference to optimal power output but many don't believe that either even though bike fits can show a minor adjustment can make big differences. Its not that hard to believe small measurement will make big differences. 2mm difference in tyre width make a lot of difference. 2mm! yet not many dispute that.0 -
Trivial poursuivant wrote:
Just because to you there is no difference it doesn't mean there isn't. IMO there is a huge difference. I read plenty of stuff about how aero is better than lightweight, etc. I never read anything to the contrary except from amateurs who are all too ready to just dismiss it. I cant remember hearing a pro, or a bike magazine or web page review suggest its all rubbish and there is little difference. If you are going on a 20 mile pootle around the countryside on a sunday, then any bike will feel the same. If you are racing and on the edge of its performance ther differences will be noticeable.
As I've said on two seperate occasions now - nobody is saying there are no differences, and I don't think anyone is saying that the differences (such as they are) will not be noticeable to some people.
The only issue is whether the differences actually matter as much as some are claiming. My argument is that they do not.0
