Dropped seat stays - good bad or ugly?!

General cycling advice ( NOT technical ! )
mattheus
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Re: Dropped seat stays - good bad or ugly?!

Postby mattheus » 22 Oct 2019, 11:23am

Marcus Aurelius wrote:From a comfort point of view, they are superb, in my experience, they break the shock pathway up, between the wheel and the seat post to your spine, they also help with aero, and given that you spend 80% of your effort moving air out of your way, whilst cycling, every little helps. They do make the bike look fugly though. All in all, they are worth having.

The %age of that 80% that is the BIKE is about 20% I believe? And what %age is the seat stays? And how much less are they in the wind with this design??

Anyway, it's your money, your call :)

thelawnet
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Re: Dropped seat stays - good bad or ugly?!

Postby thelawnet » 22 Oct 2019, 12:15pm

mattheus wrote:
Marcus Aurelius wrote:From a comfort point of view, they are superb, in my experience, they break the shock pathway up, between the wheel and the seat post to your spine, they also help with aero, and given that you spend 80% of your effort moving air out of your way, whilst cycling, every little helps. They do make the bike look fugly though. All in all, they are worth having.

The %age of that 80% that is the BIKE is about 20% I believe? And what %age is the seat stays? And how much less are they in the wind with this design??


The entire frame is 8% (excluding fork, handlebars, cable,s etc.), which is about the same as the front wheel. And that's at a steady 25mph.

Image

If you're doing, say, 15 mph on the flat, then it's going to be around ~4% for the frame, much less uphill.

Considering that gains with aero wheels are small enough, and that wheel drag is similar to frame drag, but seat stays just a fraction of frame drag, possible seat stay aero gains look irrelevant.

Normal seat stays would require less material, which should also be a concern, i.e. weight.

reohn2
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Re: Dropped seat stays - good bad or ugly?!

Postby reohn2 » 22 Oct 2019, 12:35pm

Marcus Aurelius wrote:From a comfort point of view, they are superb, in my experience, they break the shock pathway up, between the wheel and the seat post to your spine, they also help with aero, and given that you spend 80% of your effort moving air out of your way, whilst cycling, every little helps. They do make the bike look fugly though. All in all, they are worth having.

Can you quantify that?
IMO the seatpost inserted in seatube would negate any possible suspension benefit by stiffening up the seatube/seatstay cluster unless it wasn't inserted past where the seatstays met the seatube.
EDIT,thinking about a little more,if the seatpost isn't inserted past where the seatstays meet the seatube it may cause a stress raiser in the seatube.
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kylecycler
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Re: Dropped seat stays - good bad or ugly?!

Postby kylecycler » 22 Oct 2019, 12:59pm

Funnily enough, I came across this late last night - an animation of rear frame flex as a result of the dropped seat stays on the current Scott Foil.

1_x2fduEuYJVRfWdtl3b4pYQ.gif

https://medium.bikehugger.com/scott-foi ... d4acd5ff9d

Apparently the last Foil gave an awful harsh ride; this one is something like 80 per cent more compliant. It won Paris-Roubaix, on 28mm tyres and with only one layer of bar tape, basically the same bike its rider Mat Hayman used on the Grand Tours.

It's also the bike Annemiek van Vleuten used to win this year's World Championship road race in Yorkshire.

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kylecycler
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Re: Dropped seat stays - good bad or ugly?!

Postby kylecycler » 22 Oct 2019, 1:15pm

reohn2 wrote:
Marcus Aurelius wrote:From a comfort point of view, they are superb, in my experience, they break the shock pathway up, between the wheel and the seat post to your spine, they also help with aero, and given that you spend 80% of your effort moving air out of your way, whilst cycling, every little helps. They do make the bike look fugly though. All in all, they are worth having.

Can you quantify that?
IMO the seatpost inserted in seatube would negate any possible suspension benefit by stiffening up the seatube/seatstay cluster unless it wasn't inserted past where the seatstays met the seatube.
EDIT,thinking about a little more,if the seatpost isn't inserted past where the seatstays meet the seatube it may cause a stress raiser in the seatube.


I posted the above before I saw your post, r2. I get what you mean, and there have been seat tube failures, or at least cracks, I've heard about just like that, apparently on the 3T Exploro, for one, which has a similar arrangement. And I reckon that quite possibly depends on rider's height relative to frame size and how far the post has been inserted.

You can see from the animation, though, that on the Scott Foil the flex is further down, between the seat stay junction and the bottom bracket.

I still worry, as I'm sure you do, about how long a frame can flex like that before it breaks, but I expect that's been factored in - you'll know they build test rigs that flex the frame more and for 'longer' than it will ever do in service.

mercalia
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Re: Dropped seat stays - good bad or ugly?!

Postby mercalia » 22 Oct 2019, 1:16pm

kylecycler wrote:Funnily enough, I came across this late last night - an animation of rear frame flex as a result of the dropped seat stays on the current Scott Foil.

1_x2fduEuYJVRfWdtl3b4pYQ.gif
https://medium.bikehugger.com/scott-foi ... d4acd5ff9d

Apparently the last Foil gave an awful harsh ride; this one is something like 80 per cent more compliant. It won Paris-Roubaix, on 28mm tyres and with only one layer of bar tape, basically the same bike its rider Mat Hayman used on the Grand Tours.

It's also the bike Annemiek van Vleuten used to win this year's World Championship road race in Yorkshire.


whats good for racing not necessarily good for a bike that has to last more than one season?

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kylecycler
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Re: Dropped seat stays - good bad or ugly?!

Postby kylecycler » 22 Oct 2019, 1:45pm

mercalia wrote:
kylecycler wrote:Funnily enough, I came across this late last night - an animation of rear frame flex as a result of the dropped seat stays on the current Scott Foil.

1_x2fduEuYJVRfWdtl3b4pYQ.gif
https://medium.bikehugger.com/scott-foi ... d4acd5ff9d

Apparently the last Foil gave an awful harsh ride; this one is something like 80 per cent more compliant. It won Paris-Roubaix, on 28mm tyres and with only one layer of bar tape, basically the same bike its rider Mat Hayman used on the Grand Tours.

It's also the bike Annemiek van Vleuten used to win this year's World Championship road race in Yorkshire.


whats good for racing not necessarily good for a bike that has to last more than one season?

That's true, racing is a different principle, although these frames are more or less identical to what the manufacturers sell to the public. But that's what's concerning - there are road cyclists who seldom keep a bike for more than a couple of years, but plenty more who keep them longer, and even then of course they don't just get scrapped (unless they're trashed), they get sold on.

reohn2
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Re: Dropped seat stays - good bad or ugly?!

Postby reohn2 » 22 Oct 2019, 2:10pm

I could wrong of course,I'm not an engineer after all but AFAIC it's deliberate and considered engineering to take advantage of the flex for comfort's sake and for a short service life.
Whereas having the seatstays meet the toptube means there's no flex in that area from upward or downward forces.
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mattheus
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Re: Dropped seat stays - good bad or ugly?!

Postby mattheus » 22 Oct 2019, 2:11pm

... and it's quite likely that Annemiek won DESPITE having to ride with a ridiculous new frame design.

Win on Sunday, sell on Monday...

rfryer
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Re: Dropped seat stays - good bad or ugly?!

Postby rfryer » 22 Oct 2019, 2:28pm

kylecycler wrote:Funnily enough, I came across this late last night - an animation of rear frame flex as a result of the dropped seat stays on the current Scott Foil.

1_x2fduEuYJVRfWdtl3b4pYQ.gif
https://medium.bikehugger.com/scott-foi ... d4acd5ff9d

Apparently the last Foil gave an awful harsh ride; this one is something like 80 per cent more compliant. It won Paris-Roubaix, on 28mm tyres and with only one layer of bar tape, basically the same bike its rider Mat Hayman used on the Grand Tours.

It's also the bike Annemiek van Vleuten used to win this year's World Championship road race in Yorkshire.

Am I the only person to worry about the top tube stretching? Is it made out of toffee?

JohnW
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Re: Dropped seat stays - good bad or ugly?!

Postby JohnW » 22 Oct 2019, 3:12pm

I see that frame as just a joke - gimmick for the sake of gimmick - not the rational, structural logic of the classic double triangle frame.
Each to their own though.

reohn2
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Re: Dropped seat stays - good bad or ugly?!

Postby reohn2 » 22 Oct 2019, 4:16pm

mattheus wrote:... and it's quite likely that Annemiek won DESPITE having to ride with a ridiculous new frame design.

Win on Sunday, sell on Monday...

It's possible though the buy Sunday sell Monday would be more like "this is the team supplied frames so this what you ride" :wink:
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mercalia
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Re: Dropped seat stays - good bad or ugly?!

Postby mercalia » 22 Oct 2019, 4:17pm

it reminds me of that joke frame some one posted here , a youtube video ofa bike that a guy made using only large springs :lol:



ah was very easy to find again

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kylecycler
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Re: Dropped seat stays - good bad or ugly?!

Postby kylecycler » 22 Oct 2019, 4:27pm

JohnW wrote:I see that frame as just a joke - gimmick for the sake of gimmick - not the rational, structural logic of the classic double triangle frame.
Each to their own though.

This is the same principle, though, at the front anyway (you might recognise the bike as Jan Heine's).:



Or if you want to get a lot more radical, check out the blue tape trick @ 2:11 in this video...



Jeff Jones is a genius, although I read an interview where he said, "All the best info is pre-1930s" - he's apparently a great student of bicycle history and he's just applying principles that were known and established a long time ago.

Whatever your leanings, it's seriously worth watching that video all the way through.

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kylecycler
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Re: Dropped seat stays - good bad or ugly?!

Postby kylecycler » 22 Oct 2019, 4:44pm

mattheus wrote:... and it's quite likely that Annemiek won DESPITE having to ride with a ridiculous new frame design.

Win on Sunday, sell on Monday...

Well, considering she was up out of the saddle on every incline, every slope, every hill, far more than her competitors, and for longer, at least as far as I could see* (I truly believe that's where she made the time), maybe frame compliance didn't matter so much? :)

(*Although it might have been to do with her using a 54/42 on the front and 'only' a 28 lowest sprocket on the back - far higher gearing than most of the rest (you have to click through the slideshow for the details) - Anna van der Breggen, for example, ran a 48/35 chainset with a 10-32 cassette.)

https://www.cyclingnews.com/features/an ... t-foil-rc/

https://www.cyclist.co.uk/news/7142/ann ... nbow-chain

Sorry, getting a bit off the subject now.