Steeper (effective) seat tube angle and climbing

Discuss light weight issues concerning road bikes & parts.
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Tinea Pedis
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by Tinea Pedis

Rode an Aernario for the first time this week. Did a quick set up, copied fit from my Bianchi Sempre to it and went for a spin.

Felt all kinds of different on the Storck (not in a bad way), most especially when I hit a climb. This was an easy roll after an ergo session earlier, so was already fatigued. However my initial feeling was annoyance, as I thought the bike had been fitted with a compact crankset (and I'd missed that fact when putting it together). Get to the top of a climb only to find it was standard 53/39. Climbing felt a lot more effortless.

Which given it was on a favourite lumpy 45km loop, that I have ridden hundreds of times in all winds directions possible, I'd know if it was simply due to the wind (it wasn't).


Question is: what have people found in relation to steeper ST angles and climbing*?


*my previous experience in bike fitting suggested slacker tended to yield a lot more favourable results, which this flies in the face of.

by Weenie


Causidicus
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by Causidicus

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Last edited by Causidicus on Wed Jun 18, 2014 12:02 am, edited 1 time in total.

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Tinea Pedis
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by Tinea Pedis

Tinea Pedis wrote: Did a quick set up

So, bar drop was about right.

Measured point on saddle to hoods same and saddle height fine.


Haven't got my hands on a plum bob yet, but want to get saddle setback from BB and transfer it over to the Bianchi. And want a power meter on there (hoping Power2Max Type-S hits the Australasia distributor this week) to get some real data.

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DMF
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by DMF

Don't know about the Aernario specifically, but Storck in general are very much designed around the steep STA, in regards to fork trail and weight distribution... People who need the saddle further behind the BB than intended, tend to mess up the (admittedly very unique design philosophy) steering. I think Storcks are way more sensitive that way than your average run of the mill road bike...

Just to be clear, this is about the slack HTA and longish fork rake, the combo doesn't sit very well with your body being to far behind it and steering may become unneutral.

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bikerjulio
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by bikerjulio

Tinea Pedis wrote:
Tinea Pedis wrote: Did a quick set up

So, bar drop was about right.

Measured point on saddle to hoods same and saddle height fine.


Haven't got my hands on a plum bob yet, but want to get saddle setback from BB and transfer it over to the Bianchi. And want a power meter on there (hoping Power2Max Type-S hits the Australasia distributor this week) to get some real data.


You don't need a plumb bob.

Just back up the bikes to a wall and measure back to it. Subtraction provides the answer you seek.
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DMF
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by DMF

You could do it that way, but using a plumb bob and going "Mm-hmm..." whilst you take your measure is just waaay cooler :)

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Tinea Pedis
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by Tinea Pedis

DMF wrote:I think Storcks are way more sensitive that way than your average run of the mill road bike...

Having now ridden one, I can see how there would be a segment of the market that would find the geometry really not to their liking. No different to any other bike, only (as you mentioned) Storck's are a little more unique in the design philosophy.

DMF wrote:but using a plumb bob and going "Mm-hmm..." whilst you take your measure is just waaay cooler :)

I even have theme music and all planned for it.

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by gordon

You don't need a plumb bob.

Just back up the bikes to a wall and measure back to it. Subtraction provides the answer you seek.[/quote]


Presuming that the chainstay length and bb drop are the same that would work. Otherwise it maybe inaccurate.

eric
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by eric

Subtract the wall to seat nose measurement from the wall to BB center measurement.
BB drop won't affect that. You do however need to make sure your measuring tool is square to the wall.

I find the plumb bob (mine's a large nut on a string) is easier.

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euan
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by euan

one of the edges of an open door lined up with the bottom bracket, book against the nose of the saddle and mark from the edge of the book to the edge of the door. Hey presto you have the setback.
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KWalker
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by KWalker

A few companies experimented with this in the 1980s- Rigi was the most famous for it. They had very steep STAs and also very short chainstays with a very popular wishbone ST designed to give the tire proper clearance. At the time the logic was that putting the rider both more over the rear wheel and over the pedaling axis at the same time. I think the bikes had 77 or 78 degree STAs stock. They also handled like absolute shit.

I don't know about everyone else, but I scoot forward a tad on steep climbs to maintain the same orientation around the pedaling axis. So does almost every pro cyclist. My guess is your seat is more forward of where it normally does and what you are actually seeing is a slightly greater pedaling velocity, but probably less torque due to the decrease in ankle movement over the top of the stroke. Looking at the Storck geo they have a slightly more aggressive STA in my size (57) by .5 degrees and shorter chainstays by about 1CM than most bikes. The very low amount of fork rake probably offsets this trait by adding a ton of trail to stabilize things with such a short wheelbase. I can't imagine liking that part of the geo, but the rest doesn't seem too weird.
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gordon
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by gordon

Steve Hogg has a good article on chainstay length and bike handling. Worth a read.

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Tinea Pedis
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by Tinea Pedis

To be clear, I'm not looking to break down the handling of the Storck. That's another thread of it's own.

Rather that in riding up my local climbs, same as I've done (on a lot of bikes now) the effort required and RPE 'felt' like it was less.

All I can narrow it down to is the ST angle...given I'm lacking a power meter at the moment.

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by em3

Tinea Pedis wrote:Did a quick set up, copied fit


Define "copied fit"....there is no way a steeper STA Is going to effect ur power output so I suspect ur contact points (most importantly ur saddle setback) were not set identically. Tell us how you copied ur contact points and adjusted for reach assuming ur steeper STA resulted in longer reach on "faster" frame. EM3
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Tinea Pedis
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by Tinea Pedis

viewtopic.php?p=1050561#p1050561

But if that's still unclear, imagine my saddle height and bar position (and drop) as being 'x' and 'y' - kept them in the same position. External to the relative difference in space to the BB.

Which, just measuring, is 5mm. So what, half a degree in ST angle between the Bianchi and the Aernario.

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