New geometry and consequences for bike fit

Kerplunk

Likes Bikes and Dirt
The whole steep seat tube angle thing these days interests me in regards to peddling performance. It looks like the bb is positioned right under seat post, which I reckon would require a different position/muscles to produce the same power. No doubt it feels weird/different considering a time trial roadie still has a bb well infront of the saddle tip. I suppose it is all compromises considering how better the bike decends.
On topic JD, that bike is too small for you mate..
 

Petero

Likes Dirt
Just because a Process was mentioned previously, and is hyped, decided to do a little comparison, although I'm sure others have done their own...
My Genius XL has a reach of 470mm (on low BB setting) and ETT of 650mm, The new Process 134 has a ETT of 664 and reach of 510mm - so the combination of steep seat angle and slack head angle means that while the "reach" of the bike is 40mm longer, the actual length from headtube to seatpost is only 14mm more! Still longer but nowhere near what the "reach" figures seem to indicate. Given this I feel that maybe calling "reach", well, the "reach" is highly misleading. Certainly not enough to change a frame size based on the hype of longer reaches.
Throw into that that a slacker head angle brings your bars closer as your stack goes up, and that a steeper seat angle brings you closer to the bars relative to a slacker one - no one rides with the seatpost slammed and the bars below the head tube.. So effectively those geo figures shorten up way quicker than the "old" geometries which I imagine is why JD feels so weird seated on the XL frame vs the XXLs.
EDIT: Unsure if ETT measurements are taken from Actual seat angle or Effective seat angle?
 
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PJO

in me vL comy
I reckon steeper seat angles perch the rider higher and so the frames require more stack. I don't think manufacturers have increased stack heights on newer geo frames, the trend is for lower rather than higher stack heights (long, low, slack). It is further exacerbated by the slacker front.

Taller riders are impacted to a greater degree since every degree increase in seat angle perches them higher, compared with median-sized mortals like myself.
Reach and stack need to be considered together, two frames with the same reach but different stack heights should feel different when seated. The effective top tube would be a giveaway though because the frame with the greater stack should also have a longer theoretical top tube (for the same reach length), and should be roomier when seated.

Is there an XXL Ripley?
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
Is there an XXL Ripley?
Nope, which is most of the problem here. In my opinion XL sizes are almost always sized for the small end of XL (ie: around 6'1"-6'3"), so they just make the biggest size an arbitary from "6'1" to X'X"..." sizing that kinda screws really tall blokes like Big JD when the bike looks long but doesn't "fit" long.
 
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Big JD

Wheel size expert
We need to meet up JD - quite a predicament.


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Look forward to it mate. Im not too concerned about it. Will try the setback post and if it doesnt fell right- I will sell it and probably get another Highball/ Chameleon. Looking at exotic german alloy frames but its just a bike.
 

born-again-biker

Is looking for a 16" bar
Just because a Process was mentioned previously, and is hyped, decided to do a little comparison, although I'm sure others have done their own...
My Genius XL has a reach of 470mm (on low BB setting) and ETT of 650mm, The new Process 134 has a ETT of 664 and reach of 510mm - so the combination of steep seat angle and slack head angle means that while the "reach" of the bike is 40mm longer, the actual length from headtube to seatpost is only 14mm more! Still longer but nowhere near what the "reach" figures seem to indicate. Given this I feel that maybe calling "reach", well, the "reach" is highly misleading. Certainly not enough to change a frame size based on the hype of longer reaches.
Throw into that that a slacker head angle brings your bars closer as your stack goes up, and that a steeper seat angle brings you closer to the bars relative to a slacker one - no one rides with the seatpost slammed and the bars below the head tube.. So effectively those geo figures shorten up way quicker than the "old" geometries which I imagine is why JD feels so weird seated on the XL frame vs the XXLs.
EDIT: Unsure if ETT measurements are taken from Actual seat angle or Effective seat angle?
All of what you say is true.

But, as I've typed in other discussions, there is a point you're missing.
When you're standing in the attack position, descending, the only number that matters is reach because that's the only two points of contact.
It doesn't matter where the seat is or what the actual /effective seat angle is... because you're not sitting on it. And ETT can be anything you like.

But longer reach for tall guys is what makes it feel secure /confident when you're balls deep in a double black rock garden steep-as-fuck trail.

I don't buy an Enduro bike and prioritise the seated climbing position.
It's like measuring a Hilux's lap time at the track.

The new Geo has been pioneered by the Enduro category.
Enduro bikes prioritise descending.
Reach numbers are about descending.


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Petero

Likes Dirt
Absolutely agree. It's no question that long, low, slack has huge benefits when descending. I think the crux of it is, don't change or choose your frame size based solely on reach numbers. Except for the small majority of people, like anything, geo numbers are always going to be a compromise and when they change, they will feel weird for a time.
Bike fit is of course very subjective, and depends on who uses the bike, where they ride, and how they ride. I think we have all learnt to compromise to an extent so no 'one bike' or one geo philosophy is a good fit for everyone.
 
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Big JD

Wheel size expert
All of what you say is true.


The new Geo has been pioneered by the Enduro category.
Enduro bikes prioritise descending.
Reach numbers are about descending.


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surely an xc/trail/ all rounder shouldnt be based on the Enduro rigs.......................................

just saying- we arent all charging rock gardens and timed 20 minute descents.
 

born-again-biker

Is looking for a 16" bar
surely an xc/trail/ all rounder shouldnt be based on the Enduro rigs.......................................

just saying- we arent all charging rock gardens and timed 20 minute descents.
For sure BigJD. An all rounder "trail" bike should have different Geo numbers... different enough to be noticeably better for climbing or possibly more comfortable (depending on individual body shape etc etc etc)

In the real world lots of us use Enduro bikes as "all rounders"... myself included.
Every time I finish a long climb I question my sanity!

But....

Without picking on our friend Petero, I respectfully felt he was mixing geometric apples with oranges if we're having a purely theoretical discussion about geo numbers.

... And another separate point I was thinking about regarding seat angles.
As an example, my Process has a steep effective SA, but the actual SA is slack.
This can be a good thing for 6'+ orang-utans like me. Because as the saddle moves up to the top position for climbing, the cockpit/ETT gets longer.
But bikes with steep actual SA would feel more cramped in the seated position because the saddle ends up less rearward.
Yeah/nahh?


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beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
But bikes with steep actual SA would feel more cramped in the seated position because the saddle ends up less rearward.
Yeah/nahh?
surely an xc/trail/ all rounder shouldnt be based on the Enduro rigs.......................................

just saying- we arent all charging rock gardens and timed 20 minute descents.
Trail/all-rounder/backcountry/downcountry/whatever will still benefit from the geo changes unless you're riding very tight/twisting trails - it just makes getting the right size less flexible than traditional geometry. If the new-geo bikes are too short, they'll feel cramped and it'll be hard to find/stay-in the weight balance sweet spot.

@born-again-biker - (IMO) A steep "actual" seat tube angle is good for climbing as it puts your weight a lot further forward on steep (seated) climbs. With the appropriately sized ETT and longer overall wheelbase you get a lot of extra stability as your weight is really well centered so you will be less likely to spin up the back wheel, even if leaning forward. This is a personal thing, but I feel like the suspension also works better while seated with a steeper STA as your weight's not as far back or making the rear susp sink into "deep sag" and wallow. Took me ages to get my head around it, but I think it's finally clicked for me!
 

Paulie_AU

Likes Dirt
A bloke who I was speaking with on Friday was 197cm on a 515 reach Nukeproof Mega and had a really tall set of deity bars to give him stack height without hurting reach and ett. Another guy who was 200cm there was on a pole machine with 535 reach. He said it felt awesome climbing compared to any previous bikes but did say he felt it was a little short when pedalling on flat trails but was the first bike he felt like he had room descending.

I am a short arse in comparison at 175cm but ETT is definitely something I am keeping an eye on for my next frame. I won't get anything with less than 600mm which seems to get me onto 465 reach and 65deg sta. Any steeper ETT gets to short at a reach number I am willing to run.
 

Big JD

Wheel size expert
For sure BigJD. An all rounder "trail" bike should have different Geo numbers... different enough to be noticeably better for climbing or possibly more comfortable (depending on individual body shape etc etc etc)

In the real world lots of us use Enduro bikes as "all rounders"... myself included.
Every time I finish a long climb I question my sanity!

But....

Without picking on our friend Petero, I respectfully felt he was mixing geometric apples with oranges if we're having a purely theoretical discussion about geo numbers.

... And another separate point I was thinking about regarding seat angles.
As an example, my Process has a steep effective SA, but the actual SA is slack.
This can be a good thing for 6'+ orang-utans like me. Because as the saddle moves up to the top position for climbing, the cockpit/ETT gets longer.
But bikes with steep actual SA would feel more cramped in the seated position because the saddle ends up less rearward.
Yeah/nahh?


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Big JD

Wheel size expert
It seems the only XXL 29er XC trail bikes around are Santa Cruz or a Rocky Mountain Element XC race whippet (which I just sold....... what a flog). The new XXL SC Tallboy 4 is coming out with identical geo to the Ripley with only a 10-15mm difference in length (ETT/reach/seat tube). The current model Tallboy 3 would be perfect for me (old school geo and massive ETT 27.9 inches) but they dont have any more left.Then you are into the harder hitting Hightower and LT and Megadeath.
 

Asininedrivel

caviar connoisseur
First new bike or major upgrade in nearly 7 years so it’s a custom build.

I did a lot of spreadsheet work before pulling the trigger, I wanted something with a big reach but had a decently high stack height, there’s not a lot out there. I wasn’t too worried about the travel number so long as it pedaled well.
New SC Hightower? I've noticed they've got appreciably bigger stack heights to some other bikes.


Oh and don't write off the Santa Cruz line up just yet JD ;)
 

Big JD

Wheel size expert
I ordered a 9point8 fall line dropper from Canada. Not surprised it arrived 2 days earlier than a guitar pedal from ACT which I ordered at the same time. Anyway, this dropper has a 25mm setback head and from initial carpark ride it feels better. My long legs are in a better position for the pedals and it has given me extra much needed length ETT.
I will ride and see but I reckon it just looks weird and Im totally underwhelmed. Set back post, 70mms of spacers under the 60mm stem, 40mm riser bar- all just to fit!!!!! It is now so far away from the intended setup- there must be consequences to handling. I really aint sold on the new geo changes and every manufacturer is adopting them. On paper it looked fine but reality is very different. I have never thought of looking at stack heights and HA/SA and the effect on ETT. Im perhaps in the 5% that sit outside the "norm".
 
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