MTB Tech Rumors and Innovation

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brash
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7/31/2022 2:56pm
Good looking bike!

Don't sleep on Merida, they fly under the radar a bit but they make great bikes.
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Big Bird
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Oceano, CA US
7/31/2022 4:33pm
I've always wondered a thing about flex stays. How much do the physical properties of the material being flexed effect the action of the suspension? The first ones were steel and Ti. Is there a difference in feel between them and does carbon feel entirely different? My brain wants to say that steel is the most damped, as in slower to rebound, Ti is a bit springier and carbon is max springy. Totally undamped.
metadave
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Revelstoke, BC CA
Fantasy
7/31/2022 5:14pm Edited Date/Time 7/31/2022 5:15pm
Big Bird wrote:
I've always wondered a thing about flex stays. How much do the physical properties of the material being flexed effect the action of the suspension? The...
I've always wondered a thing about flex stays. How much do the physical properties of the material being flexed effect the action of the suspension? The first ones were steel and Ti. Is there a difference in feel between them and does carbon feel entirely different? My brain wants to say that steel is the most damped, as in slower to rebound, Ti is a bit springier and carbon is max springy. Totally undamped.
If you've ever worked at a shop that sells giant, I can tell you aluminum is a very poor choice. The Stance is a cool concept until you crack a chain stay. I'm at a loss as to why they dont put a pivot on that one, the extra few bucks would make a much better bike, but I guess they can't have their budget bike out doing their Maestro stuff.

I figure with carbon they can really do anything they want to tune it just how they want it without loosing much lateral rigidity. Not sure its a great example but remember the first cannondale scalpel in '01? The entire chain stay flexed instead of having a main pivot.
Buttons
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Provo, UT US
7/31/2022 5:17pm
I don't think that's a flex stay, that fender looking thing seems to be a structural part. Plus look at the shock it's got a yoke mount which means at least two links there. Which should mean the rear end wouldn't have to flex.
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sspomer
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Boise, ID US
Fantasy
7/31/2022 5:37pm Edited Date/Time 7/31/2022 5:39pm
thanks for the non-driveside pics @Javi_NoFer11 - (deleted my other post b/c obviously no lower link LOL)
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7/31/2022 6:34pm
Buttons wrote:
I don't think that's a flex stay, that fender looking thing seems to be a structural part. Plus look at the shock it's got a yoke...
I don't think that's a flex stay, that fender looking thing seems to be a structural part. Plus look at the shock it's got a yoke mount which means at least two links there. Which should mean the rear end wouldn't have to flex.
I think the link that the rocker is attached to is one piece mounted to the seat tube. It's driven by the seatstay and drives the shock via yoke. It looked to me at first like there was a short diagonal 'pull' link connecting the seatstay to what would be a rocker link driving the shock (similar to some linkage-driven single pivot bikes like Ra Bikes .12 or .20), but I think the link is just forged that way to trim some material.
7/31/2022 11:15pm
Buttons wrote:
I don't think that's a flex stay, that fender looking thing seems to be a structural part. Plus look at the shock it's got a yoke...
I don't think that's a flex stay, that fender looking thing seems to be a structural part. Plus look at the shock it's got a yoke mount which means at least two links there. Which should mean the rear end wouldn't have to flex.
Believe me, I've seen the bike up close, that thing it's a plastic fender. It's bolted to the chainstays and it is not connected to the seatstays. Also you can see it's a matt black finish (cuz it's plastic) and it's very thin.
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Karabuka
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7/31/2022 11:25pm
brash wrote:
Good looking bike!

Don't sleep on Merida, they fly under the radar a bit but they make great bikes.
One thing that always comes to my mind when talking about Merida: A local broken frame welder once said that from the inside Merida frames are the best looking ie highest quality welding of all brands he has worked on.
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brash
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7/31/2022 11:53pm
brash wrote:
Good looking bike!

Don't sleep on Merida, they fly under the radar a bit but they make great bikes.
Karabuka wrote:
One thing that always comes to my mind when talking about Merida: A local broken frame welder once said that from the inside Merida frames are...
One thing that always comes to my mind when talking about Merida: A local broken frame welder once said that from the inside Merida frames are the best looking ie highest quality welding of all brands he has worked on.
Merida make several other brands, they are one of the big manufacturers in Taiwan.

I believe they also own 49% of Specialized still.
8/1/2022 12:26am
Merida proto spotted in Galicia, Spain ridden by Toni Ferreiro at the DHU Vila de Sarria urban downhill.[img]https://p.vitalmtb.com/photos/forums/2022/07/30/12776/s1200_IMG_20220730_222758.jpg[/img]
Merida proto spotted in Galicia, Spain ridden by Toni Ferreiro at the DHU Vila de Sarria urban downhill.
[img]https://p.vitalmtb.com/photos/forums/2022/07/31/12780/s1200_IMG_20220731_183444.jpg[/img] [img]https://p.vitalmtb.com/photos/forums/2022/07/31/12779/s1200_IMG_20220731_212752.jpg[/img]


Looking at the pics, I realize there's a couple of interesting things there. First, the bike it's mullet but there's plenty of space to fit a 29" back there although there's no flip chips on the bike. I wonder if merida will have different linkages for each wheelsize like specialized does with the stumpy. And second, I notice that the frame might be prepared for integrated droppers like the Eightpins, just above the main pivot there's like a hole that has been covered, just like the Ghost Riot.
Kale123
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Fantasy
8/1/2022 12:47am Edited Date/Time 8/1/2022 3:20am
Looks like a focus jam style link driven single pivot
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Primoz
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8/1/2022 2:23am
Big Bird wrote:
I've always wondered a thing about flex stays. How much do the physical properties of the material being flexed effect the action of the suspension? The...
I've always wondered a thing about flex stays. How much do the physical properties of the material being flexed effect the action of the suspension? The first ones were steel and Ti. Is there a difference in feel between them and does carbon feel entirely different? My brain wants to say that steel is the most damped, as in slower to rebound, Ti is a bit springier and carbon is max springy. Totally undamped.
I'd guess any metal will have roughly the same damping coefficient when compared to a polymer (composite), so there shouldn't be a difference between Ti and steel. When it comes to difference in feel with hardtails, it comes from the size of the tubes, aluminium tubes are thinner wall with a larger diameter, giving more relative stiffness compared to Ti and even more so compared to steel. But that's because of the properties of the materials, both the young modulus and density - you use each material a bit differently when it comes to tube dimensioning to have them carry the load.

As for flex stays, I'd dare to say the range and speed of motion in the area of flex will be far below the point, where the differences in metal vs. composite materials would be noticeable, especially when you have a shock mounted to the rocker. It'd be interesting to know how much force actually is applied by the rear triangle compared to the shock, given how flexy rear ends can be and how little motion there is in flex stays, I'd say te level compared to the shock should be low.

As for Al flex stays, Scott did it on the previous gen (external shock) and still does it on the current (internal shock) Spark.
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Phelp
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8/1/2022 10:39am
Salsa and Kona also used and still use Al flex stays and Banshee has CNCed dropouts and yokes on their hardtails to absorb small impacts. With a good design it should not be a problem at all. Al frames, fork stanchions seat posts etc flex heavily during riding. I have no reason to not trust an aluminum flex design.
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imonly29
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FR
8/1/2022 11:54pm




Hi all, did you see the green light on the left part of Loïc's bar during his crash?
Any thoughts of what it could be?
Maybe you already discussed that.
6
Primoz
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8/2/2022 12:04am Edited Date/Time 8/2/2022 5:32am
Phelp wrote:
Salsa and Kona also used and still use Al flex stays and Banshee has CNCed dropouts and yokes on their hardtails to absorb small impacts. With...
Salsa and Kona also used and still use Al flex stays and Banshee has CNCed dropouts and yokes on their hardtails to absorb small impacts. With a good design it should not be a problem at all. Al frames, fork stanchions seat posts etc flex heavily during riding. I have no reason to not trust an aluminum flex design.
I'm more in the opposite camp.

With carbon you can finely tune the structure through layup, making it flexy in one direction, but not the others. Thus engineered flex and all. With metals that's a bit harder, due to their properties (isotropic, the same in all directions for all intents and purposes, while composites are anisotropic and thus distinctly strong in tension along the fibers, not so much in other directions), so you can only shape the 'joint' to have the flex there. An example of this would be a thinner neck to make it less stiff there.

When it comes to aluminium, the main issue is the lack of of a fatigue limit for aluminium, which is exhibited by some steels and titanium alloys. The fatigue limit means that if you're under a given stress level of the material, you can cycle it to infinity and beyond and not have it crack. Aluminium will always crack, regardless of how low the stresses are. With frames, fork stanchions and seat posts the flexes are nowhere near what it has to be in a flex stay for it function properly.

That's why steel (and Ti) frames are 'forever', that's why any bike Al that gets used a lot for a few years is very likely to crack somewhere and that's why springs are steel or titanium and not aluminium.

https://en.wikipedia.org/wiki/Fatigue_(material)



@imonly29, re Loic, someone in our group said he broke off a brake master cylinder. Not sure if it was a joke or not as we're constantly joking about Magura master cylinders snapping off left and right with Shigura setups being quite popular around here (among Magura riders of course).

EDIT: thought the question was what happened in the crash, missed the green light part. Ignore me, just rambling.
7
8/2/2022 4:58am


New downhill bike for polygon or is it just their prototype enduro bike with a dual crown ?


Dave_Camp
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CO US
8/2/2022 5:18am
imonly29 wrote:
[img]https://p.vitalmtb.com/photos/forums/2022/08/01/12790/s1200_Light_Bruni_1.jpg[/img] [img]https://p.vitalmtb.com/photos/forums/2022/08/01/12789/s1200_Light_Bruni_2.jpg[/img] [img]https://p.vitalmtb.com/photos/forums/2022/08/01/12791/s1200_Light_Bruni_3.jpg[/img] Hi all, did you see the green light on the left part of Loïc's bar during his crash? Any thoughts of what it...




Hi all, did you see the green light on the left part of Loïc's bar during his crash?
Any thoughts of what it could be?
Maybe you already discussed that.
maybe indicator of being up/down at the splits? IE green if he's up, red if behind? he was up until the crash right?
1
4
slimshady
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AR
8/2/2022 5:28am
imonly29 wrote:
[img]https://p.vitalmtb.com/photos/forums/2022/08/01/12790/s1200_Light_Bruni_1.jpg[/img] [img]https://p.vitalmtb.com/photos/forums/2022/08/01/12789/s1200_Light_Bruni_2.jpg[/img] [img]https://p.vitalmtb.com/photos/forums/2022/08/01/12791/s1200_Light_Bruni_3.jpg[/img] Hi all, did you see the green light on the left part of Loïc's bar during his crash? Any thoughts of what it...




Hi all, did you see the green light on the left part of Loïc's bar during his crash?
Any thoughts of what it could be?
Maybe you already discussed that.
Dave_Camp wrote:
maybe indicator of being up/down at the splits? IE green if he's up, red if behind? he was up until the crash right?
He seems to be running some electronically actuated rear shock from Öhlins, so I wouldn't be surprised if the green light indicated the system is active.
6
Phelp
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DE
8/2/2022 9:31am
Primoz wrote:
I'm more in the opposite camp. With carbon you can finely tune the structure through layup, making it flexy in one direction, but not the others...
I'm more in the opposite camp.

With carbon you can finely tune the structure through layup, making it flexy in one direction, but not the others. Thus engineered flex and all. With metals that's a bit harder, due to their properties (isotropic, the same in all directions for all intents and purposes, while composites are anisotropic and thus distinctly strong in tension along the fibers, not so much in other directions), so you can only shape the 'joint' to have the flex there. An example of this would be a thinner neck to make it less stiff there.

When it comes to aluminium, the main issue is the lack of of a fatigue limit for aluminium, which is exhibited by some steels and titanium alloys. The fatigue limit means that if you're under a given stress level of the material, you can cycle it to infinity and beyond and not have it crack. Aluminium will always crack, regardless of how low the stresses are. With frames, fork stanchions and seat posts the flexes are nowhere near what it has to be in a flex stay for it function properly.

That's why steel (and Ti) frames are 'forever', that's why any bike Al that gets used a lot for a few years is very likely to crack somewhere and that's why springs are steel or titanium and not aluminium.

https://en.wikipedia.org/wiki/Fatigue_(material)



@imonly29, re Loic, someone in our group said he broke off a brake master cylinder. Not sure if it was a joke or not as we're constantly joking about Magura master cylinders snapping off left and right with Shigura setups being quite popular around here (among Magura riders of course).

EDIT: thought the question was what happened in the crash, missed the green light part. Ignore me, just rambling.
Thank you for the clarification and explanation! I was not aware that aluminum alloys don’t have a „forever“ stress-level and are always prone to fatigue. I stand corrected. But nice to hear that in theory steel and titanium could have a flex design that will work without ever altering or stressing the material (as if anyone would only ride one bike forever ha ha… hm maybe a Moods?).
1
Edthorne
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CA
8/2/2022 10:00am Edited Date/Time 8/2/2022 10:04am
jasperg21 wrote:
[img]https://p.vitalmtb.com/photos/forums/2022/08/02/12792/s1200_87A2D702_580A_445A_8AB8_727E72705BC9.jpg[/img] New downhill bike for polygon or is it just their prototype enduro bike with a dual crown ?[img]https://p.vitalmtb.com/photos/forums/2022/08/02/12793/s1200_B24EA526_073F_4B40_B133_099E12579CF1.jpg[/img]


New downhill bike for polygon or is it just their prototype enduro bike with a dual crown ?


Looks to me like it's just the enduro bike with a DC on it. Still cool though!
8/2/2022 10:09am
Evil just dropped their e-bike, The Epocalypse, 166mm 29er.
BHowell
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Reno, NV US
8/2/2022 11:00am
Poleczechy wrote:
Evil just dropped their e-bike, The Epocalypse, 166mm 29er. [img]https://p.vitalmtb.com/photos/forums/2022/08/02/12795/s1200_Screen_Shot_2022_08_02_at_11.08.05_AM.jpg[/img]
Evil just dropped their e-bike, The Epocalypse, 166mm 29er.
Yup, and we rode it! First Ride Report
1
jeff.brines
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8/2/2022 11:22am
Dave_Camp wrote:
maybe indicator of being up/down at the splits? IE green if he's up, red if behind? he was up until the crash right?
Funny, if you dive way back into the archives, I asked what the collective thought about running some kind of system like this. If memory serves, I asked this after a racer was way up in a run, crashed, and could have toned back their run to safely take the win. People were not happy with my question Wink I *think* there is a rule about this however? Or at least you couldn't run a radio in your helmet?

Interesting times...
1
8/2/2022 12:24pm
Dave_Camp wrote:
maybe indicator of being up/down at the splits? IE green if he's up, red if behind? he was up until the crash right?
Funny, if you dive way back into the archives, I asked what the collective thought about running some kind of system like this. If memory serves...
Funny, if you dive way back into the archives, I asked what the collective thought about running some kind of system like this. If memory serves, I asked this after a racer was way up in a run, crashed, and could have toned back their run to safely take the win. People were not happy with my question Wink I *think* there is a rule about this however? Or at least you couldn't run a radio in your helmet?

Interesting times...
I remember a conversation I had ~10 years ago with Martin Whitely about putting LEDs inside goggles to indicate splits. This was during the TFR days when they were definitely thinking outside the box a bit – doing things like warming their bikes up before runs to get the fluids to the right viscosity and messing around with aerodynamics. I'm surprised there hasn't been more emphasis on the latter in DH. Kerr might've been on the top box on Saturday if only his cables had been run through the headset, for instance. Wink
21
Losifer
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Sandia Park, NM US
Fantasy
8/2/2022 12:42pm
Dave_Camp wrote:
maybe indicator of being up/down at the splits? IE green if he's up, red if behind? he was up until the crash right?
Funny, if you dive way back into the archives, I asked what the collective thought about running some kind of system like this. If memory serves...
Funny, if you dive way back into the archives, I asked what the collective thought about running some kind of system like this. If memory serves, I asked this after a racer was way up in a run, crashed, and could have toned back their run to safely take the win. People were not happy with my question Wink I *think* there is a rule about this however? Or at least you couldn't run a radio in your helmet?

Interesting times...
I remember a conversation I had ~10 years ago with Martin Whitely about putting LEDs inside goggles to indicate splits. This was during the TFR days...
I remember a conversation I had ~10 years ago with Martin Whitely about putting LEDs inside goggles to indicate splits. This was during the TFR days when they were definitely thinking outside the box a bit – doing things like warming their bikes up before runs to get the fluids to the right viscosity and messing around with aerodynamics. I'm surprised there hasn't been more emphasis on the latter in DH. Kerr might've been on the top box on Saturday if only his cables had been run through the headset, for instance. Wink
The embarrassment of having cables routed through his headset would have cost BK at least another 0.4 seconds.
13
Primoz
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8/2/2022 1:44pm
To be able to have live splits, you'd need some sort of telemetry. And for that you'd need to communicate on the fly with the timing system. This is something UCI/organisers would need to implement on their side to work if you ask me.

Racecars (F1) have this, but racecars also have a plethora of sensors and telemetry going back and forth with the pits, so it's not as hard to achieve that.

Plus, at the end of the day, holding back might make you lose the race in the bottom that you would win if you hung it all out and built up enough advantage higher up.
brash
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AU
8/2/2022 3:01pm
it's quite simple. Spotter down at finish line watching the live stream on the big ass TV.

Has a garage door opener with 2 buttons, top is green, bottom is red.

As soon as he see's the split on the live stream he hits the corresponding button. Signal is passed via messenger pigeon which does interpretive dance to the rider.

His wife is pissed because the garage door keeps going up and down
21
Primoz
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SI
8/2/2022 3:03pm
Talk about thinking outside the box Tongue
8/2/2022 3:04pm Edited Date/Time 8/2/2022 3:08pm
I imagine you could have a much lower tech set-up if you just put someone at the finish line who could remotely toggle an led to red or green. Not sure if this would be allowed or if the riders would want it? Can totally imagine a situation where a team manager tries to push their rider a bit harder by keeping them in the red.

Edit: brash beat me to it. And was funnier.
2
brash
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8/2/2022 3:13pm Edited Date/Time 8/2/2022 3:18pm
But besides the pigeon part, there is maybe $5 in consumer electronics needed and it's pretty simple stuff.

I am unsure of the rules on communicating with a rider mid run. Why don't they just run airpods etc and yell at them through the phone as required? (apple watch etc)

I know in the AMA SX/MX, you cant have communication with with a rider directly, must be through pit board.

I'll be expecting a call Mr Whiteley
1
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