MTB Tech Rumors and Innovation

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Digit Bikes
Posts
181
Joined
9/22/2021
Location
Irvine, CA US
11/4/2025 4:50pm
Nobble wrote:
Fun fact about seat tubes: 31.6 just so happens to be the ID of a 1-3/8” diameter, 0.065” tube.We have 31.6mm seatposts because some engineers were...

Fun fact about seat tubes: 31.6 just so happens to be the ID of a 1-3/8” diameter, 0.065” tube.


We have 31.6mm seatposts because some engineers were lazy/clever.

Pipe is defined by it's internal diameter whereas tube is defined by it's external diameter. Metal framed seat tubes are built using tube because you can easily get hole saws in the same sizes as tube, whereas reamers are relatively easy to grind or are adjustable. I imagine the 30.9-vs-31.6 issue came about because of available material and from either a frame maker is taking the lead on the design process, or a seat post maker taking the lead.

I recall hearing that BITD Specialized put a lot of time into working out which was the best fit for their product line (using mostly aluminum and steel frames at the time) and 30.9 was their answer.

I spoke to a few seat post manufacturers who ever so slightly prefer 30.9 because the thicker wall better resists being squeezed enough to bind the dropper. They also told me there are many more 31.6mm posts in the world, so they design such that binding isn't an issue.

2
11/4/2025 7:14pm

I-beam dropper from SDG…

7
11/4/2025 8:15pm

I didn't even know SDG still made I-beam saddles. 

3
Primoz
Posts
4613
Joined
8/1/2009
Location
SI
11/4/2025 10:01pm Edited Date/Time 11/4/2025 10:33pm
You might be thinking of 31.6. But then, Specialized, Norco, and I'm sure other brands use 34.9. Seatposts are one of the last areas of MTB...

You might be thinking of 31.6. But then, Specialized, Norco, and I'm sure other brands use 34.9. Seatposts are one of the last areas of MTB standards that's just a total mess with no rhyme or reason for it. What really is the weight difference between a 30.9 and a 31.6 seat post lol we're talking .7 of mm difference.

Suns_PSD wrote:
It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid! I just had to...

It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid!

 

I just had to order my first 30.9mm dropper to fit my new e-bike as that is what it runs. I would have rather had the 31.6 because I already have one and I think a small increase in diameter is helpful for bushing overlap, reducing binding, etc. 

Jotegr wrote:
FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable...

FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable difference between the two. There's a valid argument with 34.9 but at the same time, now that droppers are mature enough, I'm not sure most people are actually experiencing the issues with 30.9/31.6 posts that 34.9 was meant to solve. Companies are just too good at making em' these days. 

A 30.9 post fits everything modern with various shims. 

34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9 mm seatpost.

As for binding and bushing overlap and the like, there are very few dropper posts that have a 34,9 mm specific upper (Bikeyoke Max series) as opposed to just running a thicker lower/outer tube with the rest of the parts the same as with 30,9 and 31,6 mm posts. 

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11/4/2025 10:28pm Edited Date/Time 11/4/2025 10:28pm
Primoz wrote:
34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9...

34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9 mm seatpost.

As for binding and bushing overlap and the like, there are very few dropper posts that have a 34,9 mm specific upper (Bikeyoke Max series) as opposed to just running a thicker lower/outer tube with the rest of the parts the same as with 30,9 and 31,6 mm posts. 


You may wish to edit that 1st sentence to "dropper post related standard". 😉

1
Primoz
Posts
4613
Joined
8/1/2009
Location
SI
11/4/2025 10:33pm
Primoz wrote:
34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9...

34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9 mm seatpost.

As for binding and bushing overlap and the like, there are very few dropper posts that have a 34,9 mm specific upper (Bikeyoke Max series) as opposed to just running a thicker lower/outer tube with the rest of the parts the same as with 30,9 and 31,6 mm posts. 

Dave Waugh wrote:


You may wish to edit that 1st sentence to "dropper post related standard". 😉

Thanks. Done. 

2
slimshady
Posts
152
Joined
9/16/2011
Location
AR
11/5/2025 1:48am
Suns_PSD wrote:
It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid! I just had to...

It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid!

 

I just had to order my first 30.9mm dropper to fit my new e-bike as that is what it runs. I would have rather had the 31.6 because I already have one and I think a small increase in diameter is helpful for bushing overlap, reducing binding, etc. 

Jotegr wrote:
FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable...

FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable difference between the two. There's a valid argument with 34.9 but at the same time, now that droppers are mature enough, I'm not sure most people are actually experiencing the issues with 30.9/31.6 posts that 34.9 was meant to solve. Companies are just too good at making em' these days. 

A 30.9 post fits everything modern with various shims. 

Primoz wrote:
34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9...

34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9 mm seatpost.

As for binding and bushing overlap and the like, there are very few dropper posts that have a 34,9 mm specific upper (Bikeyoke Max series) as opposed to just running a thicker lower/outer tube with the rest of the parts the same as with 30,9 and 31,6 mm posts. 

A thicker outer tube isn't a bad thing in my book. Less prone to suffer from excessive clamping, less prone to binding. This is particularly bad with PNW droppers, where they of en come over-machined and you need to tighten the seat clamp to avoid them from lowering/twisting. Out of tolerance frames (I'm looking at you, Giant!) are another contributing factor.

3
11/5/2025 1:59am
Suns_PSD wrote:
It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid! I just had to...

It's not about weight, it's squeezing out clearance I'm pretty certain. But then again, we are talking about .7mm. Okay it is stupid!

 

I just had to order my first 30.9mm dropper to fit my new e-bike as that is what it runs. I would have rather had the 31.6 because I already have one and I think a small increase in diameter is helpful for bushing overlap, reducing binding, etc. 

Jotegr wrote:
FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable...

FWIW nearly every single dropper post offering both 30.9 and 31.6 models use identical internals, including bushings, in both models. I don't think there's an appreciable difference between the two. There's a valid argument with 34.9 but at the same time, now that droppers are mature enough, I'm not sure most people are actually experiencing the issues with 30.9/31.6 posts that 34.9 was meant to solve. Companies are just too good at making em' these days. 

A 30.9 post fits everything modern with various shims. 

Primoz wrote:
34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9...

34,9 mm is not a dropper post related standard. I had a Scott Scale back in my xc racing days in 2005 that had a 34,9 mm seatpost.

As for binding and bushing overlap and the like, there are very few dropper posts that have a 34,9 mm specific upper (Bikeyoke Max series) as opposed to just running a thicker lower/outer tube with the rest of the parts the same as with 30,9 and 31,6 mm posts. 

The new Loam Gen 2 from PNW that we just reviewed uses a 26mm stanchion for the 30.9/31.6, and a 29mm stanchion for the 34.9.

8
matmattmatthew
Posts
374
Joined
6/14/2014
Location
Fresh Prince of Bel Air, MD US
11/5/2025 5:52am

The New offering looks pretty dialed, and I did say in a previous post that I would probably get one if they went back to Boost.  The increase in travel, both front and rear, isn’t a huge selling point for me.  My local trails are fairly mellow and my daily driver for the last couple seasons has been a 150/135 mullet trail bike.  Just small enough to enjoy my local trails and just big enough to handle rougher trails when I travel to real mountains.  

So that got me thinking about the new offering run as a mullet with a 150mm fork, run in the high setting.  Is there anyway to figure out what that would put the BB at?  

2
11/5/2025 5:58am
The New offering looks pretty dialed, and I did say in a previous post that I would probably get one if they went back to Boost...

The New offering looks pretty dialed, and I did say in a previous post that I would probably get one if they went back to Boost.  The increase in travel, both front and rear, isn’t a huge selling point for me.  My local trails are fairly mellow and my daily driver for the last couple seasons has been a 150/135 mullet trail bike.  Just small enough to enjoy my local trails and just big enough to handle rougher trails when I travel to real mountains.  

So that got me thinking about the new offering run as a mullet with a 150mm fork, run in the high setting.  Is there anyway to figure out what that would put the BB at?  

4
sspomer
Posts
6229
Joined
6/26/2009
Location
Boise, ID US
Fantasy
11/5/2025 6:53am
The New offering looks pretty dialed, and I did say in a previous post that I would probably get one if they went back to Boost...

The New offering looks pretty dialed, and I did say in a previous post that I would probably get one if they went back to Boost.  The increase in travel, both front and rear, isn’t a huge selling point for me.  My local trails are fairly mellow and my daily driver for the last couple seasons has been a 150/135 mullet trail bike.  Just small enough to enjoy my local trails and just big enough to handle rougher trails when I travel to real mountains.  

So that got me thinking about the new offering run as a mullet with a 150mm fork, run in the high setting.  Is there anyway to figure out what that would put the BB at?  

2
11/5/2025 1:07pm
2supple wrote:

435 chainstay across the board...

Brian Cahal has left the chat

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

5
62
2supple
Posts
108
Joined
1/23/2022
Location
Denver, CO US
11/5/2025 1:16pm Edited Date/Time 11/5/2025 1:17pm
Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

Aston and Cahal have their quirks but calling them mediocre riders is complete BS. Both of those guys rip. 

Also 435 chainstay on a modern XL mtb is a joke IMO. Especially for a frame that costs $4k. 

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8
11/5/2025 1:36pm
Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

2supple wrote:
Aston and Cahal have their quirks but calling them mediocre riders is complete BS. Both of those guys rip. Also 435 chainstay on a modern XL mtb...

Aston and Cahal have their quirks but calling them mediocre riders is complete BS. Both of those guys rip. 

Also 435 chainstay on a modern XL mtb is a joke IMO. Especially for a frame that costs $4k. 

They have poor attitudes that everything that isn’t this incredibly niche aftermarket brand that only exist in this one country are garbage is insane. Sorry I like to be able to pick my front wheel up.

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37
DServy
Posts
247
Joined
5/28/2015
Location
Jackson, WY US
11/5/2025 2:09pm Edited Date/Time 11/5/2025 2:10pm
Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

2supple wrote:
Aston and Cahal have their quirks but calling them mediocre riders is complete BS. Both of those guys rip. Also 435 chainstay on a modern XL mtb...

Aston and Cahal have their quirks but calling them mediocre riders is complete BS. Both of those guys rip. 

Also 435 chainstay on a modern XL mtb is a joke IMO. Especially for a frame that costs $4k. 

They have poor attitudes that everything that isn’t this incredibly niche aftermarket brand that only exist in this one country are garbage is insane. Sorry I...

They have poor attitudes that everything that isn’t this incredibly niche aftermarket brand that only exist in this one country are garbage is insane. Sorry I like to be able to pick my front wheel up.

I re-read this post and couldn't understand what you were trying to say. Not to mention your response seems filled with unnecessary vitriol over someone just mentioning a persons name. 

Judging by your response I can only assume that you're harboring some deep seeded PTSD from him crushing you at the local beer league endubro. Which I do personally feel like that might be worth seeking some help for as it's never good to cary such such a burden mentally. 

All that besides, I'm glad you feel like Evil's 435 rear center is what you want in a size XL. I certainly do not, nor do a lot of people who actually ride bikes larger than a medium. Vote with your wallet and buy one of their bikes. 

Back to tech rumors. Looks like a lot of Fox 38s and 40s are on sale. When do you think they'll announce the new forks? 

29
1
Jotegr
Posts
362
Joined
6/28/2024
Location
Interior, BC CA
11/5/2025 2:50pm
2supple wrote:

435 chainstay across the board...

Brian Cahal has left the chat

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

Post your roots and rain page, sir. 

25
11/5/2025 3:05pm
They have poor attitudes that everything that isn’t this incredibly niche aftermarket brand that only exist in this one country are garbage is insane. Sorry I...

They have poor attitudes that everything that isn’t this incredibly niche aftermarket brand that only exist in this one country are garbage is insane. Sorry I like to be able to pick my front wheel up.

Greeting people with "what's up assholes?" in videos is not poor attitudes. Leave Unc alone, he's honest and he works hard to spread the good word of long rear centres.

36
4
seanfisseli
Posts
584
Joined
4/16/2024
Location
Santa Cruz, CA US
11/6/2025 8:31am

Something that holds our industry back is that we think that bike skills = bike design skills. They don’t. It helps to have bike skills and experience to inform bike design, but we have some amazing riders designing some absolute turds. Once we accept some of the mediocre riders might actually have deep insights into bike design we will see some huge improvements overall.

22
11/6/2025 8:46am
Greeting people with "what's up assholes?" in videos is not poor attitudes. Leave Unc alone, he's honest and he works hard to spread the good word...

Greeting people with "what's up assholes?" in videos is not poor attitudes. Leave Unc alone, he's honest and he works hard to spread the good word of long rear centres.

It seems like he's backed off on that a bit lately... I  thought it was funny and kinda stood out a bit. 

12
Yoda
Posts
143
Joined
9/24/2021
Location
IT
Fantasy
11/6/2025 1:11pm Edited Date/Time 11/6/2025 1:12pm
2supple wrote:

435 chainstay across the board...

Brian Cahal has left the chat

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

Rode with Brian ages ago in Whistler. Certified shredder.

But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working on an eeb.

4
1
11/6/2025 4:53pm
2supple wrote:

435 chainstay across the board...

Brian Cahal has left the chat

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

Yoda wrote:
Rode with Brian ages ago in Whistler. Certified shredder.But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working...

Rode with Brian ages ago in Whistler. Certified shredder.

But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working on an eeb.

Rumors are 170mm aluminum ebike in the works from Atherton, probably modeled around the S-series DW4 link. Nothing confirmed on drive unit yet.

11
1
nollak
Posts
77
Joined
11/27/2020
Location
DE
11/7/2025 4:35am
Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster...

Guys a straight clown and like Paul Aston and others with mediocre skill levels use all these gimmick to try to get them to ride faster but somehow never get any better

Yoda wrote:
Rode with Brian ages ago in Whistler. Certified shredder.But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working...

Rode with Brian ages ago in Whistler. Certified shredder.

But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working on an eeb.

Rumors are 170mm aluminum ebike in the works from Atherton, probably modeled around the S-series DW4 link. Nothing confirmed on drive unit yet.

Without any knowledge to what they actually use I would guess perhaps the new Maxon Motor.

I had a quick ride on the CDuro prototype with the motor and seen the Dedicated Bike with it. Both share a similar construction as the Atherton bike and a square downtube for the battery can be integrated pretty easily. 

Apart from that the motor is pretty small and powerful. It has some nice characteristics and felt pretty natural riding it on the parking lot.

1
3
joshmtb
Posts
54
Joined
4/17/2025
Location
Haslemere GB
11/7/2025 5:15am
Yoda wrote:
Rode with Brian ages ago in Whistler. Certified shredder.But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working...

Rode with Brian ages ago in Whistler. Certified shredder.

But since this is tech rumors, via ride companion episode with Gee, sounds like Atherton could be working on an eeb.

Rumors are 170mm aluminum ebike in the works from Atherton, probably modeled around the S-series DW4 link. Nothing confirmed on drive unit yet.

nollak wrote:
Without any knowledge to what they actually use I would guess perhaps the new Maxon Motor.I had a quick ride on the CDuro prototype with the...

Without any knowledge to what they actually use I would guess perhaps the new Maxon Motor.

I had a quick ride on the CDuro prototype with the motor and seen the Dedicated Bike with it. Both share a similar construction as the Atherton bike and a square downtube for the battery can be integrated pretty easily. 

Apart from that the motor is pretty small and powerful. It has some nice characteristics and felt pretty natural riding it on the parking lot.

I was chatting to Maxon ebike manager and he had certainly visited Atherton HQ.... Whether it makes it as the final product will have have to be seen

11
1
mathieuelie
Posts
4
Joined
5/21/2024
Location
mirabel, QC CA
11/7/2025 9:51am
joshmtb wrote:
I was chatting to Maxon ebike manager and he had certainly visited Atherton HQ.... Whether it makes it as the final product will have have to...

I was chatting to Maxon ebike manager and he had certainly visited Atherton HQ.... Whether it makes it as the final product will have have to be seen

Any other rumours you've heard ? I'm super interested/curious about the Maxon motors... hopefully it comes on more e-bikes in the next year.

1
1
joshmtb
Posts
54
Joined
4/17/2025
Location
Haslemere GB
11/7/2025 10:18am
joshmtb wrote:
I was chatting to Maxon ebike manager and he had certainly visited Atherton HQ.... Whether it makes it as the final product will have have to...

I was chatting to Maxon ebike manager and he had certainly visited Atherton HQ.... Whether it makes it as the final product will have have to be seen

Any other rumours you've heard ? I'm super interested/curious about the Maxon motors... hopefully it comes on more e-bikes in the next year.

Sadly not, I'm actually just a maxon robot motors customer and managed to get a call with the guy because I was interested in the product. Still looking to maybe make my own e bike with their system tho....

3
1
11/7/2025 2:09pm

isn't there an e-bike thread?

36
5
boozed
Posts
686
Joined
6/11/2019
Location
AU
11/8/2025 2:06pm Edited Date/Time 11/8/2025 2:41pm

isn't there an e-bike thread?

When were tech rumours banned from the tech rumours thread?

Edit: Less sarcastic response: The e-bike thread is for non-tech-rumour related e-bike discussions.  The e-bike discussion above however looks very much like tech rumours to me.

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8
11/8/2025 3:01pm

For anyone interested in bracket testing!:

5
1
11/8/2025 5:31pm

Looks like the Madonna might get the Yalla V2 adjustable dropout soon. Found these on mtbnews.de for a an industry event with everyone attending bike setup pictured https://www.mtb-news.de/news/bock-auf-ballern-2025/

aHR0cHM6Ly9mc3RhdGljMS5tdGItbmV3cy5kZS92My8yOS8yOTAxLzI5MDE3MzUtZGtmOGFyc3NhenJuLWJhYjIwMjVfNDMtb3JpZ2luYWwuanBnaHR0cHM6Ly9mc3RhdGljMS5tdGItbmV3cy5kZS92My8yOS8yOTAxLzI5MDE4MDctd2w0OWViOXhlM2IyLWJhYl9iaWtlc185NDE0MC1vcmlnaW5hbC5qcGc
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