Enduro/AM - The Weight Game

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Enduro/AM - The Weight Game
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Posted: Jun 3, 2020 at 15:12 Quote
Yeah the BERD ones seem to be the best, there was a thread on MTBR on making them from kiteboarding lines, people had good success with it but they started threatening to sue people over there. The cost of the kite lines for a wheelset would be around 14-18 dollars but the labor involved with making each one is very high.

Posted: Jun 3, 2020 at 15:25 Quote
Yea that was interesting thread (HA PUN!)

I had a talk with one of the guys who was working on it, and he admitted the problem wasn't necessarily developing a competing product, it was trying to figure out how to easily copy an existing one. The problem was that there aren't too many ways to create a fiber spoke that doesn't end up looking exactly like what Berd had produced. If he found another way of doing it that didn't infringe on the patent but made it public, he was worried that Berd would be ready with patent lawyers to include that in their patents. So, any further work had to kept private.

Berd apparently didn't like the idea of producing "parts" either, so if he tried selling anything that resembled a component of the Berd Spokes, he'd get hit with litigation. Especially because he could no longer claim that such parts weren't for spoke use.

Posted: Jun 3, 2020 at 15:29 Quote
Circe wrote:
tom666 wrote:
That's cool then Salute

Generally though I don't think it's advisable to wear an MX helmet for MTB

The rational is that F=MA. The added Mass of an MX helmet increases the force on impact. There's also the argument that Motorcycle helmets are tested to more stringent standards than DH, since the speeds are often higher. They also force you to past a bump test, where the helmet has to survive skidding along the ground and having multiple impacts which causes the foam to be stiffer/harder than necessary. However, there are benefits to the Motorcycle tests. The impact tests in particular that are designed to replicate hitting a curb or landing in rocks.

The problem with all helmet standards is that they're supposed to protect your skull from fracturing. None of the tests have been updated to reflect that concussions can occur at much lower G-forces.

When I buy a helmet, I look for brands that offer technologies that protect against low speed impacts, high speed impacts, and rotational forces. On the MTB side, there are a number of brands doing a a great job. I personally wear a Bell Super DH.

For MX/DH, I wear a Kali Shiva. This is one of the lightest full face helmets on the market. Its so small, it could easily be mistaken for a bike helmet. It's unique because it's in molded, unlike the majority of full face helmets (unless they're made by the same factory as Kali, see Fox/Leatt).

They also use a proprietary mutli density foam which yields at lower speeds, but can also handle bigger hits (Fox/Leatt also use the same material, because you know why). For lower speed impacts/rotational forces, they also use a softer D30 style material that can also sheer laterally.

This is the same helmet that Nicolai Rogatkin almost killed himself in when riding at Rampage.

P.s. RC did a great article on the topic years ago. Link.
F=MA, but saying that a heavier helmet means more force in your brain isn't true. All that increases with a heavier helmet is the force of the impact on the shell of the helmet. Your head is effectively a separate system.

Unless it's changed, the impact test for ASTM 1952 DH certification and the test for the DOT motorcycle certification are almost identical. That's why the Shiva can pretty easily be DOT certified.

A lot of people have a misconception that DOT helmets achieve their impact protection from harder foam. But really they just have a thicker foam. More foam = more distance for your head to move in an impact = more time = less acceleration.

Moto Helmets are also incorporating low speed impact mitigating tech too. my Moto 9 Flex has three densities of foam and a built in slip-plane between them. Designed separately for 3m/s, 5m/s, and 7.5m/s impacts.

Edit: and I really dislike that RC Article, there's not real content in it and he basically ends it with "well there's a DH standard so that must but be safer for DH" I also like that he as a section titled "experts square off" and then only talks to one side of the argument.

Posted: Jun 3, 2020 at 16:49 Quote
The average speeds in enduro MX would be really close to DH. You don't see anyone in MX outside of maybe trials who lobby for the use of bike helmets. The whole argument is stupid. Wear what you feel safe and comfortable in.

Posted: Jun 3, 2020 at 18:00 Quote
The DOT requires “ multiple high-energy impacts on both hemispherical and flat anvils. It also features the same shell penetration test as Snell’s M2015.”

DOT has no chinbar tests.

The DH test does require a chinbar. Sort of.

“ While the vast majority of downhill helmets are of the “full face” variety, meaning they feature a chin bar, F 1952 doesn’t actually require that passing helmets possess a chin bar. If, however, the manufacturer has equipped the helmet with a chin bar, that portion of the helmet must withstand an impact test (a 5-kilogram weight dropped on the chin bar from a height of .40 meters) without deflecting more than 60 millimeters.”

The DH does not have a penetration test that I am aware of, nor the multi impact requirement. It does have a curb and anvil drop test, which is at higher g forces than the regular standard.

I hastily pulled this info from Domes website. They give a great breakdown in spreadsheet form of each test required. On phone. So hard to make a better response.
https://www.helmetfacts.com/standards/

Posted: Jun 3, 2020 at 18:51 Quote
Per your link, ASTM allows a max acceleration of 300G. DOT allows 400G but does not allow 200G for more than 2ms.

Specifying a duration is important because it limits the amount of energy that can be transferred. If you really want I can probably find the math to quantify it, but it's been a while.

edit: that site you linked is pretty interesting. It's typically difficult to find the numbers behind a lot of the standards.

I'd love to get into the helmet design field. It's a super interesting field and I feel there's a lot of unexplored room for improvement.

Posted: Jun 4, 2020 at 3:41 Quote
Was originally planning to get a Tarvo to decisively win the weight game, but after some reflection I decided against it for now, as there's no reviews or any real world info on it out there.
So, I found a set of Zipp 3Zero Moto wheels on sale, and ordered a new DVO Diamond so I finally get the tire clearance that I need, as the non-boost Diamond is quite tight.
I'll probably try to get 2 more seasons out of my Coal before looking for a new enduro bike, maybe get a Ripley next year for the mellower trails.

Anyone have much experience with the factory Zipp wheels, how do the hubs hold up?

Posted: Jun 4, 2020 at 6:12 Quote
Losvar wrote:
Was originally planning to get a Tarvo to decisively win the weight game, but after some reflection I decided against it for now, as there's no reviews or any real world info on it out there.
So, I found a set of Zipp 3Zero Moto wheels on sale, and ordered a new DVO Diamond so I finally get the tire clearance that I need, as the non-boost Diamond is quite tight.
I'll probably try to get 2 more seasons out of my Coal before looking for a new enduro bike, maybe get a Ripley next year for the mellower trails.

Anyone have much experience with the factory Zipp wheels, how do the hubs hold up?

The hubs are just sram xo hubs, should be a fair amount of reviews around, Ive heard they hold up fine but don’t have super high engagement, if you care about that.

Posted: Jun 4, 2020 at 8:17 Quote
Haven't heard anything bad about the Zipp Moto wheels. Everybody seems to love them.

Posted: Jun 4, 2020 at 8:38 Quote
All reviews note the comfortable ride and high weight, most mention a lack of stiffness, and none are impressed by the hubs.

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Posted: Jun 4, 2020 at 9:04 Quote
PHeller wrote:
Haven't heard anything bad about the Zipp Moto wheels. Everybody seems to love them.

My coworker had a massive failure on his. He was seating a new tire with the wheel in his lap and the rim buckled in half. Eek

Posted: Jun 4, 2020 at 9:27 Quote
seraph wrote:
PHeller wrote:
Haven't heard anything bad about the Zipp Moto wheels. Everybody seems to love them.

My coworker had a massive failure on his. He was seating a new tire with the wheel in his lap and the rim buckled in half. Eek

Who does this?

Posted: Jun 4, 2020 at 10:23 Quote
This community is great.

If a product has issues, we're bound to know about it.

Posted: Jun 4, 2020 at 10:40 Quote
PHeller wrote:
This community is great.

If a product has issues, we're bound to know about it.

Certainly a perk when you combine pessimists and the internet.

Posted: Jun 4, 2020 at 11:17 Quote
The Moto zipp rims....

When you have just the rim in your hand and compress it vertically they feel like soft expensive noodle. Compresses easier than an alu stans rim etc. Easily the softest rim ive fondled.

They're not worth it imo. Especially with the same old sram hub if you buy the zipp wheelset.

Co worker reports feeling both wheels flexing around in hardpack berms. Gross.


 
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