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pinkberry3 jamessmurthwaite's article
Sep 4, 2019 at 10:50
Sep 4, 2019
CeramicSpeed Unveil Prototype Telescoping MTB Drivetrain - Eurobike 2019
@Konyp: The efficiency numbers you state for bevel gears are for standard gear teeth (sliding friction). Ceramic speed is using the rollers to reduce friction and I would agree that they do in fact reduce friction and increase efficiency (rolling friction benefit versus sliding friction). So I think your statement about how it is inherently less efficient is somewhat flawed. Overall, the jump from 98% to 99% efficiency doesn’t seem like a big jump but it can be in certain situations - think tour de France where you ride for a long time. I’m not saying that this is the future, as it seems difficult to mass produce (they even admit this), but it is a valiant effort to increase efficiency and try something new. A 1% absolute gain at that high of efficiency is very hard to get! We shouldn’t stop people from trying to innovate, otherwise we don’t get any new cool shit ????
pinkberry3 edspratt's article
Jun 3, 2019 at 17:15
Jun 3, 2019
Video: Winning Runs - Fort William DH World Cup 2019
@keeqan: Flash boiling occurs when a surface is around 250C. I'd say that's pretty hot, although it may not take too much braking at those speeds. It's more impressive than anything else!
pinkberry3 redbullbike's article
Jul 12, 2018 at 13:24
Jul 12, 2018
Video: Gee Atherton's Vallnord Course Preview POV
Loved the commentary but man, with that front camera angle, I need to take some motion sickness pills next time...
pinkberry3 danielsapp's article
Jun 16, 2018 at 14:07
Jun 16, 2018
Pinkbike Poll: Do You Use Tire Inserts?
@solidautomech: Did you use the same tire both with and without the pro core? How much lower of an initial pressure did you use?
pinkberry3 danielsapp's article
Jun 16, 2018 at 6:59
Jun 16, 2018
Pinkbike Poll: Do You Use Tire Inserts?
@R26: I did not take it into account. This was a tire-centric model because I wasn't using numbers and then when you bring the suspension into account, it definitely gets way more complicated. This was kind of a back of the napkin analysis. To truly do the analysis, you would need to take everything into account, but I also looked back at the graph when I had a bit more time and saw that the volume change of the tire is not enough to cause massive pressure spikes. We may just be imagining a correlation between exploding tires and the tire inserts. I agree that the tire inserts increase the tire stiffness so the suspension does more work. That is one benefit of the system. I guess you might want to re-tune your suspension after installing an insert then!
pinkberry3 danielsapp's article
Jun 16, 2018 at 6:51
Jun 16, 2018
Pinkbike Poll: Do You Use Tire Inserts?
@acali: I agree. I don't think that the volume change is significant enough to cause a massive pressure spike. I kind of did the analysis and post hastily because I had to run some errands. When I thought about it some more and looked back at the graph, you essentially have to compress half of the volume of the tire in order to get a pressure spike that is 2.5x the original pressure. That is a massive change in volume needed and I don't think you really get that ever on impact. At normal compression (1/5th the initial volume is compressed), the pressure spike is about 1.5x the original pressure. That does not seem substantial. Still, the analysis was interesting from an engineering standpoint, but maybe I should have looked at it more closely before posting and heading out the door! I also agree that we just might be imagining this correlation between inserts and exploding tires. Sometimes it is easy to notice a phenomenon when we don't think it should be happening as much, as with the tire inserts.
pinkberry3 danielsapp's article
Jun 16, 2018 at 6:40
Jun 16, 2018
Pinkbike Poll: Do You Use Tire Inserts?
@ianwish: I have been able to set up a tubeless tire with minimal sealant (just enough to coat the interface between the rim and tire). Sealant on the inside of the tire is not really necessary, but I still use it. Car tires use what is called a "tire bead lubricant" which helps seal the rim/tire interface but they do not use sealant on the inside, as you mentioned. The main purpose for sealant in mountain biking is to help fix small punctures that occur while riding. Car tires can be as thick and puncture resistant as you want, mainly because a few extra grams won't hurt a 2 metric ton car. With mountain biking, every gram counts, so the tires are designed to have some puncture resistance, but they are not over-designed. Also, the surface that we ride on is very different from cars.
pinkberry3 danielsapp's article
Jun 15, 2018 at 13:25
Jun 15, 2018
Pinkbike Poll: Do You Use Tire Inserts?
@mikelevy: You may be onto something. By using some engineering equations (I'll spare everyone by not going into in detail), I was able to get a graph that relates tire pressure on impact to initial air volume. As the initial air volume of the tire is decreased (such as with a foam insert), the tire pressure on impact increases drastically. Essentially, this means that with a tire insert, the tire pressure will be higher on impact than what you would see without an insert. A tire without an insert doesn't have a large pressure spike for normal impacts but tires with an insert can, depending on geometry and other factors. Overall, this could be a reason for some of the failures we have been seeing recently as the tire pressure could be too high on impacts for the system to handle. There are several ways I can think of to combat this effect. First, you could start at a lower tire pressure so the pressure on impact isn't too high. Second, you can use a lower profile insert so that the initial air volume isn't reduced as much from a standard tire. I suspect that less failures have been seen with the Huck Norris, as many have mentioned below, because it is relatively low profile and is not changing the tire system as drastically as CushCore, for example. Finally, you could have an insert that can deform without a rock actually striking it, such as ProCore with a lower pressure insert... Hopefully my ramblings make sense to you. I think I'm just gonna stick with tubeless tires for now.
pinkberry3 pinkbikeaudience's article
Aug 10, 2017 at 20:34
Aug 10, 2017
Giro - EWS Whistler 2017 Fantasy Contest
Men: 1. Rude 2. Hill 3. Melamed Women: 1. Ravanel 2. Brown 3. Courdurier
pinkberry3 pinkbikeaudience's article
Jul 5, 2017 at 21:20
Jul 5, 2017
Troy Lee Designs - UCI World Cup DH Fantasy Contest - Rd 5, Lenzerheide 2017
Men: 1. Hart 2. Brosnan 3. Gwin Women: 1. Hannah 2. Nicole 3. Seagrave
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