Show notes
This week Randall and Craig take a look at the new Cervelo Aspero and discuss its fit in the spectrum of gravel bikes. We then dive head first into a discussion of the myriad of ways one achieves suspension on a gravel bike. Cervelo Aspero Support the Podcast The Ridership Automated Transcript, please excuse the errors In the Dirt 20 Craig Dalton: [00:00:00] [00:00:00]Hello and welcome to in the dirt from the gravel ride podcast. I'm your host Craig Dalton. I'll be joined shortly by my cohost Randall Jacobs. [00:00:13]Each week we muse about gravel cycling and how it's fitting into our lives. [00:00:18] These episodes are supported by listeners. Like you simply visit buy me a coffee.com/the gravel ride to support the podcast. Additionally we encourage you to visit the ridership a free global cycling community [00:00:33] It's something we created to serve the cycling community. And also serve as a back channel for any suggestions you had for the podcast [00:00:41]With all that said let's dive right into my conversation with Randall. . hey Randall, [00:00:46] how are you doing? [00:00:47] [00:00:47] Randall R. Jacobs: [00:00:47] I'm doing well, Craig, [00:00:48] Craig Dalton: [00:00:48] how are you? I'm doing okay. A little bit rainy day here in Marin. So I'm glad I got a nice ride in yesterday. [00:00:55] Randall R. Jacobs: [00:00:55] Very much needed given the water table throughout California and fire risks coming up next season. So not a bad thing. [00:01:03] Craig Dalton: [00:01:03] Yeah. Fortunately they were actually, so I looked at the weather forecast and I made sure I got our ride in on Friday, which was great to see you. And then I got a nice ride in on Saturday. [00:01:11] So I feel relatively fulfilled with my last few days of riding. [00:01:16] Randall R. Jacobs: [00:01:16] Excellent. Yeah, I've gotten been back on the bikes since being back in the Bay and I've gotten a few rides in with friends and it's been great. Two people who are vaccinated. The statistics increasingly show that the risk of transmission is exceedingly [00:01:30] low, at least with the variants that are out there now. [00:01:32] And so being able to go out for a ride with a friend and not have it be, something that has to be overly worried about is quite a relief. [00:01:39]Craig Dalton: [00:01:39] Absolutely. I think we talked about this maybe on the last, in the dirt. It is a little bit awkward right now. I We run into people on the trails and there's still, I'm pulling my mask up to be courteous, but it, I feel like there's going to need to be some statements by the government to say, Hey, it's okay to be outside. [00:01:54] If you're not, if you're vaccinated and eventually we can get back to normal trail use. [00:02:00] Randall R. Jacobs: [00:02:00] Yeah. There's a lot that shows that outdoor mask usage, when you have a lot of space can be somewhat performative. But I do think that, especially in dense urban areas, there's still some value to that. [00:02:11] And plus people are just getting over this traumatic experience of Being afraid of this pandemic. And so when I'm out and about, I have my mask with me and if I pass somebody even if I'm sufficiently distant, if they're wearing a mask, I honor their boundaries by putting my mask up and just, just so everyone is comfortable, but we're slowly getting to a greater degree of normalcy while at the same time needing to remain vigilant. [00:02:34] Yeah. [00:02:35] Craig Dalton: [00:02:35] Yeah. And we certainly have to acknowledge that other parts of the world aren't. Getting as close as we are to returning back to normalcy. So keep masking up, keep protecting yourself and keep protecting others for sure. Yeah. Yeah. But on, onto the gravel world, I saw pretty cool announcement from about their newest Sparrow. [00:02:53] Did you catch [00:02:54] Randall R. Jacobs: [00:02:54] that? I did. Yeah, it seems that they have shed some weights and gone internal with all the [00:03:00] cables and hoses and the I also, [00:03:02] Craig Dalton: [00:03:02] they did a good job of, aesthetically, it's a sexy, fast looking bike and I've always appreciated that they're very much in this race, bike category, which may not be for everybody. [00:03:13] But I think it is for some, and it's, it's an attractive package. [00:03:17] Randall R. Jacobs: [00:03:17] Yeah, and it's in the same mode of the, endurance, roadie type geometry. So this could be an excellent bike as the one bike for everything. Yeah. It's 72 head angle reasonably sporty handling and so on. [00:03:30]And they have this flip chip that is interesting in the fork too. So it's in the fork, the flip chip. [00:03:35] Craig Dalton: [00:03:35] Correct. And what's that [00:03:36] Randall R. Jacobs: [00:03:36] all about? So the way that, that they're marketing it in the way that they've implemented, it is it's really a way to maintain the same trail figure when you have tires of different radius. [00:03:49] And so if you have a six 50 by 47 tire, right? That's going to be 10 millimeters less radius than a 700 by 40. If you go 700 by 45, it's 15 millimeters. But just taking those two sizes. So it's going to be about 10, 10, 11 millimeters difference, depending on tire pressure and things like that. [00:04:07] And so they have a flip chip in there that keeps their, the trail figure at, around 58, 58 and a half millimeters, which they. Have defined as the sweet spot. And so if that's important to you to maintain the same trail with two different wheel tire volumes tire radio, and then that can be useful. [00:04:24] Craig Dalton: [00:04:24] So not effect of that. So what when for the uninitiated, what does that trail figure when you're [00:04:30] designing a bike and you said that, that 58 or whatever was what they thought was the ideal is that have to do with the steering quickness, the stability. What does it, how does it play out? [00:04:41] Randall R. Jacobs: [00:04:41] He can think of it partially as quickness. It's really like the proponent. It's also the propensity of the bison to want to travel in a straight line. And so it's hard to explain without a diagram, but just in terms of numbers, yeah. A lower trail figure is going to be a little bit more responsive. [00:04:59] So the ratio of input at the steering to output in terms of turning and so on we'll be great. Will be greater versus a. Larger trail figure, getting into 60, 65 or so that's going to be slower handling. So the inputs at the steering are going to be result in less outputs in terms of the bicycle actually turning. [00:05:19]Craig Dalton: [00:05:19] Okay. So if you talk about extremes, like if we talk about a chopper, that's got a very extreme high trail number. And as everybody can imagine riding a choppered out bicycle, when you turn the handlebar, it's very slow to steer. [00:05:34] Randall R. Jacobs: [00:05:34] Correct. And you end up with another problem. Which when you're talking about subtle differences in trail and, relatively steep head angles and the like, 70 to 73 range then you know, we'll flop, isn't an issue, but if you've ever been on like a really slacked out mountain bike, you'll notice that like the bicycle when it's straight. [00:05:54] It's at one height. And then when you turn it one way or another, the bicycle actually drops a little bit. So the bicycle has a natural [00:06:00] propensity to want to turn in. And in fact, the more it's turning the faster it's going to turn. Cause there's the weight, your weights pressing down is causing that turning it's supporting that turning. [00:06:11]And so that, that can be an issue when bikes get really, [00:06:13] Craig Dalton: [00:06:13] so that's the net effect on climbing, but the net effect on descending, if we talk about on the mountain bike side is. Just stability through rough [00:06:21] Randall R. Jacobs: [00:06:21] terrain, correct? Correct. And also when you're descending, you're, you're pointed downhill. [00:06:27] So your head angle relative to the downward vector of gravity is going to be more steep when you're going downhill. And so the steering characteristics are different. And so there's a bunch the variables here. [00:06:39] Craig Dalton: [00:06:39] Yeah. No, it makes sense. As I jumped from my. Heavily cross-country oriented 29 or a mountain bike to a more kind of all mountain bike that was full suspension. [00:06:49] It became way back in Slack and climbing became maybe less fun, but descending became a hell of a lot more fun. Yeah. Yeah, exactly. Particular bike. I know if with the gravel athlete, a lot of times maybe you don't get into thinking about the geometry and what it's going to do when you're buying the bike, but you mentioned that. [00:07:09]The flip ship is just making it a neutral change between tire sizes. If you had two wheel sets on there, right? [00:07:16] Randall R. Jacobs: [00:07:16] Yeah. And neutral in terms of, again, this trail figure. So steering input to steering output and the propensity of the bike to want to travel in a straight line. And this is one way to achieve this. [00:07:26]And the other thing that, I look at this and it's okay, that's great. [00:07:30] But actually through the bikes geo in a little CAD program, and I just, queried what if I took the just. The standard, 51 millimeter trail position, and to change the wheels without flipping the chip, what would be the the impact on trail and the impact on trails only three millimeters. [00:07:49] So we're actually not, I'm not sure that the juice is worth the squeeze. With regards to having this extra components three millimeters of trail may be noticeable to somebody who's really can appreciate that subtlety, but frankly our bike actually has the same front end geo. [00:08:05]The DOB one is the same front NGO, 72 degree head angle in the large and a 51 offset. And I've written it with the 700 by forties and the node, the difference is subtle, but actually. The higher radius tire, like a 700 by 40 will, oftentimes you'd be running that tire when you're doing more straight, flat stuff anyways. [00:08:25] And maybe you want slower trail when you put on that higher rate, the greater radius tire. And so that change in trail is actually a benefit because it's it makes sense for the the tire being mounted. So are you [00:08:37] Craig Dalton: [00:08:37] suggesting maybe this particular implicate implementation of a flip ship didn't go far enough? [00:08:42]Randall R. Jacobs: [00:08:42] And think that there's it is useful if you are, if you really have a a sense of the subtlety when you change this, but don't expect a radical difference when flipping the chip versus [00:08:54] Craig Dalton: [00:08:54] changing the tire. It sounds if you're committed to one wheel size or another. When you put the six fifties on and you [00:09:00] put the chip in that particular position, you've got the bike that the Savallo engineer designed, correct? [00:09:06] Precisely. So if you're like a one wheel set kind of guy or girl. You got, what's promised to you by the engineers, but it's not necessarily trying to change the performance from more of a road bike experience to more of a off-road bike experience. [00:09:22] Randall R. Jacobs: [00:09:22] Correct? Yeah. It's really keeping the gravel focused experience. [00:09:27]Consistent across different wheel sizes though, at the same time, like there is a, I'd have to take a look at how they've implemented here, but presumably one position there would be well, so there's a, trade-off here too, in that you, in a road bike geo you want. You also want the generally the handlebar position maybe to be lower and maybe the axle to be more underneath your where your hands are on the bar. [00:09:54] So the either bars going out, the axle coming in, so that front ends more planted because on the road take like a high-speed road descent. You really want that front end planted because you have the grip and you want to feel you don't want the wheel wallowing. And then a lot of your braking performances there too on the dirt, it's exactly the opposite. [00:10:13] You want to be able to get your weight back. You have limited traction up front, you don't want the front wheel to wash out. And so you'd want to be a little bit more upright the axle a little bit further out and so on. And it's hard to this, this implementation doesn't really achieve anything with regards to changing that dynamic. [00:10:27] So it doesn't really make it more of a road, [00:10:30] more or less of a road bike in different positions. It's really about again, maintaining consistent trail. Across the two different wheel sizes that it accommodates. Yeah. Yeah. Yeah. [00:10:38]Craig Dalton: [00:10:38] I think it's interesting. It's an interesting model. I know a number of people who ride this bike, a number of people, frankly, who have given up their road bike, because this one was so good at riding on the road, as well as off-road, as you mentioned, very close to an endurance road bike, geo with the exception that they D they have built in decent tire clearance. [00:10:57] I think at a six 50, you can go all the way out to a 49. [00:11:01] Randall R. Jacobs: [00:11:01] Correct. Yeah. And I can't recall what they allow with a 700 I'm guessing at least 700 by 40. Maybe it fits a 42 or 45. I think it was a 42. Yeah to overlap, probably come. That becomes an issue in some of the smaller sizes in particular, beyond that point, which gets into yet another one of these like variables that have to be considered when you're looking at all these geometry PM parameters. [00:11:24] Cause you can have the perfect geo, but if if you're gonna have to overlap, that's going to be a real compromise and may result in some safety issues. [00:11:31] Craig Dalton: [00:11:31] Yeah, for sure. I feel fortunate that I'm in the medium or 56 kind of size because typically I do all right. When it comes to toe overlap, [00:11:40] Randall R. Jacobs: [00:11:40] Yeah and I think we did one 70 cranks fee or one 60 fives. [00:11:44] I would not [00:11:45] Craig Dalton: [00:11:45] capitulate at the time in which I bought my bike and I went one 72, five, but I think I'm sold now that I would go one 70 in the future. [00:11:53] Randall R. Jacobs: [00:11:53] Yeah. Proportional, crank length helps with that a little bit and allows you to do a slightly tighter front-end geo on the smaller bikes without adding to that [00:12:00] risk of a tow, right? [00:12:01] Craig Dalton: [00:12:01] Yeah. And I don't have a particularly large foot, so that helps as well. It makes me skirt, the issue entirely. [00:12:08] Randall R. Jacobs: [00:12:08] So this gets into, so we talked about a little bit about geo. The other thing we wanted to discuss today is the advent of, suspension. We're starting to see suspension particularly for, front end suspension on gravel bikes. [00:12:18] Craig Dalton: [00:12:18] Yeah. I've been obsessing a little bit over it. Just trying to figure out the best way to articulate a conversation around suspension, because I think. A lot of times, and this may be true for some of the listeners out there. The moment you mentioned the word suspension, you get a hard stop. [00:12:36] I don't want to hear about it. I've got no interest in suspension whatsoever, but the reality is every single bike out there in the world is suspended in some way. [00:12:45] Randall R. Jacobs: [00:12:45] Absolutely. We u…
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