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alexdi leelikesbikes's article
Dec 28, 2018 at 21:37
Dec 28, 2018
Lee McCormack's Guide to Bike Set-Up
@whiteblur: Yes. I assume a horizontal (around -10D) stem, no spacers, and a bar with no rise, so the 'desired stack' is apportioned entirely to the frame. Few frames will be right on the money, so I use another formula to determine the depth of the spacers under the stem for a given frame. Spacer Depth = (Desired Stack - Actual Stack) / SIN(RADIANS(Head Angle))
alexdi leelikesbikes's article
Dec 28, 2018 at 13:38
Dec 28, 2018
Lee McCormack's Guide to Bike Set-Up
@whiteblur: I'm just using the TAN function in Excel and Sheets. =460-(665-590)/TAN(RADIANS(70))
alexdi leelikesbikes's article
Dec 28, 2018 at 12:54
Dec 28, 2018
Lee McCormack's Guide to Bike Set-Up
@whiteblur: Sure. When you add stack to a given frame, reach reduces because the head tube angles toward you. (Desired Stack - Actual Stack) gives you the vertical distance you're adjusting for. Dividing by the tangent of the Head Angle translates that vertical distance into a horizontal distance. "Radians" converts degrees to radians; it's only there because I pulled this formula from a spreadsheet. You'll want it with Google Sheets or Excel. The next step is to consider the stem length the frame is suited to use. The 80mm on my steep XC bike would be a rudder on a slack trail bike. If I wanted to run 40mm instead with the same bar on a new trail frame, I'd need that frame to have an adjusted reach 4cm longer. (Quick digression: this assumes the stem body is horizontal when mounted. If your stem angles up or down when mounted, your effective stem length isn't what's printed on the stem. Stems are measured on their longest axis, not the horizontal; a +30D 60mm stem will be significantly shorter than a 60mm -17D stem. This will affect how the bike steers.)
alexdi leelikesbikes's article
Dec 28, 2018 at 10:52
Dec 28, 2018
Lee McCormack's Guide to Bike Set-Up
I prefer to normalize reach for a desired stack. My saddle height is consistent across bikes and I know how high I want the front end relative to it. I also know the bar I'm using. The question is, what's the reach when the bars are at the right height? For example: Frame 1: Reach: 460 Stack: 590 HA: 70 Frame 2: Reach: 441 Stack: 645 HA: 67 Frame 1 looks longer, but let's dig into that. Say I want a stack of 665. I'd plug that number into this: Adjusted Reach = Reach - (Desired Stack - Actual Stack)/TAN(RADIANS(Head Angle)) Frame 1 has an adjusted reach of 433. Frame 2 has an adjusted reach of 433. Despite a 19mm difference in frame reach, these bikes will have an identical fit when I bring the bars up.
alexdi pinkbikeaudience's article
Dec 27, 2018 at 8:33
Dec 27, 2018
Tech Talks: Dropper Seat Posts - To Clamp Or Not To Clamp?
@Geochemistry: It depends where you're clamping. There's no generic "carbon tube strength," some sections of the frame are radically stronger than others. I'd clamp the downtube where it joins the bottom bracket without a second thought; you couldn't crack that section if you wanted to. The top of the seat tube just below the top tube join, I'd also clamp, especially if it's backstopped by a seatpost. The top tube is fine on cheaper metal bikes, but the middle span is the weakest tube section on any carbon or butted bike. The clear coat argument is a canard, the only way you're damaging that with a rubber clamp is if it's contaminated. A bit of tape or automotive film are sufficient barriers for the paranoid.
alexdi pinkbikeaudience's article
Dec 27, 2018 at 8:17
Dec 27, 2018
Tech Talks: Dropper Seat Posts - To Clamp Or Not To Clamp?
I don't clamp the inner post because I don't like having to verify my clamps are perfectly clean. Wrapping with a cloth just makes the stanchion, already narrow and slippery, even more likely to slip. Most bikes have enough housing slack to raise the post a few inches so you can clamp the outer.
alexdi mikelevy's article
Oct 22, 2018 at 7:42
Oct 22, 2018
Review: Yeti's New SB100
The bro-tude in this review is really irritating.
alexdi mikekazimer's article
Oct 9, 2018 at 4:57
Oct 9, 2018
Review: Bontrager SE4 2.6" Tire
I run the XR2 and XR4 versions of this tire. i29 is too small. I have to use +4 PSI to keep the XR2 from folding over in the back, more than I used with the 2.35 version of the same tire. i39 with the XR4 is great. Side knobs line up with the walls, low pressure, never bottoms or folds. Recommend retesting with a bigger rim.
alexdi FSA-MTB's article
Sep 13, 2018 at 7:35
Sep 13, 2018
FSA Releases Wider Gradient Wheels
I'm more interested in if the spoke holes were reinforced and they used nipple washers. For enduro use with no weight limit, spoke tension for this wheelset must be through the roof. Brass tensions more easily and doesn't round off, but that'll be small comfort if the nipple starts pulling through the carbon a few months in.
alexdi RichardCunningham's article
Aug 28, 2018 at 16:20
Aug 28, 2018
Review: Fox Live Valve Suspension
@Duffersss: The Di2 battery isn't just a battery, it's more like a battery-shaped computer with an onboard power source. Quite a lot of firmware determines how and to what it delivers current. While Shimano and Fox have worked together before, I doubt either company wants to be joined at the hip when it comes to updates on either platform.
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