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Term truss bracket and kanga rack

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Old 02-28-24, 03:43 PM
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Pe1ter
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Term truss bracket and kanga rack

I’m thinking of the term kanga rack instead of buying a rear loader rack but in checking the truss bracket size and kanga rack I’ve noticed the bunch of cables ie brakes and gears will right in the way of the bracket and rack if fitted has anyone else got this on there bike and if so how did you fit it with cables in the way many thanks Pete
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Old 02-28-24, 04:29 PM
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Ron Damon
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Not an issue...

Not an issue if your cabling is neat and trim. The fix to your problem is simply to tame and reign in your cabling. Like this:



The other, less good fix is to run the cables through the luggage truss if you can't tame them otherwise.

Last edited by Ron Damon; 03-17-24 at 03:52 PM.
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Old 02-28-24, 11:10 PM
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(above) The way Ron has his rigged is completely valid, I see many done that way. I personally don't want as tight a bend on the cables, if possible. For example, Ron has the cable from the left/front brake lever, turning downward to go vertical in front of the stem, and then that sharp hook around the bottom-back of the head tube to reach the front brakes. I personally prefer to let that cable take one long circular sweep from brake lever to caliper, staying in front of the stem but close to it, in a much more gentle radius. Same path from left/front-derailleur shifter cable, to along right side of head tube and then aft. The right brake and shifter cables take a mirror path, gentle curve in front of the stem to the left side of the head tube and then aft. The right pair are coupled together in the middle of the curve with spiral-wrap, same for the left pair. Your mileage may vary, both ways are valid, both would not interfere with your carrier.

More recently, the cable from the left brake lever, leads forward to a mid-cable lever on the front of my aero bars, then aft and down to the front brakes. This gives me emergency braking when on the aeros. This shot may show if you zoom up (I was towing a hand truck that someone had discarded as they were moving):




Better angle:


Last edited by Duragrouch; 02-28-24 at 11:17 PM.
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Old 02-28-24, 11:38 PM
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Originally Posted by Duragrouch
(above) The way Ron has his rigged is completely valid, I see many done that way. I personally don't want as tight a bend on the cables, if possible.
As counterintuitive as it may seem, shorter cabling with tighter bends (within reason) actually results in less force required to shift the cable. Try googling "capstan equation for strings with rigidity" for more info.

I trimmed the cables on my Tern X11 to fit a Tern truss and Kanga rack. No issues at all. Depending on how much you're carrying, it may make the bike somewhat front heavy though, which is fine while you're moving but may make the bike unstable when parked.
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Old 02-28-24, 11:55 PM
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Duragrouch
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Originally Posted by Kabuto
As counterintuitive as it may seem, shorter cabling with tighter bends (within reason) actually results in less force required to shift the cable. Try googling "capstan equation for strings with rigidity" for more info.

I trimmed the cables on my Tern X11 to fit a Tern truss and Kanga rack. No issues at all. Depending on how much you're carrying, it may make the bike somewhat front heavy though, which is fine while you're moving but may make the bike unstable when parked.
Capstan: I know what you are saying, but I think does not apply in this case. Capstan is for applications where you want NO slippage between a cable or belt around a roller, and a larger diameter equates to more frictional area, so smaller diameter has less area and less friction holding power. That is opposite of what we want. In this case, tighter cable bend just introduces more friction (more difficult sliding) between the inner cable and the outer housing; And, for coiled-core brake cable housing, tighter bend opens up gaps in the coil, increasing elasticity in the brakes (pics of this are on sheldonbrown). On the wiki page for capstan, is this pic and statement:



"An example of when knowledge of the capstan equation might have been useful. The bent white tube contains a cord to raise and lower a blind. The tube is bent 40 degrees in two places. The blue line indicates a more efficient design."

The bend in that tube adds friction and effort to operate the blind, not reduces it.

I recognize what you are saying about additional cable *length*, but the way I have run my cables is no longer than the tighter more constrained path, though the latter may make for a neater fold.

The difficulty with making tight bends on a Teleflex cable for boat steering, is what spurred the rise of (unpowered) hydraulic steering systems; For low flow, you can make tight bends in the tubing that you can't with Teleflex.

Last edited by Duragrouch; 02-29-24 at 12:18 AM.
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Old 02-29-24, 01:11 AM
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Ron Damon
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I'll add the sharp bend of my front brake cable to the long list of problems I didn't know I had, revealed to me by this channel.
.
.


https://www.killasgarage.bike/uncate...-and-friction/

Last edited by Ron Damon; 02-29-24 at 03:20 AM.
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Old 02-29-24, 01:35 AM
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(above) Ron, that makes sense. Only qualifier is if the coefficient of friction is not linear with regard to pressure and area (like with tire traction), but for cables and housing liners, it should be close.

While not critical, when I had a choice, I chose a rear derailleur with one of those exposed wire pulleys on it to make the 90 degree turn, it requires a lot less cable length and curvature back there.
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