Technical > General Technical

Stand Reinforcement

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jags:
seriously i just wouldn't trust them ,i seen a few bikes with the same stands and you could see where the ware started to set in which would lead to corrosion ,
what about the click stand they seem to be a great bit of kit.

love to tour in Scotland almost as nice as Ireland  ;D ;D but way to many tough hills for yours truly.

mickeg:
Greasing the bolts should make them less likely to fall out.  A dry bolt if it gets loose can easily vibrate out.  But grease is a very viscous fluid, so a bolt with grease on it is less likely to fall out from vibration.

It is so convenient to dig something out of the bottom of a Backroller pannier when your bike is lying on its side ... on a rainy day.

Andre Jute:

--- Quote from: Templogin on January 12, 2016, 09:44:50 pm ---Those stands mounted on the chainstays at the back make me even more nervous.  There isn't a lot of metalwork back there, but I see that plenty of people use them on here.
--- End quote ---

I understand where you're coming from. And I can't understand why designers don't triangulate the space immediately behind the bottom bracket and between the chainstays with a flat piece of metal, drilled and tapped for stand of either one or two legs.That's obviously the strongest point on any bike where a stand may feasibly be attached.

All the same, the rear of the non-driveside chainstay is the preferred position for attaching the kickstand of many manufacturers, including those who conduct extensive stress tests on all their frames and components and accessories. Perhaps they know something we don't.

Danneaux:

--- Quote ---...I can't understand why designers don't triangulate the space immediately behind the bottom bracket and between the chainstays with a flat piece of metal, drilled and tapped for stand of either one or two legs.That's obviously the strongest point on any bike where a stand may feasibly be attached.
--- End quote ---
I do understand why not, but I'm not sure I would have if I were not a hobbyist framebuilder who had mostly-successfully repaired damaged kickstand plates on several friends' bikes.

Here's why:

When a kickstand is mounted just behind the bottom bracket, the support is subject to fouling the left crankarm if it is left down and the bike is wheeled backwards. *If* the bike has also been left in a low gear, the torque exerted by the arm on the kickstand is remarkably high -- enough to break the joint that attaches the plate to the stays.

On the ones I successfully repaired, it was a clean "pop" of one side, though it was difficult to get it back in place because the plate was no longer flat. With care, I still managed some good repairs. In several other cases, the chainstay was holed when the plate tore loose -- those I could not fix, though on one I managed to braze a patch over the tear so the bike was minimally serviceable for a promised life of light use and leisure.

My first "good" bike (with a kickstand clamp and no frame mounting plate) was damaged similarly while parked in a university bike rack. Classes changed while I was inside, and a large lecture was due to start so rack space was limited. Someone managed to squeeze a bike in beside mine, but to do so, they had to pull my bike backwards a half-meter or so. I'd ridden up to campus on the hilly side, and so the bike was left in low gear with the stand down. You can imagine my dismay when I came out to find my chainstays obviously deformed by the kickstand clamp and the kickstand loose. There were no actual cracks and the bike continued for another 40,000km or so. I still have it, and still feel a little sick when I view the damage.

Also -- and I have seen this repeatedly with my own eyes at the local university! -- an astonishing number of people will actually remain seated on the bike while the kickstand is down. I'm not sure how this habit develops, but it places tremendous loads on the chainstays and can itself result in damage to the tubes. I think having the kickstand centrally mounted and easy to access while on the bike may encourage this, as I have never seen anyone balancing on a bike with a rear-mounted kickstand -- it is too hard to reach and too difficult to balance on it without falling over. Manufacturers know people can be unwise (perhaps innocent/ignorant, but still unwise) with surprising frequency, so they remove the possibility for temptation.

The reason kickstands mounted to the rear of the chainstays (near the left-rear dropout) work (better) is because the stays are rolled down as they taper and the wall thickness increases as a result (generally; there are exceptions. Road bikes sometimes use much thinner tubes throughout than mountain bikes sometimes do). It is usually harder to crush them with a clamp *and* there is no way they can be fouled by the left crankarm. The stays are further braced from bending by the rear hub, axle, and locknuts, which together form a triangulated structure laterally.

If one is going to mount a kickstand to the bike, it is less likely to cause damage near the rear hub than immediately behind the bottom bracket, no matter how it is fastened.

All of this becomes more problematic with a loaded touring bike. A low-mounted kickstand just does not have a good bracing angle against heavy loads mounted above the bike centerline. Given the already poor bracing angle, it doesn't take a lot more load from winds, slopes, or soft ground to allow gravity to have its way and the bike can fall over, causing damage from impact with the ground.

A couple (competing) manufacturers I have corresponded with feel brazing a plate to the chianstays behind the bottom bracket subjects the stays to excessive heat at their thinnest point. Others have told me they feel -- and have seen -- the weight of a heavily loaded touring bike exert enough load on the mounting plate to bend, fracture, or tear it loose. Interestingly, they noted they found the problem to be as bad with dual-leg stands as single ones. I still find this surprising, as I would expect a bike leaned to one side would develop both greater and uneven force on the stays. I'm still pondering this.

The Click-Stand and similar "tall props" work well because they brace against the top tube or where the seatstays join the seat collar and so can better prevent the bike from toppling over. The drawback is the bike can rotate around this prop, so some means must be used to clamp the brakes shut, preventing the bike from rolling using the prop as a pivot point.

So...that's likely why we don't see more dedicated kickstand mounting plates affixed to the forward end of chainstays, right behind the bottom bracket.

As a side note, many clamps do seem to dig into paint after a period of some use, leaving the metal beneath vulnerable to corrosion. I've seen various shaped rubber pads used to try and prevent this problem (Rivendell offers some for Pletscher kickstands: http://www.rivbike.com/product-p/k5.htm ), but I have seen these loosen and any grit that manages to come between does grind away on the paint.

One last observation: If you grease your mounting bolts or use a liquid threadlocker, then it is standard practice to follow (lower) wet-torque values and not (higher) dry ones. For one among many references on this, see: http://www.intermotive.net/Tech%20Tip/Tech%20Tip%20-%20Jan%2008.pdf My Glover "Pocket Ref" sees a lot of use when torquing bolts both dry and wet. Plating makes a difference also. See: http://raskcycle.com/techtip/webdoc14.html

All the best,

Dan.

Andre Jute:
Thanks for that detailed and convincing explanation, Dan. Now I understand why people with test equipment and a history of using it braze a tab to the hub end of the non-driveside chain stay to which to attach the prop stand: it is the least bad option in the present backwards state of bicycle design.

But I'm not wearing the rest of it. While I believe every word you say, that entire story about the disasters caused by the thinned and weakened forward ends of chain stays being ripped apart by fittings for central prop stands not only leaves me cold, but enrages me by another example of the deleterious influence of roadracing on bicycle design and advancement.

In more than a century has no one had the gumption to make chainstays with long enough forward butts, or to cast or press bottom shells with long enough integrated lugs, to resist even the force of a low geared crank being wheeled backwards?

Who cares about that little weight on a touring bike if it assures its integrity?

Please note, I'm not making a case for the central stand over the hub-end stand; I'm just pointing out that refusal of those who want a central stand is not caused by some kind of an insuperable engineering problem (or even a human one, considering how impressionable people are), but by pure stodgy "traditionalism" (read "laziness") on the part of bicycle designers overinfluenced by historical road bike design, who then offer the weak excuse that they can only build with the cheap tubes available.

Personally, I like the hub-end stand attached to a tab brazed to the rear of the chain stay for the theoretical and practical advantages conferred by its greater height, wider stance, and above all because that rear three-dimensional triangle, when closed by the axle firmly bolted in, is probably the strongest structure on the bike. That seems to me the right place to attach an everyday prop stand.

But a chain stay stand that far back on the bike does need assistance when a tourer is loaded up with front panniers, and in that case, if you don't like the idea of an additional lowrider-supporting front stand, which at best is clumsy kludge and at worst worthless weight for 99% of the time, the bottom bracket stand should at least be made possible by the designer's choice of bottom bracket shell and chain stay tubes. Where he gets them is a problem designers should have solved with the tube-makers long, long ago. I ride on tubes and lugs specially made by Columbus for a single low volume handmade bike model, so I know for a fact that a key tubemaker is willing to listen to novel ideas, and I know that Poppe & Potthoff drew a few tons of specially-developed stainless steel for bike tubing a few years ago (Reynolds got the idea from P&P), with special lugs of the same material, and examples of new roadbike tubes are penny a dozen on every continent, so it isn't the tubemakers stuck in 1895, it's the bike designers.

To tell customers in 2016 to lie their bike down on the ground is unacceptable.

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