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A few years ago, I had a bike with lousy shifters. The bike simply wouldn't shift to the middle chainring. At the shop, they got it to work, but the added pressure of me sitting on it kept it from shifting properly.
This repair stand would have rollers on the bottom for the wheels to rest
on, like a cycle trainer, to allow them to spin. There would be a piece at the top that would put pressure on the saddle, with a gauge to show how much pressure is being put on the bike. This way, the mechanic can tune the bike to work with a particular weight on it. This would help because most bikes act differently when they are in use.
A bicycle gearbox
http://my.ohio.voya.../~bdhayes/sa/sw.htm
[AbsintheWithoutLeave, Apr 01 2005]
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weight is not concentrated on the seat, it is distributed through the handlebars, seat and pedals. ideally, the mechanic should be able to move the weight so that it is transmitted through each of these in whatever proportion is needed at that time. Great idea, not large enough in scope. |
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Hmm. Maybe it should have different adjustments for each, with a gauge for the total weight, and each of the parts (saddle, handlebars, pedal). It could also incorporate something to turn the pedal at different things while applying pressure to them. |
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I do not see the problem here. Take the gearbox apart. clean and add that special stuff thingy that makes it go smoothly(I can't think of the name for it in english, Lubricant or something?) and ride your bike. Your weight on the bike does not make a difference at all. |
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Your shop just failed the repair job. I have performed this repair\adjusting job on several bikes from professional to semi-pro-bikes and I can tell you that the whole point of a well functioning gear-changing-system is that it works under all possible extreme conditions. |
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Your weight on the bike is subjective to the road surface. hit a bump in the road and your weight on the bike becomes momentarliy more then five times your weight in normal conditions. think of off the road bikes, the gearbox works all the same. |
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It is just a matter of the right alignment. |
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[zeno] - lubricant is right (eg. grease, oil, etc). |
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No, it was a cheap frame, which flexed a lot. When the bike was on the stand, it always shifted perfectly, but when I rode it, it wouldn't shift. If I got off, I could shift it just as if it was on the stand. (btw, my shifters broke, and the new ones worked better. They cost twice as much. |
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If not bad science then bad bike. |
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If bad bike, then not bad science. |
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If not bad bike or bad science then good idea. |
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Reminds me a bit of something my husband calls "torque plates," but which have little to do with this idea. |
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A bike repairstand for bad bikes? Why not fix the bike so it becomes a good bike instead. |
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[Zeno] this is exactly my point. The stand can be used to fix the bad bike, so it works. You can get a new frame, but then it would be a new bike. |
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It just keeps nagging at the back of my mind. so listen. if you use your invention and then gain weight, you would have to use your invention again yes? And then you might lose weight and so on ad infinitum right? |
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What I propose is fixing the gearboxthingy so that it is no longer influenced by weight as it shouldn't be in the first place thus making your idea useless. |
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Trying to think of analogy**. and failing. still, I said it before and I'll say it again: bad science. |
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[zeno] There is no "Gearbox" on a bike. I suggest not complaining about what you don't know about. If you are talking about the freewheel/cassette, why don't you say so? |
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I just used the word gearbox because I don't know the proper names for bike parts in english and they are hard to find in dictionaries. If we are talking about tandwielen, kettingspanners, derailleurs, kruipolie, versnellingskabels and the like, I assure you my knowledge is adequate to say the least. I can take apart any bike to the smallest piece and put it back together and it will function better than before. Thus I know your weight on the bike does not matter, wether you gain weight or lose weight or lend your bike to a friend or whatever. |
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Your latest annotation was not in response to the actual body of my annotations but instead you attacked me on form. Therefore my claim of bad science still stands. |
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[--___,] //There is no "Gearbox" on a bicycle// What were the old Sturmey-Archer 3-speed hubs, if not a box containing gears? I suggest not annotating about what you don't know about. [link] |
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// What were the old Sturmey-Archer 3-speed hubs, if not a box containing gears?//
A flaming nightmare, with nasty habits of shifting unexpectedly. |
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It's not the flexing that messes up the shifting, it's the extra tension in the chain when the wheel is driving the bike rather than spinning in thin air. |
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When properly adjusted, it should work well over the full range of tensions that can be experienced, as the rider will put a wide range of tensions through the chain whether he is accelerating hard or just cruising. |
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A properly adjusted transmission must cope with this, or it'll start slipping every time you pedal hard. |
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Incidentally [zeno] this is the first I've noticed that your English is not that of a native speaker. It's very good. Apologies for the stereotyping, but from the knowledge of bikes and the terminology, are you from Holland? |
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Yes [david_scothern] I am, thank you for the compliment. |
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[zeno] my apologies. Sometimes I can be quite impulsive. |
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Hmm. It could include something to put strain on the drivetrain. |
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Strain on the drive chain. Now there's an idea. When taking apart the gear thingy, putting it back together again, you never know you did a good job until you actually give it a go. So a stand that would simulate the actual driving conditions, uphill, downhill, potholes etc. would come in handy. |
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Maybe like a flight simulator... but for bikes. |
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