Andymann Posted October 6, 2015 Posted October 6, 2015 Now that is smart! Just like that BMW that was on Top Gear. Drive the track once and it memorizes it and then drives it again on it's own.. Or just link your shifters to your cadence and they shift up or down accordingly, sort of like an Auto gearbox shifting according to the revs...Ya but the revs on a car are determined by the power and torque curves and where they are at an optimum - so you would need to know your bodies HR vs. FTP curves and set your cadence so that you will always be in the sweet spot. Interestingly enough I have been doing a lot of graphing and plotting of all my races and training sessions over the last couple of years, and I have a pretty good idea of where my cadence, HR and Power intersect to give me that "sweet" spot. My wife thinks I should spend more time training and less time analysing!
JKK Posted October 6, 2015 Author Posted October 6, 2015 I spoke with Greg once when we were on the Roof, and he reckoned there was nothing special inside that gearbox - it was pretty much just reversed with the RD in the front. The big thing there was that the "cluster" did not have a spline setup, so while you were freewheeling down hill, the cluster still turned which allowed you to shift gears without pedalling Clever Engineering. I wonder what the net weight gain of that gearbox was, and why it never made a reappearance?
Andymann Posted October 6, 2015 Posted October 6, 2015 Clever Engineering. I wonder what the net weight gain of that gearbox was, and why it never made a reappearance?I do recall he said it weighed a ton! and it was only about a second or so faster which I suppose in downhill was a lot, but of you are not a big pedal masher then you would have no real advantage I guess. Hell Aaron Gwin won a race without a chain..... I think for now there is nothing to beat the simplicity of a RD and cluster - I suppose when people start losing races because they keep on ripping off their RD's on rocks, they will look at something, but until then it's probably just Engineering for Engineering's sake!
Pure Savage Posted October 6, 2015 Posted October 6, 2015 Ya but the revs on a car are determined by the power and torque curves and where they are at an optimum - so you would need to know your bodies HR vs. FTP curves and set your cadence so that you will always be in the sweet spot. Interestingly enough I have been doing a lot of graphing and plotting of all my races and training sessions over the last couple of years, and I have a pretty good idea of where my cadence, HR and Power intersect to give me that "sweet" spot. My wife thinks I should spend more time training and less time analysing! Problem is when you are sitting in the gutter and your rear cluster is playing musical gears when you go in and out of the slip and trying to keep up with the surges.
JKK Posted October 6, 2015 Author Posted October 6, 2015 I do recall he said it weighed a ton! and it was only about a second or so faster which I suppose in downhill was a lot, but of you are not a big pedal masher then you would have no real advantage I guess. Hell Aaron Gwin won a race without a chain..... I think for now there is nothing to beat the simplicity of a RD and cluster - I suppose when people start losing races because they keep on ripping off their RD's on rocks, they will look at something, but until then it's probably just Engineering for Engineering's sake! Yes I have also read that a chain drive is the most efficient form of power transfer. Therefore I think it will be around for many years to come. Maybe I should start strategically placing rocks along the single tracks
Paul Ruinaard Posted October 6, 2015 Posted October 6, 2015 DAF, the truck manufacturer, made a little compact car in the 1960s, called the Daffodil. It had a belt drive variable transmission that worked on the same principle. I helped someone re-build one of those sometime in the 1980s, so excuse if the detail memory is a bit faded. Here's the link. https://en.wikipedia.org/wiki/DAF_DaffodilAudi also built a CVT boxed car about 10 years ago. Thing is that the engine always runs at optimal RPM and the CVT box can match the torque curves. The thing accelerated like a greyhound. WRT the DAF: DAF actually stands for Doorns Auto Fabriek, it was a bunch of fellows with clogs. The Dutch used to have reverse races for a lark. So you drove the car around the oval in reverse looking out the back window. Being CVT it went as fast in reverse as forward so this thing was the fastest reversing car in the world. Trust the cheeseheads to do this. Also raced Citroen 2CV boats but those werent CVT.
Andymann Posted October 6, 2015 Posted October 6, 2015 Yes I have also read that a chain drive is the most efficient form of power transfer. Therefore I think it will be around for many years to come. Maybe I should start strategically placing rocks along the single tracks I'm thinking you would still have the final drive as a chain - exactly as on a motorbike. I even thought of buying an old steel frame bicycle and fitting the gearbox (just the two gear clusters and the shift drum) from an old bike engine from a scrapyard just to see if the concept would work. And if it did, start manufacturing a new gearbox from scratch to suit a bicycle, but I've go so much *** on my plate right now with the Mines I doubt if I will ever do it....
Andymann Posted October 6, 2015 Posted October 6, 2015 I also have a design for a disposable set of rollers which could be used to warm up while waiting in the start block of the Argus and 94.7 - you buy them for around R100, use them once and then toss them. I made a working prototype for around R60 but because they only work on the rear wheel, and you have to rely on your front brake to keep from riding into the bloke in front of you, I decided the risk was too much!
Pulse Posted October 6, 2015 Posted October 6, 2015 Or just link your shifters to your cadence and they shift up or down accordingly, sort of like an Auto gearbox shifting according to the revs... This has been done. Electronic BB-based gearbox with either full automatic (allows for 5rpm variation), or manual override
Paul Ruinaard Posted October 6, 2015 Posted October 6, 2015 I am a Mountain Biker and a Mechanical Engineer... Of which I am sure there are many.. Naturally, engineers want to design something new, innovative. I have had ideas that sound great, but when I start doing a bit of thinking, they become laugh-able. From my collection:Me trying to re-invent the wheel...Capture.PNG Secondly, trying to design a CVT type belt-drive drive train...The distance between the alu discs increases as the rear wheel spins faster, thus decreasing your cadence the faster you go and increasing it when you ride up a hill, removing the need for gears. 1.PNG2.PNG Maybe with some outside input, something could come of our silly ideas...? Einstein said that imagination is a preview of the future... Who else has had some crazy ideas??? Please share! Nothing in this league but i have fantasised and priced up a rig using the Shimano Alfine hubs or the like (closed hub 8 speeds - no chain line change) and possibly a planetary gear front crank with a Gates Belt Drive as the drivetrain. Its all closed in so it would be very reliable and would need little to no maintenance. CVT is a great idea, however what happens when it gets wet or gets mud in it - not sure that you could keep it sealed? So you would have all sorts of issues with the friction layers. That is the problem I was trying to solve. Other ideas I reckon have a future in MTB are "solid" wheels" that I have seen tested on some cars which look like your wheels - essentially relying on flexible carbon/plastic fingers. So there is suspension in the tires as well. http://www.gizmag.com/bridgestone-airless-tires/20710/ Similar idea - the Michelin Tweel: http://www.gizmag.com/go/3603/ I am not sure if they ever got near production as there are so many vested interest in current technology that it will likely be killed off until we have landfills full of tires that cant be processed. Great ideas though.
JKK Posted October 6, 2015 Author Posted October 6, 2015 I also have a design for a disposable set of rollers which could be used to warm up while waiting in the start block of the Argus and 94.7 - you buy them for around R100, use them once and then toss them. I made a working prototype for around R60 but because they only work on the rear wheel, and you have to rely on your front brake to keep from riding into the bloke in front of you, I decided the risk was too much! That would require serious balance
JKK Posted October 6, 2015 Author Posted October 6, 2015 Nothing in this league but i have fantasised and priced up a rig using the Shimano Alfine hubs or the like (closed hub 8 speeds - no chain line change) and possibly a planetary gear front crank with a Gates Belt Drive as the drivetrain. Its all closed in so it would be very reliable and would need little to no maintenance. CVT is a great idea, however what happens when it gets wet or gets mud in it - not sure that you could keep it sealed? So you would have all sorts of issues with the friction layers. That is the problem I was trying to solve. Other ideas I reckon have a future in MTB are "solid" wheels" that I have seen tested on some cars which look like your wheels - essentially relying on flexible carbon/plastic fingers. So there is suspension in the tires as well. http://www.gizmag.com/bridgestone-airless-tires/20710/ Similar idea - the Michelin Tweel: http://www.gizmag.com/go/3603/ I am not sure if they ever got near production as there are so many vested interest in current technology that it will likely be killed off until we have landfills full of tires that cant be processed. Great ideas though. I based my wheel design on the tweel concept. I came up with the curved blades to try incorporate suspensipn into the front wheel along with tyre profile. Depending on how tight you tighten your skewer/thru axle, you would increase the curvature of the "spokes" resulting in a stiffer suspension and narrower tyre footprint. So you could adjust your ride setup simply by tightening or loosening your skewers. Problem would be mud and dirt getting into the wheel though...
JXV Posted October 7, 2015 Posted October 7, 2015 If your combine your suspension wheel with your CVT sprocket idea you get a variable radius pulley that varies in relation to the torque applied. Once tuned to the rider's power it changes ratio automatically with the gradient. Useable as a front belt drive but works against the rider at the rear.
JXV Posted October 7, 2015 Posted October 7, 2015 Here's an ideaThermocouple mounted to brake disc or disc pads uses Peltier effect to generate a small current from waste heat that can keep your DI2 batteries charged - does not drain pedalling pedalling power but you must descend and use brakes occasionally .A hub or crank generator could do the same thing but steals some energy from the rider. Both options permit using a smaller lighter battery.
JKK Posted October 7, 2015 Author Posted October 7, 2015 Here's an ideaThermocouple mounted to brake disc or disc pads uses Peltier effect to generate a small current from waste heat that can keep your DI2 batteries charged - does not drain pedalling pedalling power but you must descend and use brakes occasionally .A hub or crank generator could do the same thing but steals some energy from the rider.Both options permit using a smaller lighter battery. Out of interest, how long do Di2 batteries last on a single charge?
HTFU Posted October 7, 2015 Posted October 7, 2015 Someone reinvented the wheel already...https://www.loopwheels.com/products/mountain-bikes/
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