NotSoBigBen Posted April 23, 2008 Share http://www.bikeradar.com/news/article/sea-otter-2009-bikes-herald-crank-design-revolution-15943 Link to comment Share on other sites More sharing options...
Johan Bornman Posted April 23, 2008 Share The standard BB we have today is due for a dramatic overhaul and a move like this is one in the right direction. We need to get the BB shell much, much bigger so that a far bigger tube can replace the current small tube and solid BB spindles. The right reason for doing this shouldn'd be as this press release suggests, but to increase bearing life. The bearing life in today's BBs is pathetic and for one reason only: They're too small to do what they're asked to do. Wee need to increase the diameter and the size of the balls not, as the external BB did, increase the diameter and REDUCE the size of the balls. Unfortunately I'm not convinced yet, it seems as if it's all done for the sake of saving weight. I hope I'm wrong. Phrase from the press release: "All other things being equal, it?s lighter and stiffer than current external-type bottom bracket systems. It also reduces pedal stance width and increases bearing life thanks to the narrower, but larger diameter, bottom bracket shell. Stiffer is nonsense, we don't need stiffer and reduced pedal stance is nonsense, we don't walk with our ankles touching. The last phrase in the last sentense is a non-sequitur. Hopefully there is some real engineering in here after all.Johan Bornman2008-04-23 08:27:26 Link to comment Share on other sites More sharing options...
Man with no name Posted April 23, 2008 Share Is cannondale leading the pack ... again? Link to comment Share on other sites More sharing options...
lowracer Posted April 23, 2008 Share also from the same site: electronic shifters from campag and shimanohttp://www.bikeradar.com/news/article/new-campagnolo-electric-prototypes-15555http://www.bikeradar.com/news/article/2009-shimano-dura-ace-revealed-15308 is this also a solution looking for a problem? will the pros ride it because they have to/sponsored? do we need it like a fish needs a bicycle. Link to comment Share on other sites More sharing options...
AndreZA Posted April 23, 2008 Share I just don't know whay the same system for headsets is not used fot BBs. Looks like the BB30 is close to being that. Johan, what do you think of that? Link to comment Share on other sites More sharing options...
R2S2 Posted April 23, 2008 Share Yes. The pack of clever marketing.Traditional ball bearings are not ideal, as the wear characteristics, and load bearing capacity is not class leading. All I can assume is that they are a holdover from times when bearings were expensive, and the ability to make up for wear by tightening "cups" was the accepted norm. With sealed bearings (that most BBs have these days), that has become a moot point, and I can for the life of me not understand why we still see them in bottom brackets. A far better approach would be to pursue the use of conical or cilindrical roller bearings. Even better would be needle rollers, as these have immense load bearing capacity, as well as very low rolling resistance, not to mention low weight and compact design. Link to comment Share on other sites More sharing options...
Johan Bornman Posted April 23, 2008 Share I just don't know whay the same system for headsets is not used fot BBs. Looks like the BB30 is close to being that. Johan' date=' what do you think of that? [/quote'] It won't work. In the Aheadset system you need something to tension the bearings to eliminate play and there won't be space on the sides of the BB to do so, even if you could put the tensioning bolt inside the BB spindle tube. I just found www.bb30standard.com. The description is there for all to read. One thing that worries me about this standard is that they've eliminated the cup to save weight. The cup wasn't a bad thing since in some cases it was a wear part that saved the frame. Now with the bearings directly pressed into the alu or carbon frame, any fretting there will enlarge the BB hole and ruin the frame. We've already seen this with the so-called "ovalisation" of head tubes on certain alu frames. It is evil. Link to comment Share on other sites More sharing options...
R2S2 Posted April 23, 2008 Share This is where the future of the bottom bracket lies: Link to comment Share on other sites More sharing options...
Johan Bornman Posted April 23, 2008 Share Yes. The pack of clever marketing.Traditional ball bearings are not ideal' date=' as the wear characteristics, and load bearing capacity is not class leading. All I can assume is that they are a holdover from times when bearings were expensive, and the ability to make up for wear by tightening "cups" was the accepted norm. With sealed bearings (that most BBs have these days), that has become a moot point, and I can for the life of me not understand why we still see them in bottom brackets. A far better approach would be to pursue the use of conical or cilindrical roller bearings. Even better would be needle rollers, as these have immense load bearing capacity, as well as very low rolling resistance, not to mention low weight and compact design.[/quote'] The throw-back is the cup size. This is a legacy that we need to shed. With a small BB cup the bearing size is restricted and that's the problem, not balls vs needles. Shimano tried fitting some needles into the standard BB cup with disastrous results. It was the most unreliable, fragile BB system ever. Once the cup is big enough to put decent bearings in there, then we can start fretting about balls vs needles. Link to comment Share on other sites More sharing options...
AndreZA Posted April 23, 2008 Share It won't work. In the Aheadset system you need something to tension the bearings to eliminate play and there won't be space on the sides of the BB to do so' date=' even if you could put the tensioning bolt inside the BB spindle tube. [/quote'] Lay a fork on it's side and rotate it. That is the way the BB will work. The crank axle can be any length you like and it gets trimmed to your specifications. It can have all the grooves to make sure you line it up properly. And just like you would tighten the headset with the top cap bolt, you would tighten the BB. Link to comment Share on other sites More sharing options...
R2S2 Posted April 23, 2008 Share The throw-back is the cup size. This is a legacy that we need to shed. With a small BB cup the bearing size is restricted and that's the problem' date=' not balls vs needles. Shimano tried fitting some needles into the standard BB cup with disastrous results. It was the most unreliable, fragile BB system ever. Once the cup is big enough to put decent bearings in there, then we can start fretting about balls vs needles. [/quote']I agree on the point of larger cup size, and that is one of the things that external bearing seem to attempt to solve. However, if you compare a BB cu diameter with that of say a crank journal in a small engine (where the loads are much greater, you will see the difference is very small indeed. The engine copes through using non-roller bearings, so as to ensure the biggest contact surface possible between the journal and the engine block. The downside is friction. This has been solved in the past by substituting needle rollers for solid bearings in some high-revving engines, as needle rollers provide a very good comparative ratio between shaft and cage size, as well as to provide for load bearing capacity that nears that of solid bearings. Need to dash, but would love to continue this discussion later today! Link to comment Share on other sites More sharing options...
NotSoBigBen Posted April 23, 2008 Share Nice to read some interesting discussion/debate on a cycling related subject for a change - thanks! Link to comment Share on other sites More sharing options...
madmarc Posted April 23, 2008 Share also from the same site: electronic shifters from campag and shimano http://www.bikeradar.com/news/article/new-campagnolo-electric-prototypes-15555http://www.bikeradar.com/news/article/2009-shimano-dura-ace-revealed-15308 is this also a solution looking for a problem? will the pros ride it because they have to/sponsored? do we need it like a fish needs a bicycle. Here an interesting article on electronic gruppos. I think the problems revolve more around the battery life (imagine a pro leading a race and his battery dies on him) and wet weather. the major problem is there is no back up, if it fails, it fails, your race is over!!!!!! http://www.pezcyclingnews.com/?pg=fullstory&id=4772 sorry forgot to include the link madmarc2008-04-23 04:39:13 Link to comment Share on other sites More sharing options...
dirtrider Posted April 23, 2008 Share Johann I think you right about the weight thing . After reading weight for the 3rd time I stopped reading . Anyway like you have also already said if it does not go into a sleeve then I will try and avoid it for as long as possible . Press-fitting in cast iron works very well but it will only work at the most 2 times before the bearing also spins inside it's enclosure . Go and try it with the wornout bearings on your lawnmover . Link to comment Share on other sites More sharing options...
madmarc Posted April 23, 2008 Share The standard BB we have today is due for a dramatic overhaul and a move like this is one in the right direction. We need to get the BB shell much' date=' much bigger so that a far tube can replace the current small tube and solid BB spindles. The right reason for doing this shouldn'd be as this press release suggests, but to increase bearing life. The bearing life in today's BBs is pathetic and for one reason only: They're too small to do what they're asked to do. Wee need to increase the diameter and the size of the balls not, as the external BB did, increase the diameter and REDUCE the size of the balls. Unfortunately I'm not convinced yet, it seems as if it's all done for the sake of saving weight. I hope I'm wrong. Phrase from the press release: "All other things being equal, it?s lighter and stiffer than current external-type bottom bracket systems. It also reduces pedal stance width and increases bearing life thanks to the narrower, but larger diameter, bottom bracket shell. Stiffer is nonsense, we don't need stiffer and reduced pedal stance is nonsense, we don't walk with our ankles touching. The last phrase in the last sentense is a non-sequitur. Hopefully there is some real engineering in here after all.[/quote'] Johan - i honestly believe the pathetic BB life has more to do with how we maintain our BB than in the design. Bearings are selected based on load capacity and speed at which they will operate, if we check out the spec in a bearing cataloge of the size normally used in BB's then one can see that they operate far below the load spec as well as the RPM they were originally designed for when used in a BB, so by rights they should last longer BUT! BB's are generally never maintained and only looked at when there is a problem, which by then is to late as the damaged is usually done, so they need to be replaced. The BB has to tolerate a lot of dirt and water. The Bottom tube is not sealed so without cleaning and regreasing the bearings will wear and rust. I have rebuilt many BB's and whereever i can i replace OEM bearings with sealed for life bearings and then packk the tube with lots of grease during reassembly, this has increased the life 10 fold. Bearings are consumables and will need replacement at some point, manufacturers design BB's to fail so they can make money in aftermarket sales, so we ned to live with it, but make sure we extend the lifetime by stripping cleaning BB's at least once a month in the rainy season and once every 2 months in winter. Link to comment Share on other sites More sharing options...
Guest Big H Posted April 23, 2008 Share It won't work. In the Aheadset system you need something to tension the bearings to eliminate play and there won't be space on the sides of the BB to do so' date=' even if you could put the tensioning bolt inside the BB spindle tube. [/quote'] Lay a fork on it's side and rotate it. That is the way the BB will work. The crank axle can be any length you like and it gets trimmed to your specifications. It can have all the grooves to make sure you line it up properly. And just like you would tighten the headset with the top cap bolt, you would tighten the BB. Waar op die handlebars gaan jy die trappe vasmaak, watse soort trappe gaan jy geberuik en is dit drop handles of reguit soos MTB handles??????? Link to comment Share on other sites More sharing options...
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