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| *Vultures Knob>>>Cycling |
What is the largest diameter sprocket and where can I find it? |
I was looking at those record breaking breaking high speed bicycles, with the fairings, and I saw a huge sprocket on one of them, I think it was Sam Whittingham's bike. Although I will need it for a different reason, I still need a large diameter sprocket like that one but I can't find one online. Do I need to have one custom made? Thanks. Bike Friday can supply a 60 tooth chainring http://store.bikefriday.com/index.php?cp... There is also a Shimano Capreo hub that enables a special cassette to be fitted (down to 9 teeth.) http://www.sheldonbrown.com/capreo/index... These are common among small wheeled bikes like moulton, birdy, bike friday etc. Also check out offering from recumbent manufacturers like greenspeed, trimuter, trisled http://www.greenspeed.com.au/specialites... I think you mean chainring. Sprocket refers to the cogs at the back. If you want a huge gear, try the smallest possible size on the rear first. Some road bikes come wth a 13t, yet 11t is available, giving a bigger gear. Some specialists do manufacture large size chainrings, just look around. I know that Boone Titanium offer custom chainring sizes and that fibrelyte (carbon) offer stock up to 65t, but can also make custom requests too. Don't expect either of these offerings to be cheap. I'm sure there are plenty of cheaper chainrings available, check out some Time Trial mags / websites, as these guys often use oversize chainrings. Before splashing the cash - do you really need it? The effort involved in spinning up these gears is huge, and unlikely to occur in most situations if you are spinning the pedals at a decent rpm. The largest I've heard of is 56 tooth chainring and the largest rear sprocket I've heard of is 34 tooth. The smallest rear sprocket I've seen is 11, although there may be smaller. That would make the largest gear ratio of 56 x 11, which would be a monster gear! Check out your local bike shop and see what they can get. Or depending on what you're going to use it for, maybe something from a motorcycle might work? I know you can buy chainrings (I assume this is what you mean by sprocket, not the rear cogs) in sizes up to 56t most places. The problem with finding huge ones is the USCF limitations....if you can't race with them, most people won't make or sell them. Another problem, so I have heard, is rigidity of the ring under power. One of our local shops has some big monster chainrings in back that they'll probably never get rid of. I think these are leftovers from days when some time trialists and triatheletes used them for training. You can have your shop try to order extra huge rings like that through QBP or BTI, but if they're available they won't be cheap. If you want, I might be able to hook you up with one from this shop here in Oklahoma City....shoot me an email with your bolt pattern and I can check to see what's in that box. Getting one custom made might be tough and will surely be expensive, but it wouldn't be difficult for a decent machine shop to do. I'm sure you're aware that these usually work best as singlespeeds because of all the issues with derailleurs when you get outside of their designed limits. If you wanted to run a double up front, you might be able to squeak by with an outer ring substituted for the middle, and your monster ring for the new outer.....not sure, and there are probably people who can tell you for certain. I'd assume that you'd need to use mountain bike front and rear derailleurs to make any of it work. Here's Sam Whittington's site, you may be able to get in touch with him for better info: http://www.timetogetnaked.com/index2.htm... Please post back with what you find out....I'm curious! The monster chain rings you refer to are all custom made. They would be VERY expensive. look in the web "world speed record on a bicycle and look at the chain-ring of Alfred Latiner and the gearing by the current record holder using multiple chains to set the present record of almost 150 MPH. then you can see for yourself world speed records on bicycle |
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