madmarc Posted January 2, 2008 Posted January 2, 2008 What is the difference between a compact crank set and a standard crank set
Guest Big H Posted January 2, 2008 Posted January 2, 2008 It is all in the size of the chainrings (amount of teeth) I do not know the specs but I am sure somebody will post it.
madmarc Posted January 2, 2008 Author Posted January 2, 2008 It is all in the size of the chainrings (amount of teeth) I do not know the specs but I am sure somebody will post it. Thanx BIG H your cheques in the mail
Tumbleweed Posted January 2, 2008 Posted January 2, 2008 a compact crankset is kinda the middle ground between a standard double crankset and a triple. the standard is usually a 53/39 combo, while the compact is usually 50/36 or a 50/34? (please correct if i'm wrong anyone). the bonus is the lower gearing for climbing - and it's lighter than both the triple blader and (marginally so) the standard double - while obviously you'll spin out the higher gears a lot quicker! ps if you want lower gearing for climbing, i know of some people who have managed to fit a mtb cluster - the size of the rear derailleur allowing, of course - to a road bike.
racman Posted January 2, 2008 Posted January 2, 2008 You might fnd this interesting ...::: 700C Wheel At 90rpm :::...<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> 53-39 Rings, 11-21 Cogs50-34 Rings, 11-21 CogsetHigh speed33.2 MPH31.3 MPHLow speed12.8 MPH11.5 MPHCommentsChanges between each gear are the same (cssettes re the same). The tradeoff is easier climbing as the expense of a small loss of top speed. This s the lightest configuration for either set up. 53-39 Rings, 11-23 Cogs50-34 Rings, 11-21 CogsetHigh speed33.2 MPH31.3 MPHLow speed11.7 MPH11.5 MPHCommentsLow speed now almost the same. 11-23 cassette is heaver with gear ratios wider apart. 53-39 Rings, 12-25 Cogs50-34 Rings, 11-21 CogsetHigh speed30.42 MPH31.3 MPHLow speed10.74 MPH11.5 MPHCommentsThe 12-25 cassette lowers the top speed on the conventional Crankset and makes climbing easier but at the cost of even wider gear ratios and weight. 53-39 Rings, 12-25 Cogs50-34 Rings, 11-23 CogsetHigh speed30.42 MPH31.3 MPHLow speed10.74 MPH10.18 MPHCommentsWith slightly wider gear ratios the 11-23 cogs further ease climbing with the Compact Crankset while maintaining top speed. 53-39 Rings, 12-27 Cogs50-34 Rings, 11-23 CogsetHigh speed30.42 MPH31.3 MPHLow speed9.98 MPH10.18 MPHComments12-27 is about the biggest (heaviest) cassette seen on Tri Bikes. Almost the same climbing can be achieved with the 11-23 cogs with a compact Crankset with a higher top speed, closer gearing and reduced weight.
bobbie Posted January 2, 2008 Posted January 2, 2008 wow thats interesting! was talking to someone about this just the other day. might be a solution for me as i do sometimes struggle up hills ...(read: always struggle up hills) what sort of price?
Tumbleweed Posted January 2, 2008 Posted January 2, 2008 i stand corrected, but i reckon you should be able to pick up a 10-speed compatible crankset for just under R2000
bobbie Posted January 2, 2008 Posted January 2, 2008 I replaced the back set (sorry dont know what you call it..) and now have 12/27 cogs... can I keep those or do I replace the whole lot?
IanJ Posted January 2, 2008 Posted January 2, 2008 I replaced the back set (sorry dont know what you call it..) and now have 12/27 cogs... can I keep those or do I replace the whole lot? You can keep it but you actually don't need it, I have been riding a compact crankset since I went to France last year. You don't really need anything bigger than 12-25, I only use 11-23 on mine. You will save some weight over the 12-27 cassette. The price of the Shimano compact crankset is about R 1500, there is a very nice new Ultegra SL Crankset available for between R1800 - R2500 depending on where you buy.
bobbie Posted January 2, 2008 Posted January 2, 2008 He IanJ - thanks for the info. I am seriously going to look into this. Pity my birthday has just passed and Father Christmas has parked his sleigh - guess I'll have to start saving a little extra - from me to me!!
racman Posted January 3, 2008 Posted January 3, 2008 If I'm not mistaken you may also need a compact front derailleur. I use a 11-23 with my compact which works fine and very similar to my old 12-25 with 39-53. I chose this because of the following advantages: 1) As can be seen in my earlier post - slightly more speed on the 11 2) Slighlty lower speed (easier gear) on 233) Closer gear ratios which mean more useable gears4) Fewer duplicate gear ratios5) There are supposed spin-offs with lower HR due to smaller front chainrings but I cannot prove it. I personally think that Triple Chainrings will become obsolet in future on Road Bikes in favour of compacts. Also FSA (Full Speed Ahead) has quite a bit of info on their website as well. Browse http://www.fullspeedahead.com/ as well for info.racman2008-01-03 00:13:15
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