| Subject: | USCF returns to Jr. Gearing in 2001 |
| Date: | 12/18/2000 12:27 AM |
| From: | mmur-@teleport.com |
|
While we debate whether OBRA should have junior gear limits it would make some sense to consider what you need to do to meet the gear limits that USCF has, as described below. Imagine a kid new to bike racing, without the support of a cycling adult, trying to figure out how to do this. From my point of view we need to balance the possible benefits of gear limits against the negative impact on participation. Can we really afford to lose even one potential junior racer? It is also interesting that I don't hear any attempts to limit gearing in mountain biking. Clearly if pushing big gears is a real problem it is much more likely that the junior will be grinding along on a mountain bike. I propose that OBRA adopt rules that require gear limits at the track, where it is easy to do and may have some real benefits, but ignore road gear limits. Mike Murray "M. Creed Sr." <mcre-@msn.com> wrote in message news:<91ltag-@nnrp1.deja.com>... There is a standard way of meeting the rollout. DO NOT USE A 45 CHAINRING! There are too many problems with front derailleur height adjustment and shifting problems. Depending on the frame construction the front derailleur may not be able to move enought to match a 45T ring. Braze-on tab slot is not long enough and tubing flare (some carbon and aluminium frames) will not accept lower postion of the front derailleur. Use a 52T front chain ring, easily available and virtually no adjustment to front Derailleur. To make the required 14T in the rear cassette is made possible by using any 9 speed cassette that starts with a 12T cog. You will replace the second position 13T with a spare 14T (available by itself from most shops or from Loose Screws in Oregon for about $5.00). Most of us have spare cogsets, or ones that are used that we can pull the 14T. In some cases that could give you back to back 14's, thats ok.You end up with a 1st position 12(which you can block out) and a second postion 14T. Internationally, blocking out isn't allowed, but they grind the teeth off the 12T to render it unuseable. They adjust the set screw to the 2nd cog, essentially making it an 8 speed.Granted not the best situation, outside of Shimano & Campy making 14x23 cassettes. This configuration is standard fix in Europe for UCI races and for the national team. MC In article <91ep6p-@glisan.hevanet.com>, "Martin Clan" <mar-@hevanet.com> wrote: Boy did I blow it by not printing the complete passage figuring that the columns would get all screwed up. Here are the ratios also provided in the complete text: Chaingear Ratios 2.2.024 For Junior Men & Women, the authorized maximum chaingear ratio is 7.93 meters. Gear Development Charts The charts below give development (distance covered in one revolution of the cranks) for various combinations of chain ring and rear sprocket, assuming 26.5 inch wheels. Note that other wheel sizes are widely used. For example, 27 inch wheels have a development about 2% larger than the figures listed below. The formula for development is: (wheel diameter) x pi x (chain ring teeth)/(sprocket teeth) where pi is about 3.14. These charts are provided only for general guidance in selecting gears. Do not depend on calculations or charts to determine whether a particular bicycle satisfies gear restrictions - use the roll-out test (distance traveled by the bicycle in one revolution of the crank with the tires inflated to racing pressure). Gear Development (meters) chain ring teeth 44 45 46 47 48 49 50 51 52 53 54 55 12 7.75 7.93 8.11 8.28 8.46 8.63 8.81 8.99 9.16 9.34 9.52 9.69 13 7.16 7.32 7.48 7.65 7.81 7.97 8.13 8.30 8.46 8.62 8.78 8.95 14 6.65 6.80 6.95 7.10 7.25 7.40 7.55 7.70 7.85 8.01 8.16 8.31 Gear Development (feet, inches) chain ring teeth 44 45 46 47 48 49 50 51 52 53 54 55 12 25'5" 26'0" 26'7" 27'2" 27'9" 28'4" 28'11" 29'6" 30'1" 30'8" 31'3" 31'10" 13 23'6" 24'0" 24'7" 25'1" 25'7" 26'2" 26'8" 27'3" 27'9" 28'3" 28'10" 29'4" 14 21'10" 22'4" 22'10" 23'3" 23'9" 24'3" 24'9" 25'3" 25'9" 26'3" 26'9" 27'3" 15 20'4" 20'10" 21'3" 21'9" 22'2" 22'8" 23'2" 23'7" 24'1" 24'6" 25'0" 25'5" "Theodore Heise" <the-@netins.net> wrote in message news:20001115205-@netins.net... Casey Kerrigan writes: So if you could only block off one gear with the set screw then it sounds like blocking off gears will not work. This means all junior riders will have to buy new gears in order to race. Couldn't you just buy a longer set screw? If so, it's a lot cheaper than a chainring. Ted -- Theodore W. Heise <the-@netins.net> West Lafayette, IN, USA PGP public key: http://showcase.netins.net/web/twheise/theise.asc Sent via Deja.com http://www.deja.com/ |
