Further to a question that has been asked:
During the year the Club runs a series of 10 and 25 mile events (and nominates a few open events to cover other distances and add extra 25s). Some of these 10s or 25s include special events, like the Medium Gear and Consolation 25s or the 2Up and Championship 10s.
In these special club events it is the special event and the riders adhering to the special conditions (like limited gear for the Medium Gear or riding a 2Up in the 2Up) that attract the club awards - the prizes that are credited to riders for handicap and placings. Any club member wishing to just ride a regular TT at the distance is welcome to do so and (if entered in advance) will be credited with 2 club event points for supporting the club event, but will not necessarily be entered in the handicap competition for the event.
Riders who enter any of the club events late or on the line - subject to there being enough space (we are allowed only a certain number of riders for each event) - will be riding only for a time, but the time will be recognised by the club for all of the other Club Trophies.
So the bottom line is that you can enter the Medium Gear 25 but choose not to ride the limited gear if you wish - just tell Frank.
Do I have to ride "fixed" in the Medium Gear?
No. You can use fixed, single free, or regular gears as long as you keep below the 72" limit.
If I ride gears do I have to stick to the one gear?
No. The 72" is a maximum, you can use lower gears.
Do I have to stop the mech off to prevent me using a higher gear?
No. We trust riders. Stop it off if you don't trust yourself! If you inadvertently change to a higher gear for a couple of pedal revs and immediately change back down you maintain the spirit of the event. If use the higher gear for any length of time we expect a confession at the finish!!!
What does 72" mean?
For a fixed wheel bike this is easy, for a geared bike you must roll the bike backwards so that the rear wheel pushes the pedals round. For one revolution of the pedals, the bike must travel no further than 18' 10 1/4" (which should be 5.8m, but I'm not guaranteeing that!).
Alternatively it is recognised as a chainring of 48 teeth and a rear sprocket of 18 teeth.
As most geared bikes don't come with a 48 chain ring, divide the chainring size by 2.66666667 (2 & 2/3) and round up. So for a 52 tooth chainring the rear sprocket needs to be 19.5, and as you can't get a sprocket with 19.5 teeth the answer is 20. With really light tyres you can get away with a slightly higher calculated gear, so we measure the gear out on the morning.
Do I have to ride on a limited gear?
No.
If you want to ride the Medium Gear Club Event and compete for the club awards - yes.
If you just want to ride a 25 on the same morning as everyone else - no, but tell Frank when you enter.
Can I ride Tandem?
If you want. You'll probably just be riding a 25 rather than the Medium Gear Club Event (we'll talk about it at the committee meeting - if we remember!) but yes you can ride tandem.
I bet this all just confuses things...
Lisa
A bit more about what does 72inch mean? - copied from Wikipaedia
ReplyDeleteOrigin
With old-fashioned "penny-farthing" bicycles, the crankarms were directly attached to the large drive wheel. One turn of the pedals moved the bicycle a distance equal to the circumference of the wheel. The larger the wheel, the farther the bicycle went for each turn of the pedals. The gear-inch system is a holdover from the days of the boneshakers, when wheel diameter determined the bike's "gearing" and was the key measurement on the bike.
Riding in a high gear on a modern bicycle is mechanically equivalent to riding a high-wheeler with a large wheel, where a low gear on a modern bicycle is the equivalent of a smaller wheel on a high-wheeler.
[edit] Calculating gear inches
Gear inches express gear ratios in terms of the diameter of an equivalent directly-driven wheel, and are calculated as follows:
Diameter of drive wheel in inches × number of teeth in front chainring / number of teeth in rear cog.
gi = Gear Inches
dwd = Drive Wheel Diameter
fct = Front Chainring Teeth
rct = Rear Cog Teeth
For example, suppose the drive wheel is actually 26 inches in diameter. If the front chainring and rear cog have equal numbers of teeth, one turn of the pedals produces exactly one turn of the drive wheel, just as if the pedals were directly driving the drive wheel. That combination of gears and wheel is said to be "26 gear inches." If the front chainring has 48 teeth and the rear cog has 24 teeth, then each turn of the pedals produces two turns of the rear wheel. This is equivalent to doubling the size of the drive wheel; that is, it is like a directly-driven bicycle with a 52-inch wheel. That gear is said to be "52 gear inches."
A bicycle with a 26-inch wheel, a 48-tooth chainring, and a cassette with gears ranging from 11 to 34 teeth has a lowest gear of 26 × 48 / 34 = 36.7 gear inches and a highest gear of 26 × 48 / 11 = 113 gear inches.
For bicycles with 700c wheels, most cyclists quote gear inches based on a nominal wheel diameter of 27 inches, corresponding to the old British tire size of 27 x 1¼" (ETRTO 630). This means that a 48/18 setup is usually considered to be 72". Strictly speaking, the rolling diameter of a 700c wheel is significantly lower, at about 26" for a 20mm tire or 26.3" for a 23mm tire. This means that the true gear on a 700c wheel can be as low as 69", which is the equivalent of only 46/18 on an actual 27" wheel, and can be the source of some confusion when comparing gears unless it is clear whether gear inches have been calculated using the actual wheel size or a conventionalised 27".
The accurate way of calculating true wheel diameter is to take the rim diameter and add twice the tyre diameter. For example, 700c x 23mm. 700c wheels have a rim diameter of 622mm. Add 46mm (2x tyre diameter of 23mm). 622mm + 46mm = 668mm which is equal to 26.3 inches (rounded to 1 decimal place). 26 inch mountain bicycle wheels have a rim diameter of 559mm.