roflmao147

im am starting to race this year, and im still in the under 16 age group, therefore i have to comply to the gearing restrictions for my age. the problem is, my carbon frames rear stays are shaped in such a way, that a 16/25 cassette will not fit, it barely fits with a 12/25 ie the chain is close to the rear stay. so i need to keep the cassette and change the front outer chainring, i am currently using a 52 tooth outer ring, will a 50 tooth make any difference, or will i have to go for something less to be under the roll out distance?

Homebrew01

Do the math ... a 52 chainring is legal with a 16t ? Then, if you want to use an 11 or 12, what chainrings give you the equivalent gear for each ?

This is your homework assignment for today. Calculators are allowed.

roflmao147

i have no idea how to work it out lol

ericm979

https://www.sheldonbrown.com/gears/

use gear inches

eippo1

Just google it or check out the rule book and do some reading. Doesn't anyone know how to do research anymore?
https://www.usacycling.org/forms/rule...DJUSTMENTS.pdf

Homebrew01

52/16 = x/12

eippo1

Reminds me of this:
https://www.guzer.com/pictures/findx.php

Harlan

I believe 46 is near the right chainring size with a 12t cog, but it depends on your tires also.

Though that equation says otherwise. Maybe my memory sucks, but maybe 52/16 isn't the exact limit.

Upon googlation, it's 52/14. So I was right.

Homebrew01

Just adjust your derailleur to the allowed gear:

====================

1M6. Junior Gears. The maximum chaingear ratio for Junior riders is based on age and discipline. Blocked gears will be allowed, except in National Championships. All tests for compliance shall be done using the "roll-out method.” There is no restriction for cyclocross or MTB races. For road and track the limits are:
Road
17-18: 7.93 meters (26‟)(52x14)
15-16: “
13-14: “
10-12: “
54
Track
17-18: Unrestricted
15-16: 6.78 meters (22'3")(48x15)
13-14: 6.36 meters (20'10.5")(48x16)
10-12: 6.00 meters (19‟8”)(48x17)
The gear limit for a rider is determined by the age of the rider and the discipline, and applies in all events in that discipline subject to the notes shown below:
(1) For Juniors 16 and under who are competing in Championship team sprint, team pursuit, keirin, or Madison the 17-18 (unrestricted) gear limit applies.
Note that the gear combinations listed are merely suggestions – the distance rolled out is the governing standard

Psimet2001 

+1 - Forget about your gear and concentrate on what matters - rollout.

If you can not fit a junior cassette on your frame then I would highly suggest blocking out using the rear derail. Block out until you get one that works with your wheels, etc.

Be familiar with how a rollout works and is done - I found this in a couple of seconds on Youtube:


Do it at home on your own. Mark out the distance and try it. When you get to the venue go up to an official and ask if they can go over rollout with you and test your rig before competition. If you have problems ask them how they would suggest fixing it.

If you block gearing you could actually eventually pick up spacers for a freehub conversion to single speed kit and remove the unneeded cogs. Saving weight and removing the possibility that an official might have a hard time understanding you have the gearing blocked.

In general I have a soft spot for junior gearing because I was called out for many violations on it when I was a junior and no one ever really explained to me how to make it legal.

urbanknight

They don't always do it that way, at least not when I was a junior. Back then, some officials made you sit on the bike and pedal, while others did the "unweighted" backward rollout you linked to. The former is more accurate, and if you fail the latter, it's smart to request the weighted one and protest the findings if they don't.

ultraman6970

In my country and Europe they do the same than in the video. As for the RD, just adjust it, in juniors you use at most 3 to 4 gears anyways. If you can, change the 53 crankset with a 50 or just go compact with a 48 or a 50 chainwheel, then you will be able to use smaller cogs.

mkadam68

FWIW: a 52x14 passes roll-out (unweighted) for my son (15yr-old).

But yeah, if you're just starting racing, try blocking out your gears. If you like racing and intend on pursuing next year, then get a 14x25 cassette. I found ours for about $75 (online somewhere).