wsuhoops1000

Hello everyone, my first race is coming up this saturday but I have to get my gears in proper order. Unfortunately right now, I just don't have the money to buy a new cassette so I need to block out gears. The question is....

With a 50 teeth compact crank and 12-27 cassette. This came standard on bike. How many gears will I need to block out to pass roll out.

Will 50x13 work?
50x14?

Thanks so much.

rpenmanparker 

Could you please translate your question into English? What does blocking out gears mean? What does pass roll out mean? Glad to help If I could figure out what you are talking about.


Robert

jsutkeepspining

you have to roll a 50x14. 50x13 will fail the rollout.

David Broon 

For junior racers, our bicycles can only have so large a gear, which is dictated by the rollout distance, or the distance a bicycle will roll backwards in one full revolution of the cranks. That distance happens to be 7.93 meters, or the approximate equivalent of 52x14.

To do that, one can a)Buy a junior cassette, which has a 14t as the smallest gear, or b) adjust your derailleur using the limit screws to make it so your chain will only shift as high as the 14t cog on your standard cassette.

To the OP, We have a juniors specific forum under the "Racers" Heading, which is full of helpful juniors scared of venturing into the scary world of the 41, and seriously helpful adults who know what roll-out and blocking gears means, no offense Robert.

rpenmanparker 

None taken. What I like about the 41 is there is something "new" to learn every day.

Homebrew01

Isn't it age dependant ? Ages 14 and 17 have different gear restrictions (I think... loooooong time since I was a junior)

wsuhoops1000: You can look up the rules on line, then check the rollout in your driveway or sidewalk ..... Get some firsthand experience.

Also, there's a Junior Racing specific forum

cplager

Out of curiosity, why is that? (I'm assuming they don't limit the lower gear range.)

Homebrew01

Save their knees by preventing them from grinding big gears.

merlinextraligh

And teaches them to spin, but that's more a positive side effect, with saving their knees, as mentioned, being the rationale for the rule.

Homebrew01

Rules: https://www.usacycling.org/encyclingp...ry.php?id=4203

carpediemracing 

You should check the rules first. You really should know the rules before you go do a race - how do you know you're not breaking them if you don't know them?

Then you should figure it out yourself.

Finally you should confirm that you'll pass roll out.

The rules:
https://www.usacycling.org/usa-cycling-rule-book.htm

Figuring out roll out. This is a math type thing.

Chainring/cog = number of rear wheel revolutions for each crank revolution. Get that number and multiply by circumference of rear tire (in meters or centimeters or millimeters).

Work out the numbers yourself. The short answer is that the 50x14 is probably going to be the highest gear you can use assuming a tire circumference of about 2090 mm.

If you run into trouble working out the numbers then post what you come up with here and I/we'll be glad to help.

Checking roll out:
Mark two spots on a flat surface (garage floor, quiet/safe pavement, even a long hallway or deck). Put the bike in the biggest gear it can go into, as adjusted with blocked out gears etc. Line up the crank with one mark (point the crank down at the mark). Roll bike backwards towards second mark in a straight line. The crank should point down at or before the second mark. If it does then you're okay. If it doesn't then you have too big of a gear.

carpediemracing 

One other reason, cited specifically in an officials' seminar I attended, is to even out the effect of different maturity rates. The idea is that the lower top gear will limit the usefulness of outright power by transferring the workload to the aerobic system. A 200 lbs muscular 16 year old should be closer in top speed etc as a 100 lbs skinny 16 year old, based on the capped gear limits.

Keep in mind that good Juniors can stay with, and beat, Cat 1-2 racers, even with Junior gearing. I know that top Juniors would average 30 mph in time trials. It's not like you can't go fast, it's just that it's harder to go fast.

carpediemracing 

Moving to Junior Racing forum.

https://www.bikeforums.net/forumdispl...l-Disciplines)

David Broon 

There is, but I've never seen them enforced except at nationals, and at a few huuuuuuuuge cadet (15-16) races.

carpediemracing 

In New England the gear limits are enforced. There was one Junior who insisted on using Senior gearing in one race, Junior in another. He'd be duly disqualified from the "Senior geared" race.

I wouldn't encourage anyone to break rules regularly on the assumption that there's lax enforcement. It would really suck to have a good race and then have the result stricken from the records due to failing rollout. I've seen this happen, even the state TT "winner" one year was disqualified for failing rollout. One of the instructors (Cat A official) had to fail a Nationals winning rider due to failing rollout. The first race I went to watch, that year's National Crit Championships, the winner of the Junior race was disqualified for failing rollout.

Other poor examples of indirectly encouraging riders to break rules...

"Taking out other riders is fine, you can crash a whole field in a training race on purpose and you won't lose any racing time, even if you don't appeal the official request for suspension. In fact you can do that and then promote your own stage race if you want to."

"Doping is fine, I've never seen it enforced even at Nationals, so take all the testosterone/EPO/HGH you want."

"Running stop signs in my town is fine. I've never seen anyone pulled over for running one."

David Broon 

Sorry, I`m talking about the shorter rollout for u17`s. Junior gears are normally enforced as a blanket rule with the 52x14, instead of the 52x16 that they`re supposed to use.

Don`t do drugs.

chasm54

That's interesting, in the UK there's a gearing roll-out at even very small, local junior and youth races. And it's a good thing, I think. Quite apart from anything else, it protects kids from their over-competitive parents. Believe it or not I have seen parents present their child's bike for a gear check, pass it, and then sneak off somewhere and readjust the gears in an attempt to give little John/Jane an advantage. Talk about setting an example... to say nothing of the kids' knees.

Skyline516

Not necessarily true, my tires are slightly worn down and my bike passes with a 50x13.

To address the question. Roll your bike out with a 50x13, if that works, great and if not, block it out to 50x14 because that will definitely work.

pmt

It's enforced every time in the Mid Atlantic; you better test it ahead of time to be sure.

It's probably a good idea not to be too close to the limit, as you never know if you'll get an official who flunks it because of a slightly short marking on the road or such.

My juniors use 46 chainrings so they can use 13x25 or 13x28 10s cassettes.

Sheldon Brown (RIP) has a gear calculator here-> https://sheldonbrown.com/gears/

jsutkeepspining

i've never seen a 50x13 work on any bike, every single one has failed, but most people don't ride on worn out tires ( i once saw three different guys fail all at once with this gear ratio. they all thought it would work). Junior gears are silly in the idea that they save your knees (if someone insists on riding in a 53/11 all day they'll get dropped so quickly if they dont spin over 90 rpms. But it's a rule, so we have to follow it. it really only gets in the way of super fast sprints where a junior has to jump at 130-145 rpms and peak at 160, where as an adult can jump at 110, peak at 120, shift, rinse, repeat.

jsutkeepspining

i've never ben asked to roll out in ohio, but everywhere else you have to the second the race is over. there was one race i was at in ohio where one junior madea fuss about another junior not having a 53/15 or 52/14, so we all had to roll out for the rest of the weekend. I didn't care, i beat all the other juniors, so i don't know why i should care if someone else chooses to use a bigger gear (especially if they are too weak to use it right).

Skyline516

Yeah, I was amazed that it worked. I measured and rolled it out on the front path and it worked and I wasn't sure, so I had both my parents watch and check it. I have rolled out with officials twice so far this season and passed both times, so I guess my bike is just weird.

getaklug

I've been (or was supposed to have been) rolled out at all of my races. Thats BRAC (CO) for you.

David Broon 

I get rolled out all the time. I just don't see the cadet gearing enforced, most of the time they just have to ride the standard junior gears.

sstang13

I failed my first circuit race which was after a TT, the guy asked me how I got past it and just fixed it for me before the race, no DQ. Truth is that in the TT the guy wasn't at the start of the roll out and me not knowing any better I started at the bottom of my back wheel instead of my pedals I just fixed my own gears this weekend for the first time though and passed