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Youth road racing...gearing...
My son has just started road racing this year, and has actually done really well.
All had been going well until Saturday when we ran into a slightly overzealous comm...he said he was overgeared, he wasnt, we'd checked it over and over again and he's been fine at every other race he's done. ( I think the issue was they were getting the kids to do their own rollouts)
Anyways...he wasnt allowed to start on his bike, high limit screw plate snapped...long story. So I'm now thinking of getting him a youth cassette but looking at ratios I'm slightly bamboozled, he's youth a just now so 6.93 metres but will go up to junior at the start of nexr year so 7.93 metres then.
Hes on a 50 tooth at the front which ideally I diont want to change but I cant work out what cassette to get to get as close to those ratios as possible...
Any advice or experience from parents who I'm sure have gone through this would be much appreciated!
If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.
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A junior with a 50t front will want a 14t top gear- all the juniors use miche cassettes if they're on 11 speed- https://www.merlincycles.com/miche-primato-light-cassette-11-speed-22824...? Probably the 14-28 would be best. If it's 9 or 10 speed I believe Miche also do options for that but he'll want a similar ratio regardless.
Would recommend one of those and locking off the 14 and 15 if he's going to race on it before 1st January.
Pretty poor form from the comm getting kids to do it themselves and not double checking. It's fairly common for someone to fail the rollout initially, start again after checking the cranks are lined up properly with the line and pass the second time.
Have a look at The Cycle Clinic website, they do the Miche cassette in 10 and 11 speed and you can buy individual sprockets too if you need to customise for a particularly hilly event
I recall using extra spacers from an old cassette and even grinding the teeth off a 12t lockring when there was a rule that blocking off cogs by limit screws wasn't enough. It may have been the Youth Tour of Assen!
While not really advice per se, I recall my own challenges with this as a youth rider. A suitable cassette for a Shimano freehub was extremely expensive, as I recall, prohibitively so! Frustratingly, it was quite easy to find a suitable, secondhand freewheel cassette for not much at all. But in my case, this would have meant a new wheelset.
Solution was the limit screws and some tape! I managed to replace one of the limit screws with something about twice the length of the original, which kept the gearing within regulations. I was then advised, for the avoidance of doubt, to carefully tape over the unusable sprockets with electrical tape, so it was clear after the event that they had not been used.
It used to be easy when 39/53 chainsets were standard as you just locked off the big ring and maybe a sprocket or 2 depending on age/cassette. With 5 arm compacts a 46t chainring was cheap and useful but now the cost of outer 4 arm chainrings is silly. Not something I need to do anymore but I wonder if a 39t inner would be a good solution nowadays (much cheaper than an outer) although as you say bigger tyres have also messed up the old standard calculations.
Yeah it's not simple eh?!
And as any of you who've been involved in kids racing will know it was all my fault too....certainly according to my son!
46t rings are still available cheaply for 9 speed Sora etc.
I'd not give my kids a bike with an 11sp groupset anyway, it won't win them a race and neither would they appreciate the cost or look after it. They're kids. The money saved by using 9sp chains, cassettes etc can go towards race entry fees, a Zwift subscription or whatever. If he crashes it then the cost of replacement STIs won't hurt quite so much. When he has to save up his own money from the paper round or part-time job to buy something he'll more likely take care of it.
The money saved by using 9sp chains, cassettes etc can go towards race entry fees
9 speed Sora is very good in its own right, and is not just cheaper rubbish. When I put the Sora gravel disc back on the road with replacement wheel I was suddenly having trouble with gears. I thought it was deteriorating- then it stopped changing altogether and I thought it was knackered. To cut the story short, I found the cable ferrule was jammed in the mech. and I had to discover how to get it out (beneath the rubber cover is a screw, remove it and the bottom shaped plastic piece comes out). New cable and it's back to smooth perfection again- this is the first shifter I have had with the gear cable following the handlebar. The others came out straight towards the midline of the bike. I haven't had a cable break in the shifter before, and it's only 22 months old- do cables break more often in these cable-concealed shifters? The course of the cable looks nicely smooth and the new inner went in easily
Agree 100%.
I have seen discussions online about the fact that the more convoluted routing required for Shimano's concealed cables to go under the bar tape has led to fraying and breakage inside the STI itself. I don't have any direct experience of those models.
Was the commissaire / scrutineer over-zealous or just applying the rules properly? Not that it matters, you just need to ensure the gearing will in comply in future. Sheldon's gear calculator agrees with a table I found showing that 16t is the smallest cog you can use with a 50t front chainring on 700c wheels for Youth A. 42x13, 46x14, 48x15 or 52x16 are alternative combinations.
https://heanorclarion.org.uk/go-ride-for-youngsters/gear-restrictions-fo...
https://kidsracing.co.uk/blogs/bikes/british-cycling-triathlon-youth-gea...
In the end no-one wins or loses a youth race because of 0.1m difference in gearing so don't fret over it.
Yeah it was the 50 x 16 he was in, been the same gear all season, same tyres too which I know affect it, and it's been checked every race and been fine, I think the problem was they were getting the kids to do the rollouts themselves, and as you'll all know, it's not actually that easy! a good few failed.
it went from bad to worse too, when I tried to limit it into the 17 the plate the high limit screw pushes against snapped.... we've had better days!
50 x 16 does come out a good 30cm short too which I think does make a difference over a whole race, good for their cadence anyways!
think I'll try and get closer to the maximum length next year some way, the youth/junior cassettes seem the best plan.
I'm not familiar with the regs but as always, isn't the answer just "Sheldon knows"?
https://www.sheldonbrown.com/bicycleGears.html
https://www.sheldonbrown.com/gear-calc.html
No, sheldon brown doesn't know the answer to everything. Despite it being a parameter in his gear calculator, crank length has no bearing on a gear ratio. If your chainring is 3 times the size of your sprocket then for every turn of your chainring your sprocket (abs so therefore your wheel) will turn 3 times regardless of the length of crank used to turn it.
Heretic!
Crank length does have an effect on the apparent gearing - a longer crank will mean that the foot and pedal travel further for each rotation of the back wheel and require less strength (with a shorter crank being harder to push). Similarly, the wheel size doesn't directly affect the gear ratio, but does affect the apparent gearing (c.f. penny farthings).
Please explain to me what "apparent gearing " means. If I am in 50x13 I will travel a given distance regardless of crank length so ther is one, and one only, gear ratio for any combination of chainring and sprocket.
Wheel size doesn't affect gear ratio but it does affect gear size. That's why in good old GB we tend to talk about gear size in inches which goes back to the penny farthing and the wheel circumference of the driven wheel. Just ask yourself what happens to the gear of a penny farthing if you alter the crank length. That's right, nothing at all, it's still the same size gear
Still waiting to find out what "apparent gearing" means.
It's the ratio of force applied to the pedal versus force provided to the rear wheel for propulsion (i.e. where the tyre hits the ground). It's basically like gear inches but also taking into account the crank length (i.e. size of lever).
To be fair, the difference between different crank lengths is a small effect and most of the time you'd choose a crank length to fit your legs (and hopefully not hit the ground).
If you consider your 50x13 gear example - a longer crank would propel you a certain distance for the distance that your foot moves, whereas a shorter crank would propel you a longer distance if you moved your foot the same distance. Your feet are moving along the circumference of a circle with the crank length being the radius.
Additionally, different size tyres would also make a small difference to apparent gearing.
So, "apparant gearing" is all about transfer of forces then and not gear ratio or gear size.
A few issues with your thinking: If my foot goes around once, regardless of the radius/crank lenght then my chainring will go around once and my rear wheel will go around 3.84 times (50/13), my foot will travel different distances depending on my crank length but my chainring and wheels will still go around in the ration determined by their respective sizes, this ratio DOES NOT change with crank length. Gear ratio is exactly that, the ratio of the size of your chainring and sprocket and to alter that ratio you have to change the size of either (or both) of these parameters. Crank length does not alter that ratio, if it did then the size (number of teeth) on either my chainring or sprocket would have to change and i think we can all agree that changing the crank length does not chnge the size of the chainring or sprocket. Secondly, the tyre size DOES change the gear size (but not gear ratio which i hope we have agreed is the ratio of the chainring and sprocket) because it alters the diameter (and therefor circumference) of the wheel so for one revolution of the wheel you will go further with each wheel revolution for a bigger wheel. This is why you can fail or pass a roll out gear check depending on your tyre choice.
I believe the crank length parameter is so the same programme can calculate gear ratio/cadence/speed- mostly only useful for fixed riders, but still handy.
But none of the parameters you mention change with crank length, the only thing that does change is the distance your foot moves to complete one revolution, a longer crank means that your foot travels further (bigger circle) but nothing else changes. Think of a wheel, the hub is revolving (cadence) at exactly the same speed is your rim and every point along the spoke (think crank length) so crank length doesn't affect cadence, gear ratio or speed.