Kids MTB gearing help
dirkpitt74
Posts: 518
My 6y/o daughter has a Carrera Luna 20" and she's loving riding it.
Slight issue we're having at the moment is hills - she wants to do longer rides but after a while is struggling on the hills due to the slightly rubbish gearing on the bike.
Current gearing is 36t front and 7spd 13-28t on the back.
This set up give the following gear ratios:
High - 1:2.8
Low - 1:1.29
So on high when on hills she's still having to work quote hard.
Now my initial thinking is to just get a wider range rear cassette - these are available in either 12-32t, 14-34t and 11-34t.
This should help on the climbs as it brings thing closer to 1:1 at the low end (1:1.12 for 32t and 1:1.05 for 34t).
But I then got to thinking that I could improve things further by swapping the front ring. This would mean changing the crank - but I can get a 152mm Suntour with bolt on rings for £24 - and sticking a 32t single ring up front.
This would improve the climbing a bit more and would give a 1:0.9 ratio for a 34t cassette.
Question is, is it worth changing the front or should I just swap the cassette and see how she gets on?
The 'bike-tart' in me is thinking change the front a stick a purple chainring on for extra coolness and 'Dad points'.
So do I spend £12 on a cassette only or another £30 on new crank & ring?
Am I missing anything?
Slight issue we're having at the moment is hills - she wants to do longer rides but after a while is struggling on the hills due to the slightly rubbish gearing on the bike.
Current gearing is 36t front and 7spd 13-28t on the back.
This set up give the following gear ratios:
High - 1:2.8
Low - 1:1.29
So on high when on hills she's still having to work quote hard.
Now my initial thinking is to just get a wider range rear cassette - these are available in either 12-32t, 14-34t and 11-34t.
This should help on the climbs as it brings thing closer to 1:1 at the low end (1:1.12 for 32t and 1:1.05 for 34t).
But I then got to thinking that I could improve things further by swapping the front ring. This would mean changing the crank - but I can get a 152mm Suntour with bolt on rings for £24 - and sticking a 32t single ring up front.
This would improve the climbing a bit more and would give a 1:0.9 ratio for a 34t cassette.
Question is, is it worth changing the front or should I just swap the cassette and see how she gets on?
The 'bike-tart' in me is thinking change the front a stick a purple chainring on for extra coolness and 'Dad points'.
So do I spend £12 on a cassette only or another £30 on new crank & ring?
Am I missing anything?
_______________
Chris
Current FS: 2017 Nukeproof Mega 275
Current HT: 2017 Nukeproof Scout 275
Kids Carrera Blast Refurb/Upgrade
My Blog - Midlife MTB Mutterings
Previous FS: 2014 Nukeproof Mega TR 26'er
Chris
Current FS: 2017 Nukeproof Mega 275
Current HT: 2017 Nukeproof Scout 275
Kids Carrera Blast Refurb/Upgrade
My Blog - Midlife MTB Mutterings
Previous FS: 2014 Nukeproof Mega TR 26'er
0
Comments
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7 speed 13-28 could be a freewheel, not a cassette. Have you checked?
Poor girl, that bike weighs as much as my full sus 29er.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
Yes, it's a freewheel - my bad, still sunrace and shimano do 13-34 and 14-34 respectively.
She doesn't struggle with the weight, and once I've swapped the forks over it should be a bit lighter still._______________
Chris
Current FS: 2017 Nukeproof Mega 275
Current HT: 2017 Nukeproof Scout 275
Kids Carrera Blast Refurb/Upgrade
My Blog - Midlife MTB Mutterings
Previous FS: 2014 Nukeproof Mega TR 26'er0 -
I would change the cranks, I'd also look at other weight saving things you can do, its pretty heavy and anything you can do to save weight will make a big difference, tyres/tubes, grips and those cranks and you could drop 1-1.5Kg.
As CD says, freewheel or freehub/cassette, I would expect it to be a freewheel, you can get a 7speed 'mega-range' 13-34 BUT the gear spacing isn't great.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
I'd go down to a 30 or 32 ring and the biggest freewheel you can find.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
cooldad wrote:I'd go down to a 30 or 32 ring and the biggest freewheel you can find.
That's pretty much my plan at the moment.
Ordered cranks and a 30t and 32t ring to try to see which suits her best._______________
Chris
Current FS: 2017 Nukeproof Mega 275
Current HT: 2017 Nukeproof Scout 275
Kids Carrera Blast Refurb/Upgrade
My Blog - Midlife MTB Mutterings
Previous FS: 2014 Nukeproof Mega TR 26'er0