Eldest scruffykid got gears for Christmas, unfortunately only 6 on a freewheel hub. She’s struggling with the thickness of the bars and the revoshift (full length outer in good nick). I’ve got a 10speed hub coming, SDG grips and bars to fit but how many gears with what trigger shifter? Aiming for the lightest shift action, lightest weight and cheapest price second hand

– does she need a clutch mech or would some 9sp deore or xt kit be a good compromise?

8 or 9sp cassette to save some weight, 10sp clutch mech and a sram shifter combo?

It’s a 20″ bike, with soon to be a narrow wide 34t chainring, so probably don’t need anything bigger than a 34t at the back, so shortest cage option might also be wise?

WWSTWD?

Clutch makes it harder to shift.
9 speed is perfect I’d say, cheap and good.

Edit- 20 inch wheels
I’d leave the 6 speed, see how it goes.

Cheers, She’s flying on the 6 speed, but the bars and grips are too fat for her hands so she finds it tiring (and they aren’t pink), so the gripshift needs to go, can’t see any decent shifters for 6 speed?

What’s the pick of the 9sp bits?

I think you’re over thinking it a bit too much! Best doing a parts-bin special from whatever 9sp bits you have.

But as you’ll also presumably have to build a new wheel, I’d do as jkomo says and leave it as 6. Thin pink grips and see how she gets on.

Edited to add, last time I did this I used xt short mech, SLX 11-32 cassette and Deore shifters. Why? Cos I had them already and the cassette was the cheapest I could find. New cables and outers. Clutch off. Don’t worry about the NW chairing. Anything will do (I just took off the mech and outer of the existing chainset).

Depending on what you have planned but I would look at a smaller chainring. We had a 30t on my sons frog and he was able to climb pretty much any hill. Enabled him to do longer rides with me including 15 miles over the South Downs.

The reason for the narrow wide is the standard cranks are a bit too long, the replacement 125mm ones are 110bcd,so limited to a 34t.

Unfortunately new to mtb, so no parts bin to raid, plenty of 10sp road bits though.

Not sure how much you’re wanting to spend but sjs do a 127mm chainset including ring for 15 quid. That’s 36t.

If you’re committed to new rear wheel and NW then just use your roadie 10sp stuff with Deore shifters and new cables. If there’s not enough range for her then new cassette.

Probably worth asking on here to see what folks have?

I think you will struggle with chain line and retention trying 9 speed on a 20″ wheeled bike with short stays. There is a reason why they stick with 6 speed, and it isn’t just cost.

I think lower gears are more important than the number gears. If you are stuck with 34 up front, Sunrace do wide range cassettes. My son’s bike has 11-40 8 speed at the moment. Very handy for hills.

Mech cage will be very close to the ground on 20″ wheels.

Fwiw my daughter’s 24″ orbea has deore 10spd which seems light to shift. She has no problems with it.

I’d be leaving it as is other than thinner grips. A bit more width on the shifter section matters less. Grip shift is easier for younger children to understand.

Roadie 10 Spd has the same shift as MTB 9 spd I think.
Don’t try using MTB 10 spd shifters if you’re using a roadie mech.

On the other hand a 105 10 spd mech, 9 spd XT shifter and 9 spd XT cassette works beautifully with a nice light action.

Take the grips off and use bar tape to wrap. It’ll give a much slimmer grip.

Kids bikes are almost always massively overgeared – you need the smallest chainring you can find and about 5 or 6 at the back with the lightest simplest shift mechanism possible. Shame that Shimano don’t do a 6sp trigger shifter; most bikes come with Gripshift which is crap.

I thought I knew best and fitted a trigger to my eldest’s first geared bike. She did not take to them, after a couple of kids bike builds the best option I’ve found is SRAM X3.

You can have 7 or 8 speed to suit the hubs/spacing, triggers or gripshift, lower cable pull ratio means a lighter action than old Shimano, the mechs can stretch a bit fo a bigger sprocket and it’s all dirt cheap parts…

Just stick it in 1 gear and leave it there. In my experience they only use gears because they’re there and randomly change them, usually in the wrong direction at the wrong time anyway.

The SDG bar & grip combo is great (both my kids have them) but I’m not sure it will work with a gripshift. It does come with a plastic adapter to stick inside the brake levers and shifter clamps to adapt the size but they’re quite thin and may struggle with the gripshifter.

Oh and I wouldn’t bother adding gears as a new hub is a fair amount of faffage and she’ll only be on it for 5 minutes (it will feel like) before you upgrade to 24s. Will it be 10 rides?

Also what bike is it and what crankset? I’d be surprised if a kids crank on a 20″ bike has a 104BCD spacing but happy to be corrected. All the ones I’ve seen have a riveted ring.

I know it’s nice to do custom stuff for your kids but I wouldn’t go beyond the bars/grips for now.

Big John, she’s already skidding to a stop and demanding a faster or easier gear depending on what’s in front of her, which surprised me for a 4.5yo.

Speeder, she’s got my build with short legs for her height, so I got a set of 120mm square taper cranks from china but they are 110bcd, only superstar seem to offer a NW down to 34t. she’s pedalling squares compared to how smooth she was on a cnoc 16. The std ones are pressed steel ring peened onto 127mm ali arms. Might not make much difference, or I could fit the ones from her Cnoc.

The Sdg kit is driving most of this, I can’t see any options to fit the sdg bars with 6 speed. She’s got a bit of growing room and it’ll get handed down at least twice so I’m happy to bite the bullet on the hub now.

It’s a forme sterndale, not as light as an isla but hopefully more robust and easier going on trails. Felt lighter than her riding buddies 20 inch carrera.

https://photos.app.goo.gl/TfY1b68m6SxLZeo96

Big John, she’s already skidding to a stop and demanding a faster or easier gear depending on what’s in front of her, which surprised me for a 4.5yo.

Stick some electrical tape or something on the shifter then you can say Red/Blue…(or whatever for up/down)

I’d try for the smaller chainring so smaller BCD cranks (if not for gearing to prevent catching it) though not to the exclusion of correct length cranks.

Thumb up (hill)
Finger fast (flat and fast)

Is the biking rule in our house

Surely AXS or DI2 would be perfect for kids as it would be much easier for their small fingers and thumbs to press a button.

Agreed. The only people who should be allowed Di2 or AXS or the like are those without the hand strength for standard gear systems.

TX50 shifters may work for you and come as a 6 speed at an exhorbitant £11.

Alternatively Sunrace do a DLM400R7 at a shade under £10.

Surely AXS or DI2 would be perfect for kids as it would be much easier for their small fingers and thumbs to press a button.

Be bloody expensive every time they wreck one. Not to mention would they ever remember to charge them. Mine’s 11 now and rarely remembers to check his brakes and bolts before we ride.

I’m impressed she is on a 20″ at 4.5. My lad isn’t the tallest in the class but is still on an 18″ at 6.5.

I bought a 20″ Carrera and its massive, unfortunately no one seems to do gears on anything smaller than a 20″. I’ve considered getting a Brompton and swapping bits off their 2 x 3 speed internal hub but its a total faff.

Good shout on the TX50s, I’ve been looking for some 6 speed shifters for the wife’s city bike to replace the massive twist shifter.

Just in relation to the actual Q (lest we forget)… I guess the answer is it’s range that matters more than number of gears.

no one seems to do gears on anything smaller than a 20″.

Probably too much danger of sticking the mech into the ground when cornering on 18″ and smaller wheeled bikes.

Tried the big bike out again today and he’s getting closer but still needs to grow.

Got back from riding his 18″ and I found a Sturmey Archer 3 speed on eBay which will fit so that’s the next experiment.

How tall is he?

Get them as many gears as possible and now, before they fall into the grasp of some weird cult.

Cheers everyone, got a zee mech cheap on ebay and will run it with the clutch off for now. I’ve got a 10sp 11-34 in the shed and a new hub inbound. May leave the cranks for now with the 32, or look at shortening something with a sensible bcd. It’s a considerable increase in gear range 15-28 to 11-34.

She’s pretty tall for her age, but the bike does look big, I think the step up from a cnoc 16 to anything other than another isla is quite big to 20″. She loves it though, and is already way more capable on it than the 16, steaming through roots and rocks that would have hung her up on the 16.

I’m impressed she is on a 20″ at 4.5. My lad isn’t the tallest in the class but is still on an 18″ at 6.5.

Don’t forget some 20″ bikes have a really low saddle height. This is why I went for the Isla beinn as it had the lowest saddle height of any kids bike for that size. My boy went from a frog 42 to the Isla bike.

Saddle height isn’t too bad, it’s the huge cranks. If I was to scale them up to an adult size they’d be well over 200mm. I could swap them out for something more sensible but don’t really want to go down that route.

What length are they podge? loads of ali crank / fixed steel ring on Aliexpress or ebay and square taper is a few minutes to change? That’s where Isla and frog do so well, everything is sized appropriately,brakes,grips,pedals,seats and cranks.

Slight variant on the triple chainset that came on my Marasa, for £28 (24/34/42).
https://www.rutlandcycling.com/components/gears-drivetrain/suntour-triple-chainset_98523

Quick glance says cranks are 110 on 18″ 140 on 20″.

We have two Isla in the cellar and yes they are well thought out but his Cuda is just as good at a fraction of the price.

Borrow the cranks off one of the islas? The cnoc 16 had 105mm so 127 on the forme isn’t a huge difference but you can see it in her pedalling

I guess I could swap loads of bits around but would like to get rid of the two Isla, price of those things mean I’m sitting on a gold mine.

I’ll see how the experimenting goes, no point on squeezing him on to 20 if 18 is still fine.

I’ve got a set of short 114mm Hoy Bonally kids cranks in the garage that I bought for the same reason when I first got a slightly dated Frog for my lad ages back.

They do have a fixed (riveted) ring (32T I think) but it features guides on both sides so it’s nice and safe and can’t come off.

They were from Evans but I think they’ve reduced the range since the takeover so no links available.

If anyone is interested PM me and I’ll sort details/pics.

G

I think you will struggle with chain line and retention trying 9 speed on a 20″ wheeled bike with short stays. There is a reason why they stick with 6 speed, and it isn’t just cost.

My daughter has 9sp as stock on her 20″ and never had issues, all she has is one of those plastic pegs over the chain where a front mech would go. It is just cost. All I did since was swap the SGS mech for a GS to give better clearance.

So the 1×10 conversion is done, along with the SDG kit. No time for a test ride but she can operate the shifter at least. She’s stoked with more pink and mentioned she can hold the grips all the way round. Not sure I’d do it again, or maybe I’ve learnt all the lessons! New jockey wheels, BB to fix the chainline, bent mech hanger, wheel rebuild, converting the xt shifter to band on – it was endless.