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Posted
5 hours ago, quade said:

Interesting

I will see if I can find out how much the Alex rims weigh, switching the hub and spokes will be less painful, I could just de-lace the wheel and figure it out from there, but a big task if I decide to switch the rim and have to rebuild!

A hub and spokes switch might just do the trick

So you have a 7.2kg 20" rigid mtb? That is impressive ! Mine is slightly over 8kg with aluminium frame.

 

24" is a headache 

26" is super easy, AliExpress have Mavic crossmax wheel set for around 2k, they are around 1680g for the 2, sadly nothing in the 24" 

Loads in 20" due to the Asia folding bike market 

 

You're welcome to borrow my wheel trueing stand if you go all in. 

You'll need to rebuild the wheels anyway. 

Good luck. It's a deep dive, but a lot of the 'upgrading' is just fluff. Once the kids are on 26 inch bikes it's probably worth investing.

My boy is probably going to ride 20" bikes for a long time. I am in my 40s and still ride 20" bikes daily......

Bigger wheels isn't always better because it's easier for us. Stay smaller longer IMHO

Posted
On 3/29/2024 at 9:59 PM, quade said:

Hey all

My kids are racing in the Western Cape schools league, I bought a new bike for one of them, it's the lightest available but still horribly heavy, so I'm switching out the forks and trying to find light wheels

I can find a 32 hole rim but for XC racing a 24 hole rim will be fine ( he doesn't jump) 

Any ideas where to find the rim so I can kick off a wheel build project ?

 

Alternatively are there any other light weight rims or wheel sets in 24" available ?

 

Thanks 

Mark

Both my daughters were on Stans Crest Mk3 32 hole wheelsets, one had Hope hubs and the other with Shimano SLX hubs. Used light as possible spokes. Ended up way more expensive than I planned for but were worthwhile. And were very light. 

Reason for 32 holes was it was all that was in stock in 24" 

24 hole hubs and rims are very scarce. 

Sold both wheelsets recently on the hub. 

I still have a set of 24" Maxxis 2.2 tires for sale though. As tires are another headache. I imported Schwalbe's, but again painfully expensive. 

Best bet for fork is old Fox 26" dropped down to 70-80mm travel with simple internal plastic spacers. Nothing comes close to it. 

Youre welcome to PM me for more details on the wheels. 

Posted
On 3/31/2024 at 5:37 PM, Jewbacca said:

You're welcome to borrow my wheel trueing stand if you go all in. 

You'll need to rebuild the wheels anyway. 

Good luck. It's a deep dive, but a lot of the 'upgrading' is just fluff. Once the kids are on 26 inch bikes it's probably worth investing.

My boy is probably going to ride 20" bikes for a long time. I am in my 40s and still ride 20" bikes daily......

Bigger wheels isn't always better because it's easier for us. Stay smaller longer IMHO

That is very kind of you thanks

The local shop is pretty cheap and very skilled at wheel building so going to get a quote from them on a full set first 

I stumbled across this 20/24".full sus bike/frame.which you probably already know about 

https://tiny-rock.com/products/20carbon-ds-frame?pr_prod_strat=e5_desc&pr_rec_id=7a36b9cc6&pr_rec_pid=7110703153344&pr_ref_pid=7121562992832&pr_seq=uniform

 

Posted
On 3/31/2024 at 9:37 PM, Kuys said:

Both my daughters were on Stans Crest Mk3 32 hole wheelsets, one had Hope hubs and the other with Shimano SLX hubs. Used light as possible spokes. Ended up way more expensive than I planned for but were worthwhile. And were very light. 

Reason for 32 holes was it was all that was in stock in 24" 

24 hole hubs and rims are very scarce. 

Sold both wheelsets recently on the hub. 

I still have a set of 24" Maxxis 2.2 tires for sale though. As tires are another headache. I imported Schwalbe's, but again painfully expensive. 

Best bet for fork is old Fox 26" dropped down to 70-80mm travel with simple internal plastic spacers. Nothing comes close to it. 

Youre welcome to PM me for more details on the wheels. 

Now I'm just.annoyed I missed out on these ;)

Posted
On 3/31/2024 at 12:17 PM, s14phoenix said:

My boy just turned 6 and has been on his 24inch the last 6months. I have also been on this mission lately - started with the usual Titan 24" which came with 3x7 setup and 13ish KG.

Change to a 1x kiddies crank which was R400 and then relaced the rear rim to a normal freehub rear hub. A lot of the issue is the 36 holes and spokes which limited the hubs available - which needed to just about be free. I then fitted old SLX 9sp shifter and XT rear derailleur with a Sram 980 11-34 cassette. Maxxis Snyper tyres.  kcnc cockpit with a carbon seatpost - in total I shaved about 3kg off the bike but STILL weighs 10kg. 

It is rediculous what the kids bikes weigh for their size. I have now decided that no futher upgrades would be going onto the 24" and would focus rather on the carbon XS 26er @ 9.5kg (currently) that I have "waiting" for his as soon as he fits - that my wife rides when we go out as a fam.

The aim is to get the 26er to about 8.5kg which with careful parts selection shouldn't be too difficult as it has not even been converted to tubeless yet and has a very heavy gel ladies saddle.

good luck bikehub daddies - glad to see I am not the only fool suffering with this 😄

Which crank did you get ? And what was the length ?

 

These are my latest purchases 

Crank - 155mm with 30T ring

https://a.aliexpress.com/_Euzs4U1

 

Forks - 100mm 24" (1.6kg)

https://a.aliexpress.com/_Evc9ied

 

I didn't know about using spacers on a 26" fork, that would have probably been more sensible !

Posted

I just got one of the 1x square taper cranks that come on the Titan kids bikes. It is 155mm also but not as heavy as the 3x that was on the bike at least. 

Posted

I've figured out my current rims on the Momsem JSL40 are AlexRims DP21
According to this https://alexrims.com/wp-content/uploads/2020/02/2020-Alexrims-China-Cambodia-Catalog-DIGITAL.pdf
They are 390grams per rim

Thanks Two wheels for your link
I see the MK3 24 is 295grams (assuming 24 holes)
https://www.notubes.com/crest-mk3-rims

and the mk4 is 323 grams
https://www.notubes.com/crest-mk4-rim

The no doubt stronger mk4 version is R2,750 for a 67gram saving (134 grams for 2 rims)
so for R5,500 I get to save 134 grams by upgrading the rims
@Jewbacca seems to be on the money here, its the hubs that are the issue

I think I might look at lighter hubs and spokes, just means I cannot sell on the existing wheels

Posted
12 hours ago, quade said:

That is very kind of you thanks

The local shop is pretty cheap and very skilled at wheel building so going to get a quote from them on a full set first 

I stumbled across this 20/24".full sus bike/frame.which you probably already know about 

https://tiny-rock.com/products/20carbon-ds-frame?pr_prod_strat=e5_desc&pr_rec_id=7a36b9cc6&pr_rec_pid=7110703153344&pr_ref_pid=7121562992832&pr_seq=uniform

 

If you're going to spend that money, just buy this?

https://bikehub.co.za/classifieds/item/dual-suspension-bikes/655473/2021-commencal-clash-24

As I said, I got to a point where scraping grams vs ease of build became a battle that wasn't worth fighting.

A proper groupset with short reach (the cassette is the big gram saver here) along with the hubs and good cockpit. Tubeless tires in their various forms can save you 400g too. The Vee tyre Snap are pretty readily available here and work brilliantly. 

The rest is just a hack and will land up taking loads of time, efford and cash for almost no real gain.

I build all my own wheels and have done all my own carbon work and rebuilding, but it's still been costly.

I would also really recommend a light weight Alu bar and stem over carbon.

Kids tend to fall a lot and also tend to be less precious about how they lean it/lie it down. A good set of alu bars and stem will weigh roughly the same and offer peace of mind in terms of damage and longevity.

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