# Yama Jama 20" put on diet



## wallander (Jul 22, 2018)

I've been lurking this forum for some time, big thanks to everyone in previous posts with great input on components to swap!

I got the Yama Jama 20" a few weeks ago and now I've put it though a diet. Got it down to *9.4kg*. Note that this includes a *KS Lev integra dropper*.

Stupid me didn't put the original bike on the scale before starting with the mods, but I estimate original bike to have been around *10.1kg* incl pedals and tubes. Quite much heavier than I expected. Then the Commencal Meta 20" might not have been so bad if put on a diet with crank, tire and drive chain mods.

The *Kactus pedals* seems to be very nice (except the crappy pins which I replaced with the ones included with the bike), hope the magnesium will hold up.

The *KS Lev integra 125* I found second hand, but unused. I have reduced the travel to about 50mm now (using a cord as seen on the picture below). But I doubt my kid will ever need more than 100mm before outgrowing this bike. So if I had bought new, I'd go for 100mm for more weight saving. It has a bit of stiction, kid need to apply some force to pull it up. I don´t want to put more pressure in as my kid already now has problems getting it down by just sitting on the saddle. Anyone with similar problems and tried to reduce stiction? I found this site with tips on swapping damping fluid to a lighter one, might try that: KS LEV rebuild and travel adjustment | Peter Verdone Designs

I tried to go for the *Wren stem*, but it was not possible to source in EU, and with shipping and tax, it was not worth getting it from the US. But I found an alternative with Propain, cheap but a bit heavier.

Now I'm looking into reducing HTA and I'll try increase fork travel after svinyard's tip.

See my nerdy spread sheet below for sorted cost/weight savings, hope it can help someone further on!


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## BikePilot1 (May 15, 2006)

Nice work Sir!

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## svinyard (Aug 14, 2017)

I wish there was a way to get a larger range cassette on this bike. Any ideas?


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## wallander (Jul 22, 2018)

svinyard said:


> I wish there was a way to get a larger range cassette on this bike. Any ideas?


I think Sunrace 11/40,11/42 or 11/46 might fit, but I don't know the limitation of the rear mech, see SunRace | CSMX3


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## onawave (Jan 4, 2019)

how has your kid liked the jama 20? my son will soon be turning 5 - and im thinking about getting him this bike


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## wallander (Jul 22, 2018)

onawave said:


> how has your kid liked the jama 20? my son will soon be turning 5 - and im thinking about getting him this bike


He likes it! It's a huge difference on trails compared to his ("now commuter bike") Islabike Beinn 20" small. The gearing is perfect for our rolling hills. The geo is very nice. He's 120 cm and the fit is spot on (hopefully he can use it next year too...). I'm a little bit dissapointed on the fork, it has quite some stiction compared to "real" forks. Maybe it was a bad sample? I'm guessing that the new Manitou Machete 20" will be more on par with "real" forks. I wonder if Spawn will source that?

If you are in North America I'd look at the new Trailcraft Blue Sky 20, they have completed the diet for you  I considered it, but it would have been too expensive with European toll and tax.


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## svinyard (Aug 14, 2017)

wallander said:


> He likes it! It's a huge difference on trails compared to his ("now commuter bike") Islabike Beinn 20" small. The gearing is perfect for our rolling hills. The geo is very nice. He's 120 cm and the fit is spot on (hopefully he can use it next year too...). I'm a little bit dissapointed on the fork, it has quite some stiction compared to "real" forks. Maybe it was a bad sample? I'm guessing that the new Manitou Machete 20" will be more on par with "real" forks. I wonder if Spawn will source that?
> 
> If you are in North America I'd look at the new Trailcraft Blue Sky 20, they have completed the diet for you  I considered it, but it would have been too expensive with European toll and tax.


Your fork should be sick. Check the compression knob. If that doesn't help... tear it apart. There is very little oil if any. All slick honey. I have the video tutorial on my YouTube of the guy that helped design it servicing it. Pretty simple. Plus you want to shave down the plastic bumper so you get more travel and better ramp up. It should be ultra smooth. It's by far the best 20" fork we've used... Tho yeah the new Junit one is more capable I'm sure. I think it's heavier tho. This one hasn't held us back. We are using 1 psi per lb of kid.

On the cassette thing. The 11-36 is the max that the gx short cage supports. It's fine but a 28t chainring would be better.


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## wallander (Jul 22, 2018)

svinyard said:


> Your fork should be sick. Check the compression knob. If that doesn't help... tear it apart.


I got your video in another thread and followed it to shave that bumper, but there was none! So, travel was not restricted.

I'll follow it again and do the full service now and see if it gets better!


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## svinyard (Aug 14, 2017)

wallander said:


> I got your video in another thread and followed it to shave that bumper, but there was none! So, travel was not restricted.
> 
> I'll follow it again and do the full service now and see if it gets better!


Gotcha. Take some pics of your inside without bumper pls. I don't want the bumper if it's not needed. Thx!


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## wallander (Jul 22, 2018)

svinyard said:


> Gotcha. Take some pics of your inside without bumper pls. I don't want the bumper if it's not needed. Thx!


Funny, I now rembered that I already did that  See https://forums.mtbr.com/families-riding-kids/reducing-hta-yama-jama-20-a-1097355.html#post14019218


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## onawave (Jan 4, 2019)

how do you think the yama jama would compare to the commencal?

https://www.commencal-store.com.au/PBSCCatalog.asp?ActionID=67174912&PBCATID=3534507


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## wallander (Jul 22, 2018)

onawave said:


> how do you think the yama jama would compare to the commencal?
> 
> https://www.commencal-store.com.au/PBSCCatalog.asp?ActionID=67174912&PBCATID=3534507


I did consider Commencal Meta HT 20+ also,
cons:
- Heavier plus-tires, I would have swapped those for lighter ones.
- Longer crank arms 145mm vs 130mm, I would have swapped those for shorter ones
- Heavier with stated 10,7kg (which I suspect does not include pedals?), compared to about 9.8 kg for the YJ without pedals. Maybe with the mods above plus the ones I did to the YJ (see below) they'd be on par?
- Slightly longer chain stay 350 mm vs 340 mm.
- Worse gearing with 32t front and 11-34 rear vs 30t front and 11-36 rear. I'd have swapped to better gearing.
pros:
+ Longer travel fork

Cheers


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## onawave (Jan 4, 2019)

wallander said:


> I did consider Commencal Meta HT 20+ also,
> cons:
> - Heavier plus-tires, I would have swapped those for lighter ones.
> - Longer crank arms 145mm vs 130mm, I would have swapped those for shorter ones
> ...


yeah overall the spawn does seem like the better bike. i just gotta write off around $500 of value


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## onawave (Jan 4, 2019)

onawave said:


> yeah overall the spawn does seem like the better bike. i just gotta write off around $500 of value


well i dove in the deep end and have pre-ordered one of these. hopefully they are worth the extra $

good thing is we are picking it up in squamish.


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## eyeballs (Sep 16, 2016)

svinyard said:


> On the cassette thing. The 11-36 is the max that the gx short cage supports. It's fine but a 28t chainring would be better.


One would think. I put a 28t on my kids YJ, but I think I'm going to put the 30 back on before we go to Highland. She absolutely will not use the 2 largest cogs with the 28 on. As soon as the trail goes up (or down) she is out of the saddle. Not the worst problem to have I suppose.


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## wallander (Jul 22, 2018)

onawave said:


> well i dove in the deep end and have pre-ordered one of these. hopefully they are worth the extra $
> 
> good thing is we are picking it up in squamish.


Excellent, you'll have fun!


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## rabitoblanco (Feb 21, 2017)

eyeballs said:


> One would think. I put a 28t on my kids YJ, but I think I'm going to put the 30 back on before we go to Highland. She absolutely will not use the 2 largest cogs with the 28 on. As soon as the trail goes up (or down) she is out of the saddle. Not the worst problem to have I suppose.


Explain, please?

If I understand what you're saying, it sounds like she has two extra gears if she needs. But if you're changing to 30t, I must not be understanding properly haha

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## RMCDan (Feb 28, 2008)

He's saying she never uses the easiest two gears, so might as well put the 30t so she has more top end for bike park riding.


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## JRod0981 (Apr 26, 2017)

Can I ask how old your daughter is? Considering this bike for my almost 5 year old. He's about 45" tall with a 19" inseam.


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## wallander (Jul 22, 2018)

JRod0981 said:


> Can I ask how old your daughter is? Considering this bike for my almost 5 year old. He's about 45" tall with a 19" inseam.


My kid is almost 5 years now, he's big for his age at about 48" with 20.5" inseam. Now the bike is spot on in size. Saddle is about 4" extended and we have a flat bar now. I think it should work for your junior.


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## JRod0981 (Apr 26, 2017)

Awesome good to know. Anyone know how this bike compares to a 20" spawn savage? 

I can't find specs on the savage but there is a used one for sale nearby that I might grab.


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