# New Scott Spark JR 20" Modifications?



## Billinsd (May 10, 2012)

I just bought my 8 year old daughter a 20" Scott Spark for a good price at a LBS. 

It is a really great bike as it is, however, I am interested in lightening it a bit and making it more user friendly without breaking the bank. 

I have read the other thread about the 20" Scott build and liked the 2 inch riser handle bars, since the stock ones are real low. 

The bike weighs the same as her Huffy 20" or less. 

The gearing seems to be low enough for her to go up hills, but I am not sure if she will need that big outer chain ring? 

What are some options for riser handle bars, stem, wheels, tires, and possibly shifters? 

This bike will be passed on to my 4 year old son, so I do not mind spending money on it, especially replacing parts that wear out.

Thanks
Bill


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## stom_m3 (Jun 28, 2011)

Check you PM.

Congrats! I'm sure your kid is happy. If you want to drop weight, check the tires. I was able to drop 1 lb just by swapping out the stock tires. You will also find the cranks and BB to be on the heavy side. Good luck. We're heading up to MT. Laguna on Sunday if you want to give it a run.


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## ThornPatch (Jan 21, 2004)

Couple of suggestions:

1) replace the bottom bracket, that will save some weight.
2) handlebars - any riser bar will work you'll just have to cut it down. Two things to consider: 1) be sure to buy a bar that works with the existing stem (that is if you're going to keep the stem); and 2) if the seat height is already lower than the bars you may want to go with a flat bar instead of a riser, adding a riser bar that increases the bar height will make the bike feel too "chopper" like. I used a FSA XC190 riser bar for my son's bike, it's alloy (so it was cheaper than carbon) and was easy to cut down, and its relatively light.

3) Replacing the wheels is the best way to knock off some weight, but it will cost you. I purchased a set of 28-hole hubs and SunRingle rims on eBay and had them built by a local shop. This saved considerable weight, but I also had to buy a 9 speed cassette, new rear derr. and a set of new shifters. Works way better, but cost lots.


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## Billinsd (May 10, 2012)

stom_m3 said:


> If you want to drop weight, check the tires. I was able to drop 1 lb just by swapping out the stock tires. You will also find the cranks and BB to be on the heavy side. Good luck. We're heading up to MT. Laguna on Sunday if you want to give it a run.


Thanks! We are planning to go to Mt. Laguna in two weeks to camp and will ride the trails, thanks.


ThornPatch said:


> 2) if the seat height is already lower than the bars you may want to go with a flat bar instead of a riser.


Her seat is a little lower than her handle bars, however she is used to them being a little higher.


ThornPatch said:


> 3) Replacing the wheels is the best way to knock off some weight, but it will cost you. I purchased a set of 28-hole hubs and SunRingle rims on eBay and had them built by a local shop. This saved considerable weight, but I also had to buy a 9 speed cassette, new rear derr. and a set of new shifters. Works way better, but cost lots.


That is good to know, both what is possible and that it is expensive.

This bike is perfect for where my daughter is as far as riding skill, height, strength, etc. I was planning on waiting for a 24" diameter wheeled bike, but she would not be ready for that for at least a year. Even with this bike she is slowly getting used to shifting gears and the handle brakes. I will pass it on to my son, so I feel justified buying the bike.

Thanks
Bill


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## ThornPatch (Jan 21, 2004)

Bill, I spent about $550 on a new custom built wheelset for my son's bike, which is crazy expensive for a 20" wheelset, but that price also included a new Sram 990 cassette, x-9 sort cage rear derr, and x-7 shifters. I built the bike for my 9 yr old, he's average hgt, and some might say I should have put him on a 24" bike, but since he likes to jump a lot he's better off on the smaller 20" wheels. The small wheels gives him more control over the bike, and boosts his confidence. Hopefully I can at least 2 -3 years out of it before he's ready for a bigger bike. Either way the parts can transfer over to a new bike pretty easily.


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## Billinsd (May 10, 2012)

ThornPatch said:


> Bill, I spent about $550 on a new custom built wheelset for my son's bike, which is crazy expensive for a 20" wheelset, but that price also included a new Sram 990 cassette, x-9 sort cage rear derr, and x-7 shifters. I built the bike for my 9 yr old, he's average hgt, and some might say I should have put him on a 24" bike, but since he likes to jump a lot he's better off on the smaller 20" wheels. The small wheels gives him more control over the bike, and boosts his confidence. Hopefully I can at least 2 -3 years out of it before he's ready for a bigger bike. Either way the parts can transfer over to a new bike pretty easily.


Thanks, I got your PM too. That really helps me out. Did you build the wheelset for better performance and/or weight reduction? I would spend that kinda money to make my daughter's bike better, if I know she is going to use it. My goal is to spend more time with my daughter doing stuff we both enjoy. 
Thanks
Bill


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## stom_m3 (Jun 28, 2011)

ThornPatch said:


> Bill, I spent about $550 on a new custom built wheelset for my son's bike, which is crazy expensive for a 20" wheelset, but that price also included a new Sram 990 cassette, x-9 sort cage rear derr, and x-7 shifters. I built the bike for my 9 yr old, he's average hgt, and some might say I should have put him on a 24" bike, but since he likes to jump a lot he's better off on the smaller 20" wheels. The small wheels gives him more control over the bike, and boosts his confidence. Hopefully I can at least 2 -3 years out of it before he's ready for a bigger bike. Either way the parts can transfer over to a new bike pretty easily.


I did something similar to ThornPatch. Sun Envy Lite, XT hubs, Sapim dbl btd spokes. Cost was $280. Dropped a ton-o-weight. I reused my cassette and shifters from an older bike so I didn't have that cost. You can purchase 2010/11 Sram shifter/cassettes cheaper than 2012.

Finished Wheel weights
Front Wheel 739g
Rear Wheel 906g


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## JRS73 (May 26, 2012)

Is the cassette flip-flop hub compatible?


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## Billinsd (May 10, 2012)

Is it possible to buy a Middleburn 140mm cranks, with a 32 chainring and bashguard? And a Irod 7 speed cassette, 15, 17, 21, 24, 28, and 32? That is considering the bike has a 34 and 42 chainrings and a different cassette? Thanks Bill


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## ridemtn (Aug 25, 2009)

I used cranks from bikesmithdesign.com, he recommends much shorter than that, I believe he said 10% of height plus 5mm, max length on the cranks. Anyways, if you look at a serious kid specific bike manufacturer like islabikes.co.uk then you'll see their 20" models have cranks from 114-127mm max.
I downsized the stock 152mm cranks on my son's 24" bike to 137mm and have been really pleased with the outcome.
I got the race face bash guard on race face rings. The crankset looks awesome and he delivered it fast too! Well worth it, imo.

Correction: he said 10% +5 mm at most.


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## Billinsd (May 10, 2012)

ridemtn said:


> I used cranks from bikesmithdesign.com. Correction: he said 10% +5 mm at most.


I calc'd 136.5 for my 51" tall girl. Thanks. I have read good things about bikesmith. Bill


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## stom_m3 (Jun 28, 2011)

Billinsd said:


> I calc'd 136.5 for my 51" tall girl. Thanks. I have read good things about bikesmith. Bill


If she is 51" she needs to ride 145-150mm length crank arms. I would go 145 conservative and 150mm for growth. For reference, my son is 48" tall and uses 140mm. The 10% thing is way off for kids. If you are planning on running a 1x setup, buy Sinz, redline or AC mini cranks ($50-70). If you need to run 2x/3x setup, bike smith will shorten cranks for a price. I like the 1x setup and personally run it on my mtn bike.

The right way to decide gear ratios is to review the numbers. Look at the gear ratios and decide where your kid will be able to operate best. Below are quick charts I did to show you some gear inch numbers. If you would like to know the roll out, multiply by pi (3.14).

The first chart shows a single speed gear inch setup for your 20" (15-32t setup). The next chart shows my son's 1x8 setup. And for comparison, the last chart shows 26" mtn bike gearing for 1x, 2x and 3x setups. For example, my 1x10 setup uses a 36 front and 11-36 rear cassette. My gear inches run from 25" to 83". My son uses a 35 front 12-32 rear cassette or 21" to 57". My son rarely uses his top 3 gears except on the occassional down hill but that usually involves more coasting, feet flat and looking way ahead (+20mph).

Based on the cassette that you want to run, 15-32, I would be a little worried about running out of steam on the upper (tougher) gears. Either increase the cog count or include a 13t in there. If you build custom wheels think about doing a 9 or 10 spd. This will solve most of your issues. Hope this helps.

Gear inch chart for 20" mtn bike 7spds









Gear inch chart for 20" mtn bike 8spds









Gear inch chart for 26" mtn bike (provided so you willl know what the level of effort is needed to push on a pedal per respective gear on your own bike).


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## Billinsd (May 10, 2012)

Great info, thanks!! I was meaning to also ask, if I get the Schwalbe Mow Joes, I would get the 20 by 2 inches wide for the stock wheels and if I upgrade my wheels those tires should fit on say a sun envy lite, right? 

Seems like the Mow Joes are not carried by many places? What are some good lightweight inner tubes?
Thanks
Bill


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## Shayne (Jan 14, 2004)

stom_m3 said:


> If she is 51" she needs to ride 145-150mm length crank arms. I would go 145 conservative and 150mm for growth. For reference, my son is 48" tall and uses 140mm. The 10% thing is way off for kids. If you are planning on running a 1x setup, buy Sinz, redline or AC mini cranks ($50-70). If you need to run 2x/3x setup, bike smith will shorten cranks for a price. I like the 1x setup and personally run it on my mtn bike.


I agree with this.
My 48" son has no problem spinning 140mm arms at high cadence. Anything shorter than 135 for him would be super awkward. The cranks on his 16" bike were ridiculously short and were the main reason I built him a 20".
+1 for Sinz and AC cranks. Good stuff.


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## stom_m3 (Jun 28, 2011)

Actually, after further thinking, I wouldn't go larger than 145mm on a 20" bike. At 51" she could ride either 145 or 150mm cranks but on a 20" bike you may get a lot of pedal/ground strikes. If she was on a 24" you could go larger.


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## Billinsd (May 10, 2012)

I cut about 2.5 pounds by exchaning the spark with a scale. I did this a few days after I bought the spark. The LBS has great customer service!!

I let my daughter ride the bike around for the last month or so and decided what else I wanted to do. 

I recently bought an IRD 13-32 freewheel in place of the Shimano 14-28. I cut off the big outer chainring that my daughter will never use. I bought a Paul Compents chain keeper, purple handle grips and a Shimano Trigger Shifter. 

My daughter likes the improvements and it seems to help her confidence. 

Thanks again all for the help!!!
Bill


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## Surfpoodi (Sep 14, 2011)

So is your local bike shop unloading a used Spark? Wonder if they'd ship it? It isn't easy to find used Spark 20's


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## Billinsd (May 10, 2012)

My daughter rode the spark around the block and it showed no signs of use. The LBS is selling it as new. He sold it to me for $400 and could come down. I don' t know about shipping. Bill


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## bugger (Aug 24, 2004)

*ideas*

I got a fusion x air shock from the manufacturer. Big differences in adjustability. Had cranks cut down to 130. I also am getting a new wheelset built up. Stock they weigh 28 pounds with pedals. My goal is to get it sub 25.


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## xc71 (Dec 24, 2008)

bugger said:


> I got a fusion x air shock from the manufacturer. Big differences in adjustability. Had cranks cut down to 130. I also am getting a new wheelset built up. Stock they weigh 28 pounds with pedals. My goal is to get it sub 25.


Great score getting the X-Fushion air shock. So nice having adjustable rebound damping so the rear end isn't a pogo stick. With this shock on the Spark its the best rear suspension you will find on a kids bike - works awesome.


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## bowhunter (Aug 1, 2009)

I've got a used Spark 20" (White) Full Suspension, that is like brand new. She's only ridden it a few times and may have hit a mud puddle once or twice. She outgrew it and needs to move up.


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## heckler11 (Jul 10, 2012)

*x-fusion*



xc71 said:


> Great score getting the X-Fushion air shock. So nice having adjustable rebound damping so the rear end isn't a pogo stick. With this shock on the Spark its the best rear suspension you will find on a kids bike - works awesome.


Hi, where and how to buy X-fushion schock to scott spark jr? What is the cost?
I live in Poland, but I have friends in the U.S..
Thank you for your reply.


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## sashae (Dec 19, 2008)

I picked up a Scott Scale Jr 20 for my son as well, I'm hoping to make a few improvements over time... are those Velocity Aeroheats really the best bet for at 20" rim? I'm thinking about picking up some Novatec or Circus Monkey hubs to build wheels.


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## heckler11 (Jul 10, 2012)

Hi, look at the weight of new models islabikes. 1 kg down each model.
Beinn 20 small 7.8 kg!!!!!!
I need to talk with son to sell his scott spark jr.


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## xc71 (Dec 24, 2008)

heckler11 said:


> Hi, where and how to buy X-fushion schock to scott spark jr? What is the cost?
> I live in Poland, but I have friends in the U.S..
> Thank you for your reply.


Not sure on cost as this shock came stock on my son's Spark RC JR. I would contact X-Fushion USA.


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## bugger (Aug 24, 2004)

*What a difference*

So I live in the mountains of NC and wanted my son to join me on some great rides. At this point, I am done. He has: 
127mm custom cut Truvativ triple crankset from BikeSmith. In hindsight, I think 135 or so might have been better to give him room togrow. If anyone wants to buy these from me PM me. 
X9 hubs with Velocity Aeroheat rims. Expensive upgrade ( I did find a bargain on the parts) but the way I look at it, when he outgrows this, I will relace the hubs with 24" rims and ebay the 20" rims. 
Air shock from Xfusion _ I just called the company and spoke with someone who sold the air shock to me. Worth the money
34-tooth cassette in back - there is little flat here
New platform pedals - no grip on the plastic ones

So - in all I spent a fair amount of money, but less than what I will spend on a new wheelset for me. I figure for 2+ years of use, plus the possibility of extending the use of hubs even longer, it is worth it to me.


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## heckler11 (Jul 10, 2012)

Hi,
where you bought dumper X-fusion 02 R and what the cost?
Thanks for reply


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## mtbhead (Jun 17, 2004)

Just picked one up for my 8 yo (he's a little small). Ive been holding off on upgrading his Performance Burnout. I plan to build some disc wheels, but I know that the rear would need a disc adaptor. I also plan on replacing the rear shifter and cassette (8sp). Disc brakes, better tires, and a riser bar. Lots of good info in this thread and elsewhere, but a few questions I have still are:
1. anyone find a good rear disc brake adaptor?
2. What are the rear shock dimensions, and how much do they cost?
Thanks for any help!:thumbsup:


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## Axe (Jan 12, 2004)

heckler11 said:


> Hi,
> where you bought dumper X-fusion 02 R and what the cost?
> Thanks for reply


I bought one directly from X-fusion, for Spark 24. They told me at that time it was the last one they had around in their office.


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## sashae (Dec 19, 2008)

I'm slowly losing my mind on my son's Scale Jr 20. I hit the Trexlertown swap a few weeks back looking for bits, and I'm getting ready to build up a new set of wheels. What'd I find?

Inexpensive 31.8 Bontrager bars and stem, new grips.
XTR V-brakes and levers.
X.0 rear derailleur, medium cage, and X.9 trigger shifter.
140mm Sinz cranks with 34t ring.
Syncros Ti seatpost.
Nokon derailleur cables ($6!!! haha.)
XTR M950 non-disc hubs, which'll get built to a new set of rims.

Ditched the stock tires in favor of Kenda Small Block 8s which lost an /amazing/ amount of weight. I'm hoping to get this bike under 20lbs once finished... going to be running 1x9, which should be MORE than enough. Too much fun.


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## mtbhead (Jun 17, 2004)

Awesome Sashae. I've been geeking out on parts for building up my son's Spark JR 20 - plan is to give it to him as a Christmas present. 
* I've identified some older 32-spoke disc hubs I have in my garage, and I plan to build them up with the stock rims
* I found the answer to my previous question about a rear disc adaptor and bought an A2Z DM-UNI adaptor from eBay. Also picked up some used F&R Elixir CR brakes (no discs) from eBay for $100. I've got extra (used) 160mm discs, but I might splurge for some 140mm ones.
* I plan to get some Small Block 8 tires
* I'll be pulling an 8-speed cassette and SRAM Rocket trigger shifter from my dirt-jump bike and plan to put it on this one - I might use the front chainguide as well.
* Next is the front crank/ring. I'm thinking Sinz 40mm from eBay, 32 ring, and re-using an old square taper BB that I should have in my garage (ps - anyone know the width? I'm guessing 68mm...)


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## sportfish258 (Sep 17, 2010)

Well looks like we are all in the same boat. Is the suspension on the scott Jr set up accurately for a 55 pound child. I think full suspension is a great idea for a little one as long as it is made for their weight. Feel free to comment. 

Thanks , Kevin


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## heckler11 (Jul 10, 2012)

Does anyone know where I can buy shock X-fusion 02 R 125 mm to scott spark?
X-Fusion Shox-USA did not sell those any more.
Thanks.


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## Axe (Jan 12, 2004)

heckler11 said:


> Does anyone know where I can buy shock X-fusion 02 R 125 mm to scott spark?
> X-Fusion Shox-USA did not sell those any more.
> Thanks.


I got it from them a year ago, and guy (John) said it was the last one they had around the office and they are not making them. Nice shock, real rebound with wide range. I wish they did not have that stupid Manitou eyelet size, as I can't use needle bearing shock mounts. Stock ones are quite sticky - especially for a light rider.


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## Axe (Jan 12, 2004)

Looking aroun the web saw this one: KS Rear Shocks for Downhill Bike Mountain Bicycle Rear Shock 125mm/170g Free Shipping-in Bicycle Frame from Sports & Entertainment on Aliexpress.com


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## heckler11 (Jul 10, 2012)

what do you think about this shock KS? (my eanglish is not well,sorry). I will buy one.
What about adjust dumping in this KS?


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## xc71 (Dec 24, 2008)

heckler11 said:


> what do you think about this shock KS? (my eanglish is not well,sorry). I will buy one.
> What about adjust dumping in this KS?


Looking at the pic it appears to be an air shock only with no external adjustable rebound damping, hopefully I'm wrong as its light weight & the price is right.


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## xc71 (Dec 24, 2008)

Axe said:


> I got it from them a year ago, and guy (John) said it was the last one they had around the office and they are not making them. Nice shock, real rebound with wide range. I wish they did not have that stupid Manitou eyelet size, as I can't use needle bearing shock mounts. Stock ones are quite sticky - especially for a light rider.


I had the same problem with X-Fushion shock sticking on my son's Spark RC. I solved the problem by going to torontocycles.com & purchasing Ti shock bolts with low profile Ti lock nuts.The lock nut allows you to back off the torque slightly & this eliminated all the sticking. To loose & the shock moves/knocks, every once and while I have to give the lock nut a hair more torque to stop this, but its well worth it to eliminating the sticking. Its going back a couple of year now, but I remembering having to buy the shock bolts too long for what I needed in order to get the correct shoulder length, which is important. I then cut the bolt to the correct length.Also ran a washer only on the locknut side.
If he doesn't have the right shock bolt shoulder length then I may have just bought Ti allen bolts to get the correct shoulder. If you're considering this let me now & I'll try & find the purchase order.


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## Axe (Jan 12, 2004)

xc71 said:


> I had the same problem with X-Fushion shock sticking on my son's Spark RC. I solved the problem by going to torontocycles.com & purchasing Ti shock bolts with low profile Ti lock nuts.The lock nut allows you to back off the torque slightly & this eliminated all the sticking. To loose & the shock moves/knocks, every once and while I have to give the lock nut a hair more torque to stop this, but its well worth it to eliminating the sticking. Its going back a couple of year now, but I remembering having to buy the shock bolts too long for what I needed in order to get the correct shoulder length, which is important. I then cut the bolt to the correct length.Also ran a washer only on the locknut side.
> If he doesn't have the right shock bolt shoulder length then I may have just bought Ti allen bolts to get the correct shoulder. If you're considering this let me now & I'll try & find the purchase order.


This does sound like a plan? I think M8x75 should work - I will measure. I will also get the Manitou heavy duty mounting kit.

I think they did it on purpose as the stock shock has no damping whatsoever. 

P.S. Looks like a good idea with the sandpaper on pedal axles. Will go get the scraps back out of trash from the skateboard grip I was installing yesterdays.


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## mtbhead (Jun 17, 2004)

Sweet - finally another air shock option since X-fusion stopped production! Anyone try order/try one of these KS shocks yet?


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## heckler11 (Jul 10, 2012)

I just ordered this dumper KS from Taiwan, and now I'm waiting for it.
I'll try to write about it.
Weight of the bike is slowly coming up to 9 kg.


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## Axe (Jan 12, 2004)

heckler11 said:


> I just ordered this dumper KS from Taiwan, and now I'm waiting for it.
> I'll try to write about it.
> Weight of the bike is slowly coming up to 9 kg.


I found the product information page for A5-RE. Apparently it is a friction damper. No oil.

A5-RR1 version adds a topout adjustment. It would be about 180g weight saving compared to the coil, if I remember correctly.

But realistically, for the amount of travel, and stiction in suspension, not much damping is needed. I keep X2 fully open.

There is 5.5x1.0 Fox. I wonder if it could be made to work by flipping the link and adding a 5mm internal shim (or making it 100mm rear travel). By looking at the picture it seems that rotating the link backwards will easily add about an inch eye to eye distance.

Well, I do have Xfusion, so will not really try..


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## xc71 (Dec 24, 2008)

Axe said:


> I found the product information page for A5-RE. Apparently it is a friction damper. No oil.
> 
> A5-RR1 version adds a topout adjustment. It would be about 180g weight saving compared to the coil, if I remember correctly.
> 
> ...


Axe, I don't think you can flip the links. I remember someone complaining of the air can being dented by the cable stop ( you can see it on my son's Spark a few posts up), I had suggested the links got flipped by accident and that was his problem.


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## Axe (Jan 12, 2004)

xc71 said:


> Axe, I don't think you can flip the links. I remember someone complaining of the air can being dented by the cable stop ( you can see it on my son's Spark a few posts up), I had suggested the links got flipped by accident and that was his problem.


I think he flipped it upside down, so that the axle is higher. I suggest flipping it backward, so that the axle is further away, so that a shock with a 140mm e2e distance fits (not sure what would be the actual distance). such shock will have 25mm stroke, which can be shimmed easily to 20 (or whatever frame allows).

You can also dremel away the cable stop in a minute. I did it, partially, to run full length raillery and disk brake housing.


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## heckler11 (Jul 10, 2012)

I have fliped the links up side down on both bikes, (spark JR RC 24 and 20).
But before I had cut a piece of "cable stop." In this position the suspension is much softer and travel is longer.


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## Axe (Jan 12, 2004)

heckler11 said:


> I have fliped the links up side down on both bikes, (spark JR RC 24 and 20).
> But before I had cut a piece of "cable stop." In this position the suspension is much softer and travel is longer.


Huh. Should try that. I do not need the cable stops anyway, as I have switched to full length housing, it stays in place well enough.


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## heckler11 (Jul 10, 2012)

Hi,
I just installed a rear shock A5 KS to spark 20
Suitable bushes from coil stock shock.
It weighs 170 g with mounting bushes.
The stock coil shock weighs 290 g (with bushes)
KS A5 it is a friction damper - it is loud. Works like poof, zzzzz, poof, zzzz 
Dumping is not sufficient. It works as a stock coil shock without dumping with pogo effect.

X-Fusion 02 from spark 24 is much better (I have one in spark RC)
It is difficult for me to write, I do not know English well.


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## mtbhead (Jun 17, 2004)

Thanks Heckler11 - your English was good enough to get the point! It sounds like the A5 KS sucks. I plan to stick with the stock shock until I can come up with something better like a used X-fusion that shows up on Ebay or something. Thank you for the write up.


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## Axe (Jan 12, 2004)

mtbhead said:


> Thanks Heckler11 - your English was good enough to get the point! It sounds like the A5 KS sucks. I plan to stick with the stock shock until I can come up with something better like a used X-fusion that shows up on Ebay or something. Thank you for the write up.


I will try measuring today what flipping the link gets. Shimmed 140 x 25 stroke Fox would probably be a better choice if it can be fitted. I may have an XFusion for sale then...if I can get more then half price of the cheapest new old stock 140x25 I can find.


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## mtbhead (Jun 17, 2004)

Definitely report back on that, Axe! If it works, that would be awesome...


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## heckler11 (Jul 10, 2012)

Hi,
I just finished building spark 20th
It weighs now 9.07 kg / 19.99 LBS  with tuned fork RST Capa, titan BB 160 g, titan skewers 32 g, lite kcnc v-brake 200g/pairs, XTR shifter 1x9, XT casette 11-32 with chain, light alu cables. 
Now I think it's a little pointless it was. A lot of work, a lot of money, the lack of a true rear schock (kind A5), and still not too light.
But we'll see in the spring how it will go.
It's possible to building 8,5 kg/18,7 LBS but you now, $$$$$$$ to much.
Next bike (for next children) probably from islabikess.
Soon I'll make pictures and show you.


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## Axe (Jan 12, 2004)

heckler11 said:


> Now I think it's a little pointless it was.


It was not. If they like it, it was not. And every pound counts more on a kid's bike.


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## heckler11 (Jul 10, 2012)




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## heckler11 (Jul 10, 2012)




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## xc71 (Dec 24, 2008)

Nice job Heckler11


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## Surfpoodi (Sep 14, 2011)

Killer build. I have a lot of the same parts on my sons Hot Rock.

What was the length and stroke on the replacement fork?


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## heckler11 (Jul 10, 2012)

What does mean 'killer build"?
the fork is stock, but tuned - changed steerer tube from cro-moly to aluminium, and cuted litle parts.
Weight before 1,69 kg, now 1,54 kg. Total lenght is 38 cm, stroke before 3, 5 cm, now 5 cm.


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## Surfpoodi (Sep 14, 2011)

heckler11 said:


> What does mean 'killer build"?
> the fork is stock, but tuned - changed steerer tube from cro-moly to aluminium, and cuted litle parts.
> Weight before 1,69 kg, now 1,54 kg. Total lenght is 38 cm, stroke before 3, 5 cm, now 5 cm.


Sorry about that.... "Killer build" translates to "You did a good job improving that bike by choosing nice parts that look good"

And I intended to asked about the stroke/eye-to-eye distance on the new rear shock. I used the wrong term. I was trying to figure out how much replacing a rear shock on a Spark would cost, and I was looking for a suitable replacement shock online. Maybe an easier question for you to answer is, "where did you get the rear shock?"


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## heckler11 (Jul 10, 2012)

Killer build, thanks
The stock shock (old spring), and new Kind Shock K5 has 125 mm eye to eye.
I bought Kin Shock on alliexpress (95 $) from this seller: KS A5 RR1 Rear Shock for MTB Bikes 150mm/175g Bicycle Parts Free Shipping-in Bicycle Frame from Sports & Entertainment on Aliexpress.com. 
But now i see hi hasn't got KS A5 with right size 125 mm. Try to write to him.


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## heckler11 (Jul 10, 2012)

I rode today with my son, and i saw that KS A5 works unexpected good. Not pumped (pogo effect) as old shock, on the small obstacless worked really good (sensitive, plush).
Only the travel is litlle shorter, but it's not a big problem. And suppression could only be stronger.


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## A10 Wingman (May 12, 2006)

*BB Suggestions*



ThornPatch said:


> Couple of suggestions:
> 
> 1) replace the bottom bracket, that will save some weight.
> 2) handlebars - any riser bar will work you'll just have to cut it down. Two things to consider: 1) be sure to buy a bar that works with the existing stem (that is if you're going to keep the stem); and 2) if the seat height is already lower than the bars you may want to go with a flat bar instead of a riser, adding a riser bar that increases the bar height will make the bike feel too "chopper" like. I used a FSA XC190 riser bar for my son's bike, it's alloy (so it was cheaper than carbon) and was easy to cut down, and its relatively light.
> ...


I got from Scott that the stock set up for the bottom bracket is: Frame 68 and BB 116 so what are my options regarding an upgraded and lighter square taper BB? I seen in your post where you have suggested lightening up in this area. I've already re-laced the front wheel to an XT hub, 2012 deore v-brakes, carbon ct-2 seat post, bontrager race light handlebar, Avid single digit 5 brake levers and thinking about re-lacing the rear but may just convert the axle to a QR instead. Thanks for the ideas and keep em' coming cause my little man is in love with this ride. 2011 Scott Spark Jr.


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## snipes1 (Aug 13, 2011)

I don't know how to lace a wheel. Any body know where I can just buy a set of 20 inch disk wheels for my boys spark.


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## Axe (Jan 12, 2004)

snipes1 said:


> I don't know how to lace a wheel. Any body know where I can just buy a set of 20 inch disk wheels for my boys spark.


I bought a set of cheap Circus Monkey 28h hubs off Ebay, some light Alex rims and had LBS lace it up for me (too much time by myself). I found that most everything available is much too heavy, with BMX rims.


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## Surfpoodi (Sep 14, 2011)

I did the same. Circus Monkeys 28h off EBay, Alienation Deviant rims. Makes a light wheelset. I don't think there are any commercially available disc 20" wheels, and if there are, they would be HEAVY.


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## snipes1 (Aug 13, 2011)

OK thanks, can I have opinion on which to get; circus monkeys, aleination, sun ringle envy lite or cr-18. and what specifics should i look for when shopping. rim depth, width what hole count


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## Axe (Jan 12, 2004)

snipes1 said:


> OK thanks, can I have opinion on which to get; circus monkeys, aleination, sun ringle envy lite or cr-18. and what specifics should i look for when shopping. rim depth, width what hole count


You do not need more than 28h for a kid. Narrow rim is fine too.


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## snipes1 (Aug 13, 2011)

Thanks again, one more quick question, what spacing on the axles do i need is the scott 9x100 and 10x135


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## Axe (Jan 12, 2004)

snipes1 said:


> Thanks again, one more quick question, what spacing on the axles do i need is the scott 9x100 and 10x135


Yes.


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## Surfpoodi (Sep 14, 2011)

I don't think you want the CR-18. I believe it is a mini rim with a 451 diameter. I've used the Alienation Deviant for disc brakes and the Crupi Rhythm expert 20 x 1.50" with rim brakes, both of which have the 406 diameter, which will give you more appropriate tire choices for a mt. bike.


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## Rondo (Oct 14, 2011)

Surfpoodi said:


> I don't think you want the CR-18. I believe it is a mini rim with a 451 diameter. I've used the Alienation Deviant for disc brakes and the Crupi Rhythm expert 20 x 1.50" with rim brakes, both of which have the 406 diameter, which will give you more appropriate tire choices for a mt. bike.


CR-18's come in both 451 and 406. I believe you might be thinking of the Sun M14A.


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## snipes1 (Aug 13, 2011)

i found cr-18s, 406 iso, 22.2 mm width, 15mm rim depth 32h. will those work. I can only find the envy and devients with 36h


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## snipes1 (Aug 13, 2011)

also anyone no where I can find the A2Z DM-UNI adaptor they are no where to be found


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## Rondo (Oct 14, 2011)

snipes1 said:


> also anyone no where I can find the A2Z DM-UNI adaptor they are no where to be found


Are you in U.S.?


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## Rondo (Oct 14, 2011)

Hit this guy up. He told me he gets them in all the time. I just bought this one last week as I'm working on a similar project as you it would seem.

A2z Rear Disc Brake Mount for Tabless Frame DM Uni | eBay


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## Rondo (Oct 14, 2011)

And yes that CR18 you found is the right fit. It will allow you to run a nice size tire for a kids mtn bike.


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## snipes1 (Aug 13, 2011)

Yes I'm in the us


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## snipes1 (Aug 13, 2011)

Thanks everyone for your help


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## snipes1 (Aug 13, 2011)

what size cage RD did everyone use and what size cassette, im thinking small cage 9 speed, what size cassette can i use with that


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## snipes1 (Aug 13, 2011)

I believe i am getting x9 hubs and sun cr-18. What kind of SPOKES are recommended


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## Axe (Jan 12, 2004)

snipes1 said:


> what size cage RD did everyone use and what size cassette, im thinking small cage 9 speed, what size cassette can i use with that


Any, if you have a single front ring. If I was building again, I would use the same setup as on my light bike - front SS ring with no guards (waiting on wide/narrow Raceface, but even current Salsa does not drop chains) and Zee short cage derailleur with 11-36 cassette and Saint shifter (it has longer levers, much easier to shift) - ordered from Germany they are cheaper than 9sp stuff...


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## snipes1 (Aug 13, 2011)

Will anyone give me thoughts on a single ring crankset. How is the sinz in 140 and which one specifically


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## Axe (Jan 12, 2004)

snipes1 said:


> Will anyone give me thoughts on a single ring crankset. How is the sinz in 140 and which one specifically


I use Sinz with Rennen 34t single speed ring. It has deep tooth profile - chain did not jump without any guard. Now there are those narrow/wide rings that may be even better - Wolf tooth components and Race Face just came out. Not sure what they have for 5 bolts. Wolf tooth makes a 30t one, with spacer that fits 104mm middle.

Apparently Rennen comes in 33t as well: Rennen BMX Pentacle Chainring at Danscomp


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## stom_m3 (Jun 28, 2011)

snipes1 said:


> Will anyone give me thoughts on a single ring crankset. How is the sinz in 140 and which one specifically


I used a sinz 140mm on my sons Marin. Pay attention to the seating depths of the various cranks you can buy which could affect chainline. For my sons 1x8, I use a BBG Superlight Bashguard.

superlights

To prevent the chain from dropping off on the inside, I use a front derailluer with the limit screws set close to the chain. He's never dropped a chain in this configuration.


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## stom_m3 (Jun 28, 2011)

snipes1 said:


> I don't know how to lace a wheel. Any body know where I can just buy a set of 20 inch disk wheels for my boys spark.


I bought my XT hubs off Amazon and had them sent to Dan's Comp. They laced them up with the Envy Lites.



I running the Kenda SB8's now though. My son noticed an increase in grip after the change.

Here is what it looks like now.


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## snipes1 (Aug 13, 2011)

Which sinz crankset is it and did you use 140


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## stom_m3 (Jun 28, 2011)

snipes1 said:


> Which sinz crankset is it and did you use 140


Sinz expert 140mm w/ square taper. Table below shows weights I took while building my sons bike;


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## tubored (Mar 13, 2012)

stom_m3 said:


> I running the Kenda SB8's now though. My son noticed an increase in grip after the change.
> 
> Here is what it looks like now.


I believe you're in San Diego County? A lot of people seem to like Small Block Eights here. I put 2.1/1.95s on my son's Marin Hidden Canyon and they dropped 195g/290g respectively per wheel compared to the original Kendas on it.


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## snipes1 (Aug 13, 2011)

I have found an mcs 34t 5bolt 110bcd on ebay for 15.00 has anyone heard of these. what is your impression, will it work for 9 speed


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## mtbhead (Jun 17, 2004)

I did a custom wheel build from Universal Cycles a couple months ago. They let you send in your own hubs - including used ones if they are in good shape. I sent in a used rear Sun-Ringle 32h disc hub that was laying around in my garage. Went with the Sun CR18 rims (20" x 1.5" x 32h, 406 ISO), SRAM X.7 front disc hub, Wheelsmith butted (1.7-2.0) spokes and alloy nipples. Total cost: $203. Now I just need time to put everything on my son's Spark 20...


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## stom_m3 (Jun 28, 2011)

snipes1 said:


> I have found an mcs 34t 5bolt 110bcd on ebay for 15.00 has anyone heard of these. what is your impression, will it work for 9 speed


I use both MCS and Sinz on my sons BMX and MTN bike. You can get them from Dan's Comp or JR Bicycles for the same price. He's currently running a SRAM 870, 8spd chain and the chain/sprocket/cogs work well. I have not tried the sprockets on a 9 spd chain.


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## shaun2k (Dec 4, 2013)

Hi guys

i have recently ordered the 2014 Scott spark JR 20 (exactly the same as the previous models it seems) yet more expensive.. although i got 40% discount as my friend works for wheelies.com

my build is geared more towards downhill, so weight isn't so much of an issue in one sense, but is in others, i need my lad to be able to throw it about a bit, and so i really need to keep it under 22 to be satisfied, once the better forks are on.















I too want to upgrade virtually everything on it to save weight.

options Ive looked into are:

White bros RC80 20" forks with 80mm travel
rear shock????
Kore 20" rims bespoke with HOPE pro 2 hubs 
A2Z Rear Disc Brake Mount
A self shortened Ultegra Crankset and upgraded Deore XT Rear Mech with 10 speed XT Cassette

Hydrolic disc brakes probably HOPE or cheaper..

Can i ask if the A2z rear disc mount fits out the box or does it need adjusting? as i don't have the bike here to check as it's not arrived yet? and did anybody sort the shock replacement apart from the OP

cheers guys

ps i'm pretty sure i can get this to fit with a bit of effort









if i have to i will make the lower brackets and adjust the top bar width, it WILL go in there, i too will be chewing of the cable stopper


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## snipes1 (Aug 13, 2011)

A2z fits right out of box


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## xc71 (Dec 24, 2008)

The WB fork and Fox shock should make for an excellent suspension package. You may want to re-valve the shock to a low/soft compression tune. As your going for more of a DH set-up, hopefully the fork will also raise the headtube some.
Get an Uno lightweight stem, used carbon bar and a Thompson Elite 26.8mm seatpost. I ended up using a 27.2 Elite on my son's Spark RC. I only had to mill 0.25mm off the seatpost as Thompson's are often undersize, sure enough it was 27.11mm and the seattube on the frame was oversize at 26.85mm. Fit perfect. I also replaced the top cradle with KCNC yokes and Ti bolts to make a nice lightweight post.


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## snipes1 (Aug 13, 2011)

And I can not get the brake tabs to come out of frame


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## shaun2k (Dec 4, 2013)

snipes1 said:


> A2z fits right out of box


That's good news, i will order one today off ebay

i must admit that by the time Ive done the upgrades i probably wont be far off the price of a lil' shredder bike, however, i think every father that enjoys the slopes or any form of riding can take pride and excitement in building his kids bike, as it's maybe something we wish our parents did, although when i was 6 we didn't have anything like this about.

the Rc80's will raise a little on the front, but from what i have seen it's marginal. great ideas on the stem and seat post I will investigate further, i may not put a 10 ring cassette on the back, its just i thought it would be good for normal rides as and when. it looks a bit funny with one on there from pictures Ive seen.


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## Smurf (May 10, 2006)

Hi from the UK

I appreciate it's been a while since anyone posted on this thread but it's been a really useful source of info as I build a decent Scott Spark 20 Junior for my oldest daughter.

I managed to pick up a second hand bike as a starting point and I've been picking up parts for a month or so now. Given the (poor) condition of the starting point, I think everything bar the frame will be replaced.

I've got 2 questions for you all though:

- Has anyone been able to remove the v brake bosses?

- I need to get the lower swing arm off the main triangle so I can check / replace the bearings and get the frame off to the powder coaters but I can't work out how to get the pivot hardware out of the frame.

Removing a thin plastic dust cover on the pivot reveals (on each side of the bike) what looks like two round tubes of metal that have been pressed into the swingarm / main frame connection point. There is a 6mm allen bolt on one side...and this seems to tie these 2 bits of round metal together. Removing this bolt reveals a 10mm allen key style "hole" on the opposite side. Putting an allen key in this and turning either way results in nothing visibly happening.

There doesn't seem to be much of a gap between these metal pieces to allow you to tap them out from opposite sides and I'm a bit stumped.

I can email photos to anyone if that would help. 

Scott UK aren't being any help at all. If anyone has a phone number for Scott USA that would be appreciated.

Thanks all


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## Lincoln.3 (Dec 4, 2014)

Hi,

Thought this might help those looking for a replacement shock. Not tried it but it had come highly recommended from J-Tech Suspension in the UK...

Scott Spark Jr. Genesis Damper, Risse Racing Technology Online Store

Just got my son a Spark JR20 & looking at upgrading!


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## Smurf (May 10, 2006)

Hi Lincoln3

I've slowly been building a Spark Jr20 and I introduced J Tech to that Risse shock after talking to them about various options. J tech reduced the travel on some 24" forks for me so they would work with 20" wheels / the Jr20 frame.

I came across someone else using the Risse shock (Building the Perfect Kids 20" DH / AM Shredder - Pinkbike) and I got in touch with Risse and ended up ordering one. I went with the Astro 5 version to give me a bit more adjustability.

It's not been used in anger yet (nearly finished the build!) but seems decent enough based on a few indoor bounces.

If you'd like more information on the shock, getting one to the UK, or my build, please drop me a PM.

BTW - I sorted out the 2 issues above as well - v brake bosses came out fine after heating them to break down the thread lock, and the main pivot pushes out once you've undone the hex bolt.

smurf


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## Lincoln.3 (Dec 4, 2014)

8 year olds rip up Bike Park Wales on Scott Jr 20's!


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## Lincoln.3 (Dec 4, 2014)

And another!!!

Hope you enjoy


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## arsene2000 (Jul 6, 2015)

my turn to upgrade my DS's scott spark jr 20 !!!
i want to regear it since the 34t / 28 doesn't get him anywhere uphill

thinking about going SS with 34t. I guess i'll have to get sinz expert square taper cranks (140mm) + BB + 34t chainring + chainguide
Any recommendations/specs for these parts ?

Then for the rear: 
9sp cassette 11-32 + rear derailleur + shifter (SRAM attack 9sp) ?
Any recommendations/specs for these parts ?

Anything else ?


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## aleeann (Oct 18, 2005)

arsene2000 said:


> my turn to upgrade my DS's scott spark jr 20 !!!
> i want to regear it since the 34t / 28 doesn't get him anywhere uphill
> 
> thinking about going SS with 34t. I guess i'll have to get sinz expert square taper cranks (140mm) + BB + 34t chainring + chainguide
> ...


I just purchased these from Trailcraft for my son's Spark.

Trailcraft Cranks

I'll be installing this weekend.


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## petho (Nov 16, 2005)

this is my mod of scott...[video]https://www.facebook.com/pethorvath/videos/10206324117333509/?pnref=story[/video]


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## petho (Nov 16, 2005)

home made disc brake adapter


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## leechungsr (Sep 23, 2009)

Hello, y'all. I'm reviving this thread and came for some advice. I just picked up this Spark for my son, 7y/o 47in tall. It's a little too big for him, but I'm hoping he gains an inch or two by summer. He wanted a trail bike to take around camping this spring and summer. The previous owner bought the bike after seeing this thread, but found the bike didn't fit his son.

I replaced most of the cables/cable housing, got a new derailleur and shifter as the original revos were trash and the derailleur cage was bent beyond repair. We decided to go with a simple 1x6 setup. The original flat bar was too wide for my son, so I trimmed about 3/4 inch off each side. Eventually going to get a new stem/bar, but going to take my time finding the right one.

Son's ONLY complaint is the crankset. The arms are way too long, and since we're 1x6 he says the 34t is "too easy" and 42t is "too hard. I'm looking at these 36t eBay 140mm cranks What do you guys think? I'm not worried about weight but finding a good fit for him to take camping this summer.


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## rton20s (Aug 27, 2010)

I wouldn't touch those cranks. 

For a 20" bike, look for something at 130mm or less. On our boys' 20" bike we used the Spawn 127mm on a square taper BB with great success. 
https://spawncycles.com/spawn-cycles-alloy-cranks-127

@POAH recently found these inexpensive cranks on Alibaba available in 114/127/152/170mm lengths. I think you just need to contact the supplier and tell them the length and quantity you need. You'll need to order a BB to work with the new hollowtech cranks.
Lightweight Hollowtech Cnc Kids Children Direct Mount Crank Arm 114/127/152/170mm Bicycle Parts Chainrings Mtb Crankset - Buy Direct Mount Crank,Children Crankset,Mtb Crankset Product on Alibaba.com


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## leechungsr (Sep 23, 2009)

Those Spawn cranks look sick! Too bad they're OOS. Trying not to spend a fortune on a bike we'll ride for 2 years tops. Feel like I need to get my order in soon for spring especially if it's shipping from China


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## POAH (Apr 29, 2009)

rton20s said:


> @POAH recently found these inexpensive cranks on Alibaba available in 114/127/152/170mm lengths. I think you just need to contact the supplier and tell them the length and quantity you need. You'll need to order a BB to work with the new hollowtech cranks.
> Lightweight Hollowtech Cnc Kids Children Direct Mount Crank Arm 114/127/152/170mm Bicycle Parts Chainrings Mtb Crankset - Buy Direct Mount Crank,Children Crankset,Mtb Crankset Product on Alibaba.com



They are the same ones I got. came with a BB though. Work really well on the little ones bike and the middle child.


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## leechungsr (Sep 23, 2009)

It's done. My son's Priority Start 20 has 114mm cranks that fit well, so I found these $30 eBay "6061 Forged" 114mm cranks. They appear well made.
Reran cables, tidied up cable housing, new Altus rear der, sis thumb shift, adjusted brake levers out as far as possible for my son's short fingers, shorter stem, riser bar, new seat and pedals. The bike fits him PERFECT for now...until he grows...


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## thchen (Sep 24, 2013)

POAH said:


> They are the same ones I got. came with a BB though. Work really well on the little ones bike and the middle child.


Fwiw, my order of one 127 + 152 ended up being ~ $60/ea shipped, which isn’t too much savings over the suntour zeron, but at least you get the actual shorties options. 



leechungsr said:


> View attachment 1975478
> 
> 
> Slowly coming together...I forgot I had this bar in my parts bin. Didn't realize the stock bars are steel...super heavy
> ...


The hollowtech shorty cranks are being shipped DHL from Tianjin, I was told. How many days has it been? Should get here in about a week.


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## leechungsr (Sep 23, 2009)

thchen said:


> How many days has it been? Should get here in about a week.


Took 13 days from order to ship to California. This is the exact one I bought.


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## thchen (Sep 24, 2013)

leechungsr said:


> Took 13 days from order to ship to California. This is the exact one I bought.
> View attachment 1977054


Those aren’t the ones. No wonder you got them in 2 weeks. I was talking about these hollowtech shorties, which apparently takes a month to produce samples:

Based on that weight of the 152mm with bb, there should Be a whopping 400g saving over the 152 sun tour sct jr I’m running with alumi nw chainring + bolts, which should put the kids stumpy A1 at roughly 3.5 lbs lighter than oe.


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