My son has outgrown the 24" wheel Felt F24 I built up for him. While the dimensions are still suitable, his abilities exceed the performance of the little wheels. After much searching I decided on the Kinesis Racelight KR-210L frame in a 40cm size.

http://www.kinesisbikes.co.uk/products/junior-female-fit/racelight-kr-210l

It's not the lightest frame out there. But, honestly, I can't afford to spend the kind of money necessary for a lighter frame that he will outgrow in a year or two. I seriously considered a 44cm Specialized Dolce or Ruby, but the frameset can't be had and I didn't want to buy a complete bike knowing I would strip the parts and never use them.

Planned build is as follows:
Kinesis Racelight KR-210L Frame 40cm
Enve 2.0 Fork
Shimano Ultegra di2 Drivetrain
Converted BMX crankset with ti bottom bracket
Homebuilt ~1200g carbon clinchers (separate thread to follow)
Cockpit and other bits TBD based on what we have available

I'm doing this on a budget. The di2 group was given to us by a friend in the industry. (My son has fans.) The fork is dependent on my luck with ebay. Other parts except wheels I already have. Wheels are shaping up to be a fun project of Archtek 20mm carbon clincher rims with Bikehubstore hubs and cx-ray spokes. If things go to plan I can build the wheels in the 1200g range for around US$500.00.

My goal will be to get the build under 6kg. The frame is portly though and I'll likely use alloy bars, stem, and seatpost. So that is an ambitious goal. I think frame, fork, wheels, and the di2 parts alone are around 5kg so I'll see what I can do creatively. My son is going to be racing so there are rules to be followed... clinchers, minimum spoke count, junior gearing, etc. But this should be a fun project... frame was just ordered, other parts to follow. I'll post updates as I have them

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Williams has some nice light alloy bars that are not that expensive. for a stem you could get a Ritchey 260 stem and that is a pretty light set up. Maybe something like a Omni racer post as they can be had for cheap and are pretty light.

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BIG DADDY B FLOW
AERO & LIGHT is RIGHT

Cervelo SLC 5890g/12.98 lbs

Looking forward to this. It's gonna need some serious tuning, and light parts.

You want to build a 1 X 10 speed ? Put a normal front brake, no FD or shifter ?
What's the max gearing for the kid's age ? What cassette options does that leave you with ?

Louis

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http://www.ccsalma.com

While Di2 is great, sram would be a lighter way to go especially if you are going to run 1 X 10. Could have a standard shift lever on the right and the S900 on the left.

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BIG DADDY B FLOW
AERO & LIGHT is RIGHT

Cervelo SLC 5890g/12.98 lbs

Not a bad idea Ted.

You're going to get a great price on that Di2 group.

Well, it just can't be done I guess, sell a "gift" to the nephew...forget what I just wrote...


Louis

_________________
http://www.ccsalma.com

I can't sell the di2... best I could do is return it to the person who gave it to us. But it's kind of a sponsorship thing so we'll work with it. Besides, he (and most kids) have a tough time shifting the front derailleur from small to big, so this takes care of that problem.

I considered 1x10 for him, but I think the full range of gearing is better. besides, we're hitting the Alps before I deploy this summer so he's going to need a little ring.

We have to make the most of our time together in Europe. Next week is Belgian cyclocross week.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Junior gearing for his age group is restricted to 5.46 meters. So it will wind up being an ultra compact crank with a junior cassette... smallest cog of 14 or 15t.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Looking forward to how this turns out! Keep the Di2 for sure, those small hands will really appreciate the easy shifting - Sram is going to be a challenge to shift for a lad of that age.

In Canada, for kids age 10-12, it's 5,60 meters, maximum.
With 700c wheels it comes to 42 X 16t. So if you want to put a 14 or 15t smallest cog, you're going to end up with something like 35 or 36T in front, maximum (with a 14t).
Hence the "good idea" of having just a single BMX crankset in front. You can match it with an alloy cassette and save almost half a pound.

The only option I know of for 16t smallest cog is Ultegra 6600 16-27, at close to 300g for just the cassette !!! There is Miche too, but I think it's as heavy, if not heavier.
You could shop for a used, light Sram MTB 2 X 10 crankset, I've seen some with shorter arms. If you're looking for super small gearings.
Don't know how it 'll shift with Di2 though...

Louis

_________________
http://www.ccsalma.com

Lightning has 160mm cranks. Enough for 8 year old. Even I would say too short.
Slap the smallest single ring you can fit on 110bcd and get casette with enough ratios. Dual ring is unnecesarry for him.

He rides 145mm cranks which, by relative standards, are a bit too long. His inseam is only 61cm. For comparison, my inseam is 81.3cm and my pro fit calls for 170mm cranks... though I prefer 172.5. 160mm is too long... his knees will be in his chest when he pedals. Conventional fitting says he should be on a 125mm crankset for proportionality, but that is just too short to turn the cranks over. He has 150mm on his mtn bike and uses 155mm for BMX (where he is standing the entire time). But the 145s seem to work really well for him on the road. Of course, that has been with 24" wheels. We can always reevaluate once the bike with 700c wheels is built.

But there is no way I could afford Lightning cranks for him anyway... we've had really good luck using BMX cranks fitted with dual rings on both his road and mtn bikes.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Wheel Build:

Dati Hubs 20/24, 260g, $150.00
ArchTek Carbon 20mm Clincher rims 20/24, 760g/pair, $220.00
Sapim CX-Ray Spokes, 44, 198g, $121.00
Sapim 12mm Alloy Nipples, 44, 14g, $7.92
Alloy Nipple Washers, 44, 8g, $4.00

Total weight 1240g
Total price $502.92

I suspect this could be plus or minus a few grams depending on the verified weights. These are all advertised weights. I'm saving over $100.00 and nearly 200g on the best-priced, similar wheelset I could find. I know I could go even cheaper with Kinlin XR-200 rims at a comparable weight, but I already have these carbon rims.

Wheels will be completed with ti qr skewers (43.5g/set) and veloplugs.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Cool !!!

I would personnaly go with round spokes (revoution or laser) at his weight and for what the wheels will beused for (unless you have a hidden agenda and plan to use his wheels also...), and put the sensible savings on another light component.

Silly quesiton: Do you have the Di2 FD and both shifters ?
I would just install the right one, and run single ring in the front. The "sponsor" will be happy.
And you can sell the front shifter, FD combo... to get some more nice light parts...

Question No 2 : What's the weight of the BMX crankset and Ti BB combo ?

Louis

_________________
http://www.ccsalma.com

I'd stick with the bladed spokes if building yourself, if only for their ease of build. revs are a pain at proper tension, near impossible to hold.
Looking at doubles, mtb double cranks now would be suitable. X.X 39/26, XTR 40/27. Granted, the low is mighty low, but the big ring is right..
Somewhere in the US online is a guy that rethreads aluminum crankarms much shorter, and then cuts and smooths the excess. possibly something to look into if you haven't acquired the cranks yet.

Yes, it is my goal to share these wheels... I'm actually building two pairs.

I'll have to weigh the BMX crank/bb combo. I'm not sure of the weight off the top of my head.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo