Kids project -Kinesis Racelight KR-210L-Pics/video p5/6/7

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xnavalav8r
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Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

Any suggestions or feedback? We'll be lowering the stem but will likely leave a bit of extra steerer so my son has room to grow. Also, I'm not happy with the I-links and the Planet-X brakes. Individually they are great. But the i-links don't fit into the cable stops on the brakes which is an issue. New saddle, some red-ano bolts, and wire grommets are on the way. We're probably going to switch to a longer crank... same design but moving from 145mm to 150mm. Otherwise, I can't see anywhere I can make changes without throwing a lot of money at the project.

by Weenie


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LouisN
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Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

Nice overall project. The bike looks huge compared to the kid.

Cool crankset ! How much do these cost ? Any link to a manufacturer, or distributor ?

So, finally, bike weight ?.......anywhere near the projected "under 6kg" ?

Louis :)

xnavalav8r
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by xnavalav8r

The front end is tall. We need to pull out the giant spacer under the stem. But when you see him on the bike, actually riding, it is a good fit. The top tube is only 49cm.

The crankset runs US$150.00. It is actually a BMX crankset. But I found it works really well with a double chainring. You can find it at http://speedlineparts.com/products/cranks/sx-mini-cranks/. The design is actually licensed from Answer BMX which has the same crank at http://www.answerbmx.com/AnswerMiniCranks.html.

My scale is dead... I think damaged in the move. I'll have to buy/borrow a new one to get the weight. But it feels close to the mark compared to my bike.

NGMN
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by NGMN

looks happy to be riding it, nicely done!

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LouisN
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by LouisN

xnavalav8r wrote: It is actually a BMX crankset. But I found it works really well with a double chainring..


Thanks for the links Ted.

So it's intended for use with a single ring ?
How (any particular placing, or modification) did you install the two chainrings on the crank ?

Very clever. I'll copy you, that's for shure :beerchug:

How tall's Ryder again ? Just for crank arm lenghts comparison with my twin daughters...

Louis :)

xnavalav8r
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Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

Ryjder is about 140cm tall (roughly 55in). I chose his crank length by measuring his inseam and comparing the proportions to my own. A professional fitter recommended I use a 170mm crank based on my 78.74cm (31in) inseam length. The 145mm crank worked great last year, but he has grown a bit so I have a new, slightly longer crank coming. Unfortunately, I have only been able to find cranks in 5mm increments. As a result, he is moving to a 150mm... but I would prefer he was on a 147.5.

As for modifications. I made a very minor modification to the spider. Using the Extralite 42/30 chainrings on the 104bcd spider is almost perfect. However, the arms extended a bit further beyond the chainring bolt holes than is normal on a road or mtb crank. As a result, the chain tended to make contact with the arms and "lift" 4 times per rotation. I used a Dremel to grind away a bit of the excess material and shaped the ends of the arms to act as lift ramps when shifting. I'll try and post a detail picture later today. To be honest, I am really impressed with the result. It's not very noticable visually, but it really did improve the shifting. Considering I did it by hand, I can't be more pleased with the result. It was about 10 minutes of effort for a huge performance improvement.

Andrew69
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Joined: Thu Feb 19, 2009 10:52 am

by Andrew69

That is seriously cool!
Congrats on the build

Your son obviously loves his new bike, you cant wipe the smile off his face!

And nothing makes me prouder than riding down the road with my son (12y/o)

xnavalav8r
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by xnavalav8r

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xnavalav8r
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by xnavalav8r

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xnavalav8r
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by xnavalav8r

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Tumppi
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by Tumppi

Hi
Nice build!
What are KNWU rules for gearing? I mean, with 38 front and 12/13 back you get 6.76/6.24m using 700c/23 wheel. We have max gearing (UCI rules) for kids under 12 -> 5.66m and under 14 -> 6.10m.

My son has felt F95 JR racebike with 650c wheels and 32/38 up front and 13-29 cassette. With this wheel size gearing meters is just under 5.7m (about 5.66m). My son has born 2004 so he is only 9 years old, but he's rather tall 147cm or so.
http://www.pellossalo.fi/content/upload ... G_0573.JPG" onclick="window.open(this.href);return false;

xnavalav8r
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by xnavalav8r

The rollout limit here is 5.78m.

We're using a 38/30 chainring with 14/27 cassette combo. He can run the 14t cog without the chain making contact with the frame. Anything larger and the chain rubs the seatstay. I made the cassette by using cogs from 2 different cassettes. This gives a REALLY low gear if needed (30x27) but maintains the mid-range accomplished by the almost straight block junior cassette without exceeding the rollout limit of 5.78m.

xnavalav8r
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by xnavalav8r

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xnavalav8r
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by xnavalav8r

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xnavalav8r
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by xnavalav8r

Ugh! Running into problems with race organizations. My son is racing the European Junior Cycling Tour in Assen next month. Of course we are abiding by the 5.78m gear restriction. The race organization wants us to provide a spare wheel to the neutral car, which I am more than happy to do, but they want it with a junior cassette no taller than 16-25. I can't fit a 16-tooth cog in my son's frame. It physically rubs on the seatstay junction. A 14-tooth is the largest I can fit in the frame without contact. But the race organization won't accept a wheel with non-standard gearing. At this point, they won't budge. I even offered to provide multiple wheels as long as a 14-25/27 was available for my son, but they won't even allow the 14-tooth cassette in the car. Our options are to buy a new frame (not realistic) or risk racing with no spare wheel option available. This sucks.

by Weenie


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