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Soh67

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Discussion starter · #1 ·
My daughter progressed quickly from her 12" Hotrock and was keen to move onto a 'big girl bike' after turning 4. After reading all the other posts in this forum and with zero experience I got hold of a used 2014 Hotrock 16.

The rear wheel with coaster brake was the first to go and this was replaced with an Alex Rims Z1000 wheel and a standard Dicta 16T screw on freewheel. The front brake was worse than useless so this was ditched completely and the Tektro 926Al mini V brake kit with a 316A lever were ordered for the rear. The evolution adaptors were the only way to secure the v brakes and it took a little smoothing of the chain side adaptor to get them to fit snugly. The chainstay side is oval but the adaptors are not so 10 minutes of work with the dremel took off enough aluminium to match the shaping.

The one piece crank was too short at 89mm and had to be changed so I took the opportunity to swap it to a 3 piece crank. It was difficult to get something around 102mm and the shipping costs from the usual places such as Spawn were prohibitive. Frog Bikes in the UK came to the rescue and provided Prowheel branded 102mm alloy cranks with a 32T steel ring and double plastic chainguard. I had to remove the inner chainguard to get enough clearance from the frame but it slotted on nicely to the Shimano UN55 68x113 bottom bracket. The most difficult part of the crank conversion was getting the Truvativ bottom bracket adaptor into place. There was a significant 'lip' inside the hotrock that had no intention of allowing the bracket to be eased or hammered into place. 30 minutes with the dremel smoothed out the lip and allowed the adaptors to be rammed into place.

The standard bars were heavy steel and had too much of a rise for a 4 year old. An FSA Afterburner bar with 15mm rise was cut down to 450mm and paired with a Kore Cubix 50mm stem which clamped straight on. The standard grips were put back on and they even left enough space for the obligatory red bell that was a non-negotiable.

A YBN MK747 Cool chain in red was the finishing touch (had to install a single half link to get a perfect fit) and a pair of lightweight VP856 pedals were a last minute addition.

Financially it probably didn't make sense to do the modifications but with the exception of a BYK (which she really didn't like) there were minimal other options to get a decent light weight 16" bike. Minor plans for the future will be to replace the steel seatpost and seat and possibly get a 68x107/110 bottom bracket as the 113mm seems a little too 'wide'.
 

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Discussion starter · #5 ·
Good spot on the fork, never noticed it while snapping a couple of photos but it does look pretty obvious! All sorted and dropped it off at the LBS this morning and the mechanic has checked it over and given it the green light. Daughter can't wait to give it a trial run.

I'm based in Sydney so most of the suppliers and prices (especially excessive shipping costs) will not be relevant to most. The wheel was from Moruya Bicycles in Australia and was AUD57 Shipped. The original wheel was like an anchor so this was a simple way to drop around 600g and lose the coaster brake. The V brake adaptors were from Pork Chop BMX and were USD57 Shipped.

I would love to upgrade the seat and steel post but struggling to justify another AUD55-60 for a Sinz, Crupi, Insight or T.H.E mini bmx seat.
 

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Hi Soh67 - keep an eye on the BMX buy swap and sell page on facebook (Im from Newcastle). Mini bmx seats come up reasonably often. They are pretty hard on the bottom though - Mr 6 has a crupi and a box seat on his BMXs but hardly ever sits on them. We went for a softer padded seat on his mountain bike.
 
Discussion starter · #7 ·
Hi Soh67 - keep an eye on the BMX buy swap and sell page on facebook (Im from Newcastle). Mini bmx seats come up reasonably often. They are pretty hard on the bottom though - Mr 6 has a crupi and a box seat on his BMXs but hardly ever sits on them. We went for a softer padded seat on his mountain bike.
Hi Silvascape - will check out the facebook page, thanks for the info. In your experience are the 'padded' seats from Crupi and Insight still a little on the hard side for a 4 year old kid? The standard hotrock seat is ok and I tried swapping out the steel post for an aluminium post but a replacement in the same square 'candle' top proved elusive. I'm not desperate to strip more weight off the bike but 200g on an easy seat and post swap would be handy.
 
The padded Crupi seats are softer but I would not say they are padded to the extent of a actual MTB seat. I have not seen the Insight ones. Try Velogear - they often have some good options. Otherwise putting in a call to your LBS, Krankit and SpeedFX to see if they have any old stock might be worth a shot.
 
...where did you get the v-brake adapters ...
Here's a USA vendor with a similar brake adaptor: Evolution Bike in Georgia.
Evolution Bike Company

They are offered in different colors (much nicer looking than the photos on their web page) and cost about US$50 or $60. I bought them to add brakes to my kids' Specialized Hotwalk run bike.
 
Here's a USA vendor with a similar brake adaptor: Evolution Bike in Georgia.
Evolution Bike Company

They are offer in different colors (much nicer looking than the photos on their web page) and cost about US$50 or $60. I bought them to add brakes to my kids' Specialized Hotwalk run bike.
Thanks!
 
Nice work! I did very similar mods minus the handlebars for my 4-year old daughter. After I was all said-and-done with the conversion and parts/cost, I said "Why the hell did I do this?" and realized I could have bought something outright already complete. :lol: Oh well, she had a lot of fun helping out with it.

Ah hell, this website isn't cooperating at all to let me try and load pictures.
 
I'm looking at upgrading my kids 16" Hotrock's crankset doing the same thing you did. How did you figure what size Bottom bracket to use?

The truvativ adapter seems pretty straight forward, but how do I figure out what size BB with corresponding spindle length to get?
 
Discussion starter · #16 ·
I'm looking at upgrading my kids 16" Hotrock's crankset doing the same thing you did. How did you figure what size Bottom bracket to use?

The truvativ adapter seems pretty straight forward, but how do I figure out what size BB with corresponding spindle length to get?
With the adaptor converting from American to Euro the only option I could see was a 68mm. A few others on the forum have completed similar crank mods with differing spindle lengths from 110 to 115. I plumped for a cheap Shimano 113mm with the thought that if it didn't line up correctly it was an easy fix. On review the 110mm is probably a slightly better fit for me but not to the extent that it justified replacing the 113mm.
 
Kids hate hard seats, don't even go there.

It's a lovely bike but kids grow out of those little bikes so fast I question that it's worth doing. Maybe if you've got a brace of others coming along behind to get the use out of it. If not, at least you'll get top money when you sell it. Specialized kids bikes hold their value really, really well.
 
Discussion starter · #18 ·
Kids hate hard seats, don't even go there.

It's a lovely bike but kids grow out of those little bikes so fast I question that it's worth doing.
The seat and post is still original. Would have preferred to simply swap out the steel post for aluminium but nothing was an easy direct fit. Even the padded bmx mini seats were a little 'bare' for a 4 year old kid.

Financially it wasn't worth it although there are limited alternatives here with the exception of a byk. However the time it took building it up together was priceless and she now has an interest in bikes that should stick. I've already got my eye on the next step to a 20" and this one will find a good home.
 
Kids hate hard seats, don't even go there.

It's a lovely bike but kids grow out of those little bikes so fast I question that it's worth doing. Maybe if you've got a brace of others coming along behind to get the use out of it. If not, at least you'll get top money when you sell it. Specialized kids bikes hold their value really, really well.
Knowing that granddaughter 1, then 2, then the youngest being the grandson will all learn on the bikes, I expect the use will be many years for each one. So with a squadron of a Strider, Hotrock 12, Hotrock 16, Hotrock 20, and a Hotrock 24, I have the bases covered for a bit. The Strider and 20 were bought new. The 12, 16 were bought used. The 24 was free and given to me. The 24 is in waiting at storage... Hopefully my investments have been wise...

PK
 
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