# Hotrock 16 mods from a beginner



## Soh67 (Jun 2, 2015)

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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## FireLikeIYA (Mar 15, 2009)

Wow, that is one sweet ride! Two quick question, where did you get the v-brake adapters and are the forks on backwards?


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## slapheadmofo (Jun 9, 2006)

That is sweet.
Fork definitely looks backwards tho.


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## GIreland (May 17, 2014)

Looks great, where did you source the wheel?


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## Soh67 (Jun 2, 2015)

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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## silvascape (Sep 11, 2014)

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.


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## Soh67 (Jun 2, 2015)

silvascape said:


> 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.


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## silvascape (Sep 11, 2014)

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.


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## ProjectMayhem (Aug 23, 2013)

I found mini bmx seats very cheap on ebay.


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## Soh67 (Jun 2, 2015)

Updated photo with the fork as it should be.


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## CeUnit (Jul 9, 2014)

FireLikeIYA said:


> ...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.


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## FireLikeIYA (Mar 15, 2009)

CeUnit said:


> 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!


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## Soh67 (Jun 2, 2015)

I used the evolution adapters on this bike. There was no option to purchase directly online from evolution so I went through Porkchop from the U.S.


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## Dave88LX (Aug 29, 2007)

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.


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## shank3r (Aug 15, 2013)

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?


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## Soh67 (Jun 2, 2015)

shank3r said:


> 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.


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## Mr Pig (Jun 25, 2008)

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.


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## Soh67 (Jun 2, 2015)

Mr Pig said:


> 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.


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## PMK (Oct 12, 2004)

Mr Pig said:


> 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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## PMK (Oct 12, 2004)

Soh67 said:


> I've already got my eye on the next step to a 20" and this one will find a good home.


What is your eye looking at 20 wise.

PK


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## Soh67 (Jun 2, 2015)

PMK said:


> What is your eye looking at 20 wise.
> 
> PK


As a local Australian purchase it will be based on a superfly 20. If I pick something up from the UK or US it opens up a few more interesting options.


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## RMCDan (Feb 28, 2008)

PMK said:


> What is your eye looking at 20 wise.
> 
> PK


On paper, I really like the Rocky Mountain Vertex 20. Spinner air fork, Shimano hydro discs and that SRAM Automatix hub for $750 MSRP is a pretty solid balance between price and performance. The auto hub on a kid's bike is brilliant since it seems like proper shifting is not the easiest concept for most 6-8 year-olds to grasp. All they have to do is ride, and we don't have to worry about keeping their RD in tune and/or them destroying it. The range could be better since it's only 136%, but that's still better than the 14-28 cassettes you see on all the 6/7-speed setups.

Norco releasing their new full-suspension 20" has changed everything though. I have said before that there was no way I would buy a FS 20", but that was when your options were Lil Shredder for $$$$$$$, the cheaper but still overpriced tank from Commencal, or try and import a Propain which seems to be a huge PITA. The Norco is "only" $1,500 with a great parts spec, and I can easily purchase it through a local dealer. My son is riding well enough that a FS is justified and I also like the geo better than any of the HT options. I've started stashing away a little money each month in anticipation of picking one up next fall.


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## RMCDan (Feb 28, 2008)

Flow Bikes look pretty awesome too, though if I'm going to spend over $1,000 the Norco seems like a better choice. Better geo than any other HT that I know of.

Flow Kid's Bikes,


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## PMK (Oct 12, 2004)

Do not rule out how smart kids are when it comes to shifting gears. They grasp the concept pretty quick.

I wish someone made a true light xc bike. We don't need a bike for jumping, just a nice light xc machine. Her Hotrock 20 is no doubt good and capable, I just know if a bit more focus went into the frame it could lose more weight.

On the xc stuff, the modified Minitou was resprung and easily works taking the hits. If and when they begin to need a DJ bike, I'll build that. Just like us grown ups, we build bikes for each discipline if we see the need.

PK


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## RMCDan (Feb 28, 2008)

PMK said:


> I wish someone made a true light xc bike. We don't need a bike for jumping, just a nice light xc machine.


Isla Beinn 20 would seem to fit that need, no? It's not a good fit for my son since his favorite thing seems to be hucking to flat, but seems like a solid choice if they're not jumping and weight is a top concern.


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## tarp43 (Mar 1, 2007)

*dremel*



Soh67 said:


> 30 minutes with the dremel smoothed out the lip and allowed the adaptors to be rammed into place.


You inspired me to order up all the parts. We started with the brake adapters last night but forget the bit about the dremeling!

Did you _simply_ grind down that inside of the chain side seat stay?


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## Soh67 (Jun 2, 2015)

tarp43 said:


> Did you _simply_ grind down that inside of the chain side seat stay?
> 
> /QUOTE]
> 
> ...


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## PMK (Oct 12, 2004)

If anyone is looking for a one of these Specialized Hotrock 16 bikes, I have one that is stock and for sale.

These are a pretty good base to do a few inexpensive mods and have a sweet mini mountain bike since the one I have for sale has an aluminum frame, wheels and bars.


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## tarp43 (Mar 1, 2007)

Soh67 said:


> tarp43 said:
> 
> 
> > Did you _simply_ grind down that inside of the chain side seat stay?
> ...


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## pharpe (Mar 24, 2017)

I know this is an old thread but I am doing the same conversion. I just picked up a used Hotrock 16 and I'm planning to add v-brakes and freewheel.

My question is around the clamp on boss mounts. Would an adaptor plate like these work as an alternative?

https://www.danscomp.com/products-parts/489051/V-Brake_Plate.html


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## Mr Pig (Jun 25, 2008)

pharpe said:


> My question is around the clamp on boss mounts. Would an adaptor plate like these work as an alternative?


Might be almost as cheap buying another fork. A specialized dealer might be able to get you a price for one. If you wanted to use that adapter, you could just weld the thing on!


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## pharpe (Mar 24, 2017)

Mr Pig said:


> Might be almost as cheap buying another fork. A specialized dealer might be able to get you a price for one. If you wanted to use that adapter, you could just weld the thing on!


It's for the rear not the front. I thought about getting the bosses welded to the seat stays but I would have to repaint the bike. I guess the Evolution ones are the way to go they are just so expensive for what they are.


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## Mr Pig (Jun 25, 2008)

pharpe said:


> It's for the rear not the front. I thought about getting the bosses welded to the seat stays but I would have to repaint the bike.


Not the whole bike, just the bosses and that part of the stays. If you get a rattle can matched to the frame it should turn out ok. I've done stuff like this and it's not that hard.


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## Garasaki (Apr 7, 2010)

I've used that same adaptor, and will continue to do so in the future.

It's bulky, ulgy, and heavy, but does give you an avenue to add v brakes to the rear of the bike. Functionally, it works great. 

I would love to see someone make a nice looking lightweight version of that for kids bikes.


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## pharpe (Mar 24, 2017)

I have contacted a couple of frame shops about getting bosses put on. Since the frame is aluminum they cannot be brazed. They can be welded on but neither of the shops I talked to welded aluminum. They also said that welding would weaken the frame at that point so it really needs to be heat treated after. Therefore, even if I could find someone to do it, the cost would be prohibitive. 

I'm going to go ahead and order the evolutions.


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