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Customizing the Specialized Riprock 20



The New Specialized Riprock bikes are innovative bikes for kids with 20x2.8 tires, low stand over height and a decent parts spec. There is just one problem though, they are heavy. The fork alone weights in at 5 pounds and doesn't work all that well anyways. The goal with this bike was to lighten it as much as possible and as affordable as possible. Well, since I build wheels, and wheels are the best upgrade you can make on a bike, i will start with that. The Rear hub spacing is 135mm QR and the front fork is a specialized 110mm qr design. You wont find any aftermarket Boost QR hub, so i will be using a Bitex 100mm QR standard hub and will be swapping forks too. The stock rims have about the same profile as a Velocity Blunt 35, 35mm external width and 30mm internal width, 28 holes drilling. The Rims are non tubeless and are said to be made by Alex rims. I will be reusing the stock rims because it is hard to find a lightweight wide 406mm 20 inch rim, so here we have one at 342 grams. Sapim Race spokes and polyax nipples are my go to and are much higher quality than stock, and they are also lighter so less rotating weight.

Drinking Cappuccino and building wheels mixes well.


Stock front wheel weight- 1012 Grams

Stock rear wheel weight- 1510 Grams with Cassette @300 Grams

Custom front wheel weight- 790 Grams

Custom rear wheel weight- 1208 Grams with Cassette @300 Grams

So the total weight saving of the wheelset comes in at 524 Grams, which is 1.15 pounds of rolling weight, this has to make a huge difference for a 45 pound kid!!! I haven't played with going tubeless, but would assume you could save some weight there too. Each tube weighs a little over 200 grams.

-I measured the rim ERD at 392.5, just for reference.

So, what about the whole bike you ask? while I didn't weight the stock bike, it is said to weigh in at 27 pounds, the weight after wheels, a new fork and a few parts is 21 pounds.


Specialized Riprock 20


Specialized Riprock 20 Rear


Specialized Riprock 20 Front


Riprock 20


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WormEffect X
WormEffect X
Aug 13, 2021

I just felt the urge to piss on specialized. Found this when searching for rear wheel specs for rip rock 20. The threaded free hub broke And its not possible to find new parts, since Specialized does not even know what they have used. Rear wheel probably sourced complete from China with no documentation for spare parts. So not even specialized knows whats been used. The local friendly specialized mechanic basically recommended me to buy another brand next time.

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orbwheels
orbwheels
Jun 09, 2020

Thanks. There are part specs in part two of the blog. The fork can be found on eBay and would work for a 24 as well. The Trailcraft fork is what I ended up with and would also work for a 24 as that is what it's designed for. You can source the hubs from myself if you wanted to do the rebuild wheel route too.

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Whitey Taylor
Whitey Taylor
Jun 09, 2020

Nice work. I just stumbled across your post while trying to figure out how to make my kids bike lighter. We have the same bike and also the 24” version. Would you mind sharing the part details and/or where to get the parts to do this? What is the fork model and where can you purchase it? Do you think the same fork would work on the 24” rip rock?

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orbwheels
orbwheels
Jun 07, 2020

Thanks! I would say that if your'e thinking of swapping the fork to stick with a flat bar. It will raise the front end a bit and slacken the bike too. A nice short stem can do wonders to remedy that XC stretched out feel too. I will say the difference from stock to custom was a huge improvement in fit and riding position with my kids.

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William Render
William Render
Jun 07, 2020

Great Job! I just bought one of these today for my little guy, I'm not keen on the flat bars, I am thinking of swapping them for some risers. Any thoughts? (riprock Coaster is like bmx) my concern is he seems stretched out like a XC racer from the 90's remember the long stems and long top tubes. I'm still wondering if I should have bought him a bmx style the high bars to get his confidence up.. overthinking it I'm sure.

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