# Rippin' Riprock 20



## dan1231 (Jan 8, 2012)

Hey everyone,

Having had such a positive early experience, I wanted to share some (ok, maybe a lot of) thoughts on our upgraded Specialized Rip Rock 20 (yup, the one with the 2.8" monster truck tires).

For background, my son is now 5 1/2, stands about 3'10" tall and weighs about 45lbs. He's been riding a two wheeled pedal bike since he was about 2 1/2 (thank you Strider!). We ride on mostly fire roads (and, over the last month, rolling single track) in New England, where roots, rocks and other surprises dominate the terrain. He'll push his bike up the steep or technical climbs, and he can descend some surprising hills at his chosen speed.

A little bit on my assbackwards build process - like a lot of dads on this forum, I originally had the notion of building up a Lil Shredder for him - only the best, right? Well, I seemed to irrevocably commit myself down that path when, after a few beers late on a Friday night last fall, I put in what I thought was a "too low, the seller will surely refuse" bid on ebay for the MRP Rustler fork. Well, maybe I should have bid even lower. "Winning" that fork ignited the typical all-consuming and expensive chain reaction of researching specs that would fit a Lil Shredder frame and buying sweet high end parts as they went on super sale. When this spring came around and it was time to pull the trigger on the frame, however, I experienced something that never quite hit me in the bike buying process before - I had pangs of doubt. Weird, I know.

Don't get me wrong, we rented the Lil Shredder frame for a two day trip to Highland last year (no, he's not like those ridiculously good kids at Whistler - after riding around the learning areas for a few hours, we eventually made 4 trips from the top of the mountain, walking the nastier parts - it was an encouraging start though!). He absolutely loved that bike, how it was less rough and how he could draw up "smoke" by slamming on the brakes. But he is only 5, and I was worried that if he dropped biking altogether or, more realistically, picked up other sports that he liked better, then I would get upset and guilt him back into riding because of the cash outlay for the bike and set a wedge between us forever &#8230; ok, maybe it wasn't that dramatic. I still blew a lot of money (sunk costs, right?), and the actual savings of going this route over the Lil Shredder is probably overstated because I hadn't made up my mind early enough in the process.

So I scoured the web looking at a number of 20" bikes with disc brakes and relatively low standover height (most of the other geometry numbers seemed within practical/acceptable ranges across bikes/models) and to see what was the best suited, most reasonably priced bike on which I could use the adult parts I bought for him. I also didn't want him to outgrow it too quickly (well, at least not before his little sister was ready to ride it). There are a lot of good threads on other frames, but for me, it came down to the Specialized Hot Rock 20 Pro and Rip Rock (it took some internal convincing to go the Spec route, considering I myself prefer the smaller, boutique bike designers). Though I liked the specs of the Hot Rock Pro, I couldn't get over those monster truck tires on the Rip Rock. So that's what we went with. Mostly because of the ginormous tires.

I think we made the right choice. Here are a few specific impressions:

Monster Tires. I am convinced that these 2.8" wide tires are, far and away, the best bike parts money can buy for a 5 year old that wants to ride on actual trails. At low pressure, traction is incredible (he's never peeled out climbing, and even his skidding on loose terrain seems relatively controlled). Those tires handle roots and rocks extremely well - he's confidently clearing obstacles that would have knocked him off his other bike (which had 2.0" tires). He can recover because of the cushion and traction. He's even riding over weird obstacles (think offcamber type obstacles and narrow channels of roots and rocks that try to force you to go a slightly different direction). Riding right behind him and cheering him on, it gives me a sense of relief to see how big those tires are underneath him. Even if you don't like the weight or the geometry of this bike, it is worth it for the tires/wheels alone (and I don't think there are any other frames out there now that would fit these monsters). It'd be great if someone posted impressions about the stock 20" bike to confirm (or link to existing threads - I haven't had time to search myself), given our slightly custom setup.

To Fork or Not To Fork? There's a lot of thoughtful back-and-forth in these forums about whether the benefits of suspension offset the increased weight of a kids suspension fork. In my own humble, unscientific, non-evangelical opinion, I believe they do for a number of reasons. It's true that the performance of kids' forks isn't as advanced as adult forks - they won't have the finesse of features and settings that handle the varied aspects of terrain and speed. But what even a cheap kids fork will do is ease the jolt of a big hit (curbs, roots, rocks) that could ultimately derail his confidence and enthusiasm for riding. There will still be jarring to deal with, but a fork puts him in the best position to recover his balance and stay on his bike.

For my son's last bike (a Commencal Ramones 16 - which is great, by the way), I bought one of those heavy/cheap 50mm RST Capa forks on Amazon for like $100. Even that fork saved him from some spills and built up his confidence and ability to maneuver over obstacles. He's not strong enough to wheelie/bunny hop and doesn't quite understand the concept of shifting weight (moving weight forward and backwards, going from light to heavy, etc.), but when he hits with some speed a 4" squared edged curb or a small log lying across the trail, I think every mm of absorption helps. These safety and confidence-inspiring aspects that a fork provides cannot be ignored.

One other thought about whether a kid should learn to ride a bike with vs. without a fork/rear suspension. My kid is riding down some hills at speed he wouldn't be able to on a stiff bike. That's teaching him to read the trail ahead of him, navigate obstacles instead of avoiding them, and it's just more fun for him - hopefully that means it keeps his interest in the sport.

Back to the RipRock, we didn't have a chance to try the stock fork (given the money I blew on the nicer one), but it seems fine and offers 80mm of coil travel. It'd be great if someone with actual experience on it would post their impressions. The MRP Rustler fork we did install is a solid, well built fork (it should be given its price!). We set it on its most compressible setting, given that he weighs nothing, and, looking at the dirt marks on his stanchions after a ride, it's clear he does go through all of the fork's 80m travel on our rides, so even now (before he gains weight) he is getting good use out of it. When I ask him to push down on the handlebars to see how much the fork compresses, he gets it to about halfway through its travel. From what I can tell, it is doing what it is supposed to for him. There's no way for me to tell what helps him more, the cushion of the plus sized tires or the fork travel, but combined, they make a stable setup.

Brakes. SLX brakes, which is what the guy at Lil Shredder seems to use almost exclusively, are perfect. The levers are the perfect size for small hands, especially when you adjust them closer to the bar. Our bike shop (a plug for them: Woody's in Middleton MA - those guys are the best!) set the front brake weak on purpose, so when he grabs a handful of front brake, he doesn't fly over the bars - the front brake still has stopping power - a nice touch I hadn't thought of. We didn't try the stock brakes, which are cable actuated, but there's no reason why they would offer solid performance, especially over rim brakes (which are harder to setup just right and are useless if the rim bends out of shape on a ride).

Frame. The chainstays do "look" long, but there aren't many other bikes with shorter chainstays out there. The great thing about the head angle (69 degrees minus whatever extra results from the slightly longer travel fork - I haven't measured it exactly) and other parts of the geometry is that the bike turns smoothly and is not twitchy in his hands (and I doubt the extra height from the MRP fork makes a significant difference over the stock). I think that's important.

Gears. I think a few gears are a must on a 20" bike intended to go on real trails. My son sticks to the same 2-3 gears on the whole ride, but it is incredibly helpful especially to avoid having him push his bike up on climbs when we can pedal himself and to motivate him to stomp down on his pedals when he is about to hang up - I'm surprised by what he can climb when he is in the right gear.

Weight. I have not tried to switch out each component for a lighter version because I don't think a few pounds matters much at this point. We're not racing - I'm teaching him, and he's learning through experience. Kids are strong peddlers for their weight (relative to adults) on a bike. I'm amazed how much he can climb and pedal over a 2-3 hour ride. Right now, I don't see a need for incremental improvement, though my tune may change over time.

Silly Stuff Because Dads Can Be Overly-Impulsive Sometimes. Because I jumped the gun and bought tons of parts before committing to an actual frame, I ended up having some capability issues which added to the cost of the bike. We switched out the parts at the outset, so I can't relay any thoughts on the performance of some of the stock parts, although they looked perfectly acceptable (and of course the smarter route would be to replace them when broken or when performance clearly suffers). A lot of these issues were created because of total dumbassedness on my part.

Rear Wheel Rebuild. I really wanted to use a Zee shifter and rear derailleur. This meant having to rebuild the rear wheel to accommodate the size of a 10 speed cassette (the Rip Rock came with a 7 speed) - we still kept the stock wide rims which fit these monster tires. This was totally unnecessary and had I not sunk money into (and my heart into the idea of) the Zee components, I would have just changed out the stock grip shifter (which I think is a bad idea for little kids) to a Shimano Acera SL-M310 Rapid Fire Shifter, Right (Black, 7-Speed), which is on Amazon for like $17. All that said, the Zee shifts great, though it still takes him conscious effort to put his thumb on the shifters when he wants to shift (which is usually at my hassling - "there's a hill coming, shift to make it easier to pedal"). The other thing about the Zee is the clutch mechanism, which the stock derailleur does not have - the bike comes with a front chain guide, but I do wonder if lack of the clutch on the stock derailleur would result in any chain drops. If someone has experience, please share with the group.

Front Wheel Rebuild. The spacing of the stock fork is wider than a "standard" 20" bike fork, so we needed to rebuild the front wheel too in order to use the MRP fork. The clearance is tight, but we've had no issues so far. Again, this was a self-created issue.

Handlebars. The stock bars are generously wide, but I had an even wider set and I think going as wide you can for kids gives them even more natural stability on the bike. We used "XLC Mountain Bike Handlebar, 30mm, 630mm, 25.4, Black," again from Amazon for like $15, and they seem perfect to keep him in a balanced attack position throughout the ride.

I went over the top (for me, anyway) with some aspects of this build, but I really think anyone with a small kid who wants to learn how to ride trails should just get the Rip Rock 20 now and start riding it. The amazing traction and cushion will speed the learning curve, and it will bring both of you to a happy place.

I have a demanding job with little free time during the week, and now I'm full on in little kids sports coaching mode, which leaves no time for adult riding. Before this season, that bummed me out, but now that the little guy is trying out the same trails I ride, I have gotten past my nature of constantly try to improve/get faster. This shift in mindset has definitely made me happier. Any way, just wanted to share some of these thoughts, because finding a bike that helps increase your kid's capabilities can only make everyone more happy, right?

Dan


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## PMK (Oct 12, 2004)

Nice.


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## Steve-XtC (Feb 7, 2016)

A few observations.... (on what is a hugely well written and informative post)

To Fork or Not To Fork? 

I can't speak for the 20" forks but the 24" RST F1rst Air (60mm) is incredible.

Brakes. SLX brakes...
XT are even better for adjusting reach. 
We have a SLX rear and XT (780) front.... 

Weight.... 
Like gears will start to matter but in our case this co-incided with a real need for "real" suspension forks and being big enough to ride a 24er. 

All in In all .. despite being busy... making a few wrong purchases etc. he got 9 months on the 20er.... (from saddle at bottom to saddle at bottom on a 24)

I'm now spending on the 24er hoping to get 2-3 years out of it and also being able to transfer what components survive to a XS 26er!


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## mtnbkaz (Feb 2, 2004)

Thanks for the write-up! Precious little non marketing info on these bikes. Your observations about the tires are exactly what I hope to see on the 24" that I have coming.


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## Tjaard (Aug 17, 2007)

about the rear hub being a 7/8 speed:
If you don't want to build a new wheel, you can use a 10 speed system by ditching one cog from the cassette and limiting the derailleur. I I did this on my kids current bike. The chain.ine on a full 10 speed hub would be horrible anyway.
This allows you to use a clutch derailleur, as well as run a 11-36 spread for larger gear range.

If you are running a non clutch derailleur, the bike comes stock with a top chain guide, so no worries about dropped chains.


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## Tjaard (Aug 17, 2007)

*Replacement fork*

I did some fitting and measuring on my RST 1st Air 24" fork.

I am fairly confident the 20x2.8" tire would fit. I installed a 20" wheel and measured a ton of vertical clearance(unsurprisingly).

The width is 75mm at the narrowest spot.

If someone could measure the width of the stock tire and rim we would know for sure, but most 2.8" measure around 70 mm, and these come with narrower rims than most.

In that case, the RST 1st air could be a reasonable priced upgrade suspension fork.


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## dan1231 (Jan 8, 2012)

Steve-XtC said:


> A few observations.... (on what is a hugely well written and informative post)
> 
> To Fork or Not To Fork?
> 
> ...


Hey Steve-XtC, thanks! How old and tall was your kid when starting on the 20" and the 24"? My wallet and pride hope this one lasts longer than one season!



Tjaard said:


> I did some fitting and measuring on my RST 1st Air 24" fork.
> 
> I am fairly confident the 20x2.8" tire would fit. I installed a 20" wheel and measured a ton of vertical clearance(unsurprisingly).
> 
> ...


Hey Tjaard, I wondered about your suggestion on dropping cogs and limiting the derailleur, and it is a good one. In my haste and tunnel vision, I didn't do the research to figure out how to do it and get comfortable that shifting would not be affected. Does it shift exactly as you'd expect?



Tjaard said:


> Bummer about the rear hub being a 7/8 speed. I was hoping it was just a 9/10 speed with a spacer.
> If you don't want to build a new wheel, you can use a 10 speed system by ditching one cog from the cassette and limiting the derailleur. I I did this on my kids current bike.
> This allows you to use a clutch derailleur, as well as run a 11-36 spread for larger gear range.
> 
> If you are only worried about dropping the chain, you could run a narrow-wide chainring (or does it come with one?). Those do a pretty god job even without a clutch derailleur.


I just whipped out the digital calipers and can confirm the 20" version of this tire is 70mm in width, and the rim is slightly less than 35mm in outer width. The radius from the middle of the axle to edge of the tire is about 10-1/2 inches.

Just a reminder, the dropouts on the stock fork and axle on the stock hub are 110mm (which is what triggered compatibility issues for the MRP fork) - on the RST website, I don't see the dropouts on the F1rst air fork specified.

If you do end up having to rebuild the wheel, also remember the rim is 28H - of course, the hub I bought originally was 32H - just another reminder to settle on a frame before you buy the parts!


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## Tjaard (Aug 17, 2007)

Yep, RST 1st air is a regular 100mm dropout spacing, so you will need a new front wheel, or at least a 'new' front hub and reuse the rim. Since that is a the normal mtb size though, hubs are easily found used.


To install the 10 speed system on the 7 speed free hub just remove one of the central cogs (15t is common) and adjust the limit screw as normal. There will be a 'dead' click on the shifter that doesn't do anything, and a big jump between the 13t and 19t.


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## Steve-XtC (Feb 7, 2016)

dan1231 said:


> Hey Steve-XtC, thanks! How old and tall was your kid when starting on the 20" and the 24"? My wallet and pride hope this one lasts longer than one season!


Hi Dan,
I can try and look up his size on the 24 as I wrote it down and could find the actual dates but as you might see its probably not that useful as kids grow at different rates and he still fits the 20.

If I remember the 20 incher was 2 months before his 6th birthday. I didn't take any measurements because it was a result of a promise on getting rid of training wheels. (He had no interest in cycling and was into his scooter before this and it was only when he saw kids at school with proper bikes he had any motivation)

I took him to the local bike shop and he was *just* big enough to get onto a 20er. It was really a tad big but I wasn't going for a smaller one as he was due a growth spurt. I chose a rigid but had no idea at he time what we'd be riding or that it was going to be his number 1 hobby.

He then had a growth spurt... so for once I made the right decision ...
We spent the first few weekends and a few summer evenings "riding" locally. (Before this he had a really horrible bike I'd got when he was 3 (cast iron or close)... which explains retrospectively why he'd never been interested in cycling)

Then the 3-4 weekends in we went a longer run (about 10 miles on a flat route.on a canal towpath)... and he surprised us both when despite his mother having driven to meet us he decided to ride back.

At this point we started running out of child friendly places to cycle. We have lots and lots of dedicated cycle paths but they don't join up.... so I ended up going to a place I used to ride nearly 3 decades ago.... I planned a route (not quite single track) and again had mum ready to pick us up... we had a pretty big decent from the parking to a town but again he decided to ride back... and I sent a friend I used to ride with (who lives in California now) a map and photo's I'd put together. 
*I'd point out he was an averagely fit kid at his point. *
"Go to Bracknell Forest" he said .....
Now my mate is pretty serious with his cycling.(he wins a lot of XC and road in our age group).so I was just a bit wary.. but he does have 2 kids a bit older than mine.

This is a local trail center ...It's not huge but with some of everything from fire-roads to very technical with all in-between. At this point I was riding a 700c hybrid bike....

As with kids their rate of progress is amazing.... we were soon riding things that were quickly wrecking the hybrid and the skinny (by MTB) tires completely inadequate... so I ended up getting a XC bike... (which now turns out to be a possible mistake as we are now riding things outside what my rigid carbon frame and 100mm forks are designed for)

and we quickly got onto trails that were really pushing his bike. (1' drop offs and lots of big roots on 20 inch wheels with no suspension)

I thought about upgrading the 20 ... past the megadrive freewheel I'd fitted and getting some 20" forks.... and then we tried a 24er at the trail center hire place. (We'd got to know the guys and they let him have a try) ... it was a stretch but he'd shot up in the 8-9 months.

I figured if I was going to put time, effort and money into a bike it should be one he was growing into. At the time he was a tad under 4' (perhaps 3'11") he's now a whisker above...

We do however still use the 20 ... indeed last night we fitted a slightly longer stem and we are just about to leave and ride to school on it. He could get another year or more out of the 20....

The 24er (medium frame) I can ride reasonably with the saddle right up and I'm 5'10 ... so this should really last to a small adult bike.

The 24er is now frame and forks (and headset) of the original bike. Nothing else is from the bike.... and weight now makes a big difference as well. His 24er with RST F1rst weighs less (just on the 20lb mark) than his rigid 20er....

He is now passing lots of adults on the ascents and riding up stuff without thinking that he would have pushed a few months ago...

I guess the takeouts from this are that gears, weight, suspension etc. all come in or become important as your kid reaches a certain ability. Our experience was that happened/co-incided just as he was just big enough to get onto a 24er.

Had we started earlier then we might well have spent more money and time on the 20 incher....


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## mtnbkaz (Feb 2, 2004)

Fwiw, mine was on the 20 at 5.5 years and maybe 45" tall. Now almost 8 and 53" and starting a 24". We tested the 24 4 or 5 months ago and it was still too big (would have been OK for bike paths but not actual trails, IMO). The 20 still fits OK but the 24 should have better trail manners. Not sure yet if I'll sell the 20 or hang onto it a bit. 

I get more use out of each bike. The smaller ones only lasted a year. The 20 was 2.5 years. Hoping for 3-4 out of the 24.


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## Steve-XtC (Feb 7, 2016)

mtnbkaz said:


> Fwiw, mine was on the 20 at 5.5 years and maybe 45" tall. Now almost 8 and 53" and starting a 24". We tested the 24 4 or 5 months ago and it was still too big (would have been OK for bike paths but *not actual trails*, IMO). The 20 still fits OK but the 24 should have better trail manners. Not sure yet if I'll sell the 20 or hang onto it a bit.


I class this as a trail ... rather than bike path  and he's just under 48"

I'm doubt he could even have ridden *up* this on his 20er simply down to clearance.... he might have descended some of it but again hard without the clearance and forks.

(I didn't stop to take pictures on the ascent... its over 1000' of 1:4... with lots of big rocks - bigger than a 20 inch wheel rocks and I was struggling on my 27.5)

So although the bike a bit big it does let him ride what he otherwise couldn't.


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## mtnbkaz (Feb 2, 2004)

I'd call that a trail too 

I was just talking about how my kid fit on the bike - 5 months ago, he was way too stretched out for riding down rocks like that. 5 months and a growth spurt later? the 24 looks just right.


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## Steve-XtC (Feb 7, 2016)

mtnbkaz said:


> I'd call that a trail too
> 
> I was just talking about how my kid fit on the bike - 5 months ago, he was way too stretched out for riding down rocks like that. 5 months and a growth spurt later? the 24 looks just right.


Now I re-read it that's what you said. I misread the 5 mo ago part ...the first time. Damned tablets... Should have put my glasses on!

Incidentally the bike has the shortest stem I could find (35mm) and the bars are rotated back shortening it further. (It came with a lump of cast iron 60mm stem). That's at Easter and he's grown enough to rotate the riser bars more vertical since then. Indeed yesterday evening I moved the stem up 5mm as well by swapping the spacers about. I'm not sure if food or bike parts make up the biggest bill when they keep growing!


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## mtnbkaz (Feb 2, 2004)

No worries. Partly my fault - my post clarity has degraded since I mainly post from a phone now


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## dan1231 (Jan 8, 2012)

Steve-XtC:

That's a great progression - and wonderful to hear your little guy is so determined to cover ground on his own! And I agree, that is a trail!

How often does he ride and how often is it on trails? My little guy will have a few weekdays riding around the cul-de-sac and over the curbs and down a little hill in our neighbors yard while I'm chained to my desk at work, and we get one or two rides in a weekend on real singletrack for a few hours each. I'd be great to compare notes on how they progress. Each time we go out, there is a point in the ride when he is stronger and better than ever - definitely not at the start, he needs to warm up and be encouraged (and calmed down if he gets frustrated). It's really cool to see, especially when he stands up and hammers on his pedals to climb and then confidently takes on the downhills and technical sections.

May I ask, what make and model were/are his 20"er and 24"er? It'd be interesting to see what fits your son (at his height and build) best, as I can imagine my son hitting those heights soon. Dork alert, dork alert: I've pulled the US CDC's growth chart to see what frame sizes might give us the most use over the next few years - despite the potential theoretical fits, in the end, when he tried a 20" Spec Hot Rock (a low end model) in person, his handling in the parking lot was clumsy due to the frame having relatively high standover height and an elongated cockpit for him, my thoughts of something bigger (a 24"er, especially the RipCord, which says it might just barely fit someone his size - if only I was convinced! - we don't have a Transition dealer nearby to confirm or deny) stalled right there. I guess we will see how much use he gets out of this 20"er (at least his 2 year old sister will extend the useful life too). I was also thinking that, even if he outgrows it, a small, lighter bike would enable him to learn some of the more nuanced aspects of riding: shifting weights, small wheelies, jumps, etc. It'd be great to compare notes as these two little guys get bigger and better in the coming months and years.

I think my second kid will get the advantage of me figuring some of this stuff out....

mtnbkaz:

Your experience sounds different than Steve-XtC, in that your little guy switched to a 24"er much later on - what makes/models has he tried/ridden? I can only imagine that the 24" Rip 'n Rock you have on order is going to be incredible for him now!


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## mtnbkaz (Feb 2, 2004)

We've been on the whole specialized line. Hot walk at 18 months, Hotrock 12 at 2.5 years, Hotrock 16 at 3.5 years, Hotrock 20 geared at 5.5 years (I think), and now the Riprock at 8. Don't read too much into individual anecdotes. Every kid is different and grows at different rates. Sounds like mine was on a 20 earlier than Steves, but his just jumped to the 24 earlier. That's just an individual thing. If the 24 fits, ride it. I don't see many 6-7yo on 24s around here, but again, if a kid hits a growth spurt, ride what fits. 

Some people try to save a few bucks and skip a size - like stay on the 12 for longer and skip the 16, or maybe stay on a 16 for longer and go straight to a 24. But I've just always bought the optimum size. Like I said, we tested a Riprock 24 about 5 months ago but my son just seemed too stretched out to stay in an attack position. Maybe not so bad but since he still had a 20 that fit him, I basically decided the "Christmas bike" could wait to become a "birthday bike".

It's amazing what they can do - even on the little wheels. In the 16-er days we mostly stuck to smoother trails. But I do remember riding Shultz Creek in Flagstaff on the 16, and I was surprised how well the little dude rocked it back in the day. (Coaster brakes, even!) And we ride all kinds of terrain on the 20. He'll ride over rocks that almost seem as big as the wheel. But there are times where the 20 seems to get hung up and he loses momentum. That's where I'm hoping the big Riprock helps.


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## Steve-XtC (Feb 7, 2016)

dan1231 said:


> Steve-XtC:
> 
> That's a great progression - and wonderful to hear your little guy is so determined to cover ground on his own! And I agree, that is a trail!
> 
> How often does he ride and how often is it on trails?


Presently (and since perhaps Nov last year): Every weekend (unless there is some reason not to), usually 3-4 hours Sat and Sun all trails



> My little guy will have a few weekdays riding around the cul-de-sac and over the curbs and down a little hill in our neighbors yard while I'm chained to my desk at work, and we get one or two rides in a weekend on real singletrack for a few hours each.


We get a little outside the weekends but it's tied into work. Jan to End Mar I was working 80hrs a week.... frequently away Mon-Thur as well.

Things have quietened down with work so I'm now working more reasonable hours and mostly from home. Because of this we just started cycling to school on the 20".



> I'd be great to compare notes on how they progress.


Sure though given the rates kids progress I think you would find the older stuff more appropriate .... we have a bunch of video on YouTube that charts his progress though the purpose is really sharing with his gran. It's also heavily redacted... due to his editorial control... (Mistakes, warm up and temper tantrums removed)



> Each time we go out, there is a point in the ride when he is stronger and better than ever - definitely not at the start, he needs to warm up and be encouraged (and calmed down if he gets frustrated).


Exactly our experience though he at least now recognises that and the initial moans and temper tantrums have disappeared...



> It's really cool to see, especially when he stands up and hammers on his pedals to climb and then confidently takes on the downhills and technical sections.


Yep not to mention the tumbles and getting back up...



> May I ask, what make and model were/are his 20"er and 24"er? It'd be interesting to see what fits your son (at his height and build) best, as I can imagine my son hitting those heights soon.


I didn't do any measurements for the 20 (or if I did I've forgotten them) ...
We are in the UK so the 20er is really only provided for reference ...
https://www.evanscycles.com/pinnacle-ash-20-inch-kids-bike-EV180825

Here is the geometry
https://static.evanscycles.com/production/pdf-media/sizing-table/Pinnacle-Kids-Size-Guide.pdf

The day we bought it, he quite literally could just get his feet on the floor with the saddle fully down. Ollie is quite tall on the UK growth charts but we forget because he's the youngest in his year at school.(technically his friend is an hour younger).. then if either of them were born a few hours later they would be a year behind now... (It seems quite weird contemplating that now)



> Dork alert, dork alert: I've pulled the US CDC's growth chart to see what frame sizes might give us the most use over the next few years - despite the potential theoretical fits, in the end, when he tried a 20" Spec Hot Rock (a low end model) in person, his handling in the parking lot was clumsy


I don't think a parking lot will give you the idea. I jumped on my commuter the other day and it felt very weird... when he got the 24er he was clumsy for a few hours.... (the 20 was his first REAL bike so that doesn't count as he had just come off training wheels so you expect a few hours for them to be steady)

Note: Yes this is the "Girls" model but Cannondale stopped selling 24" in the UK so this was what we could get in a Medium frame.

CANNONDALE RACE GIRLS 24" 2014 :: £249.99 :: Kids Bikes :: 24" Wheel (9 to 11 yrs) :: Pauls Cycles
I also then switched the stem for a 35mm and rotated the riser bars... getting about 2" back.... BUT the bike was still almost unrideable because of the cranks. The first weeks I actually just took the crank off his 20err.

I tried him on a 24er hire bike at the trail centre.... extrapolated from when he first got the 20er and took a leap of faith.. we could have borrowed the bike longer (I know the hire guys) or even hired it half a day... *but at that point I wasn't in a rush and had expected to rebuild completely before he rode it.* It didn't work out that way as he quickly (1-2 hours) got the hang of it... even with the original stem.

*The reason I got THAT bike was the F1rst fork and the frame had disc mounts. The only parts of the original bike are frame, forks and headset. 
*
Quite often exact Spec for a particular bike might be different here than in the US so even when a model is available here the spec might be different.

My perspective on that bike was the forks are the best 24er forks and WHEN you can buy them cost over half (+shipping) what I paid for the frame and forks.... If anything my shipping would have been a LOT cheaper to the UK....

RST F1RST Air 24" MTB Suspension Fork black | MTB Fork Shop



> if only I was convinced!


Size really doesn't matter long term as he will grow into it.... it's just when.

On the other hand.... if you want a real offroad bike then upgrading almost everything is a must ...* if nothing else the size main issue isn't standover height but crank length*.

Crank length is easily solved ... you can either buy 
Cranks - Cranksets products from SJS Cycles 145,Size: 140,Size: 150&page=1

Get modified: BikeSmith Design and Fabrication

Or do it yourself... (DIY is a lot easier than it sounds) in fact I just got some used cranks off ebay for $15 that I'm going to shorten for when we put on the bigger 34T chain for road and firetrails ... the 30T won't come off without taking the driveside crank anyway...as the ID is too small....

I'm keeping a casual eye on eBay for 26er XS frames.. I'd probably have already got one to start building as parts are discounted or on eBay but for not knowing if he will need a hardtail or full susp by the time he's big enough.



> I was also thinking that, even if he outgrows it, a small, lighter bike would enable him to learn some of the more nuanced aspects of riding: shifting weights, small wheelies, jumps, etc. It'd be great to compare notes as these two little guys get bigger and better in the coming months and years.


We use the 20 for any non-serious riding.... firstly it's not a disaster if it gets broken or stolen...it fits in his mum's station wagon with the wheels on.... on the odd time we go to a bike park (BMX style) it FITS on top of ramps... (the 24er is a real squeeze) ... and if he rides with friends from school it's simply more appropriate. (Hardly fair on the other kids or healthy for him )

If you like I can PM a link to the video's that show progression from the old 20er days to the 24er....


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## Tjaard (Aug 17, 2007)

*Lighter rigid fork options*

The Wiskey No7 Carbon fork is under 500g and lists a width of 70mm at the top, so with the much smaller 20" rim I would guess it would give you the 3mm on either side that I would consider minimum.
It does have 47mm offset, which is more than I would prefer for such a small wheel.

Then, in the really spendy realm:

Looks like the Trailcraft Ti fork would be an option for the 20x2.8, and possibly for the 24x2.8. Rake is not listed.

from Trailcraft: 
"_The spacing at the top is 75.42mm's. The attached picture shows a 24x2.4 Fat Albert and there is probably a solid 8-10mm's on either side. 
Also, I ride a 3.0" Vittoria Bomboloni and took a pic of this tire in the ti fork as well for reference. The rim is a Flow EX. There is also a comfortable 4-5mm's on both side with a 3.0.._"

I couldn't get the pic of the plus tire to upload, so here is the one with a normal 24" tire:


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## Tjaard (Aug 17, 2007)

Dan1231 or others,

Could you measure the approximate axle to crown height of the stock fork?

My guess would be somewhere around 400mm?


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## Tjaard (Aug 17, 2007)

*Riprock 20*

yes, axle to crown is about 400 mm.
Tires are actually reasonably light for their size: 685g for a 2.8 is pretty good. Casing is also quite supple, which should help with both grip and rolling resistance.

Fork is indeed about 400mm a-c.

Best upgrade was a Salsa Fliplock quick release seat post collar. (Stock is fixed collar). The Salsa has a really long lever that requires less force to open and close. Put some grip paste(carbon paste) on the seat post and keep the tension on the collar low. Now she can raise and lower her saddle herself.

Handle bars were to wide for my daughter, so I swapped in a old, cut down bar I had lying around and saved some weight too. Swapped to a bit lighter seat post and saddle as well, and swapped to 10 speed X9 derailleur, 10 speed XT cassette (a bit lighter) with 1 cog removed and GX trigger shifter.

If you want to run 10 speed with a new hub, I would still suggest using only 9 cogs, and spacing the cassette out a bit. The chain line is very poor on the largest cog as it is.

Got the rear wheel tubeless with some wrestling, ran out of time for the front wheel.

Current weight is 25 lbs 10 oz. With pedals.


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## Tjaard (Aug 17, 2007)

*Fork and geometry*

Got an 'Iveke' carbon fork off amazon. At the widest part of the tire the fork is about 80mm wide.
I have not installed it yet, as I am waiting for the new wheel build (needed for the regular hub width).

This fork is 460g with uncut, adult length steerer tube. I don't know the weight of the existing fork yet, but my guess is somewhere around 3000g,
so the swap should save about 2000-2500g(4-5lbs).

The fork is 425 mm axle to crown. This will raise the bottom bracket
about 1/4"/6mm, not so great, but also slacken the head angle by a degree, which is excellent.

The headangle on the bike as stock is 69 degrees, with 40mm offset.
Let's say you want 85 mm trail, which is a nice, moderate amount, definitely on the quicker, xc side of things. A Specialized Epic has 84 mm of trail.

You would need a head angle of 65 degrees! Just to get the same trail figure as an Epic, not to get some Enduro beast!

So, besides the taller fork I also ordered a 2 degree angle adjust headset.

Together, this should help bring the head angle down to 66 degrees, for about 79mm of trail, still very light, but a lot better than stock.


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## Tjaard (Aug 17, 2007)

*Weight savings*

Other weight savings:

With a quick scavenge through my parts bins, I was able to swap the rear QR skewer for a lighter one, saving 35g. Not much on it's own, but this was not a very high end one. A cheap, ultra light chinese one would save 100 g for the pair if you can cut thread to create the custom 110mm length for the front out of a normal 135mm.

Saddle is also fairly heavy as was seat post. Al of these were swapped for lighter ones out of my parts bin, none of the new parts were very high end, so you could save even more.

The stem is actually very lightweight at just around 105g.

Tubeless was doable, with some effort.


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## Tjaard (Aug 17, 2007)

*highly recommended upgrade - bottom bracket*

Highly recommend upgrading the bottom bracket.

BTW frame is nicely faced, but stock drive side cup was almost impossible to get out.

Got a ~$45 run of the mil cartridge bottom bracket.

-Saved 110g
-much smoother even compared to the brand new stock one
-sealed cartridge bearings rather than open bearings
-chainline much better (5mm)
-better stance width (_'Q factor_')

The stock spindle is 118, I installed 108, so 5 mm narrower on each side.
This improved stance width (ergonomics) and pedal clearance in corners and tight spots.
Most importantly, the chainline is much better. It is still further out than it should be, but at least 2 cogs better than before.
Tire clearance is minimal, but ok (speaking from fat bike experience).

With such a short chain stay, chainline really matters. On the stock set-up, I could see the chain almost pulling off the lower jockey wheel when on the biggest cog.


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## theskyking (May 6, 2012)

*on the road?*

Quick question for those of you who have kids with a riprock. Do they do OK on street family bike rides, or too much drag with those big heavy tires? We'll do a lot of on AND off road rides, just want to be sure they are OK for both. Thanks!


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## NYrr496 (Sep 10, 2008)

theskyking said:


> Quick question for those of you who have kids with a riprock. Do they do OK on street family bike rides, or too much drag with those big heavy tires? We'll do a lot of on AND off road rides, just want to be sure they are OK for both. Thanks!


Not a Rip Rock because my son is 11 and rides a Medium frame fat bike...
We ride our fat bikes down a 5 mile paved path to the beach sometimes for a change of scenery and we just pump the tires up a little. Rolls fine. I'd imagine you could do exactly the same thing with a Rip Rock.

Damn, I wish they made that bike when my son was 5.


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## Chad_M (Jul 11, 2013)

For those with a Riprock with stock cassette, when in the easiest cassette gear, and back pedal, does your chain fall down to the next gear? Ours does. The chain line is pretty severe on the stock bike, but I guess it has to be with the short chain stays and wide tires.


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## POAH (Apr 29, 2009)

Tjaard said:


> Got a ~$45 run of the mil cartridge bottom bracket.
> 
> -Saved 110g
> -much smoother even compared to the brand new stock one
> ...


curious, how heavy was the standard BB and what BB did you get. a UN54/55 is about 300g


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## Tjaard (Aug 17, 2007)

My 5 year old ripping the Riprock on one of our new trails.

Severely modded:
Carbon 26" rigid fork. Meaning new wheel, 36mm internal rim.
Rear stock wheel, tubeless.
11-36 10 speed cassette, 2 cogs removed. 10 speed trigger shifter.
new BB, not much money for much better bearings and a lot of weight saved
chain guide removed
syntace flatforce 60mm stem to get bars back down
Works Components -1.5 degree angle adjust headset.
lighter seat post and saddle, just random nonane stuff from other (kids) bikes.
salsa sweep bar for better elbow position and to reduce reach.

These mods have slackened the front out a lot. This achieves two things:


the front wheel is further away, so less chance of going OTB
The trail is a lot higher, so much more stable steering at high speeds and over rough terrain.


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## Tjaard (Aug 17, 2007)

Oh, and the total bike weight right now is about 21lbs.


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## Fcorriveau (Nov 20, 2016)

Is it possible to put a smaller chainring? My son is not that strong and I would like to put a 24 or 26 for winter riding.


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## POAH (Apr 29, 2009)

Not on the standard crank but it's pretty well geared.


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## Fcorriveau (Nov 20, 2016)

Excellent, thanks!


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## 779334 (Oct 10, 2014)

Their bikes are great!


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## LewisQC (Jul 3, 2013)

Tjaard said:


> To install the 10 speed system on the 7 speed free hub just remove one of the central cogs (15t is common) and adjust the limit screw as normal. There will be a 'dead' click on the shifter that doesn't do anything, and a big jump between the 13t and 19t.


Hi Guys

My brother bough a Riprock 20 for is son this winter. The bike being heavier than it's previous 20" bike, he is having some problem with steeper hills. He would need a lower gear for climbing. We've been trying to determine the better way to upgrade the drivetrain. My brother would like to fit a 40t

So if I understand ok, a 10 speed derailleur, 10 speed shifter, 11-40 cassette with one cog remove should work?

Thanks


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## NYrr496 (Sep 10, 2008)

LewisQC said:


> Hi Guys
> 
> My brother bough a Riprock 20 for is son this winter. The bike being heavier than it's previous 20" bike, he is having some problem with steeper hills. He would need a lower gear for climbing. We've been trying to determine the better way to upgrade the drivetrain. My brother would like to fit a 40t
> 
> ...


I've done this a couple of times with mixed results. The parts can certainly be made to fit. I switched a six speed 20" bike to 8 speed XT with trigger shifts and it worked beautifully. 
Then, I built a 24" wheeled bike for my son and installed a 1x10 drivetrain on it. I could only get nine gears. Either all but the 11 or all but the 36. It was more important he had the 36 for climbing so I locked out the 11 tooth with the limit screw. 
I was told it was because the rear stays were too short. If that was the case, 11 speed may work the same way.


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## LewisQC (Jul 3, 2013)

NYrr496 said:


> I've done this a couple of times with mixed results. The parts can certainly be made to fit. I switched a six speed 20" bike to 8 speed XT with trigger shifts and it worked beautifully.
> Then, I built a 24" wheeled bike for my son and installed a 1x10 drivetrain on it. I could only get nine gears. Either all but the 11 or all but the 36. It was more important he had the 36 for climbing so I locked out the 11 tooth with the limit screw.
> I was told it was because the rear stays were too short. If that was the case, 11 speed may work the same way.


I did upgrade my son's 24" to 1x10 (from 3x8) with xt derailleur/shifter and home-shortened sram cranks. Shifting is flawless. But with a smaller bike, smaller hub, I don't have any experience. My brother read somewhere that sram x4 derailleur would clear a 40t (34t max on sram website). In have x4 8 speed shifter/derailleur in my part bin so maybe we will try this first with an 8 speed sunrace cassette (11-40). If it's not working, just swapping derailleur for a 10 speed x7 should work with the 8 speed shifter... I think...


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## Fcorriveau (Nov 20, 2016)

After reading all of your posts, I decided to upgrade the rear cassette. I didn't want to spend too much money since the bike was brand new (10 speed cassette implies a new chain and shifter) so I bought a long range Sunrace cassette (model CSM680, 8 speed, 11-40t, 34 $CAN). I had to drop a cog because of the 7 speed hub and added a couple of links to the chain. The rear derailleur barely clears the 40, but it works surprinsingly well. The shifter is an Altus 7 speed (my son dosen't like Revoshift). 

My son can now climb much steeper hills, it gave him a lot of confidence. It's gonna be easier for him next winter too! I just ordered another RipRock for my youngest son and I will do the same upgrades on the new bike.


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## Tjaard (Aug 17, 2007)

POAH said:


> curious, how heavy was the standard BB and what BB did you get. a UN54/55 is about 300g


stock one was 335g.

I don't remember what I got, but it wasn't Ti or anything like that.


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## Tjaard (Aug 17, 2007)

*Travel bike*

I just got back from a trip with this 20" Riprock on a plane.

If you strip the parts off, the diagonal of the frame is small enough to fit inside a standard airline size suitcase, so no extra fees. You do need to pack the wheels in another bag though.

It only took about 15 minutes to disable/re-assemble the bike, plus a bit more time to protect and pack it.


Pull wheels
 Remove rotors and skewers
unbolt rear brake caliper from frame (uses IS mount, so no adjustment need upon install)
unbolt derailleur hanger from frame
unbolt front brake caliper from fork
remove stem from fork
remove fork from frame
remove drive side crank
remove non-driveside pedal

Handlebars stay attached to stem, so no fiddly adjustment needed after install. derailleur stays adjusted.
Handlebar is attached to frame bu shift and brake cable, but can be laid alongside. Fork fit in same suitcase too.


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## wickedwheels (Jul 20, 2006)

The axle-to-crown was mentioned at 400mm. The MRP is listed at 387. Any noticeable issues or differences? The 24" RST 1st 24 is listed at 410mm.

In general, I'm trying to find an air fork that fits a 20x2.8 for this bike, as my kid is looking at getting another year out of this bike and we have 2 boys behind him. Any suggestions would be appreciated.

My upgrades included an old World Class Ti BB and a Spawn crankset with a raceface wide-narrow ring, XTR 9-spd rear derailleur, old ti handlebar, lighter saddle, lighter post. I didn't weigh it yet and haven't gone tubeless yet. But I will at some point.


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## mcgideon (Apr 23, 2019)

dan1231 said:


> Hey everyone,
> 
> Having had such a positive early experience, I wanted to share some (ok, maybe a lot of) thoughts on our upgraded Specialized Rip Rock 20 (yup, the one with the 2.8" monster truck tires).
> 
> ...


How did you modify the front wheel to fit with the new fork? Just got my son a rip rock 20 and will want to upgrade him to an air fork when he is ready for rougher terrain. But I want to keep the fat tires the bike came with. Thanks!

Mitch


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## POAH (Apr 29, 2009)

mcgideon said:


> How did you modify the front wheel to fit with the new fork? Just got my son a rip rock 20 and will want to upgrade him to an air fork when he is ready for rougher terrain. But I want to keep the fat tires the bike came with. Thanks!
> 
> Mitch


 get the rim built onto another hub and stick with boost forks


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