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-   -   Do carbon forks matter much? Race bike. (https://www.bikeforums.net/showthread.php?t=1235047)

Russ Roth 07-19-21 11:18 PM

Do carbon forks matter much? Race bike.
 
Trying to figure out how to make my kid's bike better, 2019 Redline MX Mini. He's about 1" from out growing this but I'm thinking new parts could be swapped to a Jr. frame especially since complete bikes are either unavailable or really expensive but frames seem reasonably available and affordable. I'm finding carbon forks but what real advantage do they offer over stock forks, just weight? His bike is 15.5lbs as is, can't imagine it going too much lighter though with the kid weighing 80lbs any change is probably more advantageous. . Currently have Box Harmonic hubs, Bombshell expert rims, and ti spokes ordered for a lighter, faster wheelset; expecting a roughly 1100-1200g wheelset that should, more importantly, spin faster.

Viich 07-21-21 06:07 AM


Originally Posted by Russ Roth (Post 22149362)
Trying to figure out how to make my kid's bike better, 2019 Redline MX Mini. He's about 1" from out growing this but I'm thinking new parts could be swapped to a Jr. frame especially since complete bikes are either unavailable or really expensive but frames seem reasonably available and affordable. I'm finding carbon forks but what real advantage do they offer over stock forks, just weight? His bike is 15.5lbs as is, can't imagine it going too much lighter though with the kid weighing 80lbs any change is probably more advantageous. . Currently have Box Harmonic hubs, Bombshell expert rims, and ti spokes ordered for a lighter, faster wheelset; expecting a roughly 1100-1200g wheelset that should, more importantly, spin faster.

Hey Russ.
I wouldn't go too nuts on a Redline MX. I get what you're saying about moving parts from a mini to a junior, but forks sometimes don't make that move so well unless you put a LOT of spacers on them on the smaller size - I had a Ciari Ottomatic fork on my son's junior, but the steer tube was too short to use it on his expert. I'd wait on the fork until you're building the next bike - and if you want to move that fork on to an expert frame later, make sure you leave the steer tube as long as you dare. You might be better off just buying used and planning on selling it.

As far as carbon forks - other than the more expensive ones, (like supercross speedline or ciari piccolo) - the Answer Dagger is only a couple grams lighter than something like a Ciari Ottomatic or a Supercross SLT fork. I run a Ciari Ottomatic, and both of my boys have - the elevn steel fork is right up there too.



I don't know if you've already ordered the spokes or not, but I highly recommend double-butted steel spokes over ti - if you use ti with aluminim nipples, bad things can happen - and there isn't actually that much weight savings between double-butted and ti. The steel and aluminum nipples (which work fine together) is lighter than the titanium spokes and brass nipples. The big thing is galvanic corrosion - the aluminum nipples will corrode on the threads where it contacts the titanium. As well, you generally need high tensions with Ti because it doesn't stretch as much - you might get away with it on a kids bike that you're very careful with around moisture, but it'll eventually corrode.

The galvanic corrosion thing goes away if you use titanium nipples as well - but you're better off using butted steel spokes and aluminum nipples and putting the money into better hubs. I don't have anything against the harmonics, one of my sons uses them - but the other one has a set with the Stealth hubs, and I far prefer them (or Onyx, or Profile Elite, or Profile AC-2......) - The biggest thing in looking at hubs for BMX is the distance between engagement points - the Box Harmonic is pretty good, but Onyx and Stealth are roller bearing hubs that are virtually instant. I actually use a freewheel hub and the Box Buzz freewheel on my own bike - the freewheel solution works just fine, don't let someone tell you that you have to go cassette hub.

Russ Roth 07-21-21 08:13 AM


Originally Posted by Viich (Post 22151121)
and if you want to move that fork on to an expert frame later, make sure you leave the steer tube as long as you dare. You might be better off just buying used and planning on selling it.

As far as carbon forks - other than the more expensive ones, (like supercross speedline or ciari piccolo) - the Answer Dagger is only a couple grams lighter than something like a Ciari Ottomatic or a Supercross SLT fork. I run a Ciari Ottomatic, and both of my boys have - the elevn steel fork is right up there too.



I don't know if you've already ordered the spokes or not, but I highly recommend double-butted steel spokes over ti - if you use ti with aluminim nipples, bad things can happen - and there isn't actually that much weight savings between double-butted and ti. The steel and aluminum nipples (which work fine together) is lighter than the titanium spokes and brass nipples. The big thing is galvanic corrosion - the aluminum nipples will corrode on the threads where it contacts the titanium. As well, you generally need high tensions with Ti because it doesn't stretch as much - you might get away with it on a kids bike that you're very careful with around moisture, but it'll eventually corrode.

The galvanic corrosion thing goes away if you use titanium nipples as well - but you're better off using butted steel spokes and aluminum nipples and putting the money into better hubs. I don't have anything against the harmonics, one of my sons uses them - but the other one has a set with the Stealth hubs, and I far prefer them (or Onyx, or Profile Elite, or Profile AC-2......) - The biggest thing in looking at hubs for BMX is the distance between engagement points - the Box Harmonic is pretty good, but Onyx and Stealth are roller bearing hubs that are virtually instant. I actually use a freewheel hub and the Box Buzz freewheel on my own bike - the freewheel solution works just fine, don't let someone tell you that you have to go cassette hub.

I was being slow on the frame size to steerer tube cut, I think its because all the bikes from mini to expert use the same wheel size and only seem to get longer top tubes. Too used to road and mountain where there are glaringly obvious size changes. Not going too nuts upgrading the MX though which will be passed down to the youngest. Just more curious, with the short legs they have if they're really anything more than a minor weight difference, I think I'll wait till this winter/next spring when I order the next size up and build a bike.

Wheel parts are ordered, glad to hear the Harmonic is decent. At a clearance price the hub was a good value (150.00 due to color), and the kid is gonna have to prove himself a bit more before I drop too much on really good wheels. With King out of the game it might be a move to stealth but he's going to have to win a few races before that or come so close that he can claim a better wheelset would have given him the extra fraction of a second needed to win. I did end up going with the Ti spokes, I've built at least a half dozen wheelsets with them in the past so I know how to avoid the galvanic process but thanks for the warning.

Viich 07-21-21 03:06 PM


Originally Posted by Russ Roth (Post 22151299)
I was being slow on the frame size to steerer tube cut, I think its because all the bikes from mini to expert use the same wheel size and only seem to get longer top tubes. Too used to road and mountain where there are glaringly obvious size changes. Not going too nuts upgrading the MX though which will be passed down to the youngest. Just more curious, with the short legs they have if they're really anything more than a minor weight difference, I think I'll wait till this winter/next spring when I order the next size up and build a bike.

Wheel parts are ordered, glad to hear the Harmonic is decent. At a clearance price the hub was a good value (150.00 due to color), and the kid is gonna have to prove himself a bit more before I drop too much on really good wheels. With King out of the game it might be a move to stealth but he's going to have to win a few races before that or come so close that he can claim a better wheelset would have given him the extra fraction of a second needed to win. I did end up going with the Ti spokes, I've built at least a half dozen wheelsets with them in the past so I know how to avoid the galvanic process but thanks for the warning.

Good stuff! Are you racing as well? I got started after my boys did.

Russ Roth 07-21-21 05:03 PM


Originally Posted by Viich (Post 22152002)
Good stuff! Are you racing as well? I got started after my boys did.

Nope, wife put her foot down on that. Was thinking of taking the front brake off my mtb and running cruiser. I'm already racing velodrome, road, mtb and when the season hits, cross so it isn't like I'm not already riding. Might have to sneak in a ride but the helmet would be kind of obvious.

Viich 07-21-21 05:16 PM


Originally Posted by Russ Roth (Post 22152162)
Nope, wife put her foot down on that. Was thinking of taking the front brake off my mtb and running cruiser. I'm already racing velodrome, road, mtb and when the season hits, cross so it isn't like I'm not already riding. Might have to sneak in a ride but the helmet would be kind of obvious.

Impressive. Only racing I'm doing is BMX.... other than on Zwift. I'm considering trying CX this fall, but probably not this year. No reason to take the front brake off, at least by the BMX USA / BMX Canada ruleset. Some track operators get a little odd about things that are different like that though.

cbrstar 07-27-21 02:37 PM

With the carbon forks I'd look at how rough your kid is with his bike. With anything carbon if it gets a good impact then it's pretty much done, and IMHO I certainly wouldn't buy used ones. A friend's kid had his carbon fibre handlebar break a few years ago and he got hurt pretty bad.

Russ Roth 07-27-21 09:19 PM

Not a bad point, I went from thinking carbon forks seem like a scary idea to having carbon forks on most of my bikes including gravel and cross without worrying but casing a jump could go poorly with carbon. I think I'll hold off on that one for a while till he's better. Just waiting on the rims to arrive now.


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