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upgrading gears, shifters on kids 24" mountain bike

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upgrading gears, shifters on kids 24" mountain bike

Old 10-09-11, 05:13 AM
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mihlbach
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upgrading gears, shifters on kids 24" mountain bike

My 7 year-old son and I do a lot of trail riding. He's on a 24" GT mountain bike. The only problem with his bike (other than weighing a ton) is the 3x7 drive train with twist-grip shifters and shimano tourney rear deraileur. The twist-shifter is too hard for him to twist and the deraileur is a flimsy POS. He spends more time trying to get in the right gear than anything else, it goes out of adjustment easily, and sometimes we have to stop at the base of the hills so I can shift for him.
What he really needs are some decent trigger shifters and a rear derailleur that isn't made out of tinfoil. I considered installing some old 9-speed equipment I have lying around, but that would require a new rear wheel, which I am not willing to pay for if I can avoid it. Can anyone suggest a matching 7-speed set of trigger shifters and rear derailler that doesn't cost a ton and can be used with existing 7-speed freewheel? I've looked around and not sure what will work.

Last edited by mihlbach; 10-09-11 at 05:20 AM.
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Old 10-09-11, 05:28 AM
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Really, any of the Shimano rear derailleurs are fine. I would wait until it breaks before replacing it (based on your description, you might be there already), and I would replace with another Tourney. They shift just fine. Any derailleur bent or damaged is not going to shift well. Until then, it should work very well. One problem/nuisance on any upgrade is I am assuming your son's bike does not have a frame mount for the RD, so it is a claw unit. Most the Tourney derailleurs have integral claws, whereas the better stuff, you will need to buy a claw to mount it.

On shifters, I can't stand the twist grip stuff myself. I have installed many sets of the Tourney push button shifters, come complete with cables and housings. Find them on line for $13. The only issue for some people is the front is friction, but I prefer friction on the front anyway. I have used dozens of these over the years, on several personal bikes.


http://www.amazon.com/Shimano-SL-TX3...8159623&sr=8-4

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Old 10-09-11, 05:44 AM
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Thanks,

That shifter looks like it will solve the problem. I am still wary of the tourney deraileur however. Maybe a new one will solve the problem of constantly having to adjust it. Will any deraileurs higher up the Shimano heirarchy work with the shifter linked above?
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Old 10-09-11, 07:04 AM
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Shimano Alivio is a decent mid-grade derailleur but Altus or Acera would work fine too for a little less money. It probably isn't worth putting higher end components on a 7-year-old's bike that he will outgrown in a couple years anyway. I know a lot of people don't like twist grip shifters, but they honestly shouldn't be that difficult to operate unless there is something wrong with them. Try replacing the rear derailleur if you think that is a problem and lube or replace the cable and lube the shifter. If that doesn't get things moving smoothly, then new shifters may be in order.

One thing I have noticed when people have problems with rear derailleurs not staying in adjustment on kids' bikes is that often kids will just lay a bike down rather than finding a bike rack or using the kick stand. Dropping the bike on the drive side can screw up a derailleur.
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Old 10-09-11, 08:26 AM
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Originally Posted by mihlbach View Post
Thanks,

That shifter looks like it will solve the problem. I am still wary of the tourney deraileur however. Maybe a new one will solve the problem of constantly having to adjust it. Will any deraileurs higher up the Shimano heirarchy work with the shifter linked above?
I have used those shifters with Shimano Deore LX, and everything inbetween. They are on my wife's 1994 Trek 950 right now.

+1 Kids drop bikes, derailleurs do not like to hit the ground and tend to get bent. There are guards sold for RD, not perfect, but should help. A slight bend on that RD, and shifting is impacted.
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Old 10-09-11, 06:07 PM
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He doesn't have any trouble with the left (front) shifter. The right shifter has always been hard to shift, especially into the lowest gear, which is one of those huge "mega range" bailout gears that is way larger than the next gear. That may have something to do with it...the pulley seems to hang up on it a bit when shifting.
My son knows to lay his bike down on the NDS and he hasn't had any major crashes (yet), so I think the parts are in working order. At any rate, the rear deraileur doesn't look bent or damaged and doesn;t even have any scratches on it, and I am able to get it to shift OK, but the shifter still offers a lot of resistance for some reason, especially in the lower gears.

Anyway, thanks for the help. Looks like I'll be able to resolve the problem relatively cheaply with a new shifter or deraileur or both.
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Old 10-09-11, 06:46 PM
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mihlbach: Make sure that the shift cable housing ends are correctly prepared and fitted with the appropriate ferrules. Improperly set up, the cable housings will tend to creep and bind, causing the derailleurs to go out of adjustment easily and to be difficult to shift. Also make sure that the cable wire attachment to the derailleur is correctly routed and firmly attached. If the end is frayed it is difficult to clamp securely.
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Old 10-09-11, 07:12 PM
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It might also make sense to have the rear derailleur hanger aligned. I have run into a few bikes this year with shifting issues that were solved by fixing the alignment trouble. It should be about a $10 repair at a shop.
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Old 10-10-11, 01:58 AM
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If you have good 9spd laying around, including a hub, and can do the install yourself. I vote to go for it! Spokes will be about $30, plus lacing. It's a 24 so he'll be riding it for awhile. If you can lace them yourself you could get spokes online for $15 and reused the rim. Total cost $15

I just did the same for my son. He's 7 also. I had an old xt 9spd. Swapped out everything and relaced the existing rear with the xt hub. He loves the rapid fire over the grip shift.
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Old 10-10-11, 02:08 AM
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There are 9-speed freewheels available these days. Not the thing for heavy riding, but should work OK for your son. Seems to me it might be worth a shot to get out of having to rebuild a wheel.

You could also look into the microshift line of components, which seems to be getting solid enough reviews.

Last edited by dabac; 10-10-11 at 02:16 AM.
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Old 10-10-11, 02:33 PM
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Not to say that this applies to your 7-yr old, but I recently took a bunch of kids on a simple, mostly flat, paved path ride. And there were lots of complaints by kids and parents about shifters on their bikes. I tuned and adjusted some. But many behaved just fine. As I coasted behind and watched a these riders shift, I observed these common issues:

1. mis-shifting to the wrong gear or forgetting to shift until too late
2. shifting under FULL and ABUSIVE loads - mostly the boys that like to destroy mechanical stuff
3. shifting while coasting and not spinning the crank
4. lack of understanding of gear ratios and mechanical advantage
5. bad habit of torquing grips when honking or pedaling under stress (not good for grip shifts).

These seem to be pretty common among younger riders (and some older ones too!). What I noticed with my older kids is that as they got more proficient with shifting, they benefited more from closer-ratio gearing. So the 3x6 gears on their kids bikes could be swapped for a 2 x 7 or even 1 x 7 gearing with less range. And thumbshifters do work, but my kids still have small hands and the reach wasn't as favourable for them. My nephew has now grown taller than his Dad, so he's finding adult-sized components better fitted to him, and he's riding 1 x 7 gearing. Those are things you may want to think about in your upgrade.

But the tough part for all these kids will be to educate them (and their parents) in basic concepts and habits of shifting. I have enough challenges getting sufficient critical mass of kids to do a flat ride. And the last mtn bike ride I did with scouts got some ire from parents who's boys whined too much about the challenge of their short 8 mile jaunt, albeit, it was fairly hilly and moderately technical, to the point where the boys had to really do BOTH serious cardio AND know how to shift to make it up the hills. But there's stuff I might want to upgrade on any kid's bike. But before I do that for my own kids, I make sure they're maximizing the use of what they've already got.
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Old 10-11-11, 09:51 AM
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I hear you. My son doesn't really understand when to shift or what gear to shift into. I have to coach him from behind, which usually works, but he certainly isn't overpowering his equipment...still way to young for that. I hope we can solve this shifter problem because he's a talented MTBer and can navigate obstacles really well and can easily do 20+ miles of singletrack in a single ride.
At any rate, I ordered an Alivio deraileur and Altus 7-speed trigger shifter. We'll see how that works. Thanks for the suggestions.
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