Mechanical disc brakes into hydraulic disc brakes on 24" kids bike

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Mechanical disc brakes into hydraulic disc brakes on 24" kids bike
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flag RBL
Posted: May 31, 2020 at 13:30 Quote
I bought my son a 24" bike since he has outgrown his 20". He wants to start MTBing. I bought him a used Cannondale Trial 24". It was good price, I've done a full service to the bike in our local bike shop.

photo

https://www.cannondale.com/en-us/bikes/kids/7-to-12/kids-trail-7-to-12/trail-24-boys/2019

However, there is a problem with brakes. The ones fitted to the bike are mechanical disc brake. The levers stick too far even when I adjust them, but that's not the main problem. They are really hard for him to press. Absolutely no way of one finger braking, not even two finger braking. Heck, he has to use all the fingers and not even then the brakes are on the point. He loves how my hydraulic brakes work, how light the lever is, etc.

How can I fit hydraulic brakes to that bike? Do I need to replace the discs, or just caliper, hose and lever? Will a normal Shimano SLX or similar brake fit to the bike? If I buy a used set of Shimano SLX will I be able to fit them? I would appreciate any help. I know these are pretty basic noob questions, but I am no expert.

I would ask my local bike shop, but all of them are so busy at the moment, none is taking any more bikes to workshops.
flag JonnyTheWeasel
Posted: May 31, 2020 at 13:36 Quote
SLX brakes will be fine.
flag RBL
Posted: May 31, 2020 at 13:53 Quote
JonnyTheWeasel wrote:
SLX brakes will be fine.

Thanks! Do I need to change rotors though? Will it be just a straight swap or a little bit more complicated adventure?
flag Branmuffin
O+
Posted: May 31, 2020 at 14:29 Quote
RBL wrote:
JonnyTheWeasel wrote:
SLX brakes will be fine.

Thanks! Do I need to change rotors though? Will it be just a straight swap or a little bit more complicated adventure?

I would suggest going with a Shimano mt200 hydraulic brake. These are stupid cheap and work fantastic for a kids bike. I think you can get a set for about 60-$70 bucks with rotors on eBay. These came on a Rocky Mountain Growler 24” I bought for my kid and they have been super solid. I would definitely not use the old rotors from the mechanical brakes. They might be OK, or they might have been contaminated by previous owner. Start fresh, make sure your kid can stop sufficiently.
flag RBL
Posted: May 31, 2020 at 14:55 Quote
Branmuffin wrote:
RBL wrote:
JonnyTheWeasel wrote:
SLX brakes will be fine.

Thanks! Do I need to change rotors though? Will it be just a straight swap or a little bit more complicated adventure?

I would suggest going with a Shimano mt200 hydraulic brake. These are stupid cheap and work fantastic for a kids bike. I think you can get a set for about 60-$70 bucks with rotors on eBay. These came on a Rocky Mountain Growler 24” I bought for my kid and they have been super solid. I would definitely not use the old rotors from the mechanical brakes. They might be OK, or they might have been contaminated by previous owner. Start fresh, make sure your kid can stop sufficiently.

Thank you. Sounds great. I'll look around for a set of hydraulic brakes for him. Thanks!
flag JonnyTheWeasel
Posted: May 31, 2020 at 14:57 Quote
Should be a straight swap if you've not got any internal routing to worry about. I'd get the same sized rotors otherwise you'll need to faff with brake mount adaptors.
flag RBL
Posted: May 31, 2020 at 16:19 Quote
JonnyTheWeasel wrote:
Should be a straight swap if you've not got any internal routing to worry about. I'd get the same sized rotors otherwise you'll need to faff with brake mount adaptors.

Thanks for the tip Jonny. Much appreciated.

I'll phone a couple of local bike shops tomorrow to see if any have any stock on some cheap hydraulic brakes and want to do it for me, if not I'll order some myself and try to learn how to do it myself.
flag dood
Posted: Jun 1, 2020 at 0:26 Quote
Yeah, no issues on the rotors. Hop into the buy 'n sell, and git yerself a set of masters/hoses/calipers. Pretty much all this junk is interchangeable, given that the rotor is a standard 6" diameter. Calipers self-adjust to thickness, so it's not a concern.

No need to go crazy either. Old junk works just fine; parts & pads are still available, and since you already have all the caliper adapters, it should be very easy to do. Old Hayes, Hope, Avid, Shimano....for the most part...all of it bolts up.

Hose routing is is breeze. If the c-dale has internal cables, (doesn't look like it?) ditch 'em and find some cable ties. Done.

Haha, it's remarkable how most of my posts end up being "gear doesn't know about gear". A brake lever doesn't care about the caliper, caliper doesn't care about the hose, etc.....It's a lesson I had to learn when doing motorcycle engine swaps. The engine doesn't know what electrics it has, or what particular flavor the clutch master is. Bolt it on and see what happens. If there's a real issue, it'll let you know.
flag RBL
Posted: Jun 1, 2020 at 1:27 Quote
dood wrote:
Yeah, no issues on the rotors. Hop into the buy 'n sell, and git yerself a set of masters/hoses/calipers. Pretty much all this junk is interchangeable, given that the rotor is a standard 6" diameter. Calipers self-adjust to thickness, so it's not a concern.

No need to go crazy either. Old junk works just fine; parts & pads are still available, and since you already have all the caliper adapters, it should be very easy to do. Old Hayes, Hope, Avid, Shimano....for the most part...all of it bolts up.

Hose routing is is breeze. If the c-dale has internal cables, (doesn't look like it?) ditch 'em and find some cable ties. Done.

Haha, it's remarkable how most of my posts end up being "gear doesn't know about gear". A brake lever doesn't care about the caliper, caliper doesn't care about the hose, etc.....It's a lesson I had to learn when doing motorcycle engine swaps. The engine doesn't know what electrics it has, or what particular flavor the clutch master is. Bolt it on and see what happens. If there's a real issue, it'll let you know.

Thank you, much appreciated. Yes, I'm set on replacing the brakes for hydraulic ones. There is not MTBing without good working brakes. It's just a question of will I have to do it myself or someone will do it for me, I'll know in an hour (when my local bike shops open).
flag dood
Posted: Jun 1, 2020 at 1:50 Quote
You'll have NO problem doing it yourself, unless you're not particularly happy wrenching on stuff. Realistically, it's a matter of four caliper bolts, and a couple of pinch-bolts on the levers - maybe some grip removal (with compressed air - no big deal!)(or lock-ons - ZERO issues).

Pretty simple process. 6mm and 5(?) or 4(?)mm allen keys. That's basically it. Prior to install, use a flat-blade screwdriver to push the caliper pistons/pads back into their housings. After installation, pump the brakes a bunch of times to get everything into the correct position....after that, enjoy!
flag RBL
Posted: Jun 1, 2020 at 2:15 Quote
dood wrote:
You'll have NO problem doing it yourself, unless you're not particularly happy wrenching on stuff. Realistically, it's a matter of four caliper bolts, and a couple of pinch-bolts on the levers - maybe some grip removal (with compressed air - no big deal!)(or lock-ons - ZERO issues).

Pretty simple process. 6mm and 5(?) or 4(?)mm allen keys. That's basically it. Prior to install, use a flat-blade screwdriver to push the caliper pistons/pads back into their housings. After installation, pump the brakes a bunch of times to get everything into the correct position....after that, enjoy!

I've never done it myself, so it would take me a good few hours to do both brakes. Also it's brakes, so I need them to be done as good as possible. I do many jobs around our bikes, but I think I would feel better if I knew they are as secure as possible.

Anyway, I got my local bike shop to do that for me (I'm just off the phone). It will costs me a bit more than I would've done it myself, plus he will have to wait a week, but at least I will be sure that it is done to a good standard. A pair of Shimano MT400's, so not bad brakes. After that he can finally start learning MTBing with me. Can't wait Smile
flag dood
Posted: Jun 1, 2020 at 4:41 Quote
Awesome! Hope the new setup works well!

Now it's only a matter of time before he's flyin' past ya on the trails!
flag RBL
Posted: Jun 1, 2020 at 5:29 Quote
dood wrote:
Awesome! Hope the new setup works well!

Now it's only a matter of time before he's flyin' past ya on the trails!

Ha! It won't be hard, I'm not young any more and much more cautious than I used to be. It won't be long before I will be actually holding him back Big Grin
flag RBL
Posted: Jun 7, 2020 at 3:22 Quote
I thought I'll post an update. It might comes handy if someone would search for something similar in future.

My local bike shop has successfully replaced the brakes for hydraulic ones (Shimano MT-401). My son loves them and all is finally well in our little MTB family. All bikes are now fully operational. Next week I plan first ride on our local trails Smile

Thank you Smile
flag dood
Posted: Jun 7, 2020 at 4:54 Quote
RBL wrote:
I thought I'll post an update. It might comes handy if someone would search for something similar in future.

My local bike shop has successfully replaced the brakes for hydraulic ones (Shimano MT-401). My son loves them and all is finally well in our little MTB family. All bikes are now fully operational. Next week I plan first ride on our local trails Smile

Thank you Smile

Dude, that's SO awesome! It makes me melt a little bit!

I look forward to the first videos of him kickin' yer ass down the trail!
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