Disc brake conversion

raylo32

100 kW
Joined
Jan 4, 2019
Messages
1,085
Location
Frederick, MD USA
Did a long hilly ride recently on my Cannondale TSDZ2 bike that included some 14% grades and long fast downhills. The old rim v-brakes felt really marginal as speeds climbed to about 40 mph... which is what I limited my speed to by alternating brief applications to front and rear on the downhills. Discs would give more confidence, for sure. The fork has disc mounts but the frame doesn't. Awhile back I tried a popular adapter that fits around the rear eyelet and dropout but it just didn't fit my frame. Then I found these, but never really explored it further. Anyone here use these? How do they work?

https://www.chasertech.com/disc-brake.html
 
I have rim brakes on my cyclocross bike and have no problems using those at high 30 MPH speeds. Maybe try new pads if yours are on the older side or glazed.

The majority of braking does come from the front brake so you could just throw a disc on there and leave the rear alone.
 
I switched to discs, my main motivation was seeing all the metal scrubbing off of the rim itself, esp in wet conditions.

I don't know how old your frame is, but the shortest adaptor they show is for 145mm across the rest dropouts?

And is it full suspension? That's the main plus of the floater style with a strut as they have less effect on the suspension action, but if you have a hardtail there other simpler, lighter adaptors.

Trying it just on the front is a good idea too, it might take care of the problem. Depending on how heavy the bike is tho, too big a front rotor can collapse the fork backwards.
 
raylo, I had a '99 SC Bullit back in the day, and it had disc tabs and v-brake posts on the swingarm. Initially I did run disc brakes up front and ran a good set of v-brakes in back for a light weight effort...got down to 28 pounds. In some decently hilly off road terrain with long descents, this combo worked fairly well. It's the disc up front that will be doing most of the work, as you know. While I would no longer want to do a split disc/V setup anymore, it can work quite well in most cases.

I don't have much faith in those aftermarket disc conversion setups for swingarms "in most cases". I think you'll find just doing the front will satisfy most of your concerns on that C'dale hardtail.
 
raylo32 said:
The old rim v-brakes felt really marginal as speeds climbed to about 40 mph...

Do your old rim brakes feature old hard pads and old corroded cables? Maybe start with fresh Kool Stop salmon pads and die drawn stainless steel cables in new housings before you call your brakes marginal. V-brakes set up that way outperform the majority of disc brakes.
 
Brake shoes and rims are fine. 30 mph is fine, especially on the flats. 50 on a 15% downhill is not. 40 is marginal.

COAR said:
I have rim brakes on my cyclocross bike and have no problems using those at high 30 MPH speeds. Maybe try new pads if yours are on the older side or glazed.

The majority of braking does come from the front brake so you could just throw a disc on there and leave the rear alone.
 
Please guys, this is NOT my first rodeo. I'm probably not going to make this conversion because the rides that raise issues are rare and because of the expense of new brakes and new hubs. But I am curious if this sort of conversion really works.

Chalo said:
raylo32 said:
The old rim v-brakes felt really marginal as speeds climbed to about 40 mph...

Do your old rim brakes feature old hard pads and old corroded cables? Maybe start with fresh Kool Stop salmon pads and die drawn stainless steel cables in new housings before you call your brakes marginal. V-brakes set up that way outperform the majority of disc brakes.
 
raylo32 said:
Please guys, this is NOT my first rodeo. I'm probably not going to make this conversion because the rides that raise issues are rare and because of the expense of new brakes and new hubs. But I am curious if this sort of conversion really works.

I've seen at least a couple of YouTube videos on conversions using the unit you linked. It was one of the better options, depending on the orientation of your dropouts. That goes for most of the conversions. One video tests compares a few options, including the linked one.
 
Look into regen braking/ebrakes as it will save a lot on pads.
At 325lbs I could go down any steep hill using zero bike brakes.

203 discs up front help out as thats where the majority of the stopping power comes from but people also like to lockup the rear.

[youtube]ieeV3pLSoVo[/youtube]
 
Regen doesn't work with mid drives and besides, I normally don't want anything slowing me down on the downhills. These long steep 10%+ ones are an exception and not found on every ride. Otherwise I am looking for all the free speed I can get on the downhills. So no regen for me.

The Shimano XT hydros with 180mm rotors on my Stumpy are fantastic and all the brakes I need. Don't need or want bigger rotors... it would be too touchy for my 235 pound all up weight (me and e-bike).

markz said:
Look into regen braking/ebrakes as it will save a lot on pads.
At 325lbs I could go down any steep hill using zero bike brakes.

203 discs up front help out as thats where the majority of the stopping power comes from but people also like to lockup the rear.
 
Just saying for anyone else out there reading this, thats one of the positives about direct drives because the more weight the motors pulling more mass and momentum the more brake pads you go through and having regen braking on the fancy controllers or ebrake on the generic controllers is a real bonus. Along with the other pro's and con's.

Dual rotor disc braking with hydraulics front and rear, lock up the wheel instantly :lol:
 
raylo32 said:
Regen doesn't work with mid drives and besides, I normally don't want anything slowing me down on the downhills.
Just to clarify, regen only kicks in when you switch it on-- most use a brake lever switch that sends the regen signal to the controller when the lever is pulled only slightly, usually before much analog braking force is applied to the analog brakes. More deluxe implementations utilize variable regen.

Otherwise, yes there is a small amount of drag from a dd hub when no power is applied, but that is not regenerative braking, and it is hardly noticeable on downhills.

Anyway, as you say, in your case, not applicable.

PS, don't disqualify Chalo's suggestion of high performance pad compound pads just because you felt he was taking you for a biker newbie. They do work much better than all the others I have tried. Have you ever tried them?
 
99t4 said:
Just to clarify, regen only kicks in when you switch it on-- most use a brake lever switch that sends the regen signal to the controller when the lever is pulled only slightly, usually before much analog

Well depending on the controller. Slip region is only activated by releasing the throttle. Seems most controllers are like you’re saying it’s only activated by a switch while there’s other controllers like the one I use the region is activated by releasing the throttle. Then the E brake function is connected to a switch but set at a much higher current.

My slip regen is set to 6 A,
Then the E brake is set to 50amps.
 
99t4 said:
PS, don't disqualify Chalo's suggestion of high performance pad compound pads just because you felt he was taking you for a biker newbie. They do work much better than all the others I have tried. Have you ever tried them?

I will not begrudge someone their shining, spinning disks if they need the additional stopping power however I made a copy of this web page sometime ago ....
Disco Fever.jpg

The pain I find with my rim brakes is that I have to loosen them to remove the wheel. Of course that has given me lots of practice in tuning and adjusting them 8)
 
We have had this discussion in our road bike club. Lots of folks moving to disc bikes... but not me. My 18 pound Litespeed with high end rim brakes is just fine slowing or stopping from any speed on any grade. IMO discs are a fad for road (racing type) bikes and not worth the additional weight and complications... and certainly not worth having thru axles. Uggh. The issue gets more complicated for other classes of bikes like our e-bikes for instance. Not here to get into all that... it would be a whole other thread.


LewTwo said:
I will not begrudge someone their shining, spinning disks if they need the additional stopping power however I made a copy of this web page sometime ago ....
Disco Fever.jpg

The pain I find with my rim brakes is that I have to loosen them to remove the wheel. Of course that has given me lots of practice in tuning and adjusting them 8)
 
was wear of rim mentioned here in this thread?
with disc brake you replace pads and eventually after years disc also.
with Vbrakes rim gets thinner and thinner - replacing rim is a real cost, lacing new rim
 
LOL... yes, that's part of that "whole other thread" I mentioned. But since you went there... I once had a MTB rim actually fail. It got too thin and developed a crack that propagated around 2/3 of the circumference. Started making a strange ticking noise in the rock gardens on a ride and when I looked at it I was like =:O. Rode it gently down a fire road to get back to my car. After that I started using the Mavic rims with ceramic braking surfaces which pretty much eliminates that problem. As do disc brakes, of course. I am riding those ceramic rims on my TSDZ2 Cannondale with v-brakes.

miro13car said:
was wear of rim mentioned here in this thread?
with disc brake you replace pads and eventually after years disc also.
with Vbrakes rim gets thinner and thinner - replacing rim is a real cost, lacing new rim
 
LewTwo, love the pic of the rim brakes they used in the comparison and the example they used for the disc brake...cable pull Avid BB7's? The part about "very young" mechanics knowing how to work on disc brakes, but perhaps challenged by rim brakes...what? Bleeding hydraulic disc brakes can be challenging, especially without the specific tools for many mechanics. I was not aware of the compared difficulty of adjusting rim brakes...especially V-brakes. Well, thankfully neither involve rocket science...LOL!

raylo, I'm kind of with you on the disc brake application for road bikes in a general way. Hardcore road rocket boys can benefit from hydros, TDF honchos, and a lot of riders in high elevation descents also benefit. Extremely rainy locales can give a nod to road bike hydros too. In the real and more common riding scenarios most riders do just fine with good rim brakes.

For my mountain biking I've pretty much always used disc brakes since '99...Hayes was the thing back then. I've only ever used single piston units until recently. For my big hit bikes I just went to 203mm rotors. They got a little challenged occasionally in some places like Moab on my pedal-only bike. You could literally smell brake pad material sometimes...LOL!

With my Nomad/BBSHD now at about 50 pounds, I just installed a set of 4-piston Tektro Orions with 203mm front and 180mm rear. While there are no extreme, extended downhills here, the heavy bike with a motor require less pressure for smooth, effective braking now. Hand/wrist pump and fatigue is greatly reduced and almost eliminated on long rides. I also did away with my hydro brake shutoff sensors. With these brakes, it's much nicer to stay on the pedals a bit as I approach or go out of corners with the motor still on power, using the brakes to control entry and exit speeds in corners or obstacles. I notice many/most of the burlier trail emtbs like the Trek Rails and such are coming with 4-piston brakes. Makes sense.
 
I am still not convinced of the value of discs for hard core road racing even in the mountains. I am (or was) one of those guys and have ridden the Rockies and Alps on rim brakes. Never had the slightest issue braking hard into a late apex turn. Disc may provide a little lighter feel, I guess. Maybe. And maybe prevent a tire from overheating. But I have plenty of discs. My Stumpy came with rim brakes and I swapped in the XTs. I can't imagine needing more even with the motor. Easy one or 2 finger finger modulation. Feel like they could stop a motorcycle. I have BB7 mehanicals on a travel bike I built up and GRX hydros on a gravel bike I built up. All good stuff.

TNC said:
raylo, I'm kind of with you on the disc brake application for road bikes in a general way. Hardcore road rocket boys can benefit from hydros, TDF honchos, and a lot of riders in high elevation descents also benefit. Extremely rainy locales can give a nod to road bike hydros too. In the real and more common riding scenarios most riders do just fine with good rim brakes.

For my mountain biking I've pretty much always used disc brakes since '99...Hayes was the thing back then. I've only ever used single piston units until recently. For my big hit bikes I just went to 203mm rotors. They got a little challenged occasionally in some places like Moab on my pedal-only bike. You could literally smell brake pad material sometimes...LOL!
 
Back
Top