Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Cheap disk brakes

Old 05-09-22, 04:20 PM
  #51  
wolfchild
Banned
 
Join Date: Feb 2008
Location: Mississauga/Toronto, Ontario canada
Posts: 8,721

Bikes: I have 3 singlespeed/fixed gear bikes

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 4227 Post(s)
Liked 2,488 Times in 1,286 Posts
Originally Posted by BlazingPedals
Under hard braking, a disc brake can pull the wheel out of the dropouts, even if tightened correctly, even right over the lawyer lips.
I've never seen or heard of this happening to anybody.
wolfchild is offline  
Old 05-09-22, 04:44 PM
  #52  
DMC707
Senior Member
 
DMC707's Avatar
 
Join Date: Jan 2013
Location: Norman, Oklahoma
Posts: 5,390

Bikes: Too many to list

Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1764 Post(s)
Liked 1,121 Times in 744 Posts
Originally Posted by veganbikes
. Cheap stuff is for rich people who can afford to waste money and time.

I hate rich people !




But Egads -- where on earth did i put my tall rolly ladder? I believe the help left a coo-pon for velveeta in my book on the top shelf! Just venting chaps - but when a man desireth nachos after a long ride, whatcha gonna do?

DMC707 is offline  
Old 05-09-22, 04:51 PM
  #53  
DMC707
Senior Member
 
DMC707's Avatar
 
Join Date: Jan 2013
Location: Norman, Oklahoma
Posts: 5,390

Bikes: Too many to list

Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1764 Post(s)
Liked 1,121 Times in 744 Posts
Originally Posted by Koyote
I have a disc brake bike with QRs, and it works just fine. If anything, bolt-on wheels should hold even MORE securely.

The type of dropout is a non-issue in this case.

Correct - Used 'em on mountain bikes for a long time --- Yes - thru axles are standard now, -- but when bikes as burly as a Santa Cruz Bullitt or Nomad were using QR's years ago ---they're fine for most uses
-- my '17 Tarmac had discs with QR's also - never an issue
DMC707 is offline  
Old 05-09-22, 05:58 PM
  #54  
Kai Winters
Senior Member
 
Join Date: Oct 2008
Location: Northern NY...Brownville
Posts: 2,556

Bikes: Specialized Aethos, Specialized Diverge Comp E5

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 234 Post(s)
Liked 444 Times in 257 Posts
Wow...that is all
Kai Winters is offline  
Old 05-09-22, 08:55 PM
  #55  
couldwheels
Banned.
 
Join Date: Apr 2022
Posts: 87
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 18 Times in 17 Posts
Originally Posted by BlazingPedals
Besides an adjustment problem, this could also be a compatibility issue. Even though the builder was a bike shop, LS could have a mis-match between the levers and the pull required by the caliper. IOW, two sets of junk parts don't like each other. But most likely, it's just the nature of the brakes to need a lot of adjustments.
OP experienced a dangerous "piston reversal". It does confirm the caliper is getting pulled all the way to the limit and a little bit beyond by the brake lever. In this case, it is matched correctly.

Piston reversal, is typical on cheap mechanical disc brakes, possibly including bottom end Shimano ones too. The universally accepted reason to this is excessively worn brake pads or installed one of those cheap brake pads with insufficient pad thickness.

The solution is either replace the pads more often and checking your suppliers to make sure you avoid getting pads of insufficient thickness. Or adjust the caliper housing. Make the side the of the caliper with the piston closer to the rotor. It can prevent piston reversal problem and lengthen replacement interval of the brake pads. In most cases, this adjustment technique will also improve brake pad grip reducing the amount of force needed to squeeze the levers.

One thing you need to watch out for with this "offset" caliper adjustment is the stationary pad. The backing plate should NOT protrude beyond the caliper housing. If it starts doing so, then it's time to replace the brake pads or find a new source selling pads with more thickness.
couldwheels is offline  
Old 05-10-22, 08:01 AM
  #56  
prj71
Senior Member
 
Join Date: Jun 2015
Location: North Central Wisconsin
Posts: 4,601
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 2965 Post(s)
Liked 1,167 Times in 763 Posts
Originally Posted by wolfchild
I've never seen or heard of this happening to anybody.
https://www.bikeforums.net/bicycle-m...d-braking.html

https://web.archive.org/web/20121005...quick_release/

A front disc brake caliper behind the fork blade generates a powerful force tending to loosen a quick release and pull the wheel out of the fork. A special hub, and a fork with a hole rather than a slot for the axle, are needed to surmount this problem.

https://www.sheldonbrown.com/disc-brakes.html

https://diskbrakesqr.wordpress.com/

https://bicycles.stackexchange.com/q...brand-new-bike
prj71 is offline  
Old 05-10-22, 09:57 AM
  #57  
couldwheels
Banned.
 
Join Date: Apr 2022
Posts: 87
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 18 Times in 17 Posts
Originally Posted by prj71
https://www.bikeforums.net/bicycle-m...d-braking.html

https://web.archive.org/web/20121005...quick_release/

A front disc brake caliper behind the fork blade generates a powerful force tending to loosen a quick release and pull the wheel out of the fork. A special hub, and a fork with a hole rather than a slot for the axle, are needed to surmount this problem.

https://www.sheldonbrown.com/disc-brakes.html

https://diskbrakesqr.wordpress.com/

https://bicycles.stackexchange.com/q...brand-new-bike

For some reason, I never had those problems on disc + QR. I brake aggressively. I ride on city and constantly hit 30 mph on the streets and often had to make full stop in the shortest distance possible from 30 mph. Never had issues losing alignment with such braking treatment.

However, I do tighten my QR quite a bit with two thumbs and then I prevent the QR skewers from opening on its own by zip-tying the ends to the dropout.
couldwheels is offline  
Old 05-10-22, 10:57 AM
  #58  
vespasianus
Senior Member
 
Join Date: Jul 2019
Location: In the south but from North
Posts: 685

Bikes: Turner 5-Spot Burner converted; IBIS Ripley, Specialized Crave, Tommasini Sintesi, Cinelli Superstar, Tommasini X-Fire Gravel

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 396 Post(s)
Liked 376 Times in 210 Posts
Originally Posted by couldwheels
For some reason, I never had those problems on disc + QR. I brake aggressively. I ride on city and constantly hit 30 mph on the streets and often had to make full stop in the shortest distance possible from 30 mph. Never had issues losing alignment with such braking treatment.

However, I do tighten my QR quite a bit with two thumbs and then I prevent the QR skewers from opening on its own by zip-tying the ends to the dropout.
And honestly, every single XC MTB bike before Fox/Shimano came out with their stupid 15mm axle used a QR with disc brakes. And you never really heard of someone having this issue.
vespasianus is offline  
Old 05-10-22, 12:58 PM
  #59  
autonomy
Senior Member
 
autonomy's Avatar
 
Join Date: Jun 2016
Location: Boston Roads
Posts: 978

Bikes: 2012 Canondale Synapse 105, 2017 REI Co-Op ADV 3.1

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 507 Post(s)
Liked 237 Times in 133 Posts
Originally Posted by Koyote
And that saddle tilt. oof.
And those tires! 40mm party in the front, 25mm business in the back? What am I looking at?

P.S. I've ridden two mountain bikes and now an adventure bike with disc brakes for the last 20 years, and never had a problem with QR and disc brakes, even with the cheapo Giant bike I had in college.

Last edited by autonomy; 05-10-22 at 01:02 PM.
autonomy is offline  
Likes For autonomy:
Old 05-10-22, 01:06 PM
  #60  
autonomy
Senior Member
 
autonomy's Avatar
 
Join Date: Jun 2016
Location: Boston Roads
Posts: 978

Bikes: 2012 Canondale Synapse 105, 2017 REI Co-Op ADV 3.1

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 507 Post(s)
Liked 237 Times in 133 Posts
I only clicked on that link an didn't bother with the rest because of this:

This suggests the quick release was not properly attached or tightened at that point in time. If it was indeed loose when you were riding, the wheel could have moved in the dropouts and the disc rotor then jammed in the brake caliper.
Yeah, that's not an indication of a problem with disc brakes and QR. More like "preventing a rare accident in case of user error"
autonomy is offline  
Likes For autonomy:
Old 05-10-22, 02:57 PM
  #61  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 7,768
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,875 Times in 4,639 Posts
Originally Posted by autonomy
I only clicked on that link an didn't bother with the rest because of this:



Yeah, that's not an indication of a problem with disc brakes and QR. More like "preventing a rare accident in case of user error"
Yeah, I read enough at that link to see the same thing: lots of casual cyclists don't know how to us QRs properly, and even plenty of regular riders don't know the difference between an internal cam and an external cam QR -- much less understand why the former is superior to the latter. User error does not equate to poor design.
Koyote is online now  
Old 05-10-22, 03:08 PM
  #62  
indyfabz
Senior Member
 
indyfabz's Avatar
 
Join Date: Jan 2010
Posts: 39,062
Mentioned: 210 Post(s)
Tagged: 1 Thread(s)
Quoted: 18320 Post(s)
Liked 15,300 Times in 7,231 Posts
Back in the 90s I was leading a group on our club century to Brooklyn. After about 25 miles with ups and downs we stopped for water, etc. As we were leaving a guy picked up his bike out of a rack and his front wheel fell off. He had forgotten to engage his QR. I think that was in the days before lawyer lips were as common.
indyfabz is offline  
Old 05-10-22, 07:48 PM
  #63  
couldwheels
Banned.
 
Join Date: Apr 2022
Posts: 87
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 18 Times in 17 Posts
Originally Posted by autonomy
And those tires! 40mm party in the front, 25mm business in the back? What am I looking at?
If you have tires of different width, better to put the skinnier tire at the back. The tire that is more likely to get caught in road imperfections (the skinnier one) if put in the back is safer.

Riders on tight budgets, will try out a new tire one at a time. Consider yourself lucky if you can replace both tires on a whim. like I already have long, big cracks on my tires (tires have made around 5000 miles) and have no money for replacement so I have limited my outdoor rides to slow recovery rides only. My real training only happens in the stationary bike for now.
couldwheels is offline  
Likes For couldwheels:
Old 05-10-22, 11:01 PM
  #64  
sjanzeir
BF's Resident Dumbass
 
sjanzeir's Avatar
 
Join Date: Apr 2016
Location: Jeddah, Saudi Arabia
Posts: 1,566

Bikes: 1990 Raleigh Flyer (size 21"); 2014 Trek 7.6 FX (size 15"); 2014 Trek 7.6 FX (size 17.5"); 2019 Dahon Mu D9; 2020 Dahon Hemingway D9

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 792 Post(s)
Liked 1,493 Times in 496 Posts
LarrySellerz you might find this helpful
sjanzeir is offline  
Old 05-10-22, 11:51 PM
  #65  
sjanzeir
BF's Resident Dumbass
 
sjanzeir's Avatar
 
Join Date: Apr 2016
Location: Jeddah, Saudi Arabia
Posts: 1,566

Bikes: 1990 Raleigh Flyer (size 21"); 2014 Trek 7.6 FX (size 15"); 2014 Trek 7.6 FX (size 17.5"); 2019 Dahon Mu D9; 2020 Dahon Hemingway D9

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 792 Post(s)
Liked 1,493 Times in 496 Posts
Bear in mind that most cheap mechanical disk brake calipers are of the post mount variety with cheap, low quality IS adapters. It is those adapters that can make it impossible to get the caliper positioned properly for decent braking, even by an experienced LBS mechanic. To keep costs down, the mating surfaces that the actual caliper bolts onto are left unmachined; to make matters worse, some are countersunk too aggressively after they had been drilled and threaded leaving little or no mounting surface to to keep the caliper in proper alignment. Perhaps it was this that the bike shops you took the bike to were experiencing.

With single-piston mechanical disk brakes, it has been my experience that the ideal way to adjust caliper positioning is to use an old, worn brake pad first. Allow me to explain.

Slip the spent brake pad into the non-piston (stationary) side as you normally would. Now, turn the adjustment bolt in so that the back plate of the pad (the metal part) sits just a little recessed from the inner surface of the caliper (directly facing the rotor.) Now - assuming that your IS adapters will cooperate (see above) - position the caliper so that what's left of the spent pad's braking material barely touches the (perfectly trued) rotor - leaving a little daylight in between, just so - and tighten the two bolts down.

Now back the non-piston adjustment bolt all the way out, install the first new pad, and then turn it back in to get the braking material as close to the rotor as possible, with just a little daylight between the two (with no rubbing.) this will ensure that the rotor won't flex much when the other, piston-actuated pad presses on it from the other side.

Slip the other pad in; make sure that the actuation arm is released all the way to its resting position, pull the cable tight by hand and tighten the anchor bolt.

Don't forget to readjust the non-piston pad ad it wears down every so often.
sjanzeir is offline  
Likes For sjanzeir:
Old 05-11-22, 01:12 AM
  #66  
LarrySellerz
Senior Member
Thread Starter
 
Join Date: Mar 2021
Posts: 1,964
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2644 Post(s)
Liked 474 Times in 344 Posts
Originally Posted by autonomy
And those tires! 40mm party in the front, 25mm business in the back? What am I looking at?

P.S. I've ridden two mountain bikes and now an adventure bike with disc brakes for the last 20 years, and never had a problem with QR and disc brakes, even with the cheapo Giant bike I had in college.
performance and safety. its a 37 in the front but I inflate it to about 100 psi so I think some of the surface isn't in contact with the road unless the terrain is bad. I do feel that Im fishtailing sometimes but I attributed that to poor grip on the back tire (no idea what it is, grabbed it from an abandoned bike I found) could it be because the front tire is so much bigger? The bike is legit, I took it on a spirited hill climbing group ride yesterday and was able to finish it.

Last edited by LarrySellerz; 05-11-22 at 01:17 AM.
LarrySellerz is offline  
Old 05-11-22, 06:11 AM
  #67  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 7,768
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,875 Times in 4,639 Posts
Originally Posted by LarrySellerz
its a 37 in the front but I inflate it to about 100 psi
Larry’s next post: “Why did my front tire blow off the rim?”
Koyote is online now  
Likes For Koyote:
Old 05-11-22, 10:32 AM
  #68  
prj71
Senior Member
 
Join Date: Jun 2015
Location: North Central Wisconsin
Posts: 4,601
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 2965 Post(s)
Liked 1,167 Times in 763 Posts
Originally Posted by couldwheels
For some reason, I never had those problems on disc + QR. I brake aggressively. I ride on city and constantly hit 30 mph on the streets and often had to make full stop in the shortest distance possible from 30 mph. Never had issues losing alignment with such braking treatment.

However, I do tighten my QR quite a bit with two thumbs and then I prevent the QR skewers from opening on its own by zip-tying the ends to the dropout.
I had the problem frequently on my last Giant road bike that had QR and disc brakes. Not to the point where my wheel ever fell out, but constantly had to loosen the skewer and re-adust because the wheel would go out of alignment every now and then so the brakes would start rubbing. One of the many reasons I sold and moved to a road bike with thru axles.

As we go into the future all of the good bikes will be sold with thru axle. QR will be reserved for department store bikes and entry level bikes.
prj71 is offline  
Old 05-11-22, 10:34 AM
  #69  
prj71
Senior Member
 
Join Date: Jun 2015
Location: North Central Wisconsin
Posts: 4,601
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 2965 Post(s)
Liked 1,167 Times in 763 Posts
Originally Posted by Koyote
Yeah, I read enough at that link to see the same thing: lots of casual cyclists don't know how to us QRs properly,.
Another reason the switch was made to thru axles. It "dummy proofs" the system.
prj71 is offline  
Old 05-11-22, 10:37 AM
  #70  
prj71
Senior Member
 
Join Date: Jun 2015
Location: North Central Wisconsin
Posts: 4,601
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 2965 Post(s)
Liked 1,167 Times in 763 Posts
Originally Posted by Koyote
Larry’s next post: “Why did my front tire blow off the rim?”
I'm starting to think Larry is a couple fries short of a happy meal...
prj71 is offline  
Old 05-11-22, 10:39 AM
  #71  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 7,768
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,875 Times in 4,639 Posts
Originally Posted by Koyote
Yeah, I read enough at that link to see the same thing: lots of casual cyclists don't know how to us QRs properly, and even plenty of regular riders don't know the difference between an internal cam and an external cam QR -- much less understand why the former is superior to the latter. User error does not equate to poor design.
Originally Posted by prj71
Another reason the switch was made to thru axles. It "dummy proofs" the system.
No one has argued that thru axles aren't superior to QRs when it comes to disc brakes. But the fear-mongering over QRs with discs is a bit overwrought.
Koyote is online now  
Old 05-11-22, 06:57 PM
  #72  
couldwheels
Banned.
 
Join Date: Apr 2022
Posts: 87
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 18 Times in 17 Posts
Originally Posted by prj71
As we go into the future all of the good bikes will be sold with thru axle. QR will be reserved for department store bikes and entry level bikes.
That's totally fine with me. But never really had issues with QR and disc. Maybe it has something to do with the drop out design. Some keeps the QR from moving around.
couldwheels is offline  
Old 05-11-22, 08:28 PM
  #73  
LarrySellerz
Senior Member
Thread Starter
 
Join Date: Mar 2021
Posts: 1,964
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2644 Post(s)
Liked 474 Times in 344 Posts
Originally Posted by Koyote
Larry’s next post: “Why did my front tire blow off the rim?”
that won't happen to a tire inflated 20 psi over the max.
LarrySellerz is offline  
Old 05-11-22, 10:23 PM
  #74  
couldwheels
Banned.
 
Join Date: Apr 2022
Posts: 87
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 18 Times in 17 Posts
Originally Posted by LarrySellerz
that won't happen to a tire inflated 20 psi over the max.
I think the Koyote meant the tire exploding the rim to shreds. Resulting to this type of accident:
couldwheels is offline  
Old 05-11-22, 10:52 PM
  #75  
LarrySellerz
Senior Member
Thread Starter
 
Join Date: Mar 2021
Posts: 1,964
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 2644 Post(s)
Liked 474 Times in 344 Posts
Originally Posted by couldwheels
I think the Koyote meant the tire exploding the rim to shreds. Resulting to this type of accident:
nah cubewheels, he was under the impression that the manufacturers "limit" on the tire pressure means that if you exceed it you risk malfunction. This is just untrue, unless you double the max pressure or something
LarrySellerz is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.