sd5782 

I bought a used Jamis Coda that I believe is from 2003 or earlier. Problem is brake shudder. Wheels are true, but it has a pulsing and grabbing perhaps 10 times per wheel revolution.



Avid speed dial 5



Avid single digit

I ride all older bikes, but purchased this to set up my brother in the hills of Tennessee. My bikes generally have poor brakes except a couple with cantilever. Would this perhaps be just from hard 20 year old pads? I did play with the red brake screw on the levers which changed the feel but not the grabbiness. Lots of adjustments on these so installation will be as interesting as setting up cantis I presume. Anything else to consider beside pads, and am I on the right track? Powerful brakes are a different concept to me.

ClydeClydeson

Interesting. Brake shudder on cantilever (centre pull) brakes is common, esp. with headset or stem mounted cable hanger, because as the brakes activate, the momentum of the bike + rider causes the fork to flex back slightly, which effectively pulls the cable tighter, which pulls the brakes tighter, which makes the fork flex back more... etc etc... until the brake pads can't hold the force anymore and the brakes slip, the fork springs back forward, and the cycle repeats, usually multiple times per second.

This doesn't happen with direct-pull 'V' brakes because that type of flex in the fork does not affect the tension in the brake cable, so it must be some other mechanism causing it. Maybe small dents in the rim, or some foreign sticky substance on the rim, or uneven wear through the anodizing (or whatever coating) on the rim causing different amounts of friction as the wheel turns.

cyccommute 

The first place to start is with the headset. Check to see that it is properly adjusted. Lock the wheel with the front brake and rock the bike back and forth. If you feel movement in the headset, you need to tighten it.

The next thing to check is the brake arms. Are they tight to the frame? Wiggle them to ensure that they aren’t sloppy. New brake pads might help as well.

sd5782 

I thought headset first too. Rocked it and all solid. I will clean brake tracks and check tightness on brake arms.

_ForceD_

Just pointing out, as Clyde alluded to above, the brakes pictured are V brakes, and not cantilever. — Dan

tyrion

I'd toe-in the brake pads about 1mm.

sd5782 

Yep, I will toe them in too. I’ve not dealt with V brakes before, but brake pad setup looks similar to cantis. Perhaps I will clean up the pads a bit first as well as the braking surface on the rims. Then a little practice with adjustment, and then new pads probably. They brake arm pivot bolts were snug and no gouges or dents in rims, but I will clean them up good.

dsbrantjr

20 year old pads? I would replace them first.

sd5782 

I will certainly do that too as soon as I get some ordered. I usually hang out on the C&V forum, and half my bikes have pads 30-40 years old. Did I mention that most of them brake poorly, but I am in the flatlands. My brother will need confidence inspiring braking in the Tennessee hills with this bike. This modern stuff is an education for me.

veganbikes

V-brakes are specific to Shimano, technically linear pull brakes are the correct terminology but aside from that I do like the diagram.

_ForceD_

Also pointing out that there are center pull caliper brakes that don’t shudder. It’s really (mostly anyway) the center-pull CL brakes…with the long lead along the head tube that shudder

Dan

sd5782 

First attempts didn’t help. No new pads yet, but I spent time on this with no luck yet. I cleaned rims with a rag and brake cleaner. I took off the pads and sanded slightly to assure a flat surface. I made sure of alignment with rim. I tried toe in and then toe out. I paid attention to the perpendicular angle of the pad hitting the rim. Still gets a shudder. Rear also, so it doesn’t point to headset being loose.

I did this prior to getting new pads as I had time to fiddle and was just experimenting. Another question is that most of the linear/v brake pads I see have a longer trailing section rather than being symmetrical as these pads are. The pads on it are stamped Avid, so I believe they are stock. The rims are very true and in very fine shape. The braking system seems smooth and powerful, so this problem is quite aggravating.

fishboat

Those pads are marginal even when new, compared to good pads. At 20 years old, they're pretty much junk at this point.

Kool Stop International - High Performance Bicycle Brake Pads Since 1977

Threaded post

Salmon / Part Number KS-TLTSA

or

Salmon / Part Number KS-SUP2SA

or the blended black/salmon versions.

They say "self tow in" ..I don't think I'd go that far. tow(actually "toe") them out on the rear end about 2mm (actually 2mm when you visually test them after things are tightened up..often it may take more than a 2mm spacer to yield 2mm after tightening). Sometimes a leave the rear beak on the pad. I just rebuilt a bike where I had to file the rear beaks flat with a metal file to eliminate a shudder. They run solid now without a hit of shudder or squeak.

sd5782 

I found a set of pads in my stash and gave them a try.



Jagwire that came on another used bike


These were in fine shape so I hoped for good results. No luck, so I got out some 320 grit sandpaper and went at the rims a bit. These are Richey aero rims that seem quite nice. No dents, and I see circumferential micro grooves at the braking area, so I assume they are machined. No dings or dents.



Richey Aero

I sprayed a bit of WD40 on the pivots and of course played with toe and also the angle the pads hit the rim. I pretty much gave up and thought next to try another 700c front from another bike. Perhaps inadvertently I might have found the problem. I was pushing the bike on a level surface with the lever slightly engaged and under constant pressure. Doing this showed several spots that the brake got tight and then looser as if the rim is wider at these points. A couple spots on the rear also.

I would be under the impression that out of true would not cause this, as both pads could shift together if they had a constant width. I guess next, I will pull the tires and put on my truing stand. On the bike, the rims looked true enough that I would be happy if I got them that way. As I said, no dings or dents, and seemingly little use. I’m not sure of the next step, as sanding out some fat spots sounds like a imprecise operation.

sd5782 

I just thought of something; perhaps if there indeed are wide spots in the rim, I could measure with my dial caliper set a a constant reading and squeeze the wide spots with a clamp or big pliers. It seems crude, but just a thought. As an aside, the rims are stamped made in China. Of course new rims would be the ticket, but I am trying to keep a low budget.

Sluggo

This is unlikely on low-mileage rims, but worth checking: When the inside wall of a double-wall rim develops cracks, the air pressure of an inflated tire spreads the braking surfaces apart at the cracked areas, creating wide sections of of rim and grabby braking action. The rim walls also seem to flex some when squeezed by the brakes. Such wheels can look perfectly straight when the tire is not inflated and only subtly wavy even when inflated.

So pull the rim strip and take a look.

sd5782 

Okay, I believe these rims are more or less junk even with very few miles. Pulling tire and measuring reveals that the external width is not constant around the circumference of the rim. I actually bent the low spots out slightly with a crescent wrench ever so carefully over about 2 hours. Lots of measuring with dial caliper and a gentle touch.

I also used a 19mm open end wrench as a crude gauge at first. The wrench would fit over the rim at some spots, but be too narrow at other spots. I did my adjustments and the wrench test got better and then I got out the dial caliper to fine tune. I believe, the ultimate problem was that the brake tracks were never going to run on the same plane. Perhaps some kind of lathe could solve this. On the truing stand, the wheel runout was less than 1 mm.

This is all too bad, as the Richey hubs look very nice. I put on a cheap schrader valve Araya PX 35 rimmed wheel and no brake shudder at all. It is just kinda amazing to me in my education that these rims could look so little used and perform like this. The bike is from 2003 and as I said, low low miles. The 9 speed cassette isn’t even greasy. I will probably look for another vintage 130mm rear that will accept the 9 speed cassette. Perhaps this is why I ride older bikes.

hokiefyd 

Given what you posted, I agree. I've had this with a bike or two in the past, and I found it practically impossible to restore the overall rim width to anything even close to consistent when I had high spots like this. I'd not toss the wheels...at the very least, take a side cutter and cut all the spokes out and keep or sell or donate the hubs. (...if you're really out of options, I'd pay you to ship them to me! )

sd5782 

Actually, I was hoping that in the future I might be able to build new wheels with these hubs. I would like to reuse the spokes because of cost and the fact that they are nice stainless steel, so the question would be the spoke length and erd of these rims vs some new ones like the Sun CR18 that would be more suitable for 35s anyhow. The Ritchey rear is an offset style. My brother who will be getting this bike in the next month lives close to 500 miles away, so I hope to find another 130 bcd rear to use for now so that I can play with the nice Ritchey hubs over the winter. I am totally shocked though at the experience I’ve had with these, especially since this bike and these components are certainly nowhere near bottom grade and seem to have little use and abuse.

79pmooney

And when all else fails, go for the real dirt. Rub the rim down with garden dirt.

I had shudder as bad as I have ever seen on my rear rim after dragging a freshly glues tubular across the sidewall. (Second glued wheel after a 20 year layoff.) No combination of epoxy and lacquer thinner, Simple Green and clean dish soap would touch it. Applied the dirt and done! Three weeks later and a few hundred miles, a light re-coat would be nice.

sd5782 

If it was for me and nearby in the flatlands here of NW Ohio I would deal with it some more. As it’s for my brother in the Tennessee mountains, I want it to be correct if he grabs a handful of brake going downhill at 30 mph. Actually, more dangerous if the front wheel isn’t pointed forward. Perhaps if I find a temporary rear, I can try my hand at wheel build over the winter. I’ve built exactly 1 on a heliocomatic hub with a Weinmann concave. As an aside, I bet that the more powerful v brakes on this bike will accentuate the imperfections lots more.

Yan 

Don't get Kool Stop Salmon pads. They are notorious for squealing. Velo Orange sells some "squeal free" pads. I've used them before and they didn't seem like anything special. My brakes were already not squealing so I couldn't test the squeal free claim. But maybe you could try them.

sd5782 

I think either set of pads I have are fine as far as noise and performance goes, it is just the poorly manufactured rims. Truthfully, I wouldn’t expect this from a Walmart bicycle.

oldbobcat

Look at your front hub too. There should be no tight spots or wobble.

fishboat

I have the salmon pads on 8 different bikes. No squeal on any of them. Depends on the setup, grunge on the rims.... I've read many suggestions on BF by folks over the years that the salmon pads are a good investment, I've never heard anyone mention they are notorious for squealing. During setup trial and error I've had a squeal or two, but I can always adjust the brakes/pads to quiet them down..and they stay that way.

..just first hand experience and an observation...others mileage may vary..