Front Braking Problem

[Mtl_Biker]

The fork is not moving at all. But your suggestions have worked out for me (Thanks!) as I think it's the wheel bearings. With strong pressure on the bike and the brakes applied, I found the wheel would "wobble" side to side. I brought the wheel to work with me today and will check it carefully when I have the time. Unfortunately though, I forgot to bring the bearing wrenches (flat wrenches) I have with me so I won't be able to adjust the bearings until tomorrow. But at least I hope to be able to pinpoint the problem.

Further update... Even without the correct wrenches with me, I can see there is no play (nor binding) in the bearings. Smooth as silk. No slop. So it's not the bearings (or their adjustment) that is the problem.

I guess by process of elimination, it must be the spoke tension. Funny, as the wheel spins true. If some spokes are tighter than others, could that be what's causing the wheel to flex to one side when applying the brakes?

Again I'm at my office without proper tools to check or readjust the spokes. At home I have a truing stand and a dish tool (to make sure the wheel is centered on the hub). I don't have any way to check spoke tension other than just by feel. When I was (a lot) younger, I actually built a set of road wheels. So even out of practice I should be able to solve this problem. (I hope!)

 

[Sierratim]

Further update... Even without the correct wrenches with me, I can see there is no play (nor binding) in the bearings. Smooth as silk. No slop. So it's not the bearings (or their adjustment) that is the problem.

I guess by process of elimination, it must be the spoke tension. Funny, as the wheel spins true. If some spokes are tighter than others, could that be what's causing the wheel to flex to one side when applying the brakes?

Again I'm at my office without proper tools to check or readjust the spokes. At home I have a truing stand and a dish tool (to make sure the wheel is centered on the hub). I don't have any way to check spoke tension other than just by feel. When I was (a lot) younger, I actually built a set of road wheels. So even out of practice I should be able to solve this problem. (I hope!)

Surprising.

I agree that the spoke tension is the next most likely candidate. I too have built several sets of wheels and true up my own but don't have a tension gauge. I Check the SpokeTension by Ear . Works pretty well for me.

Good luck.

 

[Mtl_Biker]

Surprising.

I agree that the spoke tension is the next most likely candidate. I too have built several sets of wheels and true up my own but don't have a tension gauge. I Check the SpokeTension by Ear . Works pretty well for me.

Good luck.

What's surprising? That the wheel spins true?

When I flexed the wheel and the spokes there was in some areas a popping sound... The kind of sound that would be if the wheel hadn't been stressed/flexed when the spokes were tightened. You know what I'm talking about... if the spokes are tightened and the friction of the spoke within the wheel is too high, the spoke ends up sort of twisted. Stressing the wheel to remove that pressure/friction allows the spoke to untwist and then you can do proper adjustments. Right now I can't tell if the wheel still spins true (after stressing the wheel and hearing the popping noises) but once I bring my truing stand I'll be able to know.

Funny though that the bike is really quite new (bought new late fall) and only has about 1,500 km on it. I would have expected the spokes to untwist (if that is indeed the problem) much earlier.

My hearing isn't my best sense, so maybe I should invest in a spoke tension gauge?

 

[Sierratim]

What's surprising? That the wheel spins true?

When I flexed the wheel and the spokes there was in some areas a popping sound... The kind of sound that would be if the wheel hadn't been stressed/flexed when the spokes were tightened. You know what I'm talking about... if the spokes are tightened and the friction of the spoke within the wheel is too high, the spoke ends up sort of twisted. Stressing the wheel to remove that pressure/friction allows the spoke to untwist and then you can do proper adjustments. Right now I can't tell if the wheel still spins true (after stressing the wheel and hearing the popping noises) but once I bring my truing stand I'll be able to know.

Funny though that the bike is really quite new (bought new late fall) and only has about 1,500 km on it. I would have expected the spokes to untwist (if that is indeed the problem) much earlier.

My hearing isn't my best sense, so maybe I should invest in a spoke tension gauge?

I was surprised that it wasn't the hub, but stranger things have happened.

Others have reported good results with the Park Tool spoke tension meter.

One of my sons is an engineer at a cycling component supplier. Among other products they sell machine assembled wheels which apparently most bikes use these days. They'd had a rash of problems with various assemblers 'cutting corners' one of which was not consistently using spoke prep. This of course allowed the tension on these spokes to loosen over time. I'm sure they're not the only wheel supplier that had this issue. You might keep an eye out for this.

 

[rich c]

That popping sound can just be spokes rubbing together. Age doesn't mean anything related to spoke tension. Between the hole in the rim, the nipple, and the hub, there can be a change within the first 50 miles as everything seats into place. Just pluck the spokes like a guitar and you can find anything loose. There are apps now for your phone to listen to spoke tension. Not unlike a tuning app for guitars.

 

[Mtl_Biker]

I was surprised that it wasn't the hub, but stranger things have happened.

Others have reported good results with the Park Tool spoke tension meter.

One of my sons is an engineer at a cycling component supplier. Among other products they sell machine assembled wheels which apparently most bikes use these days. They'd had a rash of problems with various assemblers 'cutting corners' one of which was not consistently using spoke prep. This of course allowed the tension on these spokes to loosen over time. I'm sure they're not the only wheel supplier that had this issue. You might keep an eye out for this.

I have some Park Tools and they are superb. I was all set to buy the Park Tool tension meter, but none of the local bike shops have one. Amazon (Canada) wants $128 for it, plus $10 shipping, but the deal breaker for me was that estimated delivery was listed as July 31 to Aug 13. I just can't wait that long! So I ordered a different tool (looked similar though) which was in stock with Amazon and I'll have it tomorrow with free shipping. This is the one I ordered: https://www.amazon.ca/Testeur-tensi...=1595357645&sprefix=spoke+tens,aps,154&sr=8-7

$45 instead of $140. And tomorrow instead of 2-3 weeks from now.

So, with any luck, I'll be back in business in a couple of days and able to ride on the weekend.

 

[Mtl_Biker]

Further update... Believe it or not, after searching and searching, I was unable to find my wheel truing stand. (Old age.) It's years since I've used it and it should be somewhere in my garage but I just couldn't find it. And then I started thinking that even if I could find it, it might not work with my 29" wheels (with or without the tire installed). I must have bought it 50 years ago (not kidding!) and it was a rather simple device... "U"-shaped bracket that could be bolted (or vice-gripped) to a table, with a little arm and "finger" that you could position close to the side of the rim. Most bicycle wheels were quite a bit smaller in those days. So it may or may not work with these big wheels. SIGH

So, in the interest of getting this job done and being able to ride again on the weekend, I ordered a new truing stand. Nobody had one in stock, but I found the Canadian distributor (also here in Montreal where I am) had it in stock. And after sweet-talking a dealer (after speaking to 3 dealers) I'm going to pay full retail but I'll be able to pick it up on Friday. I'm getting a Park Tools truing stand, but not the big professional EXPENSIVE one... this one is a "Home Mechanic" model called the TS-8. Still going to cost $250! Park Tools TS-8

Meanwhile...

The spoke tension gauge arrived. I don't know (and don't really care) what tension the spokes should be but plan to use it to ensure the spokes are as evenly tensioned as possible. What I've found so far, is that some spokes are 24-28 (lbs?) on the gauge while others (mostly on the non-brake side) are as low as 16. I guess that would explain why the wheel shifts to the brake side when braking.

 

[Nova Haibike]

Unlike front wheels on bikes with rim brakes, wheel with disc rotors are not symmetrical. The left/rotor side spokes will be under higher tension than the right side. But the differential should not be as much as you are measuring.

 

[Mtl_Biker]

Unlike front wheels on bikes with rim brakes, wheel with disc rotors are not symmetrical. The left/rotor side spokes will be under higher tension than the right side. But the differential should not be as much as you are measuring.

Thanks for pointing that out.

But on the non-rotor side, the difference in spoke tension among those spokes is quite a bit also. I am very surprised that my wheel had been turning so true. In any case, I'm sure I will improve it.

First step will be to put it on the new truing stand and see if the wheel is still true (after I'd poked around with the spoke and heard the popping noises) and then I'll try to get the spokes on each side more evenly torqued, understanding from what you said, that most likely the left and right spokes will have different tensions. But on each side, those spokes should be close to each other in tension, right?

(I don't have the bike here... only the wheel, so I have nothing to put the wheel into to check whether it's true or not. I have to wait until I get the stand.)

 

[Mtl_Biker]

Just to put this thread to bed... I got my spoke tension gauge and truing stand and with less than an hour of work the bike is fine again. The reason the front wheel tilted to the left (disc brake side) when braking was because the spoke tension was way off. The wheel spun true but because so many spokes on the right side were too loose, when braking the wheel tilted to the left.

It’s pretty much perfect now.

Thank you everyone for helping me figure this out.

 

[Sierratim]

Just to put this thread to bed... I got my spoke tension gauge and truing stand and with less than an hour of work the bike is fine again. The reason the front wheel tilted to the left (disc brake side) when braking was because the spoke tension was way off. The wheel spun true but because so many spokes on the right side were too loose, when braking the wheel tilted to the left.

It’s pretty much perfect now.

Thank you everyone for helping me figure this out.

Wow! Never heard of that before. But if it wasn't the headset or the hub, it pretty much had to be spoke tension.

Glad it's resolved.

Ride On!

BTW - pumped up our mech bikes for a ride. My rear brake was rubbing when I rolled it out. Broken spoke! Naturally rear wheel drive side. Replaced it with a spare spoke salvaged from an old wheel. Tensioned by ear and trued on our old shop stand. Worked fine for the next day's ride but I have borrowed my son's tension gauge to give it a try. Old dogs and all that...

 

[Mtl_Biker]

Wow! Never heard of that before. But if it wasn't the headset or the hub, it pretty much had to be spoke tension.

Glad it's resolved.

Ride On!

BTW - pumped up our mech bikes for a ride. My rear brake was rubbing when I rolled it out. Broken spoke! Naturally rear wheel drive side. Replaced it with a spare spoke salvaged from an old wheel. Tensioned by ear and trued on our old shop stand. Worked fine for the next day's ride but I have borrowed my son's tension gauge to give it a try. Old dogs and all that...

I didn’t use the tension gauge to tension the spokes. At least not blindly. I used it just to identify grossly out of norm spokes for each side. And I just realized that I didn’t use the gauge after I’d finished... I just put the wheel back on the bike and tried it. Pretty much perfect now.

Until a week ago I hadn’t even realized that tension gauges existed.

 

[Spaghetti888]

Quick question about your Amazon tension gauge - how wide are the outer points? I've got 26" wheel with a hub which is laced double-crossed - there's about 108mm between the end of the nipple and the outer cross. I'm a bit worried I won't be able to use the tool on this