Me again with question about wheel hop

[Vicki C.]

My rear wheel seems to have a hop (it took me a while to identify, I think, what is happening). The brakes grab in the rear only as well. Cruzbike dealer checked and adjusted the brakes, but a friend watched me riding and said the wheel was doing something funny. Last night I spun it and believe I am seeing the wheel hop and it is not just a characteristic of the bike and braking system.

Has anyone else experienced this? I have emailed Cruzbike support but really need to get this dialed in right away. As always, ideas and suggestions welcomed.

 

[trapdoor2]

I have found it pretty common to require 'factory' wheels to be re-trued after the first X-number of miles. Spokes stretch initially and then take a 'set'. You may simply need to take it to your LBS and have it trued. Custom wheel-builders will do this 'stretch-and-re-true' before delivering a wheel...but it you pay for that in higher overall cost.

 

[Vicki C.]

Thanks. I appreciate the quick reply and Robert's quick reply as well. I will take it to the bike shop. It is just another new experience for me. The bikes I have previously bought new did not need re-truing ever so I wasn't certain what was happening. I am also new to disk brakes and did not know if this would impact the brakes over time.

 

[trapdoor2]

LOL, I'm a 'clydesdale', I tend to punish wheels...I guess that makes me more familiar with re-truing wheels than most.

When I built my first 'Cruzbike Conversion', I used a Walmart donor bike that I bought for less than $100. Before I had 20 miles on it, both wheels were so out 0f round that I was getting seasick! I did a 'home shop' re-true...but eventually had to have my LBS replace the spokes on both wheels...the originals just barely made the grade for 'some kind of metal'.

 

[Vicki C.]

LOL, I'm a 'clydesdale', I tend to punish wheels...I guess that makes me more familiar with re-truing wheels than most.

When I built my first 'Cruzbike Conversion', I used a Walmart donor bike that I bought for less than $100. Before I had 20 miles on it, both wheels were so out 0f round that I was getting seasick! I did a 'home shop' re-true...but eventually had to have my LBS replace the spokes on both wheels...the originals just barely made the grade for 'some kind of metal'.

Well, I am about 140 and 5'8" and shrinking.

 

[ratz]

Disc brakes use the spokes to deliver braking force to the road; that's why they have more spokes than a comparable rim wheel; and yeah it's common for wheels that are not hand made to need a trip for re-tensioning. Oddly though I'd expect the problem on the front before the rear.

 

[Vicki C.]

Disc brakes use the spokes to deliver braking force to the road; that's why they have more spokes than a comparable rim wheel; and yeah it's common for wheels that are not hand made to need a trip for re-tensioning. Oddly though I'd expect the problem on the front before the rear.

The braking on the front is smooth and I don't notice anything.

I am taking it to the shop. I talked with the mechanic and he said that the braking has nothing to do with the rim or spokes. He says it must be a bent rotor or oil on the pads. I told him that when I spin the wheel when I am not on the bike, it doesn't seem to grab. It is only when I am riding it. And I can see that the wheel seems like it moves up and down in the frame.

Well, I am riding the bike to the shop because they already looked at and adjusted the brakes and no one suggested then that there was an additional problem. I noticed some of the symptoms even after I left the shop that day but then was working on a hydration system and the seat comfort and the rack and didn't devote enough attention to the wheel. I haven't ridden but once in a few days and the hop, skip and jump seemed worse. I mean, the bike stops fine, and while the bumping feeling while I am riding is a little annoying, and definitely worse when I brake, I mostly suspect that when things are out of whack it can just get worse and eventually cause damage.

So we will see and I will report in later. Thanks!

 

[ratz]

braking has nothing to do with the rim or spokes

Well, that's a suspect statement, unless physics are different on your side of the country. If the braking force occurs at the rotor and hub interface, how does it get transmitted to the rim? That braking force is transferred through spokes to the rim to the tire to the road. The spokes are as integral to the braking as the rotor. If they don't check the wheel for true, that's lazy.

The other reason to check is because of the noise you have been hearing from the back. A loose spoke can create a ton of mysterious noises and they could even sound like a loose rack bolt. It's a really weird thing until you encounter it the first time.

 

[trapdoor2]

Well, that's a suspect statement, unless physics are different on your side of the country. If the braking force occurs at the rotor and hub interface, how does it get transmitted to the rim? That braking force is transferred through spokes to the rim to the tire to the road. The spokes are as integral to the braking as the rotor. If they don't check the wheel for true, that's lazy.

Most people simply do not "think thru" the physics of such things. They think, "brakes are brakes, spokes are spokes...and never the twain shall meet."
Loose spokes tend to become a cascading failure: one spoke leads to two which leads to many. If you have quite a few spokes that are loose, you may be able to feel the rim moving (in relation to the hub) during braking...which makes the hop seem worse under braking. The disc brake would not feel anything but 'normal' but the bike would get wiggly. Not really a very safe condition, for sure. I'd SAG it to the LBS rather than ride it!

 

[Vicki C.]

Update: Mechanic still maintains that disk brakes were intended for mountain bikes originally because wheels get torqued and with disk brakes the cyclist can continue to ride even if the wheel is messed up, meaning that the spokes and rim condition do not normally affect braking. (I am paraphrasing and probably badly.) He did seem to say that there are some spoke issues that could have caused a braking problem. The hop was attributed to perhaps the tire bead not being seated completely. Or maybe the bad rotor.

The fix: A new rotor, because the one installed had a manufacturing defect that caused a little bump or something that was hitting when the wheel went around and caused the brushing sound I heard when pedaling and the very grabby braking action that caused or contributed to my rough and bouncy stops and maybe even the hop as the wheel turned (sounds like a soap opera).

Honestly, I don't know what all caused which problems, but it makes some sense that the defective rotor could have caused the majority of the problems. He did let out the air and make sure the tire was seated properly.

So, for those of you with the basic complete, or a basic with components supplied with the frame, maybe the rotor could be an issue. I think mostly everyone is building their bikes with their own parts. The two guys at this shop, which is a Cruzbike dealership (one of the few in California), also sell trikes and they have had issue with the Clark(s?) rotors before. They replaced mine with an Avid and told me to watch for issues with the front wheel, which so far seems to be fine, leaving me to think that it does not have the same rotor defect. But I will have on my listening ears.

Thanks for the advice and suggestions. I am learning a lot. (And have a lot yet to learn.)

 

[Vicki C.]

Most people simply do not "think thru" the physics of such things. They think, "brakes are brakes, spokes are spokes...and never the twain shall meet."
Loose spokes tend to become a cascading failure: one spoke leads to two which leads to many. If you have quite a few spokes that are loose, you may be able to feel the rim moving (in relation to the hub) during braking...which makes the hop seem worse under braking. The disc brake would not feel anything but 'normal' but the bike would get wiggly. Not really a very safe condition, for sure. I'd SAG it to the LBS rather than ride it!

It's all good. About a three mile ride each way to the LBS. And I had not felt loose spokes or bubbles on the tire or the tube popping out the side of the tire or anything. Still, if you read my just recent post, it was the rotor that was defective. Who knew?

 

[trapdoor2]

Glad the solution was easy and all's well. It is very difficult to describe such issues via text (and equally as hard to try to help). Nothing like actually being there!

 

[Vicki C.]

Glad the solution was easy and all's well. It is very difficult to describe such issues via text (and equally as hard to try to help). Nothing like actually being there!

I do know that and thought about it as I was cycling home from the shop and was thinking how unfair it was of me to put people on the spot. But the question was still valid and I still find the suggested solutions valid, if not for this incidence, but for other situations, or for someone who has a similar issue. It is all helpful to me. And may be helpful to others who may have ventured for the first time into buying a bike other than from a shop, with a bit of tweaking required. Heck, I mentioned in my first post that I had never even removed and attached a chain or installed a set of handlebars before. Those simple things still involved me researching helps (like making a "tool" to hold the two ends of the chain together while I tried to install the quick link) and learning about disk brakes and seat angles and the differences between seat pads. It is part of the fun of my having this bike, to connect and learn.

 

[trapdoor2]

Well said. There's nothing "unfair" about asking questions; there's no requirement for anyone in particular to respond...but there are nuggets in any response. Much better than getting nothing but 'crickets' from the peanut gallery.

I do know that and thought about it as I was cycling home from the shop and was thinking how unfair it was of me to put people on the spot. But the question was still valid and I still find the suggested solutions valid, if not for this incidence, but for other situations, or for someone who has a similar issue. It is all helpful to me. And may be helpful to others who may have ventured for the first time into buying a bike other than from a shop, with a bit of tweaking required. Heck, I mentioned in my first post that I had never even removed and attached a chain or installed a set of handlebars before. Those simple things still involved me researching helps (like making a "tool" to hold the two ends of the chain together while I tried to install the quick link) and learning about disk brakes and seat angles and the differences between seat pads. It is part of the fun of my having this bike, to connect and learn.

 

[Jim Zimmerman]

This "wheel hop" problem is interesting, especially since the solution was to replace the brake rotor. My T50 started out from the beginning with little hissing sounds coming from both front and rear rotors. It's a little "hiss" every revolution of the wheel. It isn't loud enough to hear while I'm riding so I decided it is a "break-in" thing that will go away after awhile. In the meantime my rear wheel grabs and skids almost every time I brake. The front brake grabs too but it has better friction with the road and doesn't skid. If the grabbing doesn't go away soon I will probably end up getting new rotors.

 

[JeffParker]

Do yourself a favor and upgrade your T50 standard brakes to the TRP-Spyre brakes. Upgrade the front for sure, and the rear too, if you ride hills. Makes all the difference in the world.

 

[Jim Zimmerman]

Upgrading to a more expensive brand of brakes is not an acceptable solution, especially when the problem is the installation, not the equipment. I've had disc brakes before and never looked at them closely because they worked perfectly from the beginning. On closer inspection of these brakes I can see the rotors are not centered on the hub, and when the calipers engage the rotor actually bends (since the caliper only actuates from one side). I'm not sure whether a flexing rotor is a problem but being off-center is. I will try and re-center the rotors and find out if the calipers need to be realigned.

 

[super slim]

What is the make/model of the disk Brakes?

If the disk brakes are Avid BB5 or BB7, here are some video of how to adjust them.

How to minimise brake squeal

 

[Suz]

My T50 started out from the beginning with little hissing sounds coming from both front and rear rotors. It's a little "hiss" every revolution of the wheel.

Hi Jim, I have the same problem so I would love to hear how it turns out. I haven't had the energy to attack that yet. Glad you mentioned it, I thought it was just mine.

 

[Jim Zimmerman]

Suz, I appreciate you chiming in here. Since we both have the same problem it may be a manufacturer's defect. I read a couple of reviews for the Clarks disc brakes but nothing indicated a problem with rotor centering.

I loosened the bolts on the rear rotor and noted that it has some movement around the hub. I tried holding the rotor offset in the direction that would correct it while tightening the bolts but it didn't help. In fact I think it made the problem worse. I want to try again when I have more time, and if I don't succeed I'm going to take it to my LBS and get some expert advice.