front end shimmy due to loaded rear rack?

[Christopher Young]

Hi All,

I have a 61.5 cm AHH with a rear rack installed by Riv when I bought the bike. The rack looks great, but I've noticed that when I have it loaded, I often get a front-end shimmy when I am riding fast and take my hands of the grips, and people riding behind me have confirmed the rack is moving a lot. It sounds exactly like what Paul M described in a 2024 post about his 64 cm Clem:

"I also experienced a front-end shimmy if I took both hands off the handlebars with a loaded rear rack trunk mounted on the top of the rack". Exactly!!

Because of the size of the frame and the way it's installed (see picture), my theory is that those vertical supports are very long and hence not so rigid and I'm getting some sort of harmonic motion (like a mini-version of the Tacoma Narrows bridge). Anyway, I've tried some minor adjustments to try to make the rack supports shorter and hence more rigid, but with only minor (if any success). At this point, I'm thinking of a couple of options:

1. more radically changing the attachment points for the rack to get those longer supports a lot shorter. This could get tricky though, working around the rear brake.

2. Removing the basket (it can go on my newly acquired 64 cm Clem L) and changing to a rear bag (e.g. Sackville Bagboy) that hangs from the saddle and hence doesn't really rest all its weight on the rack. I can still strap lighter stuff on the rack.

I'm strongly leaning toward option #2 because I like the look of the rack as is and I think the behind the seat bag might look very nice. I guess another option is to install a different rear rack with more rigid supports, but again, I like the look of this rack and this isn't my bike for hauling heaving loads (that's be the Clem).

Have others experienced this sort of problem and if so, how did you fix it?

thanks

Chris Young

ABQ

[tom butcherboy]

Beware of free advice..but.  I think your rack might benefit from some 'fore/aft' connection. it seems mostly side to side. And as the load get taller, center of gravity rises.  Your seat stay eyelets are both raising their hands looking for work. I had a similar issue when downhill braking and rebalancing some sort of front-end load was helpful.  Tom.

[Eric Daume]

Riv did a poor job of installing that rack. The forward struts should go to the forward/upper attachment points on the seatstays. That will increase the triangulation and stability.

Eric

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[Brian Turner]

I have to agree with Eric - that’s an awfully wonky mounted rack, and I would not feel comfortable riding with it like that. It surprises me they would do it that way, especially when they’ve always seemed overly cautious with the way racks are mounted.

Brian
Lexington KY

[Christopher Young]

Thanks Eric! I think your assessment is right. Looking at this rack installation vs. others, what really stands out are those very long vertical struts, which don't form anything like a triangle (though there is a diving board attachment, so 5 total contacts with the frame). Anyway, I like your solution, but there is an issue that might not be apparent from the photo. There are indeed attachment points higher up on the seatstays, but they blocked by the brake, which sticks out a bit on either side. It's going to take some pretty creative bending (a bend one way and then another back) to get those struts to attach to those upper points. I'm thinking it can be done, but was wondering if anyone else had already dealt with this on an AHH so I don't end up demonstrating how poorly I can bend struts. Ironically, I installed a rack (I think the same model) on my wife's 60 cm Platy and because it has V brakes that aren't in the way I was able to have the upper/forward struts go almost horizontally from the front of the rack to the seatstays, so no bending. It doesn't look as elegant as this installation, but it definitely has that triangular strut setup and she doesn't have any vibration from the rack.

Something I tried but that didn't fix it was to lower the rack a bit (no fender, so plenty of clearance) and I brought it forward, sliding more of the diving board under the rack. I hoped that might make that connections shorter/stronger and stiffen things, but if it did, it wasn't enough. 

I will not be too upset if going for a Sackville Bagboy is a good solution (just looking for an excuse to buy one of those). For this bike, I think that would look really nice and then the rack is just a backup to keep the bag of the wheel. 

Chris

[Christopher Young]

BTW, to be fair to the Riv guys, as part of my attempt to fix this problem, I also moved the back strut attachment points up a little from the attachment points right at the dropout to the next ones, a few inches higher. I was thinking that would make them a little shorter/stiffer and make the angle a little different, but it didn't help.

Chris

[Mike Rossi]

Ahh, I see the diving board, but vertical attachments to those seat stay bosses will help. Harbor Freight sells a tubing bender (Pittsburgh 1/4”-3/8” tubing bender) for $10. One of my favorite “bike tools”. Get perfectly matched bent struts and stop looking for odds and ends around the house to bend the struts around!

Mike

On Nov 27, 2025, at 4:41 PM, Christopher Young <nmtr...@gmail.com> wrote:

BTW, to be fair to the Riv guys, as part of my attempt to fix this problem, I also moved the back strut attachment points up a little from the attachment points right at the dropout to the next ones, a few inches higher. I was thinking that would make them a little shorter/stiffer and make the angle a little different, but it didn't help.

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[Christopher Young]

Oooh! I'm getting one of those tools! I guess regardless of whether I got the Bagboy route it would still be nice to get that rack more solid. What's the limit on how much you can bend a strut? E.g., would 90 degrees be too much? It's going to take some significant bends to get around the brake, at least on the left side.

Chris

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[Mike Rossi]

What's the limit on how much you can bend a strut?

I’m not sure. I used this scrap, but it was already a little wonky.

[Guy Jett]

So many questions:

* Would be nice to see the original Riv installation. 

* Did that installation include the basket or did you add the basket?

*  Was the rack initially that high above the rear tire?

Additional Observation:

* There is basically no triangulation in this setup, especially with the near vertical angle of the diving board.   As a result fore and act movement may be a contributing factor to the lateral motion and shimmy. 

Suggestions:

* Get rid of the basket. That only contributes extra weight very high up that exaggerates the shimmy. 

* Reduce the height of the rack to 1 cm or less above the tire. Will shorten the rear stays a bit. 

* Connect the forward stays directly to the fittings above the brake.  They will be much shorter and provide better triangulation to the rack system. 

* Get rid of the bend in the left rear stay. Alternatively consider bending both rear stays inward as this may counteract the lateral motion. 

Hope you find a solution, 

GAJett

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Guy

[Christopher Young]

Guy,

Great questions. 

• Attached is a picture showing the original installation, as done by Riv. As you can see the back strut connects to a point near the dropout, so those struts were even longer. And the rack was even higher above the rear tire. I've got it a bit down and can go a little further. Maybe they put it high thinking I might add a fender?
• I did add the basket and agree that's contributing to the problem. i'm planning to move it to the Clem, but note that it's the wald "racing" basket, so pretty minimal. Note also that in this earlier picture, the basket isn't there, but I'm pretty darn sure the shimmy had already shown up.
• I'm definitely going to try to figure a way to connect those forward struts to the the higher connection points, by the brake. That's going to be challenging.
• If i do that, and I've still got issues, I may also move the back struts up to the connection point where the forward ones currently are. That would seem to be more in line with other installations I've seen in photos on the Riv site and elsewhere.
• bottom line: I think this weird installation has everything to do with the brake blocking easy access to the higher attachment points. You'd use those if you could get to them. I'm a little surprised the Riv guys didn't tell me this might be a problem and suggest a different rack setup, but maybe they thought I wouldn't put much weight on the rack (not that I've been really loading it up). Anyway, I definitely don't blame them. I'm the one that picked that rack and said to put it on the back. I could have asked them what they'd recommend for that bike.

I appreciate all the suggestions! The basket is going for sure, and I'm very likely going to get a Bagboy, but I still want to try to fix this issue. It just shouldn't be like this.

Chris

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[TOM CUNNINGHAM]

If the side pull is in the way...that's only on the cable side. The other side is open to experiment with a single strut (HD if available) to see if that seems to make a difference.

https://groups.google.com/d/msgid/rbw-owners-bunch/CAC_3U-3xe9wvm-ty827XMGgRH1FccqM9tN4LiZwKNtcH9MAVGA%40mail.gmail.com

.

[Tyler Johnson]

Hi, Chris.

I agree with Tom – experiment with those upper bosses even though one of the two bosses is currently blocked by the sidepull of the brake caliper. Before you bend the aluminum strut, determine if a triangle will stop the side-side shimmy. 

On the unblocked side, mount the strut normally to the outboard of the boss. On the blocked side, mount one of the struts from the inside of the boss. If it's still a bit blocked by the sidepull, you can use old V-brake cone & cup parts to shim it clear of the brake. (I can't recall how blocked the boss was when I saw it last month.) 

If that solves the wobble, then bend the strut. You probably only get one chance to bend the aluminum strut before it weakens when you bend it twice.

Another possibility is to temporarily switch out the rear brake so you can do your experiment with normal, straight struts with no shims. Next time we meet, I can lend you an old centerpull brake with enough clearance for your chunky tire that will free up lots of space for the struts. If that experiment works, then you have an excuse to buy a Paul Racer for the rear. 😀

Tyler

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[Paul M]

The issues with how the front struts attach to the rear eyelets definitely needs to be addressed. But even then, there is a good possibility that the front end of the bicycle will experience a shimmy while riding with your hands off the handlebar. I've experienced this with proper rear racks attached (Nitto, Salsa Wanderlust HD steel, Jannd) with moderate loads (rack trunk or panniers) and still experience the front-end shimmy when removing my hands from the handlebars. This happens when peddling <10 mph. I sense that it has to do with the long wheelbase/longer rear-end that certain Rivendells have and probably affects the taller/larger frames more. It's happened on a 64cm Clem L, Platypus 60cm but even a double top tube Rosco Bubbe 56cm. Not to confuse this with a speed wobble that happens at much higher speeds even when your hands are on the handlebars. All the bikes mentioned are rock solid when descending at high speeds. 

[Eric Daume]

Random thought: can you flip the rear brake caliper and mount it on the underside of the seat stays? Like a Havnoonian. 

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Guy

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[J J]

Christopher, just to build on Paul M’s point. Have you tried riding the Homer without the rack? I had the same shimmy issue on a Hunqapillar. Grant and Mark at Riv first had me remove the Nitto 33R (Big Back Rack). The shimmy remained. Next, Grant suggested tightening the headset to add friction. That helped, but only once I tightened it more than felt reasonable, which hinted at a headset/steerer issue.

The final fix was swapping the stock FSA (ball bearings) for an IRD DoubleRoller Drive headset with roller/needle bearings top and bottom. That eliminated the shimmy entirely, with or without the rack, loaded or not. Grant said shimmy can be mysterious and varies by frame, so starting with a rack-free test is worthwhile. Grant also said, “Keep your hands on the bar — don’t ride no-hands!”

Jim

[Patrick Moore]

+1 for seeing if the shimmy remains without (1) the basket and (2) the rack.

I’ve had shimmy come and go on at least 2 bikes from things as minor as changing tires. My 2003 Riv road custom shimmied with 240 gram 1.25”  Paselas but not with 400 gram 1.35” Kojaks (and this had stout tubing; 58 cm c-c size), and the current Matthews (much lighter tubing) replacement shimmies with 41 mm 300 gram Naches Passes but didn’t with 29 mm 175 gram Elk Passes. Slow or cruising speed shimmy in both cases, and only when riding no-hands.

I seem to recall another instance of shimmy that disappeared when I replaced or removed a rack, but I can’t remember it clearly.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[Danny]

FWIW, I have a 61.5 Homer without racks, and I get shimmy with both hands off the bars. I was planning to experiment with a roller bearing headset and tire swap this spring, so thanks for sharing your experiences Jim and Patrick.

Danny

Madison, WI

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[Gregory Johnson]

Chris,

Another option is to try a different rack.

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