Frame shimmy Wheeler loaded: use a trailer ?
08-29-18, 06:34 AM
#1
Senior Member
Thread Starter
Frame shimmy Wheeler loaded: use a trailer ?
Hi, framebuilders advice dearly needed!
I am on tour with a cyfac audax bike, loaded with 2 small fork bags and rear rack+panier (and bar bag). 16-17kg load panniers and bags Included. 3-4kg in the fork bags.
The frame is way too supple and the bike goes into shimmy going downhill past 20kmh and can even do so on the flat.
I ruptured my 28mm front tire and replaced it with a 25mm. « Speed » wobble got even worse, it can get crazy riding 20kmh on the flat now!
Prettt unusable. I could take the train home, get a new bike/Build my other frame , or i could get a Bob Yak trailer delivered to the next big town i traverse, which would be way more convenient.
But, as framebuilders, do you think a trailer has reasonable chances to solve the problem, or might the load and lever arm of a trailer be as bad or worse ? There still would be torsion on the chainstays, though keeping top and down tube less in the equation...
Many thanks,
Nicolas
08-29-18, 12:14 PM
#2
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Location: Rochester, NY
Posts: 18,048
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
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Nicolas- I hope you've had a good trip so far otherwise. I, too, have lived with a shimmying bike for many miles. Mine was very stable with a light or no load but easy to induce the shimmy when really loaded for camping. I've spent a lot of time playing around with weight location in the panniers but only have pulled a Bob for a short time and when rather unloaded. For my bike the trailer felt more stable if also slower.
I have heard of a very few Bob users that also suffered a shimmy, although more of a wobble. But overall most have found the trailer to be more stable then not by a wide margin. The number of shimmy stories with panniers and a rack top load are near legend. But I'm a pannier guy just the same. Andy
I have heard of a very few Bob users that also suffered a shimmy, although more of a wobble. But overall most have found the trailer to be more stable then not by a wide margin. The number of shimmy stories with panniers and a rack top load are near legend. But I'm a pannier guy just the same. Andy
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AndrewRStewart
AndrewRStewart
09-01-18, 01:57 AM
#3
Senior Member
Thread Starter
Hi,
sorry for the late reply and thank you for all the informations.
I tried switching all the load to the rear rack and much to my surprise it rode way better, though the rear triangle creaked and transmission grinded.
so i put minimal load (700g each side) on front panniers and it made some of a compromise.
I hit the mountains in 1 week so I need to make a decision. I prefer panniers too.
Why is a bob slower ? I asked bob riders on the road, they also said it made uphills harder than panniers.
weight diff vs front and rear rack and panniers is not huge, and rolling resistance of the extra wheel vs 2 overloaded wheels...
Thanks again !
Nicolas
sorry for the late reply and thank you for all the informations.
I tried switching all the load to the rear rack and much to my surprise it rode way better, though the rear triangle creaked and transmission grinded.
so i put minimal load (700g each side) on front panniers and it made some of a compromise.
I hit the mountains in 1 week so I need to make a decision. I prefer panniers too.
Why is a bob slower ? I asked bob riders on the road, they also said it made uphills harder than panniers.
weight diff vs front and rear rack and panniers is not huge, and rolling resistance of the extra wheel vs 2 overloaded wheels...
Thanks again !
Nicolas
09-01-18, 07:15 AM
#4
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Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,048
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
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I'm no engineer but I suspect some of the energy losses are due to the side sway/swing of a trailer having a pivot between it and the bike. So each pedal stroke sets the trailer to one side a bit, then the other side. Trailers of one or two wheels have been around for many decades and many thousands before us have found what works best for them. That so many prefer panniers, over and over, suggests that there's something real going on. But trailers do have their place. Some riders just like the loading system differences, some like the ability to carry a big load on a bike with no rack mounting capacities, some need the extra capacity (tandems). Andy
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AndrewRStewart
AndrewRStewart
09-03-18, 01:34 PM
#5
Banned
BoB and (to a lesser number) ExtraWheel single wheel trailers.. have fans ,
for touring..
those blue bags may not stay rigidly fixed ..
but I'm guessing,,
I used 4 panniers .. on my tours..
for touring..
those blue bags may not stay rigidly fixed ..
but I'm guessing,,
I used 4 panniers .. on my tours..
