always.ultra

Hello!

I just registered here in hope of hearing from other Space Horse owners if they are experiencing the same. My new Space Horse frame (size 55) wobbles badly at about 26km/h when carrying 8-9kg in the rear rack (two Ortlieb back rollers hanging as low as possible in the rack). I couldn't drive free-hands at that speed without high risk of a crash, and even have to move my hands to the brake shifters (using a drop bar) to dampen the oscillation once it started. The wooble starts spontaneously at that speed but I can initiate it with a sidewards hit to the steerer tube.

Any other suffering horsemen here? Any hints about how to reduce it? Could it be an untrue real wheel? My rear wheel is not fully true... The front one is.

Thanks for your help in advance!

groovestew

Maybe a bent or broken axle? Hold your frame and try to wiggle the wheel. It shouldn't move. That was a problem I had with an old bike once.

The mechanics sub-forum would be a good place for this question.

BobbyG

I have a Charge Plug and my wheels have been in and out of true as I've been adjusting them myself (and probably making them worse in the long run). With my commuting backpack on the rear rack and the rear wheel slightly out of true I get the wobbles when riding hands free. A quick roadside spoke adjustment (well, hopefully quick) and the hands-free shimmy is gone.

Darth Lefty 

It's a common behavior of road bikes when going downhill no-hands... indeed it's possible with any vehicle with trailing caster steering, including cars and trucks, motorcycles, and shopping carts. I've had it both on my Paramount and my Super Sport, which are pretty different models, both downhill no hands with my lunch in a tail bag. There was a somewhat underdamped mode on my R1200GS. Some cars and trucks and some motorcycles have steering dampers but I've yet to see one on a road-going bicycle.

Things to stop it... generally add resistance to the steering or break up the oscillation... lean your thigh on the top tube. Put more weight on the pedals and less on your seat. Pedal. Aim for rougher pavement. Grab the bars loosely, not firmly, otherwise you can overcorrect and feed the shimmy.

Things to fix it... Checking everything can't hurt, including frame straightness, headset adjustment, rear wheel alignment, wheels true and dished, tire beads seated. But most knowledgeable types say it's not an alignment thing.

Things to prevent it... Switch to bigger, more treaded tires or a stiffer frame... mountain bikes basically don't do this.

Jobst: The likelihood of shimmy is greatest when the only rider-to-bicycle contact is at the saddle and pedals. This position gives the least damping by hands, arms, and legs.

Grant: Do not think your bike has a mysterious perfect storm of nuancical details that culminate in a bugaboo

Zinn has also written a lot about it in his column.

unterhausen

My All City Macho Macho Man shimmies badly even at low speeds. I don't even have to lean back much. It probably would be really bad if I put weight on the back. Not sure what to suggest, shimmy usually means alignment problems, and is made worse by weight on the back.

I really don't mind it much. It has never really shimmied on me with my hands on the bars. The biggest problem I've had with it is when I'm using a hydration pack and forget to clip the belt before I get started. It's really difficult to sit up and clip it together with the bike shaking.

dynaryder

Not saying this is the issue,but just to eliminate it as a cause I would check your headset tightness. I've built a couple dozen Space Horses(and Macho Man Discs),and the Cane Creek headsets tend to 'settle'. They'll be fine after assembly,but after I've test ridden the bike around the warehouse and slammed the brakes on a few times,I've noticed about half of them have loosened and needed re-tightening. Grab the spacers on your steerer and twist,if you can get them to turn,your headset is loose.

rmfnla

My Curtlo had a moderate shimmy when I rode no-hands.

I swapped to stem from a 130mm to a 110 mm (for filling purposes) and the shimmy went away.

I assume hanging the handlebars out further changed the weight distribution; my point is lots of factors can contribute to this.