from Rookie’s Keyboard
Hello friends,
Today, I saw a bike messenger riding a fixed-gear bike with a camouflage frame and fork. He was experiencing some chain tension problems on the side of the road.
This isn’t uncommon, to be honest. The local messengers were often talking about “fixed-gear slippage” a few years ago when I was closer to the scene. The problem was many times more common for people using old road frames converted to fixed-gear.
Allow me to clarify.
Fixed-gear slippage happens when the rear wheel moves forward ever so slightly during riding. The outcome is instant loss of chain tension and with it the ability to stop via the pedals.
So, what’s the source of the issue?
In most cases, the rear wheel isn’t secured strongly enough and slides forward inside the dropout.
Even a little bit of movement shortens the distance between the rear cog and the chainring enough to decrease the chain tension and make your life harder.
However, there could also be another culprit, albeit it happens less frequently. Sometimes the problem is a rear cog that untightens itself when braking with the pedals. When that happens, the connection between the chain and the rear wheel is instantly lost. There is no slipping in this case, but it often feels like it.
That said, this is unlikely to happen on a proper fixed-gear bike as the rear cog is secured by a locknut with reverse threading preventing that outcome.
Let’s fix this.
Here are the sources of the slippage:
- Quick-release Skewers
“Real” fixed-gear bikes do not use QR skewers, but many people make their fixies by converting an old road frame with horizontal (or semi-horizontal) dropouts. Аnd in some cases, people also keep the QR skewers that those bikes are normally equipped with.
If that’s your case, consider the following:
- Make sure that the QR skewer is tight enough. If you don’t know how to do that, you have no business riding a bike just yet as this is a critical skill.
- Check the QR skewer to see if it has serrated nuts. Higher-quality models have that feature as it increases the friction against the frame and stops slippage.
- Remove the paint on the outside of the dropouts with sandpaper (modest grid) to increase the friction between the QR nuts and the frame. Ofc, that way you will increase the chances of rust (if the frame is made of steel). But honestly, the QR will eat that section of paint anyway.
- Clean the area with a degreaser. Oil, grease and the contaminations that they attract will reduce the friction between the frame and wheel.
While the above can help, the ultimate solution is to replace the hub with a model that has solid bolt-on axles and track nuts.
Bolt-on hubs provide much more clamping force and easily stop the movement of the rear wheel in the dropouts.
Consider a set of Powerful Chain Tugs
Chain tugs are somewhat of a niche tool. Their purpose is to facilitate chain tensioning of fixed-gear bikes and ensure consistency.
By default, they are designed for rear-facing dropouts (the type you see on track frames) and can’t be used on fixies made from retro road bikes.
You may be able to find models built for forward-facing dropouts, but they are very rare.
A decent set of chain tugs installed correctly makes it impossible for the wheel to move forward in the dropouts.
If the issue is coming from the QR/axle/dropouts, the methods above will 100% fix it.
But if the problem is found within the rear cog and its connection to the rear hub, then friends, we have to deploy a different strategy.
If the cog untightens itself when you perform an aggressive skid or brake as fast as possible, inspect the locknut securing it.
As I already said in the beginning, untightening of the rear cog is very rare on a standard fixed-gear bike.
The cog tightens onto the hub in a clockwise direction. Consequently, forward pedaling tightens the cog against the hub even more.
A locknut is also added to the hub to secure the cog. The locknut threads on the hub counter-clockwise.
This is a strategic choice.
When the rider backpedals, the chain spins the cog anti-clockwise. The rear wheel continues spinning forward due to inertia. Thus, it becomes possible for the cog to untighten itself.
The lockring prevents this. When the rider backpedals, the pressure on the cog is anti-clockwise. If the cog starts getting loose and rotates, it will spin the lockring too. But since the lockring is reverse-threaded, the untightening motion of the cog tightens the lockring.
That way the cog is always secured. And if that’s your setup, the only way for the cog to slip would be damaged threads of the hub or the locknut.
Another culprit could be the use of a standard road bike hub instead of a track model. Watch out for that if you’re buying a converted road bike.
Why?
Classic fixed-gear hubs have stepped threading designed for a locknut. Standard road bike hubs have a singular thread. Consequently, you can’t install a reverse-threaded locknut on them.
I know that sometimes people use a nut from an old bottom bracket. This method works but doesn’t eliminate the chances of the rear wheel untightening as the threading is clockwise.
And there you have it, friends.
Another bike issue demystified for all the rookies out there. I am about to pack my bag and head towards the warehouse where I work for now. Wish me luck 🙂
Until next time,
– Rookie
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