Do your gears stop working as well when you fit your race wheels to your bike? This is because different hubs have the cassettes in slightly different places relative to the dropouts, this can cause the gears to shift slowly at best and at worst can cause the chain to jump off the cassette and into the frame or spokes.
Adjusting your gears is really easy and only takes 10 mins or so, but please don’t do this for the first time the night before a big race, practise makes perfect.
A Bike stand helps for this as you can pedal the bike but if you can find something to hang the saddle on so the rear wheel is off the floor that would work just as well.
First things first when your swapping your wheel always have it on the smallest cog
With your racing wheel fitted once again put it in the smallest cog, here we are checking the limit screw for this end, spin the cranks and the chain should spin smoothly, if you hear a ticking here your gears are out and will need adjusting.
There are two cross head screws on the back of your mech, these are the limit screws one will stop your mech from going too far and throwing the chain off the bottom on to your frame and the other stops it from going off the top of the cassette into the spokes.
We start with the mech on the smallest cog and adjust the top screw in or out until the clicking stops and the chain is running smoothly.
Now we want to get the right tension in the cable, the correct tension is a bit “goldilocks” not too tight and not too loose. From the smallest cog shift up to the biggest cog then back down again to the smallest, if its slow going from a smaller cog to a bigger one it’s too loose, if its slow coming down from a bigger cog to a smaller one it’s too tight. Assuming your gears were working fine before on your old wheels there shouldn’t be too much adjustment needed and you can do this with the adjuster on the mech where the cable goes in, twist it a quarter of a turn at a time out if it’s too loose and in if the cables too tight.
Once the cable tension is set correctly and the gears are shifting well we now need to check the other limit screw, to do this shift the mech so that it’s in the biggest cog. You then want to tighten the other screw to the one you tightened before. Tighten this screw only a fraction of a turn, you should see the mech move in at this point if it doesn’t it will need adjusting so that the screw butts up against the stopper. Once you have done this check that you can still shift into the biggest cog, if you’ve over tightened that limit screw you won’t be able to shift into the biggest cog.
Now while you’re at it it’s a good idea to check the other bolts on your mech are tight so using the correct Allen key check the cable is tight and that the mech is tight on the frame.
Last of all its a good idea to check that your mech hanger is straight, they can easily get bent in a crash or even by putting your bike in the car
Don’t whatever you do though try this the day before a race for the first time, practise at home first and make sure you’ve got the technique down, take the bike for a spin and make sure all the gears work and if you are unsure bring your bike in to see us and we will sort it out for you.