Sound of wheel freewheeling
This is a chain tensioner and this is a chain tensioner and this is a chain
tensioner. There are two types of chain tensioners used on Brompton folding
bicycles. This is the chain tensioner used on the one and three-speed Brompton
bicycles it was also used on the five speed bicycles. This is a chain
tensioner on a three-speed Brompton. This chain tensioner can easily be identified
by the jockey wheels or the guard disc which is usually silver or sometimes
black. This is a chain tensioner used on a 2 and 6-speed Bromptons that have a
derailleur. The jockey wheels on the derailleur version move side-to-side to
allow the chain to move between the sprockets when you change gear. Inside is
a big spring that keeps your chain under tension. If you take it off your bicycle
without removing the tension first it will fly off! The chain tensioner is
aptly named it keeps the chain under pressure or
under tension
Over time the jockey wheels wear out but they can be replaced. If you keep your
chain cleaned regularly they will last longer. In preparation for setting up the
hub gears when we've replaced the chain tensioner we're going to put it into the
highest gear so the cable is at its slackest. Then we're going to undo the
nurled nut lock and then we're going to remove gear indicator chain. Next we're
going to remove the tension on the chain by folding the bicycle. This allows us to
easily remove the chain from one of the sprockets. Now we're going to put the
bicycle back to the unfolded position. Now we're going to remove the gear chain
indicator nut using a 15 millimeter spanner.
Now you just simply remove the chain tensioner by pulling it. The back of the
chain tensioner is keyed so it fits around the axle plate. We find it easiest
to get the sprocket with the chain on top of it,
and then position the chain tensioner over the axle plate. Then you can put
the chain tensioner bolt back on the axle. It's important to make sure that
the washer is seated in the nut. Then it's simply tightened with a 15 millimeter
spanner to 5 Newton meters. Now we're going to remove the tension from the
chain again by folding the bicycle, and when it's folded it's easy to swing the
rest of the chain tensioner round to re-engage the chain. Now we're going to
put the bicycle into the unfolded position. Then we're going to check that the
chain runs smoothly. And now we'll set up the hub gears. We have made a seperate
video on setting up the hub gears.
To remove the chain tensioner you should first be in the highest gear which is
the smallest sprocket. First of all we're going to remove the tension on the chain
slightly by folding it. Now the tension has been removed on the chain
we're going to remove the chain from one of the sprockets on the chain tensioner,
then we're going to put him back upright. Now we're going to undo the chain
tensioner nut and take the washer off.
Then we're going to take the chain tensioner off of the axle plate
To reinstall it you need to ensure the chain is fed into the sprocket and under
the chain pusher and then the chain tensioner pushes onto the axle plate
then having put the washer on the gear indicator nut simply put it back onto
the bicycle and screw it onto the axle. The gear indicator nut should be done up
using a 15 millimeter spanner to 5 Newton meters. Then, you release the tension on
the chain like this and then simply swing the rest of the chain
tensioner around the chain and put it through the sprocket, and then you can put
the tension back on the chain like this and now you want to check
that your derailleur is working correctly. You can do this before setting
up the hub gears if you've got a 6 speed. So, we need to remove the rear wheel because
we've got a puncture at the side of the road so what's the easiest way to remove
the chain tensioner when you don't have a stand. Step 1
fold the bicycle it makes its own stand cleverly designed! Then we're going to
undo the gear indicator chain
now we're going to remove the chain from the top sprocket on the chain tensioner
we're then going to undo the gear indicator nuts
now we can simply slip off the chain tensioner
to put the chain tensioner back on the bicycle it is easiest to have it
unfolded as we have a useful wall, we'll lean our handlebars against it! as when it was
in the stand we're going to put the sprocket onto .....
as when it was in the stand we're going to put the chain onto the sprocket and then put the
chain tensioner on to the axle plate then we're going to put the washer back
on the chain tensioner nut and screw it on to the axle
then we're going to refold the bicycle
making sure that the chain is round both sprockets then we're going to unfold it to
adjust the hub gears but even if you can't adjust your hub gears confidently
you can ride home in third gear. it's not so easy to see on the floor!
now we should be ready to ride home if you liked this video please give us the
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lets see how this goes - it might be too much information
so - how so i know which chain tensioner I need? if I've got a standard three-speed bicycle with a
deraillieur (doesnt exist)! I'm ad-libbing now!
so, the correct chain tensioner for the derailleur brompton bicycles
the one which the jockey wheels move if you think with us