Seatpost: The Jekyll will accept any 27.2mm diameter seatpost. A light
coating of grease should be applied to the seatpost or inside of the
seattube during bike assembly, and the seatpost must be inserted to the
recommended minimum insertion. For binder-bolt type seatpost collars,
grease the binder-bolt threads and tighten to 70-80 In-Lbs (8-9 Nm.)
NOTE: Make sure that the end of the seatpost will not come into contact
with the rear shock and/or swingarm as the suspension is compressed.
To check, first adjust the seatpost height for the bike's intended rider.
Then compress the rear suspension as far is possible in order to bottom
out the suspension travel. If necessary, cut the bottom of the seatpost to
provide at least 1/2" (1.27mm) of clearance between it and the
swingarm/shock when the suspension is fully compressed. Repeat this
check each time the seat height is readjusted.
Additionally, the seatpost must be inserted far enough to be properly
supported by the frame. Generally, the seatpost's minimum insertion
height will assure sufficient insertion. If in doubt, or if the bottom of the
seatpost was cut in the step above, make sure that there is at least 10cm
of seatpost insertion into the frame.
Swingarm Protector: The swingarm on your Jekyll is made of thin-
walled aluminum tubing and some CNC-machined aluminum parts. To
protect the swingarm from damage inflicted by the chain slapping against
the chainstay, we have supplied a self-adhesive vinyl protector for the
swingarm. This protector should be applied to the top of the right (drive
side) chainstay, near the chain. Please inspect this protector frequently. If
the protector becomes damaged, abraded, or peels off, it should be
replaced to prevent damage to the swingarm. To obtain a new swingarm
protector, see an authorized Cannondale retailer.
Alternative Brakes: Aftermarket brakes are a popular upgrade on many
suspension bicycles. The Jekyll is designed to accept disc brakes that
conform to the international mounting standard. When selecting a new
brake system for your Jekyll, choose one that mounts to the swingarm
and fork using only the existing disc brake caliper mounts. Do not modify
the existing mounts or clamp, weld, or in any other way add new or
Front Derailleur: All Jekylls require a standard "bottom-pull" type front
derailleur with a 31.8mm clamp diameter. Because the front derailleur
mounts to the swingarm, and has a limited range of vertical adjustment,
some derailleur designs (like Shimano "Top Swing") are not compatible.
Rear Derailleur Hanger: Cannondale equips the Jekyll with a
replaceable rear derailleur hanger. Do not use any other hanger than the
Cannondale unit that came on your bike. Replacement hangers are
available from your authorized Cannondale dealer.
Crankset / Bottom Bracket: Like all Cannondales, the Jekyll bottom
bracket shell is 68mm wide and has English threads. Proper bottom
bracket spindle length depends on the crankset being used. Use whatever
length spindle is recommended by the crank manufacturer, providing the
proper clearance between the crankarms and the frame is maintained.
Chainring Size: Maximum usable chainring size for the Jekyll is 46
teeth. Use of any larger chainrings may damage the swingarm and/or
result in contact between the front derailleur cage and the large
Use only a 27.2mm diameter seatpost and be sure that the
seatpost is held securely by the seatpost collar. The seatpost
collar clamp bolt must be tightened to 70-80 In-Lbs (8-9 Nm.)
Failure to properly tighten the collar could lead to slippage, loss of
control and risk of serious injury or death.
Do not machine (or "face") either the headtube or the bottom
bracket shell. These surfaces are accurately faced at the factory so
this traditional frame preparation step is not necessary. Further
machining could damage the frame.