How to fit a tapered fork to a Cannondale Trail SL

I have a Cannondale Trail SL 29er single speed and love it dearly. It's riotously fast and fun. However, it's fully rigid and whilst that does give a sense of speed, which is rarely matched with modern suspension rigs, it does over time get a bit bloody boring.

So enter a suspension fork. For me, I really fancied a SID RTC3 or a SID XX, but then I realised I'm comfortably on the side of 'fully framed' and I didn't fancy a light weight fork on the front of the bike flexing under my weight.

Suspension fork

Reba RL 2016

So, I went for a 120 mm RockShox Reba RL 2016. Stout enough, reliable and great value. It's only the RL model, but I figured I'm probably not going to need the complex (but awesome) RTC3 capabilities of the SID on a single speed.

I have the fork, but as Cannondale are famous users of the 1.5 standard, and almost all forks now come primarily in taper form (1.5 to 1 1/8, I'll need to make a few other purchases to get them fitted.

Headset

This is probably the trickiest item to source in this upgrade. Get it wrong and I'll waste cash and time, but getting it right involves many hours of Googling.

Fortunately, I already have half a headset that works. It's on the bike. So in reality I just need a top half of the headset for the smaller 1 1/8 steerer tube.

Enter the Cannondale HD232 headset. Designed to take the Trail from 1.5 to a straight 1 1/8 steerer tube (not tapered), but used in conjunction with the existing headset (which for reference is a KP191) you get a tapered headset for the Cannondale Trail SL frame. Sweet!

However, I couldn't help myself and I ordered a Chris King InSet 5 which allows the use of a tapered fork in a 1.5 headtube bike, like this one.

Stem

Again, because the steering diameter on the Cannondale fork is 1.5 inches, I'll need to swap it out for a 1 1/8 inch stem so that it will work with the tapered Reba.

I've chosen to go for another Thomson X4 unit in the same 70mm reach as what I had on there originally. Why change what's broke, right?

Front wheel

Because the rigid fork has 9mm dropouts, I've had to upgrade my hub to 15mm to compliment the fork. I did have the choice of saving £50 on the fork, and £72 on the cost of the Chris King 15mm conversion kit, but the additional security, stiffness and future-proofing of the 15mm, and not to mention any resale value, I opted to spend now and reap the benefits.

Check out how to convert a Chris King 9mm to a 15mm axle in my other blog post.

5 steps to fit a tapered fork to a Cannondale Trail frame

1. Buy all the parts as needed
2. Make sure you have all the tools you'll need
3. Take off all the old stuff
4. Size up and prepare all the new stuff
5. Grease, fit and align to be ready to ride

Buy all the parts as needed

Pretty much the list at the top of this post, but you may also need:

• 1 1/8th Star-nut for the new steerer tube (should come with a new headset)
• To check that your disc will use the same mount, or to get a converter
• That you have enough 1 1/8th spacers for the steerer tube

Make sure you have all the tools you need

If you've ever read this blog before you'll know that I'm a fan of Park Tools, but any good tools will do.

• Clean rag and Muc-off or similar
• Decent grease. I use Exus E-G01
• Pencil to mark the steerer tube with
• Park Tools hex set of allen keys (likely, 3, 4, 5 and 6mm sizes)
• I also required a 1.5mm and 2mm for the Chris King hub conversion
• Park Tools star-fangled nut installer 1 1/8th
• Park Tools metal cutting saw
• Park Tools steerer tube cutter
• Thin screwdriver (to prise the headset seat off the existing fork)
• Park Tools work-stand
• Curved metal file (I used a Draper Engineers file)

Take off all the old stuff

Start by literally stripping the front of the bike down and ensuring that any of the gear that's staying on it zip-tied out of the way.

• Start with a clean bike
• Remove old stem and stem-cap
• Remove wheel and disk brake from fork
• Zip-tie handlebar to the side of the frame
• Slide down and remove the fork from the bike
• Collect all headset parts and place to one side
• Remove headset seat with thin screwdriver

Size up and prepare all the new stuff

I'm presuming here that you've bought all the right stuff in the right size. I once made the mistake of buying a fork with too short a steerer tube. Ended up having to buy a new frame so that it would fit!

Anyway.

• Clean inside the headtube and where the headset / bearings press into the frame
• Measure your steerer tube from the original fork
• Decide whether you want more or less steerer
• If you want to be very precise, then fit the headset, fork, stem and spacers to get a perfect measurement
• Cut the steering tube
• File the inside and outside of the top of the cut steerer tube

Grease, fit and align to be ready to ride

This is always the fun bit. Placing all of the cool new toys and bling onto the bike and getting it set-up just right.

• Fit the star-fangled nut
• Fit the new headset to the frame
• Fit the headset seat to the fork
• Grease the headset and the headset seat
• Slide in the new fork
• Apply any spacers you wish
• Slide the stem on
• Add the stem steerer cap and gently tighten
• Tighten until there is only a little wobble in the headset
• Fit bar, if you haven't already and align to suit
• Fit disk and front wheel
• Place bike on level ground
• Tighten the stem cap to suit
• Tighten the stem bolts
• Wipe down any excess grease
• Test the front brake
• Go for a short test ride

NB: Within a few hours of riding the headset will compress and you will need to adjust it. Simply undo the stem steerer cap, the stem bolts and then gently tighten the steerer cap until the play in the headset stops. Then tighten the stem bolts.