Mate has a Cannondale Optima '04 80mm travel and is looking to (finally!) replace the headshox with a modern/proper/working fork. 😀 Presume he will need an 80mm fork or will 100mm be OK? Any advice suggestions appreciated!

Get a lefty …

http://www.cannondale.com/asset/iu_files/techcenter/2005_cannondale_maximium_fork_length_guide_technote_en.pdf

I'm sure the '04 one will be availible if you hunt. Probably the same frames for both 04 and 05 model years though.

Ta – but I think he wants a bog standard fork – something from RS probably.

RS Reba's been around ages without any issues, an oldun's are coming through at decent prices (and been about long enough that long term reliability is not an issue), convertable between 85/100/115 (or 80/100/120 on the latest versions) – highly recommended. Just factor in the cost of a reducer headset

My brother replaced a headshok with a 100mm RS Reba on a F600 – maybe 5 year old bike? Anyway, transformed the bike, much better to ride.

Cheers guys

RS Reba or SID, both can be adjusted down to 80mm. However a newer style used Reba or SID will cost in the region of £200 + reducer cups for the headset. I love my Reba and it works great without any problems. Easy to set up and common enough to have service guides on the net, get spare parts etc. However I think that my Oh's Fatty Ultra works great, small bump sensitivity with enough travel for xc, light as hell (1.29kg) so maybe it is worth servicing the Headshok on his bike. But like other have said Reba is probably one of the best value for money forks available.

The Optimo frame will (just about) take a 100 mm fork. The headshock is a very long fork for its travel due to where the telescope fits.

Ideal upgrade is a lefty. 100mm travel was on bikes of the time but a newer 110mm will fit no problems (on the flip side the leftys come up short for their travel due to their upside down nature)

Why does he want a bog standard fork? A properly set up lefty will out perform anything listed above.

Why does he want a bog standard fork? A properly set up lefty will out perform anything listed above

But I presume will be more expensive and will need new front wheel??

Where can you buy leftys? I remember Cannondale doing a Lefty-For-All thing a while back but can't see anywhere to buy them or the crown adapters that go with them.

Edit: here's the info:

Happy 10th Birthday Lefty

£1300 plus new wheel!! 😯 I think a RS at £3-400 is a better bet (not saying lefty isn't good – but too much).

So Kieran would an 80mm fork make HA too steep??

Good heavens 😯

Second hand lefties are a lot cheaper and you normally find they are sold with the wheel. Due to their construction they are bombproof. But you do need to know how to maintain/set them up. MTBR's Cannondale forum is great for info on them.

I beleive the headshock crown to axle length is 485mm and the maximum recomended length for the frame is 500mm. If your using a conventional fork the adapter adds around 15mm