I have changed the forks on my ageing Pro Connect and renewed the headset bearings at the same time.
I have installed a set of Suntour NEX suspension forks. These are not top quality forks, but I think they will be perfectly adequate for 99% road use. I chose them because they accept my existing mudguards without any sort of bodge being necessary, they are intended for disk brake use, they match the colour of my bike, they didn't have unsightly rim brake mounts and they were fifty quid off Ebay.
The main reason for changing the forks was to switch to a disk brake on the front wheel. I have installed a Shimano XT M785 caliber and lever combined with a Shimano XT RT76 rotor. The M785 is a mountain bike style lever, i.e. short. They do a variant called a XT T785, the T standing for trecking and this has a longer, more conventional brake lever. I like the shorter version. This, together with a post to IS mounting adaptor brought the total for the brake to £75 (Chainreactioncycles.com)
The front wheel is a Raleigh 700c x 17mm with 6 bolt disc rotor mount. It is supposed to be hand built, which I doubt that it is, and it cost £48 from the local Raleigh factory.
The SKS to Suntour mudguard brackets were 99p delivered from The Edinborough Cycle Cooperative. (Great service and free delivery on everything)
With the headset, rim tape and above parts, the conversion has cost about £200.
Add to this a new 18Ah battery and charger which I have just bought (£420) and the £100 which I spent on a new motor in May, this brings my expenditure on the bike to £720 this year.
I purchased the bike in June 2008 and have done a little over 19000 miles on it since then. During this time, I have spent very little on the bike apart from consumables which apply to any bike.
It now has a brand new 18Ah battery, a motor with less than 1000 miles on it and a new disk brake equipped front end. £720 may seem like a lot to spend on a 6 1/2 year old bike, but it suits me perfectly and I hope to get several more years of use from it.
I have not been far since fitting the disk brake, but it was simple to set up and seems very smooth and progressive in operation. I have always struggled with rim brakes, mostly with uneven action from one side to the other, making adjustment a pain in the ..... I am so glad to be finally rid of one set of Magura brakes. I can't do much about the rear set because the frame isn't intended to accept a disk brake caliber.