UKC

I do the odd time trial and currently do them on my road bike , a Cervelo R5 with Mavic Carbon Pro SL wheels. I hasten to add I did'nt buy it new but from a mate. I'm wondering whether a dedicated TT bike (for c£1K on Ebay) would make much difference or am I best just using the road bike? I dont think I can add aero bars as I suspect they'll ruin the carbon handlebars ... at least they did for my mate when he tried it!

When I did evening 10s a long time ago I bought a second hand Hewitt steel framed TT bike for a modest sum.  It was great, the TT geometry and TT bars helped me get and enjoy a good position, also the gearing was more suited to TTs than my road bike

So if you can get a good deal on a bike with TT specific geometry it will make you go faster with more enjoyment (well less pain anyway!).  I expect that with more expensive aero refinements, disc wheels, pointy helmet etc you will soon be subject to diminishing returns for the money you spent - but many people seem to get obsessed.  I realised there's more to life than 10 miles of dual carriageway.  Also maybe Strava segments have taken away some of the purpose for TTs?  

Pull alloy bars on your current road bike so you can use clip-on TT bars and get yourself a second hand disc wheel with appropriate cassette . I reckon that’ll cost you circa £600 and be faster than a £1000 TT bike with cheap wheels.

I did what you are thinking some time ago then sold it on a couple of years later.....it was worth it to me at the time as I was never any good in road races but could hammer out consistent watts. I reckon by the time I got comfy on it I dropped about 2 minutes on a 10 and about 4 on a 25 as I struggled a bit on the longer distance to maintain position......worth a punt in my opinion if TT is your thing but as someone else said if the wheels aren't any good you'd be better getting some tt bars and a decent set of wheels for your road bike!

I bought an old Raleigh Dyna-Tec for £70 off Facebook. It's a steel tubing bike with a low front end, single 54t chainring and an old 8 speed cassette. It took over a minute and a half of my PB (which was on a modern, fancy all carbon roadbike). 

I think there are a lot of myths out there about how to spend money when it comes to TT racing. Wheels are nice, but in terms of the seconds gained to pounds spent ratio they are one of the least effective ways of "buying seconds".

For the most cost effective ways to go quicker, its hard to find anything as good as:

Lycra shoe covers! They only cost a tenner from decathlon and are worth several seconds. If you love spending money you could by a few more seconds for lots more pounds by getting some of the rubberised ones that go up to mid calf. 

A good fitting aero helmet is worth a lot too. Second hand ones are picked up very cheaply. 

Getting your skinsuit modified to made sure it's really tight. Pay a professional seamstress less than 10% of the cost of your wheels and shave twice as many seconds off your PB. 

Speaking of shaving. I hope you've shaved your legs - seriously, wind tunnel tests have revealed that they can take nearly 30secs of a 10 mile TT in certain conditions. 

When you've done all that, I'd suggest buying a dedicated bike, but I'd go for something very cheap to start with. Ideally steal with a low front end and put some clip on aero bars on it. Play around with the position a lot. Watch your PB tumble! 

Old bikes are still damn fast if you ride them the right way - look up Alf Engers for some inspiration! Not a carbon weave in sight! 

I'd buy a full set of aero bars instead of clip-ons, with bar end shifters and aero brake levers, a lay forward seat post to change the effective seat tube angle, and a long stem.

Pick up the parts second hand/ online store bargain bin and you can convert your road bike to a proper TT position for a couple of hundred quid. Once you're happy with the setup, with tape marking the appropriate points on your seat post, etc. it takes no time at all to switch between road and TT mode.

Also highly recommend an adamo saddle on your TT seat post.

https://www.facebook.com/CyclingWeekly/videos/vb.59088097633/80334828006110...

Along with a skinsuit and shoecovers, your position on the bike is the most important thing.

Clip ons on an R5 would quite probably be slower than a position you could take on normal drop bars due to the geometry (too high front end, and clip ons raise it considerably).

If you want to go faster for free look at how world tour TT specialists ride their road bikes in a RR, and think about how you can adjust your position to reduce frontal area in a similar manner to how they do eg forearms on tops, tucking head in (use a mirror/camera).  If you do that properly that would make you faster on a road bike than most riders on a TT bike at your local ten. 

Otherwise, get a cheap TT bike/ frame and upgrade it with some super adjustable TT bars. Adjustability is absolutely key and everything else is a waste of time and money if you can't get the position right.