At what speeds does TT bike matter

morstar

I am seeking opinions on advantages of TT bikes vs road bike with clip on bars at modest speeds.

A bit of background...
Up until 2013 I spent a few years doing TT's on a road bike with clip on bars eventually getting down to a short 23 min 10 on that setup. Nothing special but I was quite happy with this. Couldn't afford loads of aero gear and TT bike to go lots faster and sought new challenges away from TT'ing.
Fast forward to today and apologies but, I have been doing triathlons amongst other things and am now in the fortunate position of owning a TT bike.
I live right in the middle of the Ironman UK course and regularly ride parts of it on both the road bike (with clip ons) and TT bike. It is a reasonably undulating route and not on particularly fast roads. Typically I average about 16-17 mph riding at top of Z2 Heart rate. However, whichever bike I ride, the speeds are almost identical.
Now, I am firmly of the opinion that I am simply not going fast enough to benefit from the aero advantages of the TT bike. I am keen to hear if people think this makes sense or not. Whenever I discuss this with triathletes, they always insist my bike must fit badly because a TT bike is always quicker. I take triathlete opinions with huge pinches of salt as they are obsessed with buying speed beyond reason in many cases. However, I am keen to hear if cyclists think a TT bike should be making me quicker at speeds around 16-17 mph. I either need to hear I'm right that a TT bike won't make much difference or someone to say it really should and I should investigate why it isn't doing.
I do have a reasonably aero setup on both bikes with seat to handlebar drop around 12-15cm on road and similar (to pads) on TT bike so I'm not a sit up and beg triathlete.
I keep looking at my TT bike wondering if I've invested money for no reason or should be getting more from it.

cougie

So it's road with tribars versus TT bike ?

Ok I'd expect the TT bike to be slightly faster so Maybe it is to do with your position ? You could be too low and reducing your power output.

Post some side on photos of you on each bike maybe ?

MiddleRinger

Well you'd notice the difference less at those speeds compared to 25 mph, but there's definitely be some aero savings even at 16-17 for sure. Without power data to compare your rides it's all a bit of guesswork. You could be putting out less power for the same speed on the TT bike, but aren't as comfortable so it feels similar.

morstar

cougie wrote:

So it's road with tribars versus TT bike ?

Ok I'd expect the TT bike to be slightly faster so Maybe it is to do with your position ? You could be too low and reducing your power output.

Post some side on photos of you on each bike maybe ?

Yes, it is road with tri bars. Will have a nosey for photo's. There are a few of me on TT bike knocking about but don't think there are many of me on the road bike with tri-bars.

morstar

MiddleRinger wrote:

Well you'd notice the difference less at those speeds compared to 25 mph, but there's definitely be some aero savings even at 16-17 for sure. Without power data to compare your rides it's all a bit of guesswork. You could be putting out less power for the same speed on the TT bike, but aren't as comfortable so it feels similar.

Interesting points. Unfortunately don't have power meter. Definitely not as comfortable on TT bike at the moment as I haven't been riding it a lot but I do get comfortable on it when riding regularly.

morstar

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whatleytom

All to do with what your position is like on both. In terms of watt savings based solely on kit, probably only likely 10-20w worth of savings due to the bike alone depending on how optimized both bikes are. The rest of it going to be down to clothing choices and position. On my road bike (no clip ons) I can do a 22min 10m TT. on TT bike have a long 18 pb, so probably 1-2mins of benefit to be had by getting the CDA right down. Those aren't comparable days, so I expect the road bike time would be lower on the right day. That said I'm told I'm fairly aero on road bike so may well be more for a lot of people.

fenix

Outlaw ? The position looks good. I expect if you used your road bike for that ride you'd see the difference in speed.
IMUK is a lot more lumpy so you might well be climbing faster on the road bike and that's masking the differences ?

cruff

I have lived on the Bolton course for four years (just moved, but still only a few miles away) and ride it (or bits of it) almost every day. In my opinion, the course is technical and hilly enough for a TT bike not to be of any benefit to you unless you're aiming for a very good time. Descending off Sheephouse on a TT bike isn't fun - and climbing it ain't much better! The horrible road surface on most of the route isn't going to help either. Of course, that's just one course - a TT bike is obviously going to be of much more benefit on other (flatter) courses.

Looking at your position as well, I don't think it's that good. Unless it's a photo taken at a particularly badtime, any aero gain you're making will be offset by the fact your head looks like someone has plonked a melon on top of your shoulders and angled it upwards :lol If you struggle with getting your back flatter (and it looks like you might, from the curve there), try dropping your head a bit more. Nothing wrong with a curved back, but the air hitting your head is going to cause a huge amount of drag if you don't try and make it flatter across your shoulders.

morstar

Fenix wrote:

Outlaw ?

Yes, it is Outlaw. Funnily enough, I grew up just down the road from Outlaw and live in the middle of IMUK so consider them both on home turf.

IMUK is a lot more lumpy so you might well be climbing faster on the road bike and that's masking the differences ?

This is the conclusion I have been leaning towards but everybody keeps telling me I'm wrong so I'm widening the net of opinions. Not very scientific I know.

I was a couple of mins slower on the TT bike yesterday on a repeated ride vs road bike but it was windier. Seems to be I was quicker in certain sections and slower in others and they're cancelling each other out.

morstar

Cruff wrote:

In my opinion, the course is technical and hilly enough for a TT bike not to be of any benefit to you unless you're aiming for a very good time.

This is exactly what I believe but general opinion is that road bikes are only faster on really hilly courses. I'm in OK shape at the moment but nothing special. If I can start increasing speed a little with more training it will be interesting if a consistent differential emerges.

Looking at your position as well, I don't think it's that good. Unless it's a photo taken at a particularly badtime, any aero gain you're making will be offset by the fact your head looks like someone has plonked a melon on top of your shoulders and angled it upwards :lol If you struggle with getting your back flatter (and it looks like you might, from the curve there), try dropping your head a bit more. Nothing wrong with a curved back, but the air hitting your head is going to cause a huge amount of drag if you don't try and make it flatter across your shoulders.

Now this is harsh but valuable feedback. I keep looking at my position knowing it's not quite right but struggling to put my finger on what isn't right. If I put my head lower, I can't see forwards though. I this just accepted as a trade off? Tends to be less of a problem on a DC TT course, but more so on country lanes.

morstar

whatleytom wrote:

All to do with what your position is like on both. In terms of watt savings based solely on kit, probably only likely 10-20w worth of savings due to the bike alone depending on how optimized both bikes are. The rest of it going to be down to clothing choices and position. On my road bike (no clip ons) I can do a 22min 10m TT. on TT bike have a long 18 pb, so probably 1-2mins of benefit to be had by getting the CDA right down. Those aren't comparable days, so I expect the road bike time would be lower on the right day. That said I'm told I'm fairly aero on road bike so may well be more for a lot of people.

Took me 3 years of effort to get below 24 mins for a 10. A young lad turned up the week after I managed that on his normal road bike in a loose jersey for his first ever TT and rode 24 mins dead. He can probably do similar to you but I can only dream of your times.
I'm certain the gains will become apparent at higher speeds, just not seeing them at the slower pace I expect to do in an IM. Maybe time to do some different timed efforts on fast flat courses to establish the differences.

imposter2.0

Aero gains are available at any speed. Having said that, your aero position does look a bit 'awkward' as has been suggested..

Vino'sGhost

whatleytom wrote:

All to do with what your position is like on both. In terms of watt savings based solely on kit, probably only likely 10-20w worth of savings due to the bike alone depending on how optimized both bikes are. The rest of it going to be down to clothing choices and position. On my road bike (no clip ons) I can do a 22min 10m TT. on TT bike have a long 18 pb, so probably 1-2mins of benefit to be had by getting the CDA right down. Those aren't comparable days, so I expect the road bike time would be lower on the right day. That said I'm told I'm fairly aero on road bike so may well be more for a lot of people.

if you rode your road bike in more TTs it would come down if you can do an 18. you must have the power. my road bike pb is a very short 22 and Id never do a 19 though i only tried for a season and never on fast courses, i just CBA with TT.

Also ive reached that age where im only going to start going slower

morstar

Imposter wrote:

Aero gains are available at any speed. Having said that, your aero position does look a bit 'awkward' as has been suggested..

Care to elaborate? Just melon head or anything else stick out?

imposter2.0

Going slightly lower/longer at the front might alleviate the melon head thing, and might flatten you out a bit...

cruff

morstar wrote:

Imposter wrote:

Aero gains are available at any speed. Having said that, your aero position does look a bit 'awkward' as has been suggested..

Care to elaborate? Just melon head or anything else stick out?

Ha - I did wonder if 'melon head' was a bit harsh, sorry!

Positions are weird. You might make aero gains, for example, by flattening out your back and dropping your head (longer stem, higher saddle for instance) but any gain you make there may be offset by an accompanying loss of power. I'm by no means an extreme example here, and my FTP on a road bike is 316, on a TT bike its 283 - and that's after numerous position changes, a fantastic TT bike fit that added almost 30 watts from what it used to be and making no other aero changes (same wheels, same sh*tty skinsuit, no slippery socks or anything else)

I do crits and road races too, so don't really pay much attention to TTs. As I get older, I'll inevitably have to accept that a fat chopper who only took up racing at 42 isn't likely to get anything above second cat and concentrate more on TTs in the future - so will be paying it a bit more attention in a couple of years

I'd suggest experimenting. Get out somewhere with a reasonably quiet DC (Rainford Bypass - the A570 between the M58 and the East Lancs Rd is your best bet if you're on the IMUK route) and baseline a three minute effort at 90%. Then make some incremental changes to saddle height & set-back, stack height, simulate stem length changes by changing pad position etc. Repeat each time you make a change. I would have thought a couple of hours testing should allow you to at least make some aero gains, and get you on the right track for where you should concentrate future changes

DeVlaeminck

Not a tester but I don't think that position is too bad !

Anyway I agree with the OPs mates that a TT rig should be faster than a road bike with clip ons on just about any course. When I did have a go at TTs a few years back first time out on a TT bike I took a minute off my best in our sporting 12.5 mile course and it was faster on our hilly course too. One of the club who was a good TTer avoided using his TT bike on the hilly because it was single front ring and he was a big lump, when he did use it one week he set a pb.