Clip on aero vs tt bike


Hey guys,

On my Giant propel I have fitted clip on bars, an ism saddle (which pushes ny position forward) and shortened the stem through a bike fit which I feel has allowed me to get pretty close to a tt aero position. Do you think I will still be at a significant disadvantage versus a full tt bike for ironman distance events? Specifically I’m racing IM Wales which involves 8000ft of climbing. I hope to afford a new tt bike next year but am trying to make the best of what I have and can afford for now…


I’m not sure if it will be significant or not for full distances but the difference between road and TT bike goes beyond the clip ons as they also have different frame geometry specially in terms of seat tube angle.
The clip ons on your road bike may help you with comfort on the long distance but i don’t think that aerodynamically it will put you close to where you would be able to get with a TT bike.
It is hard to comment on IM Wales but sharing a personal experience, i’ve recently completed a 6h non-drafting endurance race with 6000+ft of accumulated elevation and TT bikes were considerably faster than road bikes.


It really depends on what you’re trying to achieve in your race–obviously having a proper TT/Tri bike would be ideal for your best performance, but you can certainly get by just fine with your setup if you’re just looking to complete in a decent time (whatever you consider a decent time to be). Your Propel looks like a nice looking frame and you have a nice looking set of wheels which should help. I haven’t done a full IM on either a road bike or TT bike, but I did my first few years of triathlon which included HIMs on a much lesser road bike with clip-ons and had decent results. A couple other things you could look at would be a disc wheel cover (i.e. and a really steep negative angle stem to drop your front end even more to compensate for the high stack of the clip-on pads–I ran a -35° stem on mine. As is, it looks like you’ll be propped up sitting pretty high when in the aerobars which will be a literal “drag” on your bike split :slight_smile: .

This was my setup on my roadie:


Thanks for this wyku. I had thought about the negative stem. The ISM saddle definitely feels like it’s pushed me far enough over BB but then j don’t have TT experience. I have Kona as a pipeline dream and know I’ll be needing a TT to qualify but hopefully with a few more adjustments this will do ok on a hilly and windy course. Thanks again for the help :+1:


i’ve recently completed a 6h non-drafting endurance race with 6000+ft of accumulated elevation and TT bikes were considerably faster than road bikes.

Could be that those willing to invest in a TT rig are also more likely take the whole thing more seriously (i.e., more training)…and thereby post faster times…

Owing to geometry, TT bikes can be faster, but getting a dialed in position is critical!


I did the same setup on my road bike for my first season and-a-half. My setup had my butt too far back and had me hunched over too much, which I found when I went to a trainer and had this ‘Aha!’ moment, “Oh, so that’s what a dialed in tri-bike feels like.”

As a beginner, my thinking was that I needed to get in shape and assess whether I am competitive enough to justify the expenditure of a new tri bike. My roadbike/tri-bars worked fine for my initial sprint and Olympic distance events, and after 3 podium finishes I started looking closely at the performance of he people just above me. I thought my best bet at closing the gap lay in biking and running (swim improvements take time). So, now I’m going for a new TT bike. (Yay!)

The big difference between your situation and mine is in the distance involved. I would worry a full IM distance at a sub-optimal position could be pretty tough on your body. Have you tried doing a six+ hour ride in the aero position to see if your body can do it?

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I don’t know if it would work with the Propel (I think it has an aero seatpost?) but if you have a bike with a round seatpost you can use one from Profile Design called Fast Forward. Instead of a layback it has a lay forward, with the intention of replicating the steeper seat tube angles of a TT or track bike. It’s a relatively inexpensive £65 or so for the alloy one) way of simulating a steeper seat angle on a road regular bike.
In terms of how much it matters, that depends on how crunched up your position is. The value in moving forwards is that it can open up your hip angle and help with power production at a low back angle. I went from quite far back on a regular saddle,to as far forward as I could go on an ISM - when I got the Fast Forward seatpost I was able to move another 4cm forwards! This changed my pedalling mechanics quite a lot (it’s basically put me directly above my BB!), so it’s worth considering if you are happy with that idea!


Yeah, the ISM helps a lot especially if you sit on (off) it properly :grinning:. With there being as much climbing as there is you won’t be in aero for the whole ride anyway so it’s not going to be the same tradeoff as a flatter course. I’m actually going to be doing the same thing at 70.3 Worlds in Nice in September since I’m just renting a bike for it so I don’t have to drag my bike around while my wife and I travel around before and after the race. There’s a bunch of climbing on that course too, followed by a bunch of descending (on small roads with a bunch of other poor bike handling triathletes… :joy:) so I don’t think it will be a huge tradeoff (hopefully) - - I’m not going to pushing for the podium either way, so I’m okay with potentially losing a bit of time though. The lightweight road bike will also help me on the climbs, which I’m pretty bad at living on the flat Prairie :grinning:.

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Great advice guys much appreciated! I had a play with the saddle last night and will stick the propel on my turbo for some positioning later. It is an aero seat post so that sadly isn’t an option however I have changed it from -25 to -5 setback and moved the ism right forward. It feels like I’m over the BB. I have a shorter stem of 70mm which is getting my arms and elbows close to 90 degrees and will slam the front to see how it goes. I’ll get a pic if I can and see what you think :slight_smile:


And i agree wyku hopefully with the climbing it will reduce the disadvantage fairly significantly. Until I finish my renovation I just can’t justify the TT bike. I only upgraded to my propel a few months ago :see_no_evil:


I think it was this podcast that had some mention of exactly this. Don’t quote me on that but I remember it being pretty in depth

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I’ve ridden TTs/Tris on my Boardman AiR with clip-ons. And also a set of TTbars/stem, the main benefit with a TT bar setup is the adjustability. As others have said, TT bikes will have a much lower and cleaner front end so are naturally a little more slippery in the wind. Maybe some deeper 80mm rims will help even if on the rear. Also, comfort is key. Ride on the skis as much as possible to get used to it.

Another thing worth considering is your gearing. TT bikes will often run shorter chain sets and bigger chainrings (53T—60T), potentially not suitable for a hilly course, but on the flat it makes a good bit of difference.

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Not sure on that, I think that training will be put down regardless. For instance, on that same race, guys doing 12 or 24 hours were all on road bikes. They’ve done around 10000 and 18000+ ft elevation and I’m sure they trained a lot for that.
This is all observational with no scientific back up but maybe there’s a tipping point where comfort will be the main factor on the endurance realm but what I’ve seen is that up to iron distances a TT bike frame has been the weapon of choice for most people regardless of course elevation.


Not the best photo but any opinions on my current position are welcome. I feel the saddle can come up a little but don’t think I need much more of a drop?

To get here I have slammed the front and shortened the stem to 7cm. Also I have fitted an ISM saddle and brought it right forward. The seatpost is also brought forward to -5 rather than -25

There is a 10mm riser block on the aero pads so still room to drop a bit further :slight_smile:

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That looks pretty good. You can consider tilting the extension up a bit (if comfortable) to help close off the air coming towards your waist/hips.

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Thanks for the reply. Yes I had thought maybe the extensions should be tilted some more :+1:

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Quality fit will still be several minutes between your set up and a dedicated tt bike. Can be even more if your fit on the road bike isn’t good.

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Yeah I realise it is still a compromise. If I can get closer to contending as an age-grouper I will make the TT investment next year :slight_smile: hopefully I won’t be at too much of a disadvantage this year on a hilly IM Wales course

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Hows the control? :man_shrugging:

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Hard to tell by the angle but looks pretty good. Maybe bring the stem/bars just a bit forward so you’re not 90deg at the elbow.

If you’re comfortable I’d say good enough.

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