couple things...

new P2 is cheaper and same bike for the most part.

buying used, when you know your size, is a very good way to navigate the bike industry

you're not leaving any speed on the table with the bike size. Keep training.

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

The frame size isn't necessarily making you faster or slower but if it puts you in a better position (more aero, more powerful, etc.) then you will be faster.

You should probably go into the bike shop that sold you a 56cm bike and cuss them out. At 5'7" with a 29" inseam you have no business being on a 56 or Large sized bike. I ride that sized bike and I'm over 5" taller with over 5" more inseam. Height and inseam do not tell the whole story when it comes to bike fit but a 56 is guaranteed way too big for you. Depending on the bike and it's stack/reach parameters and your optimal fit, I'd even question whether or not a 54 would be the best bet. Something like a 52 or Small might actually be the best bet given your size.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

You're right that the frame is too big. Whether that's slowing you down depends on if the frame size is preventing you from getting a good position. If you can get a decent position then the aero difference between two adjacent size frames is no big deal. The Shiv is a very high stack frame, i.e. with a normal stem you are going to have very little drop from your saddle to the armpads at your size. Your average speed doesn't tell us very much, but there's a high probability you are riding in a pretty high position and not very aero given the combination of a high-stack frame and an overly large frame size.

Before you go buying a new frame you really want to figure out your positioning or you might make another mistake. Start reading the threads on this site about fitting and aerodynamics. If you get a professional fitting, do some research and select a highly-knowledgeable professional that specializes in tri bike fit and that has a good appreciation of aerodynamics. Unfortunately, from what I've seen, those fitters are in the minority.

Try getting lower in front, take out any spacers under your stem as a starting point. I have a Sunlite adjustable stem I got for $25 on ebay, you can drop it super low and height changes are really easy with one bolt. It might be worthwhile investing in something similar. As you go lower, if you start feeling too tight at your hip, slide your seat forward a bit. Don't be afraid to experiment, you body is more adaptable than you think.

Good luck.

tnywest,
In addition to my previous comments I'll second getting a a fit done. Not a fit on that bike that's too big. Get a fit done from a good and reputable tri bike fitter who can use their skill and experience on a fit bike to get your optimal fit parameters. Once armed with those numbers you go find a bike that can hit those numbers, and that fits within your budget.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

It may be worth trying to get fit on what you have, the shiv is plenty adjustable. Are you able to stay aero for all of an Olympic? You have no spacers under your stem or pads?

It's arguably two sizes too big. There's pretty much no way he can get a good fit on that bike. Sure, it will get the job done as far it being rideable but it's probably far from optimal. But if getting a new bike is not in the budget or wife approved he might be stuck making lemonade out of lemons.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

I get that but to go from a 56 shiv to 54 p3 only makes sense to me if you have no spacers on the shiv and can't get any lower. Of if you go the 54 p3 and end up with a bunch of spacers putting you at the same height as the shiv anyway. I guess it depends on what his current position is vs what he feels he wants to be at.

Curious, do you have a photo of the bike as it is currently set up that you could post?

Are you using any spacers at all under your stem?

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
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As others said, there's no way to know what if any speed is being given up due to the frame size because we don't know what implications the frame size has for your power, aerodynamics or comfort.
If you can get lower on the existing bike, start by experimenting with this. Remove and stem or pad spacers if you're using them and if you're using a typical low angle stem replace it with something that can get you much more drop. I've used a Specialized -24 degree Comp Multi Stem to do this on a bike that was initially too high for me. That stem is not massively expensive and allows you select the angle in 2 degree increments from 20 to 28 degrees without any compromise on appearance, security or rigidity. It could get you an extra 30mm or so of drop which is fairly significant. If this is still not low enough, you'll need a smaller frame to get you where you want to be. Reach may also be too long but I'm sure you'd already be aware if this is an issue?
Besides this experimentation, before buying a bike, go to a fitter.

If the bike doesn't fit you (and I doubt it does based on your information), then you have to be leaving speed out there. Without having the benefit of a video to assess your position, I would have your wife take a video of you on your trainer or riding down your street and then compare it to videos (pictures) you can easily find on YouYube and elsewhere of what should be a good position. If you can't make adjustments to match the correct position, then use your $1100 and whatever you can sell your bike for and get something used that will fit and give you that good position.

This is great info everyone - Thanks!

No I am not using any spacers below - they are all currently above. I can stay in aero for an oly no problem - 70.3 and 140.6 has been a different story.

My biggest issue is that I feel I am reaching too far with my upper body. I also am having a ton of issues with numbness in the land down under. I have adjusted the seat 20,000 times and cant get comfortable - started looking at a new saddle. I could put the spacers below which would bring my bars back to me slightly, but would also bring my upper body up.

I do have a couple pictures, but no idea how to post them

you need a new seat. Try Fizik Tritone, Cobb, or ISM split nosed ones.

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Info about posting photos is here, it is pretty easy:
http://forum.slowtwitch.com/...post=1250878#1250878

The reason I ask about a photo is that then you will get more specific and more helpful advice. Right it is (mostly) guess work.

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
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Your seat and comfort issues could be due to the fact that you are stretched WAAAY too far. I'm 5'7" as well and ride a 52 Specialized road bike and a 51 Cervelo OLD (read lower) P2 TT bike.

A correctly fitting bike will be a more comfortable, faster bike.

Get a fitting on a fit bike, buy whatever you can that fits and go from there.

http://www.slowtwitch.com/...ike_sizes__1173.html


I am 5'8" about 30" inseam on the medium shiv. I probably could have gone smaller as well (was sold med by the "Professional fitter" not 100% happy but didn't know any better. live and learn.) but I feel fine when on the bike. you can always get a - degree stem to try and go lower in front like stated above. as far as being stretched out you could try and flip the seat post to get closer unless you have already done that and get a saddle that feel better and has longer rails. if you can get in optimal position on the contact points they bike size wouldn't matter. if you are all out of options like stem is as low as can go with - degree's and cant get closer with saddle and seat post flip then it is really too small.

Another thing would be aerobars that adjust the reach back a little more than the stock shiv aerobars they really do not have a lot of adjustment to move back besides shortening a stem.

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2019 T-Rex Tri Series

I bought a bike in 2013 from a LBS and in 2015 finally went back for a real fit. Ends up my bike frame was 1 size too small, long legs short torso. In theory it was the right size. The shop ended up replacing my frame for free and upgraded it. The new frame was brand new. They said my old bike frame was in great shape and they sold it. So it worked for them. The frame was a couple years old but was new. They were able to get a deal. The shop that sold it to you may work with you. I would start with a conversation at your LBS.

I am really tempted to do this for mine as well. I have only had it a few months with minimum miles. Would this be a rare example of a shop doing this?

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2019 T-Rex Tri Series

I'd be curious if Dan still has that opinion with the option of pedastaling (how do you actually spell that?) the pads in an aero way now being pretty common. At the end of the day I would default to a smaller size because it gives you more flexibility with how to fit the bike and get the big blob of human into as aero a position as possible.

It doesn't hurt to go into your shop and ask this in a polite, respectful manner. I would say it is pretty rare, and I wouldn't expect it without some sort of prior agreement, but with closeouts available on last years models and wanting to keep you happy there is no telling what they might do.

If you go in demanding something I can pretty much ensure that you will get a big fat 'no' and you'll be lucky if you don't get a 'hell no'.

I thought it was comforting as I have the same fear about being sold a size too big.

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2019 T-Rex Tri Series

No I wouldn't go in demanding. I purchased a 2015 shiv on sale in August 2015. Would be worried I wouldn't be able to get a small they might not be available.

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2019 T-Rex Tri Series

Is your frame size a large or medium based off of specialized sizing?

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2019 T-Rex Tri Series

So if you feel too far stretched you would need a smaller size than 54 of the p3 as I think the reach is close to a 56 shiv. You could try a shorter stem on your shiv or trimming the aero bars down. If you're comfortable working on your bike trimming the bars isn't hard and on the shiv the cables are super easy to route. this is where going to a shop to fit you will help. I can tell you from my experience if I'm stretched out too far I get more crotch pain as I'm not anchored on the saddle. Raising the bars doesn't help this at all, i need to bring those in. Before you elect to move you seat forward to reduce this know that you'll e changing your hip angle which may or may not be the right thing to do.

The small is a 52.5cm the medium is 55.1cm. For the shiv.

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2019 T-Rex Tri Series