sbs z31

Carleton, heres the link to the frame. I have a size small and the built was intentionally for road tt but do plan on doing some track tt with it too, sorry if I word it wrongly.

https://unknownbikes.bigcartel.com/pr...meset-preorder

Quinn8it

It is really hard to determine fit from general measurements..

The OP is 5'6" with a 30" inseam..
I'm 5'9 with a 29" inseam- I ride a 57cm Dolan
I'm pretty sure BabyPuke is 5'10+ and he is on a 55cm Dolan

queerpunk

I'm not convinced that Elvis's bike is too small; rather, I think that the stem is too long and that due to a few factors (lack of experience, flexibility, or fitness? and maybe a bit of extra material around his belly? unless that's just an open or baggy jersey...; and the long stem) he's too far forward on the bike... but based on being too far forward in the saddle (Carlton, you point out a big KOPS problem) not due to being too big for the frame.

I think the challenge of this situation isn't the size of Elvis's bike, I think it's some inherent challenges in TT fits for short people (Fitting small people is weird, especially for pursuit/tt positions!) combined with the difficulty of diagnosing problems over the internet

carleton

Here is the geo chart:

queerpunk

If I didn't forget my trigonometry, I'd be able to calculate what the effective top tube length of that frame would be if it had a reasonable seat tube angle (74-75deg). But it ought to suffice to say that that bike is actually a bit bigger than a 52, and with what looks like a 100mm stem on there, Elvis is scooting forward a lot to be in the aerobars.

Elvis, I think your stem is too long, the extensions may be too long, and you're trying to rest your elbows on the pads (they're more for your forearms; yes, it's less comfortable).

Quinn8it

My guess would be +2cm
in terms of gained cockpit versus same TT on a 74.5 ST

sbs z31

Mattio, yes it's a 100mm stem on there. I guess I'll do some adjusting tonight.

Quinn8it

This is where it gets tricky-
he is on a zero set-back seat post with an adamo saddle in the middle of the rails..
That is a very forward position on a 77deg seat angle...

If this bike was "built for road TT's" it is surely way out of compliance on the -5cm set-back rules.. Even with that short saddle

sbs z31

Quinn, you are correct and I did measure for the nose/bb distance and I'm too fad forward, only 2cm behind center line of bb. I'll mess around with the settings of the bike some more. So far it sounds like my options are:

New frame
Setback seatpost
Shorter stem
New bike fit

Thanks for all the advices and help so far guys!

queerpunk

Close. I spent some time with a notepad and https://www.carbidedepot.com/formulas-trigright.asp and I got 1.7cm.

Baby Puke

Quinn, my seat was at regulation -5cm for that photo, I've moved to -3cm. But I think the op needs to start at sonething like -10cm of where he's at now. Agree that he's way out of UCI compliance and I would guess that bike must handle very scary.

carleton

1st rule of bike fitting: Set the relationship of your butt to your bottom bracket first, then decide on the top tube length that will give you the desired reach.
2nd rule of bike fitting: DO NOT move your saddle back to get more reach for your upper body. This will change how your legs address the pedals.

Your fit on the bike is a 2-part system:
- Butt to the Bottom Bracket
- Butt to the Front Axle.

They are related, but should be considered separately, one then the other.

Baby Puke

This sounds like you're advising he not move his saddle back. Is that your intention? This seems like the obvious first step to me, from a mechanican perspective, though it will also go a good way towards fixing the reach problem. I also agree that the bike size may be ok. Start with the butt!

carleton

Sorry. Yes, it does sound like that.

I guess he should set his setback first. Using a bike with a really aggressive 77deg seat tube, you have to use a setback post to bring it in line with the track standard of 74 degrees. Road standards are around 73 degrees. Road TT is more 76-80deg.

I think the discord started when he got a TT frame and took it for fitting from a TT fitter for a Road TT then posted it in the Track forum.

Quinn8it

obviously Saddle position and Hip position are related- but the relationship is not static. there is a lot of wiggle room on hip placement on the saddle and the resulting hip angle. on a normal saddle 270mm, there is at least 10cm of potential positional travel..

thats how i was able to ride a sprint saddle at 0cm, and switch to a TT saddle at -5cm, when the rule changed- and never change my body position and my hip angle..

i like this article for Aero Fitting-
https://www.slowtwitch.com/mainheadin...r/bikefit.html
lots of good info on hip angle..

Quinn8it

i think what we are having trouble understanding is:

how did the OP leave a bike fitting with a "road TT bike" that was set up with an illegal saddle set-back?

since saddle position is ground zero on bike fit..

Baby Puke

I think the answer to that one is: Fitter is a triathlete. Non-UCI position are the norm, right?

sbs z31

This, I'll set my saddle relation to the bb tonight but it if iirc it also states that the rules can be an exception to shorter riders depending on individual build.

Quinn8it

You will not qualify for the morphological exemption- you have longer legs than me, and I don't qualify. It's based on knee over pedal pedal spindle or something similar..

One thing that could be exacerbating the situation is that you are using a saddle that is specifically designed to be run at -5cm, yet allow the rider a more forward position. So running that saddle at -2cm yields a Net result of an extremely forward position...

queerpunk

Bike Measurements for Commissaires has the ME guidelines.

Basically, if your saddle setback isn't in compliance, then you have to be KOPS-compliant.

Baby Puke

sbs z31, I think the take away from this is that you probably should not jump in with the most radically forward position possible/legal. There is a point of diminishing returns with forward saddle position after which you start losing the ability to apply full power. MY ADVICE would be to start from a neutral fore-aft position with a STANDARD saddle, and then tweak from there. 5 cm back from the BB center would be a good place to start, and happens to be the legal limit for a road TT or track enduro position. This will be especially important for a road set up as you will encounter hills, and the extreme forward stuff is really designed for the flat, works worse on an incline.

Moving your saddle back will have dual benefits of giving you a more powerful bio-mechanical position and stretching out your cockpit thus lowering your head and shoulders. Good things, right?

carleton

Exactly.

In order to get the exception of having your saddle inside of 5cm of the BB, the rider must mount the bike, set a crank arm at 90 degrees, and the official will observe the knee position. If the knee is at or behind the pedal spindle, it is legal. If the knee extends past the pedals spindle, it is illegal.

OP, your knee is waaaay past the spindle.



In terms of Triathlon rules, it depends on what governing body you are racing under.

USA Cycling/UCI says that the saddle cannot be within 5cm of the BB.
USA Triathlon says that the saddle can not only be within 5cm of the bb, it can extend up to 5cm PAST the BB:

The 15cm rule is probably to disqualify recumbent bikes.

sbs z31

BP, thanks and I think this is what I'm going to do first thing I get home tonight.

Baby Puke

Nice, sbs31. If you can, try to post a new vid of you in the revised position. After all this talk, I'm thinking of posting a video of myself for the heads to dissect!

By the way, why TT's? You look like a sprinter, dude!

carleton

OP, UCI (and by extension, USA Cycling) do not like the "Superman" Position that Graeme Obree pioneered. He got the idea from watching skiers. It worked.



UCI basically said, the saddle should be far back and the hands cannot be far forward.

UCI has a hard-on for Eddy Merckx.

https://en.wikipedia.org/wiki/Graeme_...aithful_banned

Watch The Flying Scotsman for the story. It used to be on Netflix.