Burning thighs on road bike but not TT bike

Hi all,
I wonder if anybody has experienced the same and/or knows how to fix the following:
On my roadbike i have burning/blocked upper thighs (all over) and glutes when increasing power. It feels like my muscles are suffocating and cant keep pressure. I have been checked for arterial problems and all other kind of stuff, they did find poor blood circulation/lactic acid clearance from the muscles, but no causes or whatever.
The weird thing is that on my TT bike I dont suffer from this issue and feel amazing on high power, with no burning thighs at all. For example i managed to do 430watts on 20min on tt bike and barely 400 on the roadbike with the same powermeter.
Ive had bikefits for both bikes multiple times, but everybody says i should not change my position on my road bike towards my tt bikefit since it would only give me problems. The difference between the two bikes is the saddle of the tt bike being 15mm higher, and 30mm more forward.
Has anyone experienced this and or fixed this? I’ve had this for four years and I never found any answers. It comes to the point that racing on the roadbike is not fun anymore because it feels like im half as strong as on the TT bike :smiley:

That sounds like terrible advice given your circumstances….you don’t have to necessarily match the TT saddle position, but moving towards may well alleviate your symptoms.

Try moving your saddle forward 5mm and uo a similar amount and see how it feels. You can always go back if needed.

(You may need to get a longer stem at some point to fully compensate for the saddle changes)

If it were me, there might be 1000 PhD Physiologists and Bike Fitters that would tell me not to change my roadbike position.

I would still change it. 30 watts is a lot so if you could get all or a part of that just by changing pos’n? Yikes. Go for it.

If 1000 Coaches told you a cat was a dog, would you start calling cats dogs?

That said, isn’t there some official UCI rule dictating how far the saddle has to be behind the bottom bracket? I’m not sure. If your bike regularly gets jigged you probably know what the rule is. I don’t.

Move your saddle forward on your road bike. Maybe go for an inline seatpost rather than one with set back.

I have to agree with all of the above. While having bike fits has helped me immensely, my fitter, who is now also my good friend and coach, told me that there is one golden rule in bike fitting that trumps all else: “If it works, it works”. By this, he meant that things don’t necessarily have to make sense in order to be correct. Some people just ride better with a slightly higher or lower saddle than is the norm. This may cause them to fall outside of the general “rules” in terms of angle of knee extension at the bottom of the pedal stroke, or perhaps they don’t illustrate perfect KOPS in their pedalling motion. While guidelines and general “rules” are great in many cases, individual variation should always be allowed to occur. For some, this will be more pronounced than for others.

It sounds like your road bike position impinges your hips. The TT position allows for a more “open” hip position which subsequently results in more effortless knee and hip extension. If this is more comfortable than the road bike position, why on earth would you NOT go towards it? If you know what makes you more powerful and comfortable on the bike, steering away from it seems counterintuitive.

Personal anecdote - I had a similar issue to you. My fitter initially set me a little too far back and raised my bars a little too much. While this looked great on video, I felt quite restricted. The position simply didn’t feel athletic and powerful. By moving my saddle forwards and slightly higher while lowering my bars, I felt much more connected to the bike while pedalling.

My fitter also gave me a great self-evaluation for determining bike position. He said that I should feel ready to chase Jonas Vingegaard up a mountain whenever I’m on the bike. The point being that if I had to do such a thing, I’d never in a million years think “well, it would be nice to sit higher and a bit further forwards, but my fitter said this is optimal, soooo…” - no, I’d want to make sure everything felt exactly the way I wanted it so that I could focus 100% of my energy into producing power.

One additional thought worth considering….you could try a shorter pair of cranks if you do’t want to move your saddle closer to your TT position.

This would have a similar effect of opening your hip angle, which seems to be the root of your discomfort.

Do you use different saddles ?

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Don’t TT bikes usually have shorter cranks?

That’s very acute to want to be more obtuse. (sorry, couldn’t help the math joke…)

NOt necessarily…but the issue here is with his road bike. So even if his TT bike has shorter cranks, switching to shorter cranks on his road bike will help open his hip angle.

Thanks for your replies, I’m not sure how to quote individual suggestions so i’'ll just adress them on by one. I’ll adress the saddle and crank comment first.

Saddle: @Ede71
On my tt bike i run the flat Pro Aerofuel TT saddle. On the roadbike ive ran over 15 saddles in the past five years i think. I now have the Sella Italia Flite which is also flat and short which i like. I also try to get the synchros belcarra cutout saddle, which looks like the aerofuel, short, very wide nose and for endurance purposes a kickup the end for back support
I tried running the aerofuel on my roadbike, but in not all out efforts its not supportive.
I’d say the flite saddle is a good one for me though after trying everything the past five years.

Cranks: @Power13
I always used 175mm cranks on all my bikes, but recently decided to try shorter ones. I tried 170mm and 165’s. On the roadbike the 170 felt better than the 175’s. The 165 didnt give me additional relieve on feeling plus that in the races and criteriums i ride, PLUS my personal slightly lower rpm preference (when I’m on the maxmax ill ride in between 85and95 rpm) I feel like the 165’s are too heavy on my muscles by the extra force i need. From 175 to 170’s my cadance rised a little, 165’s didnt rise further so by same rpm torque is higher so it didnt work for me)
However i tried the 165 on my TT bike which I really liked, but i was also almost completely painfree with the 175’s, the 165 just feels a little better . So for now the setup is:
Roadbike 170mm
TT bike 165mm

I saw @Calle making a comment about hip impingement:
In hospital they ruled out vascular problems, but kept suspicious after finding somewhat poor blood circulation to my legs. After four years, the only thing they found is that on an MRI, my Psoas and Piriformis were overdeveloped, not ruling out some sort of impingement of the sciatic nerve or maybe in high effort the artery. Since january I’m twice a week at the physio working on hip mobilisation. Relatively weak hip flexors and hamstrings and the glute medius being overloaded constantly.
But on my TT bike i do feel almost without suffocating/burning thighs and on my roadbike i have it a lot. Indicating to me that there is an angle or somehting in the saddle position triggering poor bloodcirculation and completely blocked thighs.

Setback Saddle height
I find it interesting everybody says i should move forward my saddle over raising the saddle. The problem is the following. I have a team bike which doesn’t have zero setback posts. Bikefitters recommend me a 85mm setback and the most far forward position with this post is 80mm. I’m trying to get a post which is adjusted by a carbon repairshop being more forward so i’d be able to try more forward positions.
What i felt at 80mm setback was that it felt initially easier, but in endurance rides i’d feel more exhaustion in my thighs than regular. (not the burning feeling but normal exhaustion)
Higher saddle height feels great. I’m able to pedal in the anaerobic zones way more controlled and composed. But after a little while my back would start to hurt so much and after and hour i feel kinda blocked.

I tried 15mm height change in a training a few times @2min 500w:
Low saddle. after a minute my legs started to block and i could complete the interval by standing and going all out and uncontrolled
High saddle: I did the two minutes seated without a blocked feeling

It’s hard to put these two together. Saddle higher yields low back problems. And i suspect being more forward more thigh exhaustion. I havent tested it enough but it was my initial feeling. Also it was only 5mm more forward. I hope the saddle post story works out so i can try a more extreme setup and can evaluate from there. (85mm sb on roadbike, 55mm on the tt bike, I would like to try 60mm on my roadbike for example)
And @Brennus, UCI restricts riders going forward more than 50mm behind the BB for roadbikes as well as TTbikes, so in my case it’s not a limiting factor

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