Why is my new bike slower than my old one? Aero?

[jamiebae]

Brakes backed right off, wheels spin freely at both ends, same Michelin tyres (23 on one, 25c on the other) so no rational explanation at all. I'm travelling the rest of the week, but will get the two bikes side by side and see if I can tweak the seat height, stack height etc and see if that helps

[lukeyman]

Just a quick thought. My cycle speedo has a setting for 700/23 and 700/25... Is there a subtle difference? And do you adjust yours?

[WinstonWolf]

Do you feel strong on the new bike? If you don't feel as strong it's probably just a fit thing.

[jamiebae]

WinstonWolf said:

Do you feel strong on the new bike? If you don't feel as strong it's probably just a fit thing.

I don't feel strong on any bike, my BMI is significantly lower than Chris Froome or Nairo Quintana's

I think it must be a fit issue, so that's where I'm going to look next. The speedo is a Garmin GPS one so no risk of data corruption there.

I have also stuck an ad on one of the ex-pat websites on the off chance someone wants to give me back what I paid for the bike, as I like shiny new stuff and want this...

https://www.facebook.com/GenesisBikesUK/photos/a.1...

[s4avant]

Have you factored in air temperature and wind speed/ direction in your calculations and were these the same on the days that you tested the bikes?
I would think that you would travel faster in warmer, less dense air.

[okgo]

Read his posts at least. He rode the old bike yesterday, it was still faster.

Something not right.

Over that sort of distance even a full on time trial bike would only be a minute or two faster...

[jamiebae]

Just to update this, I got the old and new bikes together, and with the new stem and bars the riding position is as good as identical so no issues there.

I have decided that I just need to man up and push the pedals harder, and any difference is in my head, or possibly just that the wind is blowing in a different direction sometimes.

So, I have been reciting rule 5 to myself every night before bed in the hope that it helps (and also because I need to make up for buying full Belkin kit and having a saddle bag).

[TwistingMyMelon]

OP I find it takes a few days/sessions to adapt between bikes, for example if I ride my MTB to work all week then go out at the weekend on one of my road bikes, whilst im quicker than the MTB my times during intervals are not that quick for me. After riding the same roadie 3 sessions in a row, times really pick up and I feel stronger/more used to the bike , it just feels more "right" like my body is in sync with it

I always find there are loads of subtle differences between bikes and it takes me a couple of sessions to get going

[WarrenG]

I think the tyres are underestimated. You ran the 25's on the 'faster' bike and couldn't match it on the 23's with the same pressures. Swap the tyres and try it? If all the current thinking is correct, for the same pressure, the 25's are more aero, have better rolling resistance and crucially are more comfortable - I find that too high a pressure on my bikes kills rolling speed on flats, due to every ripple in the tarmac feels like a rumble-strip. (5'10" - 77kg running only 95psi in Vittoria Open Paves (24mm) and Corsas (23mm) any higher and I may as well fit a vibrating seat-post)
I recently resigned some 25mm gatorskins to the parts bin because they roll so dead and slow, I'll just pay for the punctures if I have to.

[HereBeMonsters]

As I said on the previous page, you need to up the pressure for a narrower tyre, given the same weight on top.