# 数据和下坡赛车与尼克·莱斯特（Nick Lester）的赛车 -

### 3 评论

• Eli Ricca

I keep seeing adds for these tubes, would like to know if Josh has any data to back up it refute the claims

https://www.tpubiketubes.com

• Luke

Hello!

Firstly thank you for the content, I love hearing about all of the different ways to go faster!

Secondly, I have a question for Josh. In triathlon, people have all sorts of crazy ways to carry hydration through the course and use it to lower their CdA. What are your opinions about putting a water bottle under the aero bars ( as well as above, but I’m referencing a 2 bottle system on the front of the bike), and how would that affect the aerodynamic optimization of the bike? What is your opinion on other triathlon hydration “solutions” (bottle behind the seat, or Camelbak bladder in the front of the jersey), are there any other optimizations that should be made around hydration?

Thanks all!

• Ty

Hey folks,
Since you’re branching out a bit from road and XC, how about a little BMX marginal gains?
As in any cycling sport tyre pressure is a question that always comes up, especially for new people to the sport.
For those that don’t know BMX tyres come in a mix of sizes based around the riders age and size, kids up to 35ish kilos use 1 1/8th inch tyres commonly inflated to around 90psi, 35kg to 55 kg 1 3/8th to 80psi, 55kg and up move to “decimal” tyres (1.5" to 2.1") which are also slightly smaller diameter and people run from 60 to 80psi.
In Australia we generally run a surfaced track (simlar to the Olympics) which is a combination of sand and glue, with concrete berms, these are generally the smoothness of good tarmac but has a very slight give to it, standard gate heights are 5 to 6.5 meters high, which appears to be higher than the average U.S track hill but lower than a supercross/Olympic hill.

Do these tyre pressure still sound about right?

Considering the speeds on the track are upto 50km/h and lap times are 40 seconds are marginal gains such as internal cable routing and aero seatposts of any value?
What about the new generation of carbon frames such as the Chase ACT or Prophecy scud EVO which have a quiet an aero look to them?
Large chainring/rear sprocket combos for greater chain wrap/reduced angle are starting to become popular too, again worth it?

Besides the standard marginal gains like removing bearing shields what other options are there?

Thanks