gycho77

thanks you for your explanation.
I was just wondering why would they make their top tube shorter(custom frame) to fit long stems.

mrwonton

Anyone use a Planet X track frame on the street? With the Planet X stealth fork for brake? I love the look of this bike but don't ride velodrome. Thanks.

carleton

Hi. This sub-forum is specifically for training and racing on the velodrome. There is a sub-forum for street riding. You should ask here: Singlespeed & Fixed Gear - Bike Forums

mrwonton

Ok thanks. Didn't realize this was so pacific.

carleton

I find that hard to believe, being that your first 2 posts were in Single Speed - Fixed gear last month.

But, it's all good. Good luck.

mrwonton

I just meant I didn't think it was a big deal to post it here and not there since the bike itself is mainly a dedicated track bike and not very associated with street riding. I'll try over there.

taras0000

It isn't a big deal. We're happy to field questions from anyone that comes through here. We'll redirect only when we think you'll get a better answer somewhere else. Most guys that come through here don't ride their track bikes on the street, and if they do have a tarck bike for the street, it will be very different from their track steed. It's not that we can't help you with the bike, it's that we don't have any experience with what your end use of it is going to be.

tobukog

New member here. Just wondering if anyone had any experience with Planet X pro vs Planet X Kochi-san frames. I was also wondering if any aero testing data was public available for track bikes frames. Thanks!

carleton

Hi and welcome to the forum.

I used the Planet X Stealth Pro Carbon back in 2009. It's probably different now.

Aero testing data isn't common and is usually only released as part of marketing materials, so should be taken with a grain of salt. Independent aero testing (like you see with many road components) is rare for track components.

gycho77

Welcome to this forum!

Aerodynamic is not a big issue in track world.
Instead Stiffness and geometry is more important than aerodynamic.
Carleton once said "If you are not losing by .01second aero equipments are not going to make a difference"

Also Planet X frames are not that stiff, so I recommend other track bikes such as Hoy track bike and other

tobukog

Well, being a small endurance rider, I'm not sure stiffness is too much of an issue for me. Frames at my size tend to be pretty stiff anyway. As for aero, I kind of hoped on aeroing my way to a medal at Masters Nationals. I doubt I can make over 1000w in a sprint finish, so I have to get my speed from somewhere.

Dalai

Please remove your sprint coloured glasses for a second... Aero is very important! Why do you think we use double discs for the pursuit? Rear disc all the time... Sprint races are often won by 0.1 of a second.

The Planet X frame geometry is fine.

Where you you get the Planet X frames are too flexy? Especially since we don't know the weight or race preference of the person asking. I have both a Planet X Track frame which you say is flexy and an overweight and over engineered BT Stealth and personally can't notice a difference.

tobukog

That's what I thought. Let the buyer beware I guess. All the equipment in the world won't help unless I have the legs -- I guess I'll find out this Saturday at Atlanta. It's been over 10 years since I've felt competitive in an A field, but this year I've been flying on the road so I figure I have a decent shot at doing ok. Ok, as being able to finish with the field. Of course you always hope for a little better...

Dalai

I am yet to see independent aerodynamic test results for track frames.

Planet X do make some claims about the Kochi San frameset... But as Carleton alludes to, you need to take anything a manufacturer says with a grain of salt.

Dalai

Predator hub finally gave way at the glue interface with the disc. Luckily it wasn't a total failure so gave gave way slightly under full load. Was repaired by Raoul at Luescher Teknik who drilled small holes in the hub flange and injected glue to rebond.

Dalai

Not comparing frames, but some Interesting journal articles in the following topic -https://www.bikeforums.net/track-cycling-velodrome-racing-training-area/987591-journal-articles.html

Particularly note the opus - Aerodynamics of Track Cycling by By Lindsey Underwood in the first post.

tobukog

Thank you. I'm really a big picture / passion type of rider, but I've had to change the way I think over the past several years. All these stupid marginal gains in tires, even different skin suits, position, shoes, wheels, frames, etc add up.

Dalai

I'm a true believer in aerodynamics. Though on the TT bike, I came out of my windtunnel session ~43 Watts the better. Only 10 Watts was from a faster helmet, the rest positional! No way I could have made that improvement in 2 hours training...

If going out and needing to buy a frame anyway, why not also consider aerodynamics! It's not like focusing on aerodynamic gains is mutually exclusive to all the other necessary things required to be a fast cyclist. It just complements it...

Dalai

I haven't seen the Koichi in the flesh, but can comment on the stealth.

The tube shapes such as the down tube are surprisingly not true aerofoils. Appears more 'aero' than the aluminium frame it replaced.

For pursuits - I had to use an adjustable stem to get lower due to the tall head tube.

Since you are in the US, have you considered the Affinity Kissena?

tobukog

Well, I'm on a Masi Coltello right now. The version I have is known cracking at the seat collar, and I've had it repaired once. It will probably have to be replaced at some point soon, so I've been thinking about other bikes. I've been out of the latest track developments for a while, so I really don't know what's out there. I'll look at the Affinity.

Koogar

Thanks, Dalai, interesting reference. I'm not deep in this literature and wondering if I'm interpreting the following from Underwood in the same way as others (emphasis is mine):

"A. Lukes et al. [2005] state that an aerodynamic frame is 3% faster than a normal frame, and by shielding the components the drag can be reduced. Kyle and Weaver [2004] also state that by hiding the screws, bolts, fastenings and other external components, covering the under saddle, smoothing the cranks and sprockets, and having long, thin aero elements for the frame, the drag can be reduced by as much as 14%. According to Lukes et al. [2005] the handlebars contribute to 10% of the total drag on the frame and components (excluding the wheels, saddle and seat post) which is equivalent to approximately 3% of the total drag on a cyclist (the frame, wheels and components account for only 30% of the total drag on a cyclist)."

Doesn't this imply that the reduction in total drag of bike+rider that can be expected by optimizing the frame for aerodynamics is less than 0.14*0.03 or about 0.4%?

Koogar

Does anyone know of a good SRM PC8 stem mount? I use 3T Scatto bars, so the regular mount isn't an option, and I don't want to resort to the so-pro under saddle setup unless and until forced to do so.

carleton

I'd ask on slowtwitch. They have a lot of funky setups with aerobars and SRMs are popular. That's where I learned of the stem mount for the SRM that you see in my pics. I think it was made by an engineer working out of his home as a side project. I got it back in 2011, so the details are fuzzy.

Dalai

Something like? REC Mounts SRM Onry Computer Mount Bolt Clamp Type SRM Bolt FOR POWERCONTROL8 | eBay

Koogar

Thanks, Dalai - that's pretty slick. Any experience with it? My only reservation would be around not knowing the quality/specifications of those spacer bolts and not wanting to find the bars no longer connected to the stem while riding some day. I've reached out to the seller to try to find out if it's compatible with a Thomson X4.