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-   -   Interesting finds around the web (https://www.bikeforums.net/showthread.php?t=929230)

Flatballer 04-25-18 11:54 AM


Originally Posted by 700wheel (Post 20306586)
I agree.
As the number of sprocket teeth decreases the chain link at the top of the cog carries more of the chain load and following links take less of the chain load. This results in deformation of chain components and increased bearing stress on the sprocket teeth; the result is more friction and decreased efficiency.
There is an interesting article on the effects of bicycle chain efficiency here:
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
Figure 2 shows measured drive chain efficiency for 21, 15, and 11 tooth cogs. My guess is that a 9 tooth cog would yield a transmission efficiency of 91% or less.

The hub shown in post 1939 seems to be a special design; there are several hex headed bolts holding the hub body together.

That's a really interesting article.

Surprised that the highest chain tension was the most efficient (but I don't know how high the tension was, 305N doesn't mean much to me, maybe there's a limit where it gets less efficient again, like we've all heard?).

Bigger difference in the efficiency with smaller cogs than I thought there would be too. I knew they were less efficient, but I didn't know they were THAT much more less efficient.

I'm curious if their results hold up at higher RPM and higher power, or if the loss in power isn't dependent on power and the actually efficiency would go up across the board at a more reasonable power (and RPM).

70 RPM and 175W isn't a scenario that occurs very often.

Flatballer 04-25-18 05:21 PM


Originally Posted by spartanKid (Post 20307276)
I wonder how applicable are these chain tensions measurements to track/fixed gear bikes. Their testing setup as a rear derailleur.

Ah, good point. I was just skimming quickly and didn't actually read much of it. Just looked at tables and charts.

carleton 04-29-18 10:23 AM

https://i.imgur.com/h6PN89u.jpg
From: https://www.instagram.com/p/BiESPd6h...aurinevriessen

Non-NJS stuff I see:
- Carbon frames from those that make steel NJS frames
- SRM
- modern Shimano Dura Ace pedals
- G-Race pedal straps (I think)
- Mavic Ellipse
- Saddles of choice
- Carbon handlebars (not sure what make/model)

Not sure if this is training or race gear, though. Interesting nonetheless.

brawlo 04-29-18 06:42 PM


Originally Posted by 700wheel (Post 20306586)
I agree.
As the number of sprocket teeth decreases the chain link at the top of the cog carries more of the chain load and following links take less of the chain load. This results in deformation of chain components and increased bearing stress on the sprocket teeth; the result is more friction and decreased efficiency.
There is an interesting article on the effects of bicycle chain efficiency here:
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
Figure 2 shows measured drive chain efficiency for 21, 15, and 11 tooth cogs. My guess is that a 9 tooth cog would yield a transmission efficiency of 91% or less.

The hub shown in post 1939 is a special design; there are several hex headed bolts holding the hub body together. To change cog size requires partial disassembly of the hub.

I think people miss the point of this whole exercise. This huge gearing is for on the bike strength training = squats on bike. Inefficiency just isn't a consideration. And then the whole inefficiency argument always gets @carleton line of "look at what others are using" in my head. The top pro guys are going faster and faster on what everyone argues are inefficient gears. Top masters guys are going faster and faster on "inefficient" gears. The efficiency argument should really die a natural death because the argument appears to be quite invalid

brawlo 04-29-18 06:59 PM


Originally Posted by seau grateau (Post 20305665)
Apparently this is the 9t cog setup Bos has been using:

https://www.instagram.com/p/Bh-pPQll...mekaanikko9239

That post prompted me to look into them again. And then this hub from Specialized came up. I'm not sure why it didn't come up in my searching some time ago, because it's been out a long time now. It is the hub used on their P.Fix. We don't seem to have ever had this model available in Oz. The hub is almost exactly what Bos is using now with the bolt up fixed option. No mods necessary. Specialized should consider making a re-run of these seeing how popular they are becoming for the track sprinting community

Slumworm: Game Changer : 9T Cogs & 14mm Axle Hubs

southernfox 04-30-18 04:13 AM


Originally Posted by Flatballer (Post 20306663)

70 RPM and 175W isn't a scenario that occurs very often.

Pretty darn typical in match sprints...but it doesn't matter :)

carleton 04-30-18 04:43 AM


Originally Posted by brawlo (Post 20313775)
I think people miss the point of this whole exercise. This huge gearing is for on the bike strength training = squats on bike. Inefficiency just isn't a consideration. And then the whole inefficiency argument always gets @carleton line of "look at what others are using" in my head. The top pro guys are going faster and faster on what everyone argues are inefficient gears. Top masters guys are going faster and faster on "inefficient" gears. The efficiency argument should really die a natural death because the argument appears to be quite invalid

Yeah, I agree.

I think it's no different than me setting up my spin bike fit to match my track bike then setting firm resistance.

It may be slightly better to do the "squatting on the bike" on the track that way you can roll through the affected muscles in slow motion as you work on everything else. But, I don't think this is a groundbreaking training tool. Repetitions in the gym happen at a similar rate.

I think this would be a must-have item for the athlete who spends 100% of their time on the velodrome, with no gym, trainer, or spin bike, or someone looking to fill in some small gap in their training program.

Very cool, nonetheless.

carleton 04-30-18 04:56 AM


Originally Posted by southernfox (Post 20314226)
Pretty darn typical in match sprints...but it doesn't matter :)

You are technically right (the best kind of right) that it occurs often, probably at some point in every match sprint. But the duration of time that it occurs is maybe 10 seconds of an approximately 1 minute match sprint.

Much different than the 30 to 120 minutes in the IHPVA test :D

carleton 04-30-18 05:44 AM

Want to see what Northern California local riders rode back in the early 2000s? I stumbled upon Garret Lau's old pbase gallery. This was before my time in the sport. Very cool.

http://a4.pbase.com/u48/garrettlau/u...2_2209_800.jpg
http://a4.pbase.com/u27/garrettlau/u...0.133_3311.jpg

Track Races Photo Gallery by Garrett Lau at pbase.com

He then posted LOTS more to Flickr (2008-2014): https://www.flickr.com/photos/garret...7621926494215/

So, if you are new to the sport and want to see what active local racers are riding, have a look. It's not the $20,000 spaceships you see at World Championships...and they ride the hell out of them.

https://c1.staticflickr.com/6/5595/1...3fc23d64_b.jpg

I think there are a few Bike Forums members in those galleries as well :D

Baby Puke 04-30-18 06:41 AM


Originally Posted by carleton (Post 20313085)
https://i.imgur.com/h6PN89u.jpg
From: https://www.instagram.com/p/BiESPd6h...aurinevriessen

Non-NJS stuff I see:
- Carbon frames from those that make steel NJS frames
- SRM
- modern Shimano Dura Ace pedals
- G-Race pedal straps (I think)
- Mavic Ellipse
- Saddles of choice
- Carbon handlebars (not sure what make/model)

Not sure if this is training or race gear, though. Interesting nonetheless.

-Training race at the keirin school. They generally use an NJS front wheel and a disc rear for races recently. There is now a separate certification for a few carbon frames and modern type stems. The rest is NJS stuff. I don't think they can race with the SRM.

tobukog 04-30-18 07:08 AM


Originally Posted by carleton (Post 20314274)
Want to see what Southern California local riders rode back in the early 2000s? I stumbled upon Garret Lau's old pbase gallery. This was before my time in the sport. Very cool.

http://a4.pbase.com/u48/garrettlau/u...2_2209_800.jpg
http://a4.pbase.com/u27/garrettlau/u...0.133_3311.jpg

Track Races Photo Gallery by Garrett Lau at pbase.com

He then posted LOTS more to Flickr (2008-2014): https://www.flickr.com/photos/garret...7621926494215/

So, if you are new to the sport and want to see what active local racers are riding, have a look. It's not the $20,000 spaceships you see at World Championships...and they ride the hell out of them.

https://c1.staticflickr.com/6/5595/1...3fc23d64_b.jpg

I think there are a few Bike Forums members in those galleries as well :D

Those are Nor Cal riders in the pictures Very different. :) At this time, the young rider in white in the top picture was a National Short Track? Speed Skating champion, and this year he won a World Cup Omnium. I think Hellyer can lay claim to making him what he is today.

carleton 04-30-18 07:45 AM


Originally Posted by tobukog (Post 20314359)
Those are Nor Cal riders in the pictures Very different. :)

Doh! I knew that. Thanks for the correction. "Hellyer" was mentioned only 100 times in the galleries :D


Originally Posted by tobukog (Post 20314359)
At this time, the young rider in white in the top picture was a National Short Track? Speed Skating champion, and this year he won a World Cup Omnium. I think Hellyer can lay claim to making him what he is today.


That's awesome! His name?

tobukog 04-30-18 07:55 AM


Originally Posted by carleton (Post 20314419)
Doh! I knew that. Thanks for the correction. "Hellyer" was mentioned only 100 times in the galleries :D




That's awesome! His name?

That's actually Daniel Holloway. Probably before he started shaving :)

carleton 04-30-18 08:12 AM


Originally Posted by tobukog (Post 20314438)
That's actually Daniel Holloway. Probably before he started shaving :)

Ha! Yes it is. Good eye. I didn't notice that that was Holloway.

Pretty fast dude.

https://twitter.com/The_Hollywood
https://en.wikipedia.org/wiki/Daniel_Holloway_(cyclist)

carleton 05-01-18 09:01 AM

UCI Interview with Azizulhasni Mohd Awang:


sarals 05-02-18 08:42 AM

He's an incredible athlete, and what a genuine person. That was a great interview.

southernfox 05-03-18 06:19 AM


Originally Posted by carleton (Post 20314245)
You are technically right (the best kind of right) that it occurs often, probably at some point in every match sprint. But the duration of time that it occurs is maybe 10 seconds of an approximately 1 minute match sprint.

Much different than the 30 to 120 minutes in the IHPVA test :D

Exactly. That's what I meant by 'it doesn't matter,' because it's so short to be inconsequential (and doesn't affect relevant energy systems).

carleton 05-05-18 03:18 PM

Watch the Keirin tournament at DLV live streaming in 40 minutes. Preliminary racing going on now.


southernfox 05-06-18 09:37 AM

Boo to rain!!!

sarals 05-06-18 03:10 PM


Originally Posted by southernfox (Post 20325084)
Boo to rain!!!

Prelude to Nats?

southernfox 05-06-18 06:35 PM


Originally Posted by sarals (Post 20325532)
Prelude to Nats?

My Nats are indoors ;)

Morelock 05-07-18 07:13 AM

dang, missed the stream :/

My moaning/complaints - Track at Aguas is being repaired/resurfaced during July... what to do now :/

carleton 05-07-18 09:35 AM


Originally Posted by Morelock (Post 20326531)
dang, missed the stream :/

My moaning/complaints - Track at Aguas is being repaired/resurfaced during July... what to do now :/

You can watch the replay. At some point, the audio cuts out towards the end soon before the rain comes that ends the event.

sarals 05-07-18 02:41 PM


Originally Posted by southernfox (Post 20325844)
My Nats are indoors ;)

Milton?

southernfox 05-07-18 03:52 PM

Naturally.

carleton 05-08-18 09:46 AM

Mathilde Gros' Keirin bike disassembly / assembly exam.

https://www.instagram.com/p/BiQw1PlH...=gros_mathilde

I don't think this should be required to race at local velodromes, but I do think it should be offered as a class/clinic for new and experienced riders alike.

sarals 05-08-18 11:16 PM


Originally Posted by southernfox (Post 20327608)
Naturally.

Nice! Jealous...!

Morelock 05-09-18 06:10 AM

https://cimg3.ibsrv.net/gimg/bikefor...0888877a04.jpg
Colby Pearce put up some pictures of his Fifty Point One yesterday. Looks good

carleton 05-09-18 07:31 AM


Originally Posted by Morelock (Post 20330285)
https://cimg3.ibsrv.net/gimg/bikefor...0888877a04.jpg
Colby Pearce put up some pictures of his Fifty Point One yesterday. Looks good

Nice!

jfiveeight 05-09-18 07:41 AM

For the uninitiated https://www.instagram.com/p/Bifx7_IB...y=colby_pearce

https://cimg9.ibsrv.net/gimg/bikefor...06fe68802b.jpg
https://cimg7.ibsrv.net/gimg/bikefor...21981bec7b.jpg


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