700wheel

There is a listing of Spanish velodromes here:
Bike Cult/ Book: Online Resource: Velodromes

It says Madrid has the 250m wood Carabenchel velodrome.

Track drop out

Which has been dismantled since.. Everytime I find deadends like these

700wheel

Maybe something on this site
Track Cycling in Spain

Track drop out

Already did, the only velodromes I could find on this list in the vicinity of Madrid are the Coslada and Alcobendas, neither of which I can find anything useful on ! It's really frustrating

calamarichris

Is it a bad idea (or impossible) to use spacers (and perhaps a different chainring?) to convert a road crankset for track use?

Just to be clear, this is not a fixie.
I've got an SRM 7800 crank and outboard bottom bracket on my road bike. I figure it'd be cheaper to buy a Shimano BB than it would be to buy a power meter for the track bike.

queerpunk

There are a few companies that make okay 130bcd track chainrings.

The chainline situation might be tricky with outboard bearing stuff - it's certainly easier with square-tapered stuff when you can just get a BB with a different length spindle.

calamarichris

Anyone have any direct empirical evidence of chainline problems with this set up?
I was worried about the chainline (err beltline) for my Gate belt drive commuter, and bought two different width spacers, but it lined up perfectly without spacers.

carleton

Hi, Chris.

You are posting in the Track Training and Racing forum which is dedicated to racing on the velodrome, not street bikes.

You should repost your questions in Single Speed / Fixed Gear: Singlespeed & Fixed Gear - Bike Forums

carleton

FYI: I am no longer a moderator.

I don't have the time/bandwidth to do proper mod duties.

[places gun and badge on the desk and walks out]

I'm a normal Joe now.

queerpunk

A track chainline is 42mm from the center of the bike. Road doubles have the inner ring further inside than that, and the outer ring further outside. I forget the numbers but they're probably not hard to come by in Shimano's technical documentation.

calamarichris

Sorry about that Sheriff Carleton; thought I qualified because I am becoming active exclusively on the track and am not riding my track bicycles on the road ever. I just pulled the bejeezus out of my hamstring a few weeks ago when I coasted after performing my first F200. Hazard of New Functions and all that...



And thanks for the info QP. You're alright for a punk who's queer. Appears the outboard BB's haven't exactly found a home in the track world.

queerpunk

eh, there are a couple well-regarded cranks with outboard BBs - sram omnium, rotor's track crank (i think), and even sugino is making one. it's not so much the bb, it's road cranks being made to put the chainring in a different lateral location. if you can find a spacer that will move the driveside cup out, then a chainring on the inside could work - as long as there's enough room for the NDS arm to grip the spindle and stay tight.

if your 7800 arm is a 110 bcd unit, then there are adaptors for 110 bcd -> 144 bcd that are designed around using road PMs on the track, and make chainline compensations.

carleton

Hahahaha,

I don't understand.

You posted a pic of a bike with a belt drive, geared rear hub, townie bars, basket, lights, saddle bag, and brakes, NONE of which are allowed on the track and asked questions about it in the track racing forum.

Yes, you may be a trackie like everyone else here, but the purpose of the rule is to keep conversations generally on-topic.

You may be a triathlete, too, but you can't go to the triathlte forum and post questions about BMX bikes, right?

Further, the title of this thread (that I started) is: "Ask your small, random, track-related questions here"

Hey, I just want you to get your answer more than anything.




...and keep threads on topic

queerpunk

hey carleton - calamarichris asked the question about a track bike.

and then later said that a similar conversion had worked on a belt-drive commuter.

carleton

Oh. Maybe I'm just confused then.


(This is probably the most logical answer)

calamarichris

Thank you! Sorry for coloring outside the lines and thank you for all the helpful guidance I've gleaned from you in this and other threads in this subforum as well. (No sarcasm at all, I really appreciate all I've learned from you.)

Koogar

Yes, the Rotor track BB has outboard/external bearings. Just installed a few. They look like this:

calamarichris

Those are cool and they look like I could torque them to 40Nm with my bare fingers, but are trackies eschewing outboard BBs because of Q-factor?
I spent a little time at the track today, both measuring the static lean angle of my current loaner bike and doing my durndest trying to elicit this dreaded pedal strike everyone talks about. And then there was a fixie with a Sram Omnium crank perched at the curb outside of the post-velodrome pizza/brewery... dang that thing looked wide!
I understand that road frames have lower BBs, which will require stubby little crankarms to reduce pedal-strike incidents; and that stubby little crankarms will make a normal bottom bracket appear wider, but the question still hit me like a hefty-bag full of vegetable soup dropped from 14 stories:
Are trackies still in love with internal/tapered bottom brackets because of the reduced Q-factor & correspondingly assuaged pedal-strike potential?

And are Sram Omnium cranks just as narrow as their older counterparts?

Koogar

I won't try to speak for everyone, but most of the people I know are just trying to look for the best option among the relatively few that are made for our niche market. Dura Ace is pretty much universally respected. I'm running Rotor right now, because I was convinced it's the obvious choice for SRM.

As for Q, I am one of those who do not believe that narrower is always better, and with respect to pedal strike, you also have to look at the BB height and pedal/shoe system.

queerpunk

They are. According to SRAM's specs, Omniums have a 134.7 q factor. DA, Sugino, and Campag Record q-factors range from 131 to 139.

calamarichris

Many thanks learned fellows for the guidance.

Next question: how do you determine the narrowest bottom bracket spindle you can get away with?

700wheel

I like to minimize Q but make sure my chain rings, crank, and shoes clear the chain stays.

queerpunk

Not much variation there - each crank is designed around a specific BB spindle width in order to place the chainring in line with the rear cog (42.5mm chainline). Changes to that are going to put the ring and cog out of alignment with each other, flex the chain, add some friction to the system. Not sure a bit less Q is worth it.

calamarichris

I just assumed narrower would be better from a pedal-strike standpoint, but that we could "tune" the chainline with an internal/tapered bottom bracket by threading the cups as needed. Not so?

Koogar

I just don't think that many people are both a) riding on tracks steep enough that the risk of pedal strike makes setup critical and b) unable to make things work through aspects of setup other than dialing in minimum BB width. If you are super worried about pedal strike, I would suggest:

1) Ask around at the track you're interested in to see what works for other people
2) Look at frames with less BB drop - say, 50mm or less
3) Consider narrower pedal systems like Speedplay
4) Use shorter crank arms

But to get back to your suggestion, I could also anticipate someone reasoning that the existing methods are fine, because high BBs make the bike more nimble, and outboard bearings and shorter crank arms are stiffer.