# BB Height for Track bike



## IcemanYVR (Jul 27, 2006)

I have a Colnago Master X-Lite that I am considering turning into a track bike. I am wondering about the BB height, if it is high enough, or if I will have trouble with pedaling in the corners.

The velodrome at which I will be riding has 47 degree corners.

Any thoughts are appreciated.


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## DY123 (Oct 5, 2006)

See here: http://forums.roadbikereview.com/showthread.php?t=96371


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## dburns (Apr 10, 2006)

IcemanYQQ said:


> I have a Colnago Master X-Lite that I am considering turning into a track bike. I am wondering about the BB height, if it is high enough, or if I will have trouble with pedaling in the corners.
> The velodrome at which I will be riding has 47 degree corners.
> Any thoughts are appreciated.


I ride the steepest velodrome out there - the Forest City Velodrome in London Ontario and it's 50 degrees.

We have a go/no-go gauge on the trackside table that lets us know whether a bike will clip pedals or not. This gauge doesn't care what the BB height, crank length or pedal thickness is. All it cares about is clearance under the pedal. I've seen converted road framed bikes pass the test and prove themselves by not clipping pedals.

Of course "speed" is the #1 factor in whether pedals will clip. Go 25mph+ and you're 90 degrees to the track surface and could use 180mm cranks. But if our gauge says you're ok, go slow enough and you will slide down the banking before you clip a pedal.

What is this miracle gauge? It's just a lowly piece of 2x4 lumber used on its edge. I guess its red paint makes it special. If it fits under the low pedal on the flat infield you're good to go. I think the finished dimension of 2x4 is 3-5/8".

Of course it's possible that this won't be good for your track. The track's banking radius plays a large part in the g-force and your angle to that track. Just ask Bob who designed (and rides) the FCV. He'll tell ya.


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## TurboTurtle (Feb 4, 2004)

dburns said:


> I ride the steepest velodrome out there - the Forest City Velodrome in London Ontario and it's 50 degrees....


This amazes me. - TF


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## dburns (Apr 10, 2006)

TurboTurtle said:


> This amazes me. - TF


And ya know, it's soooo easy to ride. A minimum speed of 30kph (about 18mph) is suggested but we know it can be ridden at 20kph (about 12mph; some have dipped below that even; I don't have the guts). At 24kph I'm getting nervous as that's awful slow. Most of the (really) old geezers ride at 28kph.

A lot of is is to do with the radius as it's this that imparts the g-force that sticks you there. A bigger track (with bigger radius but same banking angle) would need a higher speed.


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## IcemanYVR (Jul 27, 2006)

Thanks for the replies. I found out that our velodrome (Burnaby Velodrome) does not allow road bike conversions, only track bikes.

I will rent the first few times, if I like it, then the Bianchi Pista (steel) looks like a decent buy. I won't be breaking any records (of the good kind).


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## treebound (Oct 16, 2003)

dburns said:


> I ride the steepest velodrome out there - the Forest City Velodrome in London Ontario and it's 50 degrees.
> ...
> What is this miracle gauge? It's just a lowly piece of 2x4 lumber used on its edge. I guess its red paint makes it special. If it fits under the low pedal on the flat infield you're good to go. I think the finished dimension of 2x4 is 3-5/8".


http://forestcityvelodrome.ca/photogallery.aspx

Neat track. Would be nice to come see it in person sometime. Hmmm, just gave me an idea for a bike tour (but that's a different subject/thread).

I'm going to have to get out a chunk of 2x4 when I get home and compare my bikes to see how they'd measure up just out of curiosity. If I think of it I'll try and post pics, not sure if I have any red paint at home for the 2x4 though. 

I think it used to be, or something I heard/read somewhere, that 45degrees is where stuff starts to slide downhill if it isn't moving depending on surface material, tire composition and pressure, and some other variables. People used to get pedal strikes out on the Marymoor velodrome on the weekends on their street bikes when playing around on the track, and it isn't anywhere near 45degrees. (This was back in the early days though when I still lived out there, don't know if that track is still open for people to play around on and ride laps during non-event days.)


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## dburns (Apr 10, 2006)

treebound said:


> I heard/read somewhere, that 45degrees is where stuff starts to slide downhill if it isn't moving depending on surface material, tire composition and pressure, and some other variables. People used to get pedal strikes out on the Marymoor velodrome on the weekends on their street bikes when playing around on the track, and it isn't anywhere near 45degrees. (This was back in the early days though when I still lived out there, don't know if that track is still open for people to play around on and ride laps during non-event days.)


It's not possible to generalize when it comes to track geometry and bike geometry and resulting slides and/or pedal strikes. The radius and angle of a given track are the definitives in regards to a bike's reaction to their geometry.

Our steep track has a tight radius which results in a certain g-force (and lean angle) for a given speed. I used to ride on a massive 509 yard track with just 30 degree bankings in the UK (the long-gone Fallowfield in Manchester) and it needed a higher slow speed than my current steep, short track. Montreal's late Olympic Velodrome did too - it was 285 metres and 48 degrees if I remember and it needed a higher slow speed than the current 50 degrees (138 metres) that I ride. I ride with the fella who desgined BOTH of them and he supports the fact that radius induced g-force is everything when it comes to how slow the banking can be ridden.

I used to teach trackscool and to prove a point I'd take my bike and sit it vertical on the banking. The low pedal would easily touch the wood. And then I'd prove that 23kph (about 14mph; as slow as I dared go) would fix that.

Just what angle would make the average stationary bike/tire slide I'm not sure. I'd guess at about 30 degrees. There's no way we could trackstand on Fallowfield's 30 degree bankings.


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## treebound (Oct 16, 2003)

dburns said:


> Just what angle would make the average stationary bike/tire slide I'm not sure. I'd guess at about 30 degrees. There's no way we could trackstand on Fallowfield's 30 degree bankings.


Finally found a link to Marymoor (now known as Group Health I guess) geometry:
http://fixedgearfever.com/modules.php?name=Velodromes&op=showtrack&id=13

400M track with 25degree banking, was concrete surface and probably still is. Track standing on the banking "was" possible as I saw several sprint events there back in the 70's where the riders would do just that. Most people though, me included, wouldn't even try to track stand on the banking though.

I really appreciate your input here, very informative. Neat photos, thanks.

Edit: I should add in here that back when I was playing around at Marymoor I couldn't afford a bonafide track bike so I just rode it on my road bike when there weren't any track riders using it.


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## TurboTurtle (Feb 4, 2004)

dburns said:


> And ya know, it's soooo easy to ride. A minimum speed of 30kph (about 18mph) is suggested but we know it can be ridden at 20kph (about 12mph; some have dipped below that even; I don't have the guts). At 24kph I'm getting nervous as that's awful slow. Most of the (really) old geezers ride at 28kph.
> 
> A lot of is is to do with the radius as it's this that imparts the g-force that sticks you there. A bigger track (with bigger radius but same banking angle) would need a higher speed.


I ride a 382m track with only an 18 deg bank. The big dogs say they can feel the back wheel skipping out on the turns. - TF


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## dburns (Apr 10, 2006)

TurboTurtle said:


> I ride a 382m track with only an 18 deg bank. The big dogs say they can feel the back wheel skipping out on the turns. - TF


By "skipping out" do you mean sliding due to their speed being too slow? If so I find a it a bit hard to believe. Our straights are 17 degrees and no-one slides even when being held stationary for a standing start. Your 18 degree bankings would create a centrifugal force if there was any forward speed.


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## TurboTurtle (Feb 4, 2004)

dburns said:


> By "skipping out" do you mean sliding due to their speed being too slow? If so I find a it a bit hard to believe. Our straights are 17 degrees and no-one slides even when being held stationary for a standing start. Your 18 degree bankings would create a centrifugal force if there was any forward speed.


No, "skipping out" because their speed is too FAST for the low banking. - TF


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## dburns (Apr 10, 2006)

TurboTurtle said:


> No, "skipping out" because their speed is too FAST for the low banking. - TF


Ahhh I'm with ya now. All tracks are designed for a certain speed and if steepness doesn't combat the centrifugal force then, yes, you drift up the banking and it's tough to hold it down. Hold it down too much and you slide sideways.

I have problem with this on our track - at about 50kph (30mph) I'm sliding up and have a devil of a job to wail around the black line. Others do it no problem. Technique, bike geometry or tires? I dunno. It's frustrating.


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