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-   -   Racer Tech Thread (https://www.bikeforums.net/33-road-bike-racing/956936-racer-tech-thread.html)

longe 11-15-15 07:03 PM


Originally Posted by dz_nuzz (Post 18321176)
Did you not live through last winter up here? That was my Saturday workout for quite a while.

Staring at the trees, tho? I was on that diet too, only brought to you by every Miyazaki movie. Man, that winter tho..

Ygduf 11-15-15 08:19 PM


Originally Posted by revchuck (Post 18320506)
I'm in the process of buying a new house, and it has a level covered concrete back porch. Normal winter temps in the morning here are 30-50 degrees F. I'm thinking of doing trainer rides outside on the porch when it's rainy/wet/slick etc. The positive part would be fresh air while I'm on the trainer, negative would be having to stare at the backyard rather than the flat screen. Has anyone tried this, and if so, what are your thoughts?

this is my exact setup, just a little colder. I listen to podcasts and stare out at the yard. You could put table or something and watch whatever on your laptop though.

spdntrxi 11-15-15 08:53 PM

I have a tripod and a 24 inch Lcd screen I don't use much. I need to get a holder / bracket to fit the tv and tripod. Together with a laptop atleast I could zwift on a larger screen

tetonrider 11-16-15 01:52 AM


Originally Posted by mike868y (Post 18321274)
ended up making it to the shop today and they had my size! my 42.5 sworks road shoes are a little big and the 42 sworks xc fit perfect. first impressions are v positive.

the mtb shoes are very nice (as are the road shoes). not sure if you have the asymm tongue version on the road, but i find it is a nice perk.

dz_nuzz 11-16-15 04:42 AM


Originally Posted by longe (Post 18321597)
Staring at the trees, tho? I was on that diet too, only brought to you by every Miyazaki movie. Man, that winter tho..

Oh so you didn't just pull up pictures of forests on your computer last winter like me? Weirdo.

gsteinb 11-16-15 05:04 AM


Originally Posted by revchuck (Post 18320506)
I'm in the process of buying a new house, and it has a level covered concrete back porch. Normal winter temps in the morning here are 30-50 degrees F. I'm thinking of doing trainer rides outside on the porch when it's rainy/wet/slick etc. The positive part would be fresh air while I'm on the trainer, negative would be having to stare at the backyard rather than the flat screen. Has anyone tried this, and if so, what are your thoughts?

I've posted the computer caddy I use, quite a bit. It's on wheels, and I roll it outside, set up a fan, and can ride outside until it's down to around 25. In fact, since I use earphones I actually prefer to watch shows on the computer since the flat screen usually ends up too loud/too quite and I miss stuff.

http://ecx.images-amazon.com/images/I/51la9OYbLPL.jpg

dz_nuzz 11-16-15 02:30 PM

1 Attachment(s)
I have decided that this will be my winter trainer bar tape:
http://bikeforums.net/attachment.php...hmentid=488446

Heathpack 11-18-15 09:27 PM


Originally Posted by revchuck (Post 18320506)
I'm in the process of buying a new house, and it has a level covered concrete back porch. Normal winter temps in the morning here are 30-50 degrees F. I'm thinking of doing trainer rides outside on the porch when it's rainy/wet/slick etc. The positive part would be fresh air while I'm on the trainer, negative would be having to stare at the backyard rather than the flat screen. Has anyone tried this, and if so, what are your thoughts?

This is what I do. I'm a music-on-the-trainer type, so it's my iPod and staring at my Garmin screen. 42F is the perfect trainer temp IMO.

Plus two box fans. I like airflow.

topflightpro 11-19-15 09:59 AM

I bought a TV and hung it on the wall of my garage. I also had the garage wired for cable, and I have a DVD player sitting next to the TV. I also bring my laptop out and hook it up to the TV to watch Netflix or something whenever I'm on the trainer or rollers.

I'd venture that 75 percent of the television shows and movies I now watche are seen while riding in the garage.

scheibo 11-19-15 07:28 PM

tl;dr: 'did science' and learned way too much about the garmin vector. my coworkers also now have proof postive i'm insane

Spent several hours over the last two days 'calibrating' my Garmin Vector power meter after physics suggested it was reading low (312W for something that should be 330-340W, as one example). Using the recommended procedure, I brought my bike to the office and set it up on a trainer between two standing desks (which were conveniently adjustable allowing for me to get everything completely level) and weighed my weight/string/hook on a calibrated scale to figure out what value I was looking for (27.84Nm). The pedals were reading low 27's, which wasn't quite the ~10% I was looking for and were at the low end of the +- 2% that the power meter was supposed to be accurate to. I then tried everything I possibly could to get the pedals to read the 'correct' value (though if I'm being honest, if I got them to instead report at the high end of the 2% range I would still have been happy with that...).

Doing this experiment in a building full of engineers meant I had lots of curious onlookers throughout the process with a number of suggested variables to try. I tried altering:

- torque on the pedals (25-30 ft-lbs is what is recommended by Garmin - I tried at pretty much every ft-lb increment)
- the number of spacers between the pod and the crank
- amount of grease on the pedals
- static calibration angle
- pod angle (not supposed to matter)

and several other things I'm now forgetting. Each setup required dragging the bike outside and putting on my bike shoes to do a few hard sprints to settle the pedals and then allow the garmin to figure out the installation angles, followed by numerous weighings on each pedal with numerous static calibrations in between. At one point I had the right pedal pretty much perfect (27.65-27.95 Nm no matter the static calibration) but nothing I did managed to bring up the left pedal from 27.2 (27.0-27.4). After spending way too much time on it I gave up and decided to do a clean install of both pedals and to just accept whatever values I got from it. Somehow, the ultimatum worked and I ended up getting it pretty much on the nose which was rather amusing... I'm looking forward to 2-3 rides at the correct calibration before something 'slips' and its back to crap values again.

The frustrating part of this 'calibration' process is that its not so much 'calibration' as 'continually testing and modifying until the test reports the right values'. It seems like I should be able to enter what the expected torque value should be to calibrate the meter (like you can with known GPS elevation, for example) which would have made the whole process take like 15 minutes. Either way, I'm going to continue to not recommend the vectors to anyone interested in power meters - the powertap hub on my other bike is much less stressful.

spdntrxi 11-19-15 07:45 PM

so it's within the 2% out the box and your not happy?

Duke of Kent 11-19-15 08:23 PM


Originally Posted by scheibo (Post 18332110)
Lots of words.

Buy one of the many used SRMs on eBay and be done with it. Send it in once a year for re-calibration.

Enthalpic 11-19-15 09:11 PM


Originally Posted by scheibo (Post 18332110)
tl;dr: 'did science' and learned way too much about the garmin vector. my coworkers also now have proof postive i'm insane

Spent several hours over the last two days 'calibrating' my Garmin Vector power meter after physics suggested it was reading low (312W for something that should be 330-340W, as one example). Using the recommended procedure, I brought my bike to the office and set it up on a trainer between two standing desks (which were conveniently adjustable allowing for me to get everything completely level) and weighed my weight/string/hook on a calibrated scale to figure out what value I was looking for (27.84Nm). The pedals were reading low 27's, which wasn't quite the ~10% I was looking for and were at the low end of the +- 2% that the power meter was supposed to be accurate to. I then tried everything I possibly could to get the pedals to read the 'correct' value (though if I'm being honest, if I got them to instead report at the high end of the 2% range I would still have been happy with that...).

Doing this experiment in a building full of engineers meant I had lots of curious onlookers throughout the process with a number of suggested variables to try. I tried altering:

- torque on the pedals (25-30 ft-lbs is what is recommended by Garmin - I tried at pretty much every ft-lb increment)
- the number of spacers between the pod and the crank
- amount of grease on the pedals
- static calibration angle
- pod angle (not supposed to matter)

and several other things I'm now forgetting. Each setup required dragging the bike outside and putting on my bike shoes to do a few hard sprints to settle the pedals and then allow the garmin to figure out the installation angles, followed by numerous weighings on each pedal with numerous static calibrations in between. At one point I had the right pedal pretty much perfect (27.65-27.95 Nm no matter the static calibration) but nothing I did managed to bring up the left pedal from 27.2 (27.0-27.4). After spending way too much time on it I gave up and decided to do a clean install of both pedals and to just accept whatever values I got from it. Somehow, the ultimatum worked and I ended up getting it pretty much on the nose which was rather amusing... I'm looking forward to 2-3 rides at the correct calibration before something 'slips' and its back to crap values again.

The frustrating part of this 'calibration' process is that its not so much 'calibration' as 'continually testing and modifying until the test reports the right values'. It seems like I should be able to enter what the expected torque value should be to calibrate the meter (like you can with known GPS elevation, for example) which would have made the whole process take like 15 minutes. Either way, I'm going to continue to not recommend the vectors to anyone interested in power meters - the powertap hub on my other bike is much less stressful.

Even calibrated scales have error, especially when working near the limits of their calibration ranges. If you did one measurement on one scale you have no idea of what the true value is. You need the mean and std dev of both values to compare properly.

2% bias is so far from "crap values" it's funny. We pay for "certified" products where the 95% confidence interval is huge.

scheibo 11-19-15 10:40 PM


Originally Posted by spdntrxi (Post 18332149)
so it's within the 2% out the box and your not happy?

it was just outside the 2% originally. even when its 'within 2%' i also don't want the L and R to be at different ends of the spectrum (2% high on right and 2% low on left = ~right value for total but then the LR-balance is inaccurate which would bug me). i am admittedly insane.

really what I'm looking for is it to report the same values as when i had it installed on my old bike, even if it was wrong on the other bike.


Originally Posted by Duke of Kent (Post 18332213)
Buy one of the many used SRMs on eBay and be done with it. Send it in once a year for re-calibration.

i just bought a new bike and when i was picking out a crankset i 100% should have just gotten the SRM at that point. next time... :)


Originally Posted by Enthalpic (Post 18332287)
Even calibrated scales have error, especially when working near the limits of their calibration ranges. If you did one measurement on one scale you have no idea of what the true value is. You need the mean and std dev of both values to compare properly.

2% bias is so far from "crap values" it's funny. We pay for "certified" products where the 95% confidence interval is huge.

i have more confidence in the scale's accuracy than any of the other variables involved. but you're right, theres tons of variables involved and plenty of room for measurement error all over the place.

as for my unhappiness with 2% - i agree, 2% would be great, and thats all the error I saw when doing the torque test, but its hard to square with the meter reporting on the order of 10% lower (than both my previous bike and any equation would indicate) in my field tests which is what sparked this whole endeavor. i think my main frustration is that i really trusted the values i was previously getting but now that i've switch bikes i'll constantly be doubting it.

Ygduf 11-19-15 11:12 PM

I have three separate quarqs. They are all slightly different. Good enough for Nationals.

revchuck 11-20-15 05:24 AM


Originally Posted by Duke of Kent (Post 18332213)
Buy one of the many used SRMs on eBay and be done with it. Send it in once a year for re-calibration.

This is how I got my SRM. Since it's on a non-racing bike, is there a downside to waiting until the battery dies to send it in? My race bike also has a power meter, so I can live without the SRM for a while if necessary.

Duke of Kent 11-20-15 05:52 AM


Originally Posted by revchuck (Post 18332727)
Since it's on a non-racing bike, is there a downside to waiting until the battery dies to send it in?

I don't believe so.

Others with more knowledge on the subject will chime in though, I hope.

topflightpro 11-20-15 07:16 AM


Originally Posted by revchuck (Post 18332727)
This is how I got my SRM. Since it's on a non-racing bike, is there a downside to waiting until the battery dies to send it in? My race bike also has a power meter, so I can live without the SRM for a while if necessary.

That's what my plan is. My SRM started giving me warnings of a low battery after just one year - it should last more than that. I called SRM, and they told me to send it in once the batter was dead.

shovelhd 11-20-15 08:58 AM


Originally Posted by revchuck (Post 18332727)
This is how I got my SRM. Since it's on a non-racing bike, is there a downside to waiting until the battery dies to send it in? My race bike also has a power meter, so I can live without the SRM for a while if necessary.

Nope. Battery life depends a lot on age and the model. Newer models are a lot more efficient. I expect to get three years out of a battery set with mine.

echappist 11-20-15 11:38 AM

does anyone know if one could run road bike brake calipers on CX bikes?

shovelhd 11-20-15 08:04 PM

If the brake bridge and fork crown are drilled for them, yes. The question is, why? Shimano makes a great set of cheap cantis. I use Frogglegg which are also cheap.

gsteinb 11-24-15 08:48 AM

disc brakes to amateur racing in 2017.

grolby 11-24-15 09:48 AM


Originally Posted by echappist (Post 18333584)
does anyone know if one could run road bike brake calipers on CX bikes?

Yes, if there are holes drilled, but what shovelhd said. Do some quick research on how to set them up correctly, and you'll get plenty of braking power.


Originally Posted by gsteinb (Post 18342169)
disc brakes to amateur racing in 2017.

For UCI and (presumably) Nats only. Already legal under USAC.

gsteinb 11-24-15 10:14 AM

Given my archaic wheel and derailleur collection, the odds of me going disc brakes before I retire seem pretty slim.

mike868y 11-24-15 10:26 AM

as someone who is relatively small i really don't see the appeal of disc brakes on a road bikes. never have i thought "man i need stronger brakes" on my road bike.


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