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PostPosted: Tue Sep 03, 2013 7:41 pm 
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The rule for correction varies for different nipple makes, you can't generalise completely.

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PostPosted: Tue Sep 03, 2013 8:15 pm 
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I've been reading with interest about the discrepencies you guys have been finding between different tensionometers as I went through quite an exercise in this last winter. I was experimenting with several sets of identical wheels all using Ambrosio Nemesis rims laced to Campy Record hubs with DT Swiss Comp and/or Revolution spokes. I have both a Park TM-1 and a digital DT Swiss Tensio gauge and was getting significantly different readings from both, the Park reading the higher of the two. My curiosity was getting the best of me so I sent both meters back to the manufacturers for calibration. DT Swiss said the tension was spot on and Park adjusted theirs a bit. Even after factory calibration the readings are still significantly different.

I have a spreadsheet I created which makes quick work of conversion of the readings which I've reproduced for one of my wheels which I purposely built up with a very high tension, perhaps too high. There are two charts, one created using the DT Swiss Tensionometer, and the lower one created using the Park TM-1. I'm curious to see if the Nemesis rims will hold up to this tension without cracking at the nipples, particularly on drive side spokes number 7 and 8. I should say that I increased the tension after riding for a while at a lower tension only to have a non-drive side spoke go slack, albeit on a different wheel (but same specs), built using the TM-1 which in retrospect was reading high and thus built up a wheel with less than optimal tension. So, while the Park tool is fine to get relative tensions, I rely on the DT Swiss Tensiometer for what I believe is a more absolute measure, particularly when using DT Spokes.

In summary, the Drive side tension reads an average of 130kgf using the DT Tensiometer, while the Park TM-1 gives me an absurd average tension of 157kgf for the same wheel using the most current charts from both DT Swiss and Park. The DT Tensiometer also can reproduce the results within .02mm of deflection. The Park is less reproducible but still does the job.

I think the optimal drive side tension for this build is in the 120-125kgf range. The above wheel may be a little on the tight side, but I like experimenting, even if it means wrecking something here and there along the way to determine the true limits.

Image

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Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
C59 Five Years Later
Trek Emonda SL Campagnolo SR; Special Colnago EPQ


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Posted: Tue Sep 03, 2013 8:15 pm 


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PostPosted: Wed Sep 04, 2013 6:21 am 
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Location: Victoria, BC Canada
Calnago,

While your observation concurs with mine, I'm not following how youv'e derived the deflection in millimeters? These tensiometers have unitless numbers measuring relative deflection. They aren't prescribed or purported to be a measurement of the deflection of the spoke in millimeters. And 24mm deflection is rather large! 2.4cm!

Despite that, I can attest to the observation that a TM-1 records a higher tension than actual. This I have confirmed not by comparing a pre-built wheel, but by using an electronic strain gauge and readout display showing kgf. This strain gauge (a glorified wheatstone bridge) is very precise and fully repeatable, but not inexpensive. However, it is much more convenient than hanging a spoke by weights.

Having such an electronic strain gauge on hand provides a few conveniences, the first and most notable being that I create charts for spokes for the common tensions I use, rather than rely on linear interpretation between coarse values, such as 120kgf, or 130kgf, or sorting out what a reading of "25" is in kgf. I do it the opposite way - set the strain gauge to 120kgf then note what my tensiometers read. This is far more valuable than a generic chart of 'nominal value' converted to kgf or newtons.

I found that my DT Swiss chart expressed a force more than actual but only by about <5kgf. Whereas my two Park TM-1's were often more than 10kgf out (read higher than actual), and my beloved Wheel Fanatyk tensiometer was within 2kgf of actual no matter what the spoke I installed on the strain gauge jig.

My next plan is to have a CNC'ed improved jig so that I can calibrate tensiometers for shops as a service, or self-service. Most bike shops in my area are lucky if they are using a tensiometer at all, and if they do, it is most often the TM-1.

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PostPosted: Wed Sep 04, 2013 7:11 am 
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@zed: My bad. You are absolutely correct about the deflection being unitless, at least for the Park TM-1. The lower chart was just a modification for the Park Tool data and I knew that wasn't in mm but never removed it. I just modified it a bit for comparison purposes of the two tools on the same wheel. Normally I use the bottom chart for the front wheel data. So yes, your catch is good so far as the Park deflections are concerned. However, upon looking at my DT Swiss Tensio, those readings are actually the deflection in millimeters. And my "lookup tables" (not shown) were derived exactly as you say... I just linearly interpreted between the coarse values given in the charts.
I would for sure send my tension meters to you for calibration if you ever offered such a service. But don't the manufacturers of these instruments essentially do what you would do in coming up with these charts in the first place? I would like to see your charts for say, DT Comps and Revolutions should you ever produce them. Also, in your experience, does length of spoke affect the readout at similar tensions? Length is not considered in any of the charts I have seen. And what about butting. Would a double butted spoke like a DT Comp give a different reading than a straight gauge spoke of the same diameter middle section (1.8mm). Just things I've thought about before but never really answered definitively. Thanks.
And thanks for pointing out the error in my charts.

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PostPosted: Thu Sep 05, 2013 5:11 am 
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Location: Victoria, BC Canada
I am not setup to handle huge variations in spoke length on my current hacked together jig, but for the new jig design, I'll be sure to accomodate a range of spokes. That said, the Wheel Fanatyk Jobst Brandt design measures a narrow range of the spoke to assess deflection, and seems less 'fussy' as to placement on a tensioned spoke. I typically attempt to measure as centered on the spoke head to nipple as I can, and when varied, I do observe differing tension readouts on the DT Tensio and the Park, but not the Wheel Fanatyk.

Once I get my new jig built, which I hope happens over the quieter winter months, I'll let you know how it compares to the charts. My DT Tensio is rarely used, and so should not have 'drifted' from what it was calibrated to at the factory.

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 Post subject: Rim Recommendation?
PostPosted: Mon Sep 09, 2013 12:12 am 
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Joined: Sun Jun 10, 2012 5:56 pm
Posts: 19
I have a 32H White Industries H2 rear hub that I'd like to lace in the next month or so. Looking for a clincher rim that's sub-400 grams around $50. I've been leaning towards Kinlin XR-200, but I'm open to going a bit heavier or aero if it makes sense. I weigh 160 & this will be for training & logging miles this winter.

Recommendations/Thoughts?


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 Post subject: Re: Rim Recommendation?
PostPosted: Mon Sep 09, 2013 12:52 am 
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Joined: Tue Nov 11, 2003 9:47 pm
Posts: 2196
Location: Santa Cruz, California, USA
If it's for training the small weight penalty for a stiffer rim that makes a stronger wheel is not a problem.

If you're sticking with narrow rims the XR270 is a durable rim.

BikeHubStore has good prices on KinLin rims and Sapim spokes.

With 32h you can use Lasers all around.


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 Post subject: Re: Rim Recommendation?
PostPosted: Mon Sep 09, 2013 1:27 am 
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Posts: 19
[quote="eric"]If it's for training the small weight penalty for a stiffer rim that makes a stronger wheel is not a problem.

Good call...I guess I just needed to hear it from someone else. Slightly out of budget, but the Pacenti SL23 looks promising...24mm wide, good depth & decent weight.


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 Post subject: Re: Rim Recommendation?
PostPosted: Mon Sep 09, 2013 1:41 am 
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Posts: 1901
Location: Welland, Ontario
I built up a set of wheels recently using Pacenti rims, Laser spokes and the house hubs from BHS and have been very happy with them. The rims are a quality product.

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 Post subject: Re: Rim Recommendation?
PostPosted: Mon Sep 09, 2013 4:28 am 
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Joined: Sun Sep 21, 2008 12:57 am
Posts: 57
Location: Somerville, MA
I've used the XR-200s for awhile (on a set of H2s) and they have been great, especially for the weight and price. That being said, I'm currently using the wide BHS clincher rims and would highly recommend them. Rather easy to build up, stiff enough (in a 24/28 config), and the ability to lower your tire pressure a bit make them a real joy to ride. They're around your price range, but unfortunately are a bit heaver than you're looking for.


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PostPosted: Tue Sep 10, 2013 3:32 am 
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Joined: Sun Nov 02, 2008 8:51 pm
Posts: 29
At 190lbs, is 20 spokes (CX-Ray) radially laced ok with Archetype rims?

Thanks

P.S. I've raced on that configuration using Kinlin 300 for five years but are the Archetypes as stiff as the 300s?

Thanks


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PostPosted: Tue Sep 10, 2013 1:25 pm 
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Joined: Fri Apr 13, 2012 7:25 pm
Posts: 87
This might already been answered in the thread, but when I use the DT calculator to get spoke lengths, it takes the amount of flex into account and gives different spoke lengths depending on what DT spoke I've chosen.

All good so far, as long as I use DT spokes. But what if I would like to bling up my wheel with some Sapim CX Rays? Round up? Base numbers on DT Aero lites? Different spoke calculator?


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PostPosted: Tue Sep 10, 2013 1:43 pm 
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Joined: Mon Apr 11, 2011 3:16 pm
Posts: 166
So yeah, I have been riding my new rear wheel for a while now.

Everything is great. It went out of true in a couple of places on the first few rides, but I put that down the spokes bedding into the hub flanges; I didn't go mad on manually bending the spokes with my fingers into line, so bedding in may have been a little longer than it could have been.

The Tune Mag170 hub is an utter winner; rolls mega fast, looks great, polishes up lovely, sounds cool and feels good to ride.

I laced the wheel 12x12 2 cross, so the NDS is not super tight, but it seems to be holding fine. Tune state that the hub has a 100kg limit, which is low. Don't tell them, but I went up to 113kg on the DS to allow for an acceptable NDS tension.

Spokes are CX Ray, and the rim is a FarSports 38mm tubular.

Weigh in, with nipple washers is 568g. Rear wheel at 568g. Mental!

With DA9000 cassette and Vitt. CX3 it is still under 1kg.

Looking forward to building a super nice front wheel to match. Considering a Tune MIG45 if I can convince anyone to send me one...


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PostPosted: Tue Sep 10, 2013 10:20 pm 
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Joined: Sun May 19, 2013 1:01 am
Posts: 39
jockster wrote:
All good so far, as long as I use DT spokes. But what if I would like to bling up my wheel with some Sapim CX Rays? Round up? Base numbers on DT Aero lites? Different spoke calculator?


You can use the DT calculator as for Aerolites but specify 12mm nipples if you are using the Sapim 14mm. I like to correct lengths a bit shorter for front spokes and rear DS spokes.


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Posted: Tue Sep 10, 2013 10:20 pm 


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PostPosted: Wed Sep 11, 2013 3:19 pm 
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Joined: Thu Dec 22, 2011 12:39 pm
Posts: 514
Location: DC
So I have built multiple bikes over time and it looks like it's time to learn building some wheels. This will be my first and also a budget build. My weight hoovers anywhere between 158 lbs - 165 lbs, depending on time of the year. I'm not hard on wheels either. Right now I have a set of the original Neuvation wheels, the R series 16/20 spokes as well as a set of nicer Dura Ace 7900 C24 wheels. Here is what I was thinking for this build:

Rims: H Plus Son Rims 20 front and 24 rear spoke count.
Front Hub: BHS SLF71W - http://www.bikehubstore.com/SL71W-p/slf ... 1&CartID=0
Rear Hub: BHS SL210 SuperLight Rear Hub - http://www.bikehubstore.com/SL210-p/sl2 ... 1&CartID=0
Spokes: Thinking of going with Sapim CX-Ray. Should I consider anything else?
Nipples: Sapim nipples. Brass or Alu?

I did some poking around with various spoke calculators and this is what I came up with. I would really appreciate if someone could confirm my findings:

Front wheel: 20 spokes - radial lacing - 279.0mm spoke lenght
Rear wheel: 24 spokes - 2x lacing - DS 284.7mm spokes, NDS 289.2mm spokes

Seems that spoke lengths are right in between what's actually available. I assume one should always go with a longer option rathen than shorter, no?

If they can be built into 1500 gr. wheels set I'll be happy. Thanks for the help!

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