Wheels, Tires, Tubes, Tubeless, Tubs, Spokes, Hookless, Hubs, and more!
Moderator: robbosmans
Forum rules
The spirit of this board is to compile and organize wheels and tires related discussions.
If a new wheel tech is released, (say for example, TPU tubes, a brand new tire, or a new rim standard), feel free to start the discussion in the popular "Road". Your topic will eventually be moved here!
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dmulligan
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by dmulligan on Mon Jun 20, 2016 2:14 am
bm0p700f wrote:wheel builders never trust a printed or published source of ERD's they are often wrong.
Do wheel builders trust ERD's to remain the same on the same rim model?
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MattSoutherden
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by MattSoutherden on Mon Jun 20, 2016 1:08 pm
I might trust a branded, long-running rim to be consistent unless there was a known new revision to it.
For carbon, especially non-branded ones, the layup can vary enough to make it worth buying the rim first.
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whosatthewheel
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by whosatthewheel on Mon Jun 20, 2016 2:15 pm
dmulligan wrote:bm0p700f wrote:wheel builders never trust a printed or published source of ERD's they are often wrong.
Do wheel builders trust ERD's to remain the same on the same rim model?
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Yes, rims are extruded from the same dye, any difference between them will be sub-millimeter and difficult to measure and frankly irrelevant
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Marin
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by Marin on Mon Jun 20, 2016 2:23 pm
I've been lucky with published ERDs on my builds so far. I'm too impatient and typically order rims, spokes & hubs at the same time from different vendors.
Of course I'd measure the ERD myself if I had the spokes in stock in my workshop
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DamonRinard
- in the industry
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by DamonRinard on Mon Jun 20, 2016 7:21 pm
I have some experience with rim manufacturing.
Aluminum rims' cross section doesn't vary significantly, for ERD purposes.
Most of the variation happens in rolling, sawing and joining. I've seen a few millimeters change in ERD from batch to batch.
This also shows up in automatic nipple tightening machines. You have to adjust the torque setting to each batch.
Rare: I remember when Sun redesigned a rim (M14A?), which resulted in a different ERD, but no other sign of a change (same name, logo, decals, etc.)
So use your judgment. If I have the rim, I usually measure it myself. If not, the risk of ordering the wrong spokes is generally small.
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo
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dmulligan
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by dmulligan on Tue Jun 28, 2016 3:50 pm
I'm back on this again. I'm an 85kg rider who never ever sees 4 digit power numbers. I am most definitely not a sprinter. I have trouble getting beyond last place on hill climb races to which I'm going to train more and try to lose 5kg or so. However I'd still like to consider a set of climbing wheels. I currently have a great set of all rounder 55mm deep X 25mm wide carbon clinchers with T11 hubs and 24/20 cxray spokes which I built myself. With rim tape they come to ~1560g. I don't think I can lose much weight in the rubber as I'm running CP4000SII tyres and race light tubes. With my weight I don't think I can go much lighter.
What are my options for affordable and somewhat durable climbing wheels? I'm considering tubular but I prefer clincher. I'll also consider alloy or carbon.
One last consideration: I only have 395g to lose on my bike and the local commissaries weigh bikes at hill climb TT races.
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bm0p700f
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by bm0p700f on Wed Jun 29, 2016 8:08 am
The thing 400g out of 92.2kg + clothing lets say 1.5kg + water.
So thats 94.2kg
So if you average 400w on a climb. Your w/kg is 4.246 save the 400g and w/kg us now 4.244
So it is possible but it will make sod all difference as you could push out an extra watt and you will have made up the difference, wind and road conditions make more of a difference.
So get realisitic on this. The aero benefits of your out weight any disadvantage of weight.
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dmulligan
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by dmulligan on Wed Jun 29, 2016 9:12 am
bm0p700f wrote:So get realisitic on this. The aero benefits of your out weight any disadvantage of weight.
I don't wanna get realistic! Please don't ruin a perfectly good weight weenie fantasy. Besides the type of races I'm talking about are hill climb ITTs with average grades of 8% or greater, so the aero benefits are not contributing much if at all.
I do realize that first and foremost I need to do more hill repeats and drop at least 5kg.
I will likely decide that I can't be bothered to switch wheels or spend money for such small weight savings or my wife will catch on. I'd still like to fantasize about climbing wheels.
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dmulligan
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by dmulligan on Wed Jun 29, 2016 3:07 pm
Nefarious86 wrote:Flat to climb ratio? Average speed?
The race I did on Saturday had no flat sections at all. It was 1.96km with an average grade of 7.9% and my average speed was in the mid teens.
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jekyll man
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by jekyll man on Sun Jul 24, 2016 11:03 am
One of the bigger units in our club has bought some 7800? hubs on Open pro rims secondhand as a set of training wheels or spares.
However the rear is 28h built 2x with what looks like Sapims version of revolutions.
He's complaining its a bit flexy and you can hear spokes slackening off under effort although the DS feels fairly tensioned up.
They're in pretty good condition so rim isn't worn or anything like that, but any suggestions to what can be done to improve it for him?
Would a 3x DS be okay on that hub and use a heavier gauge spoke such as a DT comp?
Cheers
Official cafe stop tester
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Calnago
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by Calnago on Sun Jul 24, 2016 3:09 pm
Honest advice: rather than start rebuilding with heavier spokes etc., and since he bought them second hand anyway, I'd chalk it up to a learning experience and sell them off (hopefully he can get around the same as whatever he paid) and look for something more suitable. By "bigger unit" I'm assuming you mean he's upwards of 200lbs or more? For a low profile training rim I'd opt for a 32 hole version, 3x and something like DT Comps as you're thinking. Don't really like the idea of relacing to a different pattern as spokes bed themselves into the relatively soft hub shell material so if I was relacing I'd try to follow the same pattern as was initially used.
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kervelo
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by kervelo on Mon Jul 25, 2016 11:19 am
I am planning to build a set of wheels using the Powertap GS straight pull rear hub. So far I have only built wheels using "normal" rear hubs with common J bend spokes. Is there something special that I should know when building this type of wheels?
The spokes will most likely be CX ray and two cross. The rims will be HED C2, DT Swiss R460 or similar. According to the Powertap product support the spoke length is the same for DS and NDS. Does the straight pull hub have any effect on the spoke tension difference between DS/NDS? Anything else I should know?