Cheapish wheels (again)

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saddleworthcycler
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Cheapish wheels (again)

Postby saddleworthcycler » Mon Jan 21, 2013 19:30 pm

Hi, I'm after some advice about upgrading the wheels that came on my Specialized Allez sport. They have Mavic CXP22 rims and unbranded hubs.

I will mainly be using them for club and my own rides anywhere from 20-80miles and it is very hilly where I live. Maybe the odd sportive too.
My budget is about £200. The complicating factor is that I weigh the best part of 100kg

Options I've been considering if I go new are:
Fulcrum racing 5s
Shimano 6700 (but I'm concerned about the lack of spokes and my weight - I dont want to be having to get them retrued all the time). These are £235 on planet x at the moment.

I'm not sure whether to go second hand on ebay and try to get some Krysiums or Fulcrum racing 3s. I'm a bit wary about second hand though.

Any advice appreciated!

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ugo.santalucia
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Re: Cheapish wheels (again)

Postby ugo.santalucia » Mon Jan 21, 2013 19:50 pm

Have a read at this article on my blog about spoke failure and number of spokes

http://paolocoppo.drupalgardens.com/con ... g-fatigued

thecycleclinic
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Re: Cheapish wheels (again)

Postby thecycleclinic » Mon Jan 21, 2013 19:56 pm

What wrong with the wheels you have. What do you want from the upgrade. This will determine the spec of the wheels you could go for.

Racing 5's are not that light. There is a customer set in at the moment and with rim tape they weight 1900g without skewers. The rims are heavy over 550g each. This is how these low spoke count wheels stay ture even with 100kg riders although you do have more chance of putting once of these out. Also consider that the replacement spokes are expensive as they are staight pulls. I would not go down this route personally.

However if handbuilts take your fancy you could have a set of wheels built that would be as light as the ulgetra wheel but have alot more spokes. A 28 front and 32 rear build should work well at your weight but 32 front and 36 rear for extra relaibility. More spokes and lighter rims is the best way to go im ,y opinion rather the factory wheelset way, heavy rims and low spoke counts.

Factory wheelset are built that way because marketer find it easy to sell wheels that way and some people think they are more aerodymanic. Of course aerodymanic wheels only make sense for really fast racers and even then the advantage is very small. When riding at normal speeds aerodynamic advantage that a factory wheelset may or may not have is redudant anayway. This is even more the case if you are climbing at slower speeds.

Again what do you want out of this upgrade?
http://www.thecycleclinic.co.uk -wheel building and other stuff.

thecycleclinic
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Re: Cheapish wheels (again)

Postby thecycleclinic » Mon Jan 21, 2013 20:37 pm

ugo there are points about your fatigue blog I think I should raise. While you are right about the way spokes fatigue due to cyclic unloading and reloading I do think your statement about the way spokes radially load is not true. in your blog you claim that in a 36 spoke wheel each spoke caries 1/36th of the radial load this is the point I do not agree with.

When a wheel is on the ground and vertical with the rider sitting on it all the load is carried by the spokes in contact or near contact with the ground as the rim will slightly flatten (by less than 1mm). Radial wheel stiffnes is in the order of 3500N/mm. A 100kg rider is 980N so the rim delfection is in the order of 0.28mm. For a 32 or 36 spoke wheel all the load is carried by ~ 4 spokes and lowest point of the rim. Also radial stiffness of a wheel is determined almost soley by the stiffness of the rim. This is because a rim is aluminium alloy and is aprroximatley 10 times less stiff as the steel spokes.
Radial stiffnes of a wheel = radial stiffnes of the rim / (1+(radial stiffnes rim/stiffness spoke)) do the sums if you don't believe me. More spokes does not make a wheel more stiff radially!

Spokes will almost completey unload if the load gets to 4000N and this is possible when you hit hole and other bumps in the road. That fatigue spokes but only those in contact and close to the ground when the rim deforms.

Spoke fatigue mainly occurs though due to lateral loading of the wheel. A wheel when torque is applied does flex from side to side. How much flex and therefore how much unloading of the spokes occurs will entirely depend on the lateral stiffness of the rim, number of spokes, gauge of spokes and bracing angle the spokes make. It is the non drive side spokes that unload more complety than the DS spokes which is why NDS spokes are more likely to fail on a dished rear wheel.

A higher spoke count helps increase lateral stiffness and that helps spoke life. This is how factory wheel sets with low spoke counts and laterally stiff (and heavy) rims manage to stay true even with 100kg riders for a time.
very low spoke wheels though do have the issue that maybe only a piar of spokes carries the radial load. This may halve the spoke life when comparing a 24 spoke wheel to a 36 spoke wheel, but it does depend on the raidal stiffness of the rim as well. A wheel built with 36 spokes will have a rim that is less radially stiff in general to a wheel built with 24 spokes unless something odd has been done.

I'd like to add I do not think this means ugo's general point about spoke count is wrong he isn't and I am sure he builds good wheels it just a technical point I am making and I am pedantic like that.
http://www.thecycleclinic.co.uk -wheel building and other stuff.

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ugo.santalucia
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Re: Cheapish wheels (again)

Postby ugo.santalucia » Mon Jan 21, 2013 20:51 pm

thecycleclinic wrote:. For a 32 or 36 spoke wheel all the load is carried by ~ 4 spokes and lowest point of the rim.


Which become ca. 2 in an 16-18 spokes wheel, so we are saying the same thing...
My blog is there to provide some basic information in a format that can be digested by the reader. There are engineering studies for all these concepts, but they are so boring that one feels compelled to jump to the conclusions...

Imagine Jamie Oliver and the science of nutrition... That is blog style Information... It gets to the point without information overload

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smidsy
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Re: Cheapish wheels (again)

Postby smidsy » Mon Jan 21, 2013 21:07 pm

thecycleclinic wrote:I'd like to add I do not think this means ugo's general point about spoke count is wrong he isn't and I am sure he builds good wheels it just a technical point I am making and I am pedantic like that.


Surely this is what the PM function is for?

Can't say I agree with disecting someones hard work for all to see to then end with a somewhat shrouded, half hearted, affirmation of their ability.

Would have been much better discussed privately between the two of you, seeing as it was such (in your own words) a pedantic point!!!
Yellow is the new Black.

Paul1000
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Re: Cheapish wheels (again)

Postby Paul1000 » Mon Jan 21, 2013 21:34 pm

2013 fulcrum 5's £170 from merlin, just got some for my winter bike.

thecycleclinic
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Re: Cheapish wheels (again)

Postby thecycleclinic » Mon Jan 21, 2013 21:46 pm

I did say I broadly agree with the blog just not on one technical point. Fulcrums are cheap though and will do the job.
http://www.thecycleclinic.co.uk -wheel building and other stuff.

freddiegrubb
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Re: Cheapish wheels (again)

Postby freddiegrubb » Mon Jan 21, 2013 22:34 pm

first let me say I don't know too much about w/building, but I was watching a tv. prog. about ferris wheels development & how there was a problem with strength/ weight, need more strength= more weight etc. Till some bright person studied the bike wheel & applied the same logic to the ferris wheel, result . It was proven that the rim was supported by the fact that the frame dropouts were hanging downwards & only a small portion of the near / vertical spokes were taking any substantial load. They actually built a wheel with string spokes & rode it down the street it was a bit wobbly but the important thing was it proved the theory that the frame hangs via the spokes from the rim.I'm off to bed.

saddleworthcycler
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Re: Cheapish wheels (again)

Postby saddleworthcycler » Tue Jan 22, 2013 06:51 am

Many thanks for your advice and the interesting blog. I'll certainly look into handbuilts.

What I hope to get out of the upgrade is to make my cycling feel easier especially in my local hilly terrain! (I am aware that the best way to do this is to get more miles in the legs and shift a few kg). I put decent tyres on a few months ago instead of the supplied ones and it made a massive difference. I was hoping that new wheels would make even more of a difference. I have also searched the threads on this forum and read that lots have people have thought that they have felt a big difference even when changing to not particularly light wheels such as Aksiums or fulcrum racing 5s from the supplied ones. I also initially had a few problems with the rear wheel going out of shape. The current wheels would then be relegated to occasional commuting or when the weather is very grotty.

Any more advice gratefully received.

oxoman
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Re: Cheapish wheels (again)

Postby oxoman » Tue Jan 22, 2013 10:27 am

I actually upgraded to Mavic cxp22's from some cheap bontrager wheels that come as stock with Dawes Giro's. Pretty much bomb proof better, lighter than my originals better running and cannot fault them as paid £50 for both straight off a mates new bike because he upgraded his Allez to some fancy shimano ones. It hasn't really improved his riding as i still keep up with him on my nail with his inferior wheels ( please note his words / loss and my gain ). Also improved my comfort and commuting time/speed slightly. Save the money run yours into the ground then replace with decent handbuilts. Ask Ugo to build you something decent to suit your needs.
Moda Bolero with Shimano 105 Triple
Dawes Giro 300 Winter / Wet Commuter
Giant Anthem 27,5 SX

trek_dan
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Re: Cheapish wheels (again)

Postby trek_dan » Tue Jan 22, 2013 17:08 pm

I don't especially think any wheel in that price range would be a noticeable upgrade on what you've already got. Definatelt not in terms of weight anyways. Run them for the rest of the year and when your down to 75kg ask again :)


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