Lacing a HT into a 26" rim - flexed spokes - problem solved

[hjns]

Hi all,

I recently broke several spokes from my Clyte HT3525 which came with the stock Clyte 26" rim and probably 12Ga spokes. I ordered new 12Ga Sepim spokes from John Holmes, and a Halo SAS 36 hole DH rim, after seeking advice from MadRhino. I laced the Clyte into the Halo SAS rim, and it looks like this:

As you can see, I was not able to angle the nipples adequately at the right angle. Therefore, the spokes are flexed. I think it looks gorgeous, but I worry about the strength. Initially, I wanted a strong wheel to allow for small jumps with the HT. However, my commute changed, and now I need to keep a true wheel at high speeds (max 40mph) on tarmac with some potholes. The wheel feels MUCH stronger than the Clyte rim, despite the flexed spokes.

Do I need to worry?

 

[Chalo]

Hi all,

I recently broke several spokes from my Clyte HT3525 which came with the stock Clyte 26" rim and probably 12Ga spokes. I ordered new 12Ga Sepim spokes from John Holmes, and a Halo SAS 36 hole DH rim, after seeking advice from MadRhino. I laced the Clyte into the Halo SAS rim, and it looks like this:

As you can see, I was not able to angle the nipples adequately at the right angle. Therefore, the spokes are flexed. I think it looks gorgeous, but I worry about the strength. Initially, I wanted a strong wheel to allow for small jumps with the HT. However, my commute changed, and now I need to keep a true wheel at high speeds (max 40mph) on tarmac with some potholes. The wheel feels MUCH stronger than the Clyte rim, despite the flexed spokes.

Do I need to worry?

Those spokes are too loose. If they were tight enough, and had been stress relieved, they would be straight except where they enter the nipple. Spokes that aren't tight enough become looser, and spokes that haven't been stress relieved break at the elbows from metal fatigue over time.

The good news is that you can tighten and stress relieve them. The bad news is that they'll be likely to break at the threads in that case. Here is another case where normal 14 gauge spokes are better-- thinner nipples can tilt through a larger angle than fatter nipples, in the same rim holes.

Chalo

 

[voicecoils]

Chalo makes a good point that 14ga spokes with their smaller nipples would have more angle flexibility in the standard rim holes.

But, seeing as you have spokes and the HT motors come with enormous spoke holes in the hub flange, I think your best bet is to drill those eyelets out of the rim and enlarge your rim spoke holes.

You need to find the balance of good nipple exit angle and adequate rim material for the nipple to seat against without pulling through.

To experiment, you can find a piece of metal a similar thickness to your rim and drill different sized holes. Feed a sample spoke through, thread the nipple on and see what angle you can practically achieve. From your existing lace up, you should have a decent idea what angle the nipple will need to exit to avoid a bent spoke entering it.

A bent spoke at the nipple will not necessarily break, but will not be as strong as a straight entering one. The compromise is that by drilling out your rim, you loose the extra strength the eyelet originally gave.

 

[rathawk]

you need to take that wheel to a bike shop and let them tension/true it up for you. but, only if you want that wheel to last more then a couple rides. Definitely do not ride it in its current state.
an old school bike mechanic once told me that if you haven't built more then 100 wheels, you shouldn't build a wheel.

 

[Ykick]

...an old school bike mechanic once told me that if you haven't built more then 100 wheels, you shouldn't build a wheel.

I know guys who could build 100 wheels and still have no business doing it. However, wheel building requires practice and old trash wheels are good practice but the "old timer" is obviously protecting his livelihood with little regard to reality.

Moving on, the wheel in these thread photos isn't safe or ready to ride. I honestly dunno why so many folks go with 12ga spokes? 13/14 single butted is the much better choice for these and similar wheel builds.

 

[dogman dan]

I'm in that no bidness building a wheel category. But I think I can agree that drilling the rim with some angles would help a lot.

But if nothing else, carefully bending the spokes just above the nipple will be better than nothing. Ride it now, and the motor will do it less carefully, and once the spokes stretch out, it will look the same ( bent at the nipple) anyway. It's too loose now, and a short ride will pull the spokes even looser, but it would be better to snug it up slow and carefully in the shop first.

 

[joe tomten]

You might consider buying a round file whose diameter is a bit smaller than the spoke hole, then - while leaving the whole wheel strung together - remove spokes one by one and run that file for a few strokes through the nipplehole.

You can sight a line down the direction of the spoke engagement with the hub so the file is filing the proper shape, and only filing the material you really want removed from the rim. Also you are cutting with enough control so you stop before going overboard, and wrecking the rim.

Then put the spoke back, in and see how it lays.

it will take some time, but with less risk of blowing through an eyelet in the rim.

this makes me think i might want to try this 26" 9C double cross wheel that i did with the same issue.

then make sure you stress relieve the spokes like Chalo said.
http://sheldonbrown.com/wheelbuild.html

p.s. I am too lazy to use the file, so i would probably just grab my cordless drill and choose a drill bit just slightly larger than the o.d. shank size of the nipple, and use side of the drill bit to mill that one edge of the spoke hole while sighting down the drill towards the spoke hole on the hub.

maybe grab an extra spoke and nipple, and screw the spoke in the 'top' of the nipple and use that as a sighting / feeler gauge in the spoke hole to see and feel how you are making progress with the hole reshaping.

 

[hjns]

Hi all,

Thanks for the great feedback!

Those spokes are too loose. If they were tight enough, and had been stress relieved, they would be straight except where they enter the nipple. Spokes that aren't tight enough become looser, and spokes that haven't been stress relieved break at the elbows from metal fatigue over time.

The good news is that you can tighten and stress relieve them. The bad news is that they'll be likely to break at the threads in that case. Here is another case where normal 14 gauge spokes are better-- thinner nipples can tilt through a larger angle than fatter nipples, in the same rim holes.

Chalo

OK. So I did all things mentioned by Sheldon Brown: used a lever to bend the spokes around each other, squeeze the spokes in groups of 2 and 4 to relieve tension, and even put my weight on the wheel by standing on opposing sides of the rim and carefully "walk around the rim" while balancing on the axle, and then doing that on the other side as well. The result was still an almost true (within 1.0 mm) wheel, both horizontally and vertically, no dishing and still flexed spokes. I even used the musical pitch to estimate correct tension, and all spokes are around the G as recommended by John Allen for spokes with a length around 165 mm.

I am sure I can tension the spokes even more, but then I worry that they may be too tight. Thanks anyway, I won't ride it in this state.

But, seeing as you have spokes and the HT motors come with enormous spoke holes in the hub flange, I think your best bet is to drill those eyelets out of the rim and enlarge your rim spoke holes.

You need to find the balance of good nipple exit angle and adequate rim material for the nipple to seat against without pulling through.

To experiment, you can find a piece of metal a similar thickness to your rim and drill different sized holes. Feed a sample spoke through, thread the nipple on and see what angle you can practically achieve. From your existing lace up, you should have a decent idea what angle the nipple will need to exit to avoid a bent spoke entering it.

A bent spoke at the nipple will not necessarily break, but will not be as strong as a straight entering one. The compromise is that by drilling out your rim, you loose the extra strength the eyelet originally gave.

Yes, I will consider further drilling out the eyelet. However, the Halo SAS is a double wall rim, with a hole and an eyelet in both walls, the inner eyelet with an inner diameter of 5 mm and the outer one much larger. MadRhino adviced me to remove all eyelets and use dedicated angled shims to allow for the correct angle of the nipples. I did no do this at first, because I thought I could take the easy way and use the existing eyelets. Guess not.

you need to take that wheel to a bike shop and let them tension/true it up for you. but, only if you want that wheel to last more then a couple rides. Definitely do not ride it in its current state.

I won't ride it.

an old school bike mechanic once told me that if you haven't built more then 100 wheels, you shouldn't build a wheel.

This information is not really helping. Following this reasoning means you can not even start with your first wheel, because you have not done the needed 100 wheels before that. No, one needs to start somewhere. Of course we can discuss the risk benefit assessment prior to riding one's "first wheel".

I'm in that no bidness building a wheel category. But I think I can agree that drilling the rim with some angles would help a lot.

But if nothing else, carefully bending the spokes just above the nipple will be better than nothing. Ride it now, and the motor will do it less carefully, and once the spokes stretch out, it will look the same ( bent at the nipple) anyway. It's too loose now, and a short ride will pull the spokes even looser, but it would be better to snug it up slow and carefully in the shop first.

Thanks! I will try adding a shim on top of the outer eyelet first to allow for a better nipple angle.

You might consider buying a round file whose diameter is a bit smaller than the spoke hole, then - while leaving the whole wheel strung together - remove spokes one by one and run that file for a few strokes through the nipplehole.

You can sight a line down the direction of the spoke engagement with the hub so the file is filing the proper shape, and only filing the material you really want removed from the rim. Also you are cutting with enough control so you stop before going overboard, and wrecking the rim.

Then put the spoke back, in and see how it lays.

it will take some time, but with less risk of blowing through an eyelet in the rim.

this makes me think i might want to try this 26" 9C double cross wheel that i did with the same issue.

then make sure you stress relieve the spokes like Chalo said.
http://sheldonbrown.com/wheelbuild.html

p.s. I am too lazy to use the file, so i would probably just grab my cordless drill and choose a drill bit just slightly larger than the o.d. shank size of the nipple, and use side of the drill bit to mill that one edge of the spoke hole while sighting down the drill towards the spoke hole on the hub.

maybe grab an extra spoke and nipple, and screw the spoke in the 'top' of the nipple and use that as a sighting / feeler gauge in the spoke hole to see and feel how you are making progress with the hole reshaping.

Thanks, Joe. Very useful information! Will try this directly after trying the shim idea.

I will keep you all posted.

 

[Chalo]

Cool. It sounds like your process is good, and you have only details to work out.

Thick spokes like that need lots of tension if they are to operate within the elastic range that will keep them tight. I would consider 140 kgf of tension to be a minimum for such thick spokes. 100kgf is customary for 14ga spokes on modern rims. Your sturdy rim probably will support elevated tension, but it may be worthwhile to consult the manufacturer and ask if there is a specified maximum spoke tension. (Some rims crack at the holes when they are overtensioned.) A bike shop in your area will have a spoke tensiometer you can use to measure existing tension.

Don't let anyone's opinion deter you from teaching yourself this craft. The lesson to absorb from the old guys who have been doing it a long time is that you keep getting better at it if you continue to pay attention, no matter how many wheels or how many years that is. So don't expect your first wheels to be your best; just take care to do them as well as you can. You have armed yourself with good information and good components, so you have those advantages at least.

A very large diameter hub like the HT series often does not have a perfectly satisfactory lacing pattern at all-- radial lacing gives problems with spoke windup, and cross-one causes the spokes to enter the rim at too severe an angle. So we do the best we can, enlarging or slanting rim holes if we must, and accepting radial lacing if nothing else will work.

I would not bother with shimming nipple heads inside the rim. Nipple heads are usually conical where they bear on the rim hole, so when they slant, they just move off center in the hole if there is enough room. I doubt shims would stay in place for the whole procedure anyway.

Chalo

 

[hjns]

Hi Chalo,

Thanks!

I used the wrong word. I did not mean "shim", I meant "washer".
I went for the washers around the nipples just to try, and see here the results:

Previous lacing (same pic as above)

New lacing (with washers around the nipples, resting on the outer eyelet of the rim)

One of these days I will check the tension at a shop. All I can say right now they have a LOT of tension. I drove it, and it feels great!

 

[Chalo]

Looks great; congratulations on a thorough wheel build! I expect that you won't be having any unusual problems with that wheel.

Chalo

 

[hjns]

Looks great; congratulations on a thorough wheel build! I expect that you won't be having any unusual problems with that wheel.

Chalo

thanks again. What a great forum this is!!

Some more details on the washers:

On the right side you can see the old situation. The nipple has descended deep into the outer eyelet. In the middle, I removed the nipple, and you can see the spoke end coming through. On the left the new situation, with a washer around the nipple, resting on the outer eyelet. The nipple is able to connect to the spoke and remain at a slight angle as the washer allows the nipple to "drift" to one side of inside of the outer eyelet. Dishing of the washer pushes the nipple back to the middle of the eyelet, so there remains this balance of the angle of the spoke versus the nipple being in the middle of the eyelet. We will see....

Of course, I protected the inner tube from punctures due to the washers / nipples by adding two layers of Schwalbe high pressure rim tape. Great stuff. First a narrow band, that covers the washers and extends to the first elevated edge on the inside of the rim. Then a broad band, covering the whole inside of the rim.

The Schwalbe Energizer is a great tire, and is rated for 50 kmh at a max of 5 bar /75 psi. I loaded it up to 4.5 bar and it flies ! Remember, this is for a high speed commuter.