It’s been a little while, but SB5794 is finally getting the wheels that it deserves! When I initially built this bike I just used the set of wheels that came with the 6207/6208 600EX group when I bought it; those wheels had Shimano 6400 7 speed hubs (I fitted a 6 speed cassette to be compatible with the gear levers). The wheels also had later period MAVIC MA40 clincher rims, and I always intended to bring the wheels back to period spec by using some old MAVIC GP4 rims I had from a previous bike, with some correct spec 6207/6208 hubs I had picked up. Fitting these hubs will complete the group set, and it will be nice to experience tubular tyres again… Won’t it?
I find it hard to write quick blog posts because I like delving into the detail of what I am doing. So I’ll try to keep this post from becoming a wheel building book, and aim to keep it to more of a basic primer on the subject. There are lots of wheel building books and lots of information and theories online, and lots of different lace/build methods, but there is no substitute for practice… you can’t become a good wheel builder by just reading books.
Before I could build these rims, I needed to give them some TLC as the old rim cement had dried and was now solid! I cleaned the first rim a little while ago with acetone and wire wool and although this brought off the old cement, it left behind a lot of fluff from the wire wool – it does wipe off and leave a good clean rim surface, but it’s just an extra job I didn’t want.
I decided to clean the second rim with a wire brush fitted to a hand drill – this generates lots of dust so do this outside, but it leaves a much cleaner rim with none of that wire wool fluff! A quick wipe with a cloth and the rim surface was ready.
There were lots of old rim transfers on these GP4s. Old bike shops and wheel builders would like to fit their shop transfers, and sometimes the wheel builders name, but a little bit of work with a hairdryer and some white spirit and they were removed and ready for some replacement MAVIC transfers. I always have a selection of common transfers in the workshop and had a couple of MAVIC ready to fit.
GP4 and small flange hubs in a 3 cross (3x) pattern are a normal combination so I’ve got the spoke length in my head. However, there is nothing wrong with checking using a spoke calculator just to make sure. I use Spocalc and there are five or six measurements needed to calculate your spoke length.
There are a few of these calculators available on the internet, I just find Spocalc really easy to use and the lengths given are accurate. With my basic measurements, Spocalc gave me 300 mm for both sides of the front wheel (299.7 mm) and 298/296 on the rear. I only keep even size spokes so took the 296.8 mm measurement down to 296 mm. It is quite common to round up or round down on spoke sizes. So long as you don’t go too far away from the required size then you should be ok with spoke length.
First thing to do is collect and prepare the parts you need…
This is everything for the rear wheel.
- 2 different spoke lengths + nipples (shorter spokes on drive side)
- Spoke key (I use an old “Spokey”)
- A small screwdriver or nipple driver
- Some cycle oil in a bottle and in a container
- Wheel dish tool
- Spoke tension gauge
- Matching hub and rim
You don’t NEED some of these tools but they are handy. A straight and true frame and fork can be used to check basic wheel dish, and wheel building experience can be used instead of a spoke tension gauge, but these specific tools are handy and speed up the process in my opinion.
I’ve blogged about wheel building before when I rebuilt the wheels on SB4059. That blog post included all the details you should aim to get correct when building rims onto hubs, including rim and hub orientation, value placement and spoke direction, so I’m not going to cover them in detail again here.
The writing on this Shimano hub circles the barrel so there is no specific place I would aim to use to line up with the rim value hole, so spoke lacing can start from anywhere on the drive side flange using the shorter length spokes.
Start by oiling the flange – this means that every spoke slotted into the hub will have oil transferred onto the spoke thread. Thread the first spoke through, count four empty holes along the hub and place the second spoke into the fifth hole but from the other side of the hub flange. Making sure the rim transfers are facing you, the first spoke that entered the hub goes to the hole in the rim next to the valve hole.
There are different methods of spoke lacing and one method is not necessarily better than the others, all methods will end up with all the spokes in all the right holes, there are just different ways of getting there. Most people begin wheel building by being shown a method, they then develop the method that they were shown. I did the same, and now I always use the same lacing method. If you want to practice on an old wheel, strip it down and check out a YouTube video or one of the online manuals.
Now that the first two spokes are in, you can fit the remaining ‘outside’ spokes. A good way to get extra oil onto the spoke threads is to grab a few spokes, fan them out and dip the thread tips into the container holding the oil before pushing the spokes through the hub. I’m using a standard 3x spoke pattern so there is a set procedure to follow so all the spokes fit into the correct location at the rim.
My method laces one complete side before moving to the other hub flange, whereas some methods will do half a side at a time. As I said, there is no right or wrong so long as all the spokes end up in the correct location. This is the step where you get your spoke cross pattern; the spoke that comes from the inside of the hub through to the outside of the hub will cross over two spokes and then need to pass under the third before entering the rim (it crosses three spokes).
It is interlaced under the third spoke to aid in adding support to the other spokes in the wheel. Again, wheel lacing and spoke tension is a whole subject on it’s own. Spoke tension and the forces placed on spokes and the rim during wheel rotation is important. Lacing a wheel and getting the rim round and true is only part of the job of wheel building!
Locating the first spoke on the other side of the hub is vital to ensure that you get the rim value hole in the correct location. Once it is located and fitted, all the remaining spokes are fitted. It is a little more difficult to thread spokes through as the opposite side spokes (which are still very loose) will need to be moved out of the way to allow a spoke to thread through.
When you are lacing spokes and interlacing them, be careful that you don’t scratch the rim, especially dark/grey anodised rims like these. The aim is to have all the spokes fitted and interlaced correctly – it plays no part in the ultimate strength of the wheel, but the rim value hole should line up with the widest part in the spoke lacing… so many bike builders get this wrong and miss this detail.
Tension, True, Dish and Repeat…
Spoke lacing is just a process, it seldom changes. Likewise the final part of the wheel build is just a process that you should go through in the same way each time. You only need a couple of turns of the nipple onto the spoke thread during wheel lacing to hold the spoke in place, but this stage of the build is where you want to equalise everything.
Before staring to equalise the spokes, they need to ‘bed in’ at the hub. All I’ve done so far is thread the spokes into the hub but this just creates a ‘loose weave’ of spokes – you need to use fingers and thumbs on the spoke at the hub to push and pull alternate spokes to create a bend at the spoke head, this will give the spoke a much better angle from the hub to the rim.
Most actions you should do from now all start from the valve hole, this is so you can keep track of spoke tensioning, one wheel revolution at a time. You can see in the image below that there is a lot of spoke thread showing – all this needs to be removed by tightening the spoke nipple. I do this in three revolutions of the wheels, starting at the valve hole, using a screwdriver on the end of the spoke nipple, tighten each spoke until only four threads are visible on each spoke.
On the next revolution, take the spoke thread on each spoke to the end of the spoke nipple, just enough so that no thread is visible. On the final revolution, using the spoke key, turn each spoke so that the end of the spoke is flush with the bottom of the slot of the spoke nipple (as viewed from the inside of the rim). There probably won’t be much tension on the spokes at this point but they will now be all pulled up to the same level. I also try to leave each spoke nipple in the same orientation – you can see in the right hand image above that the spoke key is inline with the rim, this is the same on every spoke. This means that is easy to tell if you are turning the spoke key by a quarter, half or full turn.
From this point on, your are going to be adding tension to the spokes, so NEVER look straight into the rim and look down onto a spoke nipple head… if that spoke breaks, it will shoot out of the rim with a great deal of force!!
At this point the wheel will still not have much tension, so starting from the valve hole again, give each spoke one turn of the spoke key so that the key returns to the same orientation with the rim. This should start by feeling quite easy to do, but as you work up to the mid point, you should feel that it is getting more difficult to turn the spoke key as the spoke tension in the wheel increases.
You will have enough tension in the wheel to start checking radial (up and down) and lateral (side to side) movement. If your wheel truing jig is self centring and is adjusted correctly then you are aiming to have the rim run through the centre of the tip on each side of the rim – this is just a quick step so don’t try and get too accurate – you are just aiming for fairly straight and fairly round, nothing too accurate. I do this because I want to check wheel dish, and you can’t check wheel dish with a wheel that is too far out of true.
Wheel dish is one of the four features of a built wheel.
- You want a wheel that is true
- You want a wheel that is round
- You want a wheel with the rim in the centre of the hub
- You want a wheel with good spoke tension
The wheel dish tool will check that the rim is equidistant to the lock nut on each side of the hub. The tool will indicate if the rim is over to one side of the hub or the other. To correct a rim that is out of dish, you would typically adjust the spokes on one side of the wheel (starting from the valve hole). Depending on how much spoke tension is already in the wheel, most dish adjustments are made by tightening the spokes on the side of the hub that you want the rim to move towards. So if the rim is over too far to the drive side then tighten the non-drive side spokes. The amount you need to turn will depend on how far the wheel is out of dish. There is no rule book for these adjustments, it all comes with practice, but most adjustments to correct dish will be either a half or full turn. If spokes are already very tight then you might need to remove tension from one side to allow a rim to move.
All of this spoke turning and tensioning is having an affect on the spokes. Spokes get what is often called ‘wind up’. As the spoke nipple turns, the spoke will twist slightly and you need to periodically remove this spoke twist to ensure that you are getting a correct reading on the jig – as the spoke unwinds, it may affect how true the wheel is by allowing the nipple to turn. Relieving tension in spokes is best achieved by grabbing two opposite spokes on either side of the wheel and squeezing them – you will hear the spokes ‘ping’ as they untwist. Go around the wheel once to relieve the wheel and then a second time, on the second time around, the noise should be gone. Recheck your trueness.
And that is the process of wheel building… Tension, True, Dish & Repeat…
As the spoke tension increases, you might find that you get more spoke twist and the spoke nipple will feel harder to turn. Hopefully if you have used enough oil on the spoke threads during the wheel lacing process, you should be fine – you don’t need to make the threads swim with oil, a drop is fine, but it is necessary so that you can build up the tension without damaging spoke nipples and rim eyelets.
So how do you know if you have enough spoke tension? Not only that, but how do you know if all the spokes have the same tension? There are three ways to check spoke tension…
- compare the wheel you are building to another similar wheel, squeeze the spokes, do they feel the same?
- experience – there is no substitute, you get better at wheel building by building wheels and you pick up the feel for spoke tension
- a spoke tension gauge – a gauge will tell you individual spoke tension by measuring spoke deflection
You are aiming for equal spoke tension across all your spokes on the same side of a wheel. In a back wheel that will be equal spoke tension on each side, but a different tension between the sides (the drive side will be tighter than the non drive side). In a front wheel both sides will be equal. If your spoke tension is too low then your wheel will probably need regular truing; as the wheel rotates under load, the spoke at the bottom of the wheel will compress – if it already has a low spoke tension, then there is a chance that the spoke nipple will loosen. If your spokes are too tight then you may damage the rim as the tension in the spoke will be trying to pull the spoke nipple out of the rim. There are a few ways to check for equal spoke tension…
- Check spoke tension with your hands as you stress relieve the spokes. As you go around the wheel you should be able to feel spokes that are too tight or too loose compared to others
- Flick each spoke – a spoke is like a tensioned string, if you flick it then it will have a tone – all the spokes should have a similar tone
- Use a spoke tension gauge and check a random selection of spokes to see if the readings are similar
Most rim manufacturers have recommended spoke tension guides for their products. It’s difficult to find these for old rims, but there are guidelines that I try and follow. I find the GP4 a good strong rim, there are much lighter rims and now there are deep section rims – they all require a different tension.
I tend to aim for between 90-100 KgF (Kilogram – Force) on the front with between 80-90 KgF on the non-drive side rear and 100-110 KgF on the drive side rear.
The Park tool I use isn’t the most accurate that you can buy, but it is affordable and does the job adequately. You can spend a lot of money on accurate dial gauge tension meters that will tell you a similar thing. The tool fits onto a single spoke and measures the deflection in the spoke – that deflection corresponds to a reading on the scale.
You use the conversion chart to convert the tool reading to KgF. So for the 1.8 mm spoke that I am building with (2.0/1.8 double butted spokes), a reading of 22 on the Park tool corresponds to 111 KgF in the 1.8 round spoke column on the conversion chart. This means that the drive side spoke I selected has a spoke tension of 111 KgF which is exactly where I wanted it to be. I checked half a dozen spokes on the same side and they are all within the range I want which shows a good equal tension all round. If the tension was too low or too high then you would adjust the spokes accordingly remembering to adjust each spoke equally starting at the valve hole.
Wheel building is a process that just needs practice…
- Start by setting all the spoke nipples to the same depth
- correct any initial roundness and trueness problems
- check and correct wheel dish but only on a true rim
- relieve spoke tension and check trueness again
- check spoke tension
- continue to check roundness and trueness and dish while increasing and checking spoke tension
- practice makes perfect!
These are old used rims so they will never be perfectly round or true, but they are close. Old rims might also have problems such as poor rim joints, where you might see a little ‘kick’ at the joint – there isn’t much you can do about this. Later rims such as the MAVIC Open SUP had machined braking surfaces that removed the rim joint and eradicated the kick that most old rims have.
The Finished Wheels
- MAVIC GP4 36 Hole
- Shimano 600EX 6207 36 Hole Front Hub
- Shimano 600EX 6208 36 Hole Rear Hub (6207 is freewheel fitting – 6208 is Cassette)
- DT Competition 2.0/1.8 Double Butted Stainless Steel Spokes (Brass Nipples)
The rims cleaned up really well…
Now I just need to fit the tubular tyres – that will be the next blog post…