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19 Jan

Cannondale Ai (asymmetric integration) available on BORG wheels

Posted by Bold Apps

Well Cannondale introduced this for a number of there bikes.

What is Ai (asymmetric stays)? Well put simply it is the drivetrain being moved 6mm to the right meaning the stays are no longer symmetric. This has the effect of changing the dish by 6mm. So wheels built for a bike with symmetric stays cannot be used in a bike with Ai. It is not possible to redish wheels either to acco.adte this standard as spoke lengths will be 1mm off. I wont do it other may but it's a mistake as its building potential problems for the wheel. 

The upside is tensions are more even.

All disc brake wheels I build with the BORG DX hubs can be built for the AI standard. I can rebuild wheels built for symmetric stays with new spokes of the correct length for th AI standard. Some hubs may not be suitable due to there geometry but most rear hubs are suitable. 

Ai bikes are all 12m TA. 

I do dispute cannondale claim that radial and lateral wheel stifness increased by using Ai.  Making spoke tensions even does not increase wheel stiffness. Lateral stiffnes is actually reduced by a couple of percent due to reduction in the left side bracing angle. The left side bracing angle  contributed more to lateral stiffnes than the right side. That geometry and cant be argued with. Radial stiffness will be reduced as the right spoke bracing angle is increased. So the upto 60% claim in cookoo land territory. There is a weak link between tension balance and radial and lateral stiffness but since disc brake wheels have good tension balance to begin with the improvement of evening the tensions is very limited. In principle you can increase the loads required to detension spokes (often confused with stifness) but have tou tried loading a wheel till the spokes detension on  Borg wheel. Not easy. So as with all thing take the marketing with a pinch of salt. However Cannondale use it and if you like there bikes using this design feature you need compatible wheels. The Cycle Clinic builds great wheels for these bikes. 

From cannondale's website


The heart of the Scalpel-Si and F-Si System Integration is the all-new, Ai, asymmetrically offset rear triangle and drivetrain. The offset shifts the rear hub and drivetrain 6mm to the right, delivering super short chainstays without any of the usual compromises, and a rear wheel that is dramatically stiffer and stronger because the spoke tension and angles are equal on both sides. We then integrate this with our new Ai HollowGram spider, which moves the chainrings an equal 6mm to the right, balancing the system and maintaining perfect chain-line, shifting performance and Q-factor. This elegantly simple approach - Ai - enables us to have our cake and eat it too. The extra space created by shifting the drivetrain outboard enables us to have:

  • The shortest chainstays on the market, for incredible traction,
  • Stiffness and agility.
  • Up to 60% increase in rear wheel stiffness.
  • Dual chainring compatibility with super short stays.
  • Tons of mud clearance.
  • Ample tire clearance with the chain and front derailleur.



It started being used in 2017. Cannondale dont state on there website which model use this design feature. There catalogues do. The Cycle Clinic are not Cannondale dealers so it is not easy for us to identify which models have this feature. Before ordering please ensure your bike has Ai,this is best done with Cannondale or  knowledgeable Cannondale dealer. 

In the 2019 catalogue the SuperX, Jekyell 29 and 27.5,  Scalpel SE and Scalpel Si used Ai. However there maybe other models too. 

I have been stung once before with an american customer ordering wheels for Ai then using them briefly and returning them because they did not fit his bike. His credit card company forced a refund (I was going to refund anyway but no one like being forced to do something). Therefore it is important you check first. I like customers who trust me if they do I can help them. 





03 Jan

Tyre pressuree

Posted by Bold Apps

Well what you think you know is probably wrong. Let's start there.

Let's start with a manufacturers recommended tyre pressure. These are not to used. The standards organisation has an approved test using a steel rim to se when a tyre blows off. Half that pressure is the recommended tyre pressure. It's a range due to variability but it's also way too high. 

Back in 2015 when I got my first IRC tubeless RBCC tyres myself and others noted at 90 psi for a 25mm tyres (that sat at 27.5nm on a 19mm internal width rim) the tyre felt faster. What was described is zing however that road buzz is exactly what you dont want. 

Road buzz is energy lost. You get this with wheels when manufacturers build a wheel that has zing. Smoothness is better. Smoothness is less energy lost. That's faster.

There is no relationship that works between rider weight and pressure as it far too dependent on road surfaces.

So to work out for a tubular  tubeless or tubed clincher the correct pressure find a typical loop. Pick a starting pressure for a tubeless road tyre that's no more than 80 psi try it out. Your looking for smoothness I.e no buzz. Continue dropping until you feel tyre squirm in the bends

 Squirm or pedal bob means the pressure is too low. The point at which there is no squirm and you have no road buzz that your min pressure and possibly the lowest rolling resistance. Your max pressure is just below the point where you start to feel road buzz. Rolling resistance

between these two points should not be that different but on most U.K road surfaces lower seems to be better.

This works for road, MTB, gravel or CX tyres of all types. The physics is the same. 

For IRC road tyres and me 80 psi seems to be the point at which road buzz starts to become noticeable is 80 psi for a 28mm Formula Pro RBCC tyre. At 30 psi I cant really feel squirm but can bottom the tyre out. So 40 psi seems to be the minimum. 50to 60 psi is what I normally use now. With panniers I may push it up a bit. I am nearly 90kg kitted up and generally ride road biked 9 to 14kg in weight without extra load in panniers. 


19 Dec

Cycling Weekly Editors Choice 2020

Posted by Bold Apps

The BORG31 made it. £380 without tyres and £490 with. Rim brakes are not dead yet. What makes these wheels special is the details.

Alloy nipples save a bit of weight but ha e a bad reputation. Yet alloy nipples failures are practically unheard of for me. I use Sapim HM washers so the nipple is easier to turn, Sapim nipple freeze stops galavanic corrosion or slows it to a crawl and thirdly my spokes are the correct length. Do all three and alloy nipes last. 

Another detail is the spokes

 Sapim CX-rays are used on the front wheel (nothing u usual there) but Sapim CX Force are used on the rear. This is a triple utted aero spoke. It not listed on the Sapim website as it's an OEM spoke. Its 2.18mm at the elbow and 2.2mmx1.3mm for the aero mid section. 

Next are the hubs. Flange to flange distance is an overlooked miche hubs have 55mm flange to flange distance for the rear hubs. DT swiss have 50mm for comparison. That 5mm makes a big difference. 

To improve tension balance a rim with a 3mm offset is used. Tension balance is therefore 53% which is not bad for an 11 speed hub. This mean even with tubeless tyres which cause a big tension drop (250N on the drive side) spokes will never go slack. Using A DT Swiss hub would result in  high tension balance but a wheel that is less stiff laterally. So not only will the wheel feel less responsive but it wont be any more relaible because more spoke tension does not improve reliability. Spokes tension/lenght changes are the cause of fatigue when a wheel experiences load. A wheel that is less stiff experiences larger changes in spoke tension/length when the wheel is loaded. So just because DT Swiss or other hubs with a strong brand name does not mean it better. 

Miche hubs also use big 6001C3 bearings with 2RS seals. They well sealed from the elements.

This makes for a very stiff wheelset with  small aero advantage

 They handle well and are comfortable. They also offer proper tubeless compatibility. By this I mean, tubeless tyres inflate easily and seat but they stay seated without air which is a critical feature. This makes selant top up easy and fix flats easier with a plug. 

I try and think all this through so you dont ha e to and can enjoy the ride. 

07 Sep

Tubeless tyre inserts - how they work

Posted by Malcolm Borg

There is alot of misunderstanding of tyre inserts. Many think they primary function is rim defence well that part of what they do. In fact the charactetisics of the insert (size, responce to air pressure and the material itself) detemine how they work and what type of riding they are best suited too. 

So here is a detailed guide with some Physics. I used to be a physics teacher so I cant help my self. 

A tyre , insert and air system is essesially a spring with an overal spring constant.So the Insert really acts as a way of giving more control of the air pressure required to give the spring constant needed to stop your tyres botming out and squirming.  

Springs in series add in the following way. k(t) is the total spring constant of the system, K(a) is the spring contant of the air, k(r) spring contant of the rubber tyre and k(i) the spring contant of the insert. The spring contant of the air and tyre  are non linear which complicates matters

1/k(t) = 1/k(a) + 1/k(r) + 1/k(i)

or k(t) = [k(r)k(i) + k(a)k(i) + k(a)k(r)]/[k(a)k(r)k(i)]

Now it should be clear the tyre used has a big influence on the pressure that can be run.

The spring contant of the air (low pressure) is the lowest term so 1/k(a) is relatively high compared to the tyre and insert term which are lower. So for tyres with flexible casing the air term does not dominate as much as trail tyres with stiffer casings. i.e you can run lower pressures in tyres with stiffer sdiewalls then with tyres with more flexible sidewalls. That does not mean however that inserts only work best with tyres with stiff sidewalls. Thats not the case at all.

The insert is important. The firmer the insert the more dominatant the air term becomes. If you have a 1kg trail tyre you will need a firmer insert to run the lowest pressures. In the PTN range the Rokkline work well but the Revolution insert is best. 

Run flat works best with stiffer tyres but the stiffer inserts (Rokkline and Revoluition) do all run flat with light XC tyres. Most occasions where you will be running flat there will be some residual air pressure even if its 5 psi. With a stiffer tyre and  an insert the air term dominates again in other words your able to ride on air and a stiff sidewall will limit the squirm.

The lower pressures can be be used allow lower rolling resistance. However the insert needs to reduce in size with air pressure and not be in contact with the tyre with the riders weight on it. Some insert are so big and stiff when the rider sits on them the tyre is in contact or the air volume so small (vittoria airliner) that there is very little tyre displacement before your tyre is in contact with the insert. That contact increases rolling resistance. 

If the tyre is not in contact with the insert then the insert is the last line of defense when you and or strike an obsticle preventing the tyre bottoming out on the rim and the consequential damage that can result. 

The lower tyre pressure improve grip and traction and as the tyre can conform to the gorund better you suffer lower vertical accelerations (bounced about less) and that is how rolling resistance is lowered. 

Essentially these insert work. Come insert like Crush Core or the vittoria and geared more to gravity riding as they are dense and very impact resistant. Crush Core is also heavy compared to PTN. PTN actually have a new heavier (slightly) and firmer insert called rockline which is aimed at enduro riders and E bikes. . Schwalbe pro core is quite good as you can alter the spring rate of the inner chamber to tune the system. However I have punctured pro core with a long thorn. The firmer inserts are better suited to trail tyres and the lighter inserts are better suited to lighter tyres. Many of the other inserts are heavy or heavy and dont offer good inpact resistance. The is a good article on this here.

So this is a suspension system in the tyre and should be viewed as such. Sorry it got all technical.

What inserts do a summary. 

  • allow lower tyre pressures improving comfort
  • reduce rolling resistance ( see above for explaniation and caveats)
  • rim and tyre defense is a consequence of being able to run the lower pressure
  • more traction and cornering grip for the same reason as you get lower rolling reistance. 
  • Run flat potential.
  • Anti burping


22 Jul

Miche hub maintenance -how to guide

Posted by Bold Apps

Miche hubs are simple to service. 

Play in Axle:this can be adjusted out. First make sure the end caps a tight. Use two 5mm allen keys and note the direction arrows on the left end cap. reverse thread alert. 

Use a 2.0mm allen key to undo the grub screw on the left side. Use a 17mm spanner to adjust the bearing preload adjuster so there is just no play. screw down the grub screw. Be gentle with it as grub screws are easily rounded of. It only has to be secure so the adjuster does not unwind by itself. 

The adjustment is best carried out withthe wheel clamped by the QR in the frame as QR pressure loads the bearings. 

Proceeddure for the fornt and rear hub is the same. 

Freehub change:

If you chanaging your freehub due to notching then so you cassette lockring up tighter. 40Nm is the minimum required. Miche cassettes also notch shimano pattern bodies less so there your other solution. 

Undo the end caps with two 5mm aleen keys in each end cap noting the direction arrows on the left end cap. Remove the axle and change freehub. 

Assembly is the reverse of disassembly but bearing preload may need to be set again. 

Bearing Replacement

The freehub bearings can be replaced but most users will lack the bearing extraction tools to make this possible. walking the bearings out will likely damage the freehub or get the bearing stuck. 

Main shell bearings should be extracted with bearing extracter or kocked out carefully. A bearing press should be used to press in new bearings. The Miche supplied 6001C3 bearing shoudl be used. a standard 6001 bearing will fit but will wear out faster because its not a clearance bearing.


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