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My Calculus Munga Bike Built


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Calculus Munga Built

 

When you say you plan to ride the Munga, responses vary from “You’re crazy “to “Wow” or “That sounds painful”

 

As a keen middle age amateur rider, the last statement might be the most accurate; so when I planned to be “crazy “for the third time this year, I decided from the start the “painful” part should be addressed as much as possible.

 

When planning a bespoke Munga bike you need to look at the conditions you’ll be riding in most of the time.

 

Over a 1000km race like the Munga you get a bit of everything, sand tracks, a few rocky single tracks and never-ending corrugations.

 

You also have strong winds, night riding and sleep deprivation to contend with.

 

Building a bike to handle the worst of these conditions was the starting point.

 

I’m sure all Munga riders will agree the corrugations for hours on end is the worst.

 

I’ve done the Munga both times on a duel suspension carbon bike. For 90% of races this is a perfect bike, responsive, light and with lots of suspension travel…just what you need for 10% of the Munga!

 

So, let’s get to my Calculus Bike.

 

What you need is a bike for the corrugations, wind and stable for those sleep deprived nights.

 

Thinking a bit out of the box it was decided that you don't need a lot of suspension travel, you need volume in the tires and small bump compliance on the front and keeping it as light as possible.

 

You have to consider the vibrations, which is a killer for the hands and tiring on the body.

 

A slack Head Tube angle to keep the bike stable on those long straight stretches plus a variety of hand positions.

 

Working together with Millar Nienaber from Calculus Bikes in Hermanus, the following were done:

 

• First a custom geometry Titanium hardtail/gravel frame, designed to address vibrations.

• Lauf fork at the front for small bump compliance and to keep the weight down.

• 29” front carbon Nextie hoops with a 2.6 tire for lots of volume to protect the hands.

• 27.5" back wheel with a 2.8 tire, again for maximum volume and also to keep the weight down.

• Drop gravel handle bars for a variation of hand positions and riding on the drops for those head winds.

• 5 water bottle cages on the frame and a frame bag for travel gear.

 

I know a bike is like a saddle, what works for one may not work for another but thus far this one works great for me!

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I love it, such a cool build! You can see this has been very well thought out and is fit for purpose!

 

Is there enough clearance in the back triangle to take a 29x2.2 - 2.4" tyre should you want to use the bike for something like a 36One that is a bit shorter where you may not need as much comfort in the back as a Munga?

 

Another question - what tyre is that on the back?

 

Oh, maybe something to consider to keep the look nice and slick. Farr make an aero top tube bag, that attaches to the frame with two bolts. This being a custom build I am sure Calculas can add two bosses to the top tube. It will make the bike look really clean by doing away with the straps of the bag you have now...

 

EDIT: the top tube bag I am talking about: https://ridefarr.com/product/aero-toptube-bag/

 

May also be worth it to consider adding their areo bolt on for more hand positions: https://ridefarr.com/product/handlebar-carbon-farr-aero-bolt-on/

 

PS, I have no affiliation with Farr.

Edited by Grease_Monkey
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I'm no bike expert but shouldn't your tyres atleats be 2.2

Looking back at previous bikes that won the munga I saw all winners use 2.2

Isnt more tyre going to make you slower? Correct me if I'm wrong, like I said I'm not an expert.

Nope, plenty of research has been done on this, higher volume is actually faster (to a point obviously). Tread pattern and weight makes a bigger difference to how fast you roll compared to volume. More volume also equals more comfort, and a comfortable rider can ride for longer and more efficiently - which translates to better times.

 

The winning guy may be fastest on thin tyres, but the winner is also out there for alot less time than anyone else so his bike does not need to be built the same as most of the other riders.

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Calculus Munga BuiltWhen you say you plan to ride the Munga, responses vary from “You’re crazy “to “Wow” or “That sounds painful”As a keen middle age amateur rider, the last statement might be the most accurate; so when I planned to be “crazy “for the third time this year, I decided from the start the “painful” part should be addressed as much as possible.When planning a bespoke Munga bike you need to look at the conditions you’ll be riding in most of the time.Over a 1000km race like the Munga you get a bit of everything, sand tracks, a few rocky single tracks and never-ending corrugations.You also have strong winds, night riding and sleep deprivation to contend with.Building a bike to handle the worst of these conditions was the starting point.I’m sure all Munga riders will agree the corrugations for hours on end is the worst.I’ve done the Munga both times on a duel suspension carbon bike. For 90% of races this is a perfect bike, responsive, light and with lots of suspension travel…just what you need for 10% of the Munga!So, let’s get to my Calculus Bike.What you need is a bike for the corrugations, wind and stable for those sleep deprived nights.Thinking a bit out of the box it was decided that you don't need a lot of suspension travel, you need volume in the tires and small bump compliance on the front and keeping it as light as possible.You have to consider the vibrations, which is a killer for the hands and tiring on the body.A slack Head Tube angle to keep the bike stable on those long straight stretches plus a variety of hand positions.Working together with Millar Nienaber from Calculus Bikes in Hermanus, the following were done:• First a custom geometry Titanium hardtail/gravel frame, designed to address vibrations.• Lauf fork at the front for small bump compliance and to keep the weight down.• 29” front carbon Nextie hoops with a 2.6 tire for lots of volume to protect the hands.• 27.5" back wheel with a 2.8 tire, again for maximum volume and also to keep the weight down.• Drop gravel handle bars for a variation of hand positions and riding on the drops for those head winds.• 5 water bottle cages on the frame and a frame bag for travel gear.I know a bike is like a saddle, what works for one may not work for another but thus far this one works great for me!

Im hard.

Stunning

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Nice. Does no one use a dyno hub? No need for extra batteries. Seems weird to me. Good luck on your race.

assuming something in these lines:

 

60kg rider / 15kg Bike and Gear / 100 watts / Non-Dynamo Hub = 24.34km/h.

Most efficient hub: off – 24.29km/h (0.5w extra drag) +0.2%

Least efficient hub: off – 23.94km/h (4.0w extra drag) +1.6%

Most efficient hub: on – 23.82km/h (5.25w extra drag) +2.1%

Least efficient hub: on – 23.71km/h (6.25w extra drag) +2.6%

60kg rider / 30kg bike and gear / 100 watts. Non-Dynamo Hub = 23.83km/h.

Most efficient hub: off – 23.78km/h (0.5w extra drag) +0.2%

Least efficient hub: off – 23.42km/h (4.0w extra drag) +1.7%

Most efficient hub: on – 23.29km/h (5.25w extra drag) +2.3%

Least efficient hub: on – 23.19km/h (6.25w extra drag) +2.7%

80kg rider / 15kg bike and gear / 150 watts. Non-Dynamo Hub = 27.96km/h.

Most efficient hub: off – 27.92km/h (0.6w extra drag) +0.1%

Least efficient hub: off – 27.60km/h (4.75w extra drag) +1.3%

Most efficient hub: on – 27.53km/h (5.75w extra drag) +1.5%

Least efficient hub: on – 27.46km/h (6.60w extra drag) +1.8%

80kg rider / 30kg bike and gear / 150 watts. Non-Dynamo Hub = 27.51km/h

Most efficient hub: off – 27.47km/h (0.6w extra drag) +0.2%

Least efficient hub: off – 27.15km/h (4.75w extra drag) +1.3%

Most efficient hub: on – 27.07km/h (5.75w extra drag) +1.6%

Least efficient hub: on – 27.01km/h (6.60w extra drag) +1.8%

The Effect On Your Riding Time

Using the speed data, we can work out how drag translates in terms of time:

– The most efficient dynamo hubs when switched OFF add between 17 and 30 seconds to a flat ride over 100km when compared to a regular hub.

– The most efficient dynamo hubs when switched ON add between 3min 24sec and 5min 47sec to a flat ride over 100km when compared to a regular hub.

https://www.cyclingabout.com/dynamo-hub-drag-lab-testing/

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