Broken Crank Brackets

Broken Crank Brackets

As I mentioned several times, I’ve been fairly busy lately and this prevented me from riding regularly.  Last weekend was the Thanksgiving holiday in Canada and I was looking forward to riding my DF.  I had noticed that my crank had moved forward about 3 to 4 cm and wanted to move it back to the right place.  Aluminum has a tendency to slide on carbon fiber.  The same problem occurs on a road bike when you have a carbon fiber seat post on an aluminum or steel frame.  The seat has a tendency to slowly lower and you need to adjust the height from time to time.  Manufacturers have created a compound to provide better grip between the two materials.

Before leaving for the weekend, I opened the hatch and loosened the four bolts to move the cranks to the proper place on the boom.  In the process, I found that the two brackets were broken.  To some extent, I was not surprised, in the past couple of weeks, I read several posts from DF riders who had the same issue.  Their description was not unfamiliar to me including the movement of the crank on the boom, creaking noise when pedaling or sluggish feeling when pedaling.  I had noticed two symptoms: the sound and could not identify the source and the forward movement of the crank on the boom. 

I contacted Randy at Bluevelo and he’s sending me a new set of brackets.  Unfortunately, as a result I had to abandon my plans for riding over the weekend.

The question remains however: why are there so many failures of these brackets?  The same system has been in use for many years on the Quest and Strada but while a few fail from time to time, the number of failures on the DF is much greater.  I wonder if the difference of the much stiffer carbon fiber boom in the DF compared to the aluminum boom in the Quest and Strada put too much strain on the brackets.  The small flex experienced in the Quest and Strada may provide some protection to the brackets.

Notwithstanding the cause, it looks like a redesign will be considered.  Daniel Fenn has already produced a new stiffer boom for the DF but it is not part of the production, it is a special part used for racing.  The boom is drilled and the crank is installed inside the boom, not on top of the boom.; once installed, it cannot move.  This means that you would probably need to change the position for another rider for example; you would probably need to purchase and install a new boom, as it may not be a good idea to drill several large holes in the same boom.  This would most probably affect the stiffness.

Several alternatives to the current brackets are being discussed including manufacturing the brackets using another stronger material including steel or costly titanium.  Using a round pipe clamp and nylon inserts with square sides to adapt to the square crank mount and boom.  The round shape can withstand a lot more pressure than the current brackets without breaking and they may also be lighter.

Velomobiel

Theo van andel announced a price increase due to higher purchasing costs and improvements to the standard equipment of velomobiles. While cost for components have gone up improvements like 3 x10 speed is now standard and so is higher quality color finish with automotive paint, lithium batteries dimmable lights, lower weight full carbon shells and more.

The Strada now has lights, flashers and horn like the Quest.

The price increase will take place November1^st.  If you want to beat the price increase, you have until October 30^th. Do you want to buy the old price then order for 30 October!

VeloTilt

Wim Schermer reported that a new suspension is being tested for the VeloTilt.  It should address some of the shortcomings identified during testing.

Terra Cycle

Terra Cycle is testing a new 23T Sport Idler that could replace the current idler in the IntercityBike DF and DF-XL velomobiles.