Bicycle Mechanics - Custom made crank set

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.




View Full Version : Custom made crank set


KDC1956
10-26-10, 10:24 AM
Has anyone here ever made there own crank set if so why.I made one my self but it cost more than it would have if I had just order a set.But this was the only why I could get this crank set.


BCRider
10-26-10, 10:35 AM
The cost of making your own set must have been many times more than the cost of buying one. What is so unusual about your situation that required it and what length of cranks did you get?

There was a thread around here a while back about a guy that makes very short cranks so that folks with knee mobility issues can continue to ride. The fellow that started it also claimed that it was surprisingly effective. Not a lot of torque but easy to spin at a much higher than normal cadence to make up for the lack of torque. The short arms were done by simply drilling the arms and spot facing the drill points and then threading the arms. The excess being then cut off and the end re-profiled.

MichaelW
10-26-10, 10:52 AM
Besides the crank shortening service (http://www.cerddedtregaron.co.uk/) offered by a few workshops, the main reason to go custom is for large size. Specialities TA do a fair size range and Zinn do extra long ones (which require high bottom brackets for clearance).
TA and Middleburn make separate crank/spider assemblies that you can mix and match.


HillRider
10-26-10, 02:15 PM
I hope you had good metalurgical skills when you made your own cranks. Years ago there were a bunch of boutique crank makers who made custom CNC'ed cranks out of billet Aluminum. Their CNC skills were far better than their knowledge of metalurgy and the failure rate was very high.

Bianchigirll
10-26-10, 06:17 PM
KDC you mean you actually forged or CNCd a crankset or did you use a stock crank and swapp the rings around?

Michael thanks for the link but unfortunatly I can't afford such sexxy rings. although it does give me a few ideas

http://www.cerddedtregaron.co.uk/highpath/cycles/images/eggs/01.jpg

KDC1956
10-26-10, 08:17 PM
No what I did was to get a crank spider and then get my chain rings with no pins or ramp on them and built it up this way I am using the old school friction shifters.
The chain rings are 46t,36t,26t I have about 150.00 in my set.Last year I bought a crank set with 44t,32t,22t for 39.00 it works great on my Surly LHT but this crank
set I made it for my new build I will be working on this winter.This gives me something to do.

Kimmo
10-27-10, 04:37 AM
Gah... info in an OP is good.

HillRider
10-27-10, 09:11 AM
Gah... info in an OP is good.
+1 I was sure he had started with a big block of aluminum and a bandsaw.

fietsbob
10-27-10, 09:47 AM
So this is about assembling a non standard set of chainrings on an existing crank arm set..?

if that is the case, then it is safe to assume many combinations are possible,
as long as the bolt circles match up and the chainline works when you're done.

Non Indexed, friction/ratchet shifting allows more flexibility.

I put down market steel chainrings on my touring bikes crankarms , and got increased wear-life out of them,
as well as choosing them for their tooth count.

JohnDThompson
10-27-10, 05:42 PM
I hope you had good metalurgical skills when you made your own cranks. Years ago there were a bunch of boutique crank makers who made custom CNC'ed cranks out of billet Aluminum. Their CNC skills were far better than their knowledge of metalurgy and the failure rate was very high.
The problem with CNC machined crank arms was that machined billet by its very nature is less strong than a forged part. Forging changes the characteristics of the material in a way that makes it stronger than plain billet. But forging is a capital-intensive process that doesn't lend itself well to small operations.

That said, builders like René Herse would purchase raw crank arm forgings and machine them in house to their own specifications. The boutique CNC machinists used plain billet.