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-   -   152mm cranks? (http://www.bikeforums.net/fitting-your-bike/928246-152mm-cranks.html)

Crescent Cycle 01-02-14 12:29 AM

152mm cranks?
 
Has anyone with a short inseam tried them? Less than 29" inseam? I supposedly have short femurs too, and the additional saddle to bar drop and opening the thigh/stomach angles is attractive. I think most formulas place me between 152 and 165, but I'm leaning towards the 152s because of the short femurs.

I went from 170 to 165 and was fairly happy, and now I'm thinking about going even shorter. I've seen very little feedback or firsthand experience from riders of upright bicycles though.

fietsbob 01-09-14 10:32 PM

hope you are patient, these 'you go first , then tell me how it was' threads are numerous.
no guts, no glory :lol:

Origin 8 offers a range of short cranks for BMX bikes , they are inexpensive , square taper type.

jyl 01-09-14 11:49 PM

Yes, some Origin 8 BMX cranks will accept double chainrings. I built up a juvenile sized road bike for my son using those cranks in 150 mm.

ironwood 01-10-14 08:31 AM

TA makes 155, 160,and 165mm cranks. www.peterwhitecycles.com

trailmix 01-10-14 08:33 AM

Have you thought about 155mm cranks? My mother has a Terry with a 155mm Shimano double and she is 4'11''. Her Cannondale touring bike has 165mm for a little extra leverage.

fietsbob 01-10-14 02:14 PM

Some of the cranks for kids were re machined for 2 pedal hole per crank arm

also offered for tandems with a Kid Back add on BB ..

Crescent Cycle 01-11-14 09:01 PM

How does the BMX crank shift and how many speeds do you have it set up for?

I read somewhere the spider is 4.2mm thick instead of 3.5mm thick. Quite a bit of difference.

fietsbob 01-11-14 11:44 PM

As Crank arms Only ... They're a 110 BCD type , so how they shift depends on which chainrings you buy
their sizes and whether they are fully featured with ramps, shift pins and tooth profiles
all engineered to make an easier-quicker shift.

Smallest pitch is TA a 33t, that requires a bit of end of the spider machining to clear them with the chain,

typically a 34t is the smallest.. used

BMX is typically a 1 speed , then shifting is a Non Issue.

Crescent Cycle 01-12-14 12:30 AM

From what I researched on the origin 8 BMX cranks is they can mount double chainrings according to Harris, but they space the chainrings farther out due to a wider spider. That's why I'm asking about the setup and how it shifts.

byrd48 01-19-14 09:40 PM

Sugino makes triples in shorter crank lengths, I'm not sure about doubles.

hamster 01-19-14 11:07 PM

I had a 154 mm crank for about 6 months. Switching to 154 from 170 helped with the knees (I was basically just starting riding and I was ramping up the mileage pretty aggressively, and there was some minor knee pain on 170's). I was also unable to spin 170's much higher than 90 rpm, and 154's raised both my optimum cadence and maximum cadence by another 10-15 rpm.
After that I got a new bike with a 172.5 crank and I've been riding on it ever since, put 5k miles on it last year, and did not feel the need for a short crank any longer.

jyl 01-20-14 10:03 AM

Quote:

Originally Posted by Crescent Cycle (Post 16403437)
From what I researched on the origin 8 BMX cranks is they can mount double chainrings according to Harris, but they space the chainrings farther out due to a wider spider. That's why I'm asking about the setup and how it shifts.

My son's bike shifts normally and I used no special components or tricks. Shimano 600 tricolor derailleurs, 50/34 chainrings on the Origin 8 crank.


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