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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 06-17-09, 12:45 PM   #1
75PIN
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Pedal strike question

Hi Guys

I`m part way though the mock up stage on my Dawes Kingpin build,
And was wondering what length cranks the R20 builders among us use??

My Kingpin is fitted with 406 rims with Schwalbe Duranga 20" x1.1 tyres
and i have a set of 2 piece Tiagra 170mm with 34/50 cranks to go on,

Will i need to shorten these cranks??

Cheers
Adrian
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Old 06-17-09, 05:27 PM   #2
jur
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What is the bottom bracket height? If in the range of 28cm or more, pedal strike shouldn't be an issue.
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Old 06-17-09, 05:29 PM   #3
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Adrian,

On my R20 with 406 rims I have a Redline BMX crankset that is 165mm, this gives me about 3 inches or 75mm clearance, I find that is enough, but maybe an inexperienced rider may not. I will be in the near future changing these for a very nice 145mm set I have for more clearance and the 165s will go to another R20 with 451 rims.

Just remember that a 34/50, (compact), set up on a full sized bike gives it lower gearing, so on a 20" wheel you will find it very low, maybe too low? If you search Bike Friday's website you will find that the gearing on their bikes that match a full sized road bike is something like 60/48 unless it's got a Capreo system. On my R20 single speed I'm using a 58t front ring and 14t rear, this spins along nicely at 30+ kmh, but is too low for much higher speeds.
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