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Hi Guys/Gals,

I am thinking about buying a redline 9 2 5. This is singlespeed/fixed gear bike which uses a flip/flop hub. The stock gearing is 42/16 free 42/15 fixed. I am mainly using this for commuting and winter training.

The Crank Arms are 165. I normally ride 172.5 I understand why they are shorter, but would it not be better to have the same crank arm lenght on the training bike that I would normally run on regular bike. I do not race, but do want to start to do some race-like training to keep up with the pelton on our group rides. I ride a 57/58 cm frame.

are long crank ams on fixed gear bikes a reciepe for disaster.

Please provide feed back.
 

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kroettger1 said:
The Crank Arms are 165. I normally ride 172.5 Would it not be better to have the same crank arm lenght on the training bike that I would normally run on regular bike.

I don't know that you'll detect enough of a distinction between crankarm lengths that are different by only 7mm to warrant any expense you might incur by changing them, but LOTS of people use 172.5 arms on their fixed gear bikes without problems.


kroettger1 said:
are long crank ams on fixed gear bikes a reciepe for disaster.
No, but you want as much cornering clearance as possible. You can help achieve that with a careful pedal choice, and by taking your turns a little wide until you learn the bike's limits.
 

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My 58cm came with 170 crankarms

Did you end up picking up the Redline?

As it turns out, I just picked up a 58cm frame Redline 925 and it came with 170 mm crankarms. I have 172.5 on my racing bike, I can't really tell the difference in the pedal circles of the two.

-Jeff
 

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BianchiJoe said:
I don't know that you'll detect enough of a distinction between crankarm lengths that are different by only 7mm to warrant any expense you might incur by changing them, but LOTS of people use 172.5 arms on their fixed gear bikes without problems.

7.5mm is a lot in terms of bike fit. Many people cannot tell the difference in a 2.5mm change in crank length, whereas some can. A 7.5mm change in crankarms may mean that you gotta adjust saddle height, and that can affect everything else. Me, I used the same crank length for all road bikes, including FG and CX.
 

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9.2.5

Mine has cranks that are a tad shorter than my regular cranks and I do not notice the difference. I have a question I had the freewheel changed to a 18 because I ride hills and I tryed to switch it to the fixed side and I think the chain is to long? Maybe the shop had to lengthen the chain for the 18 freewheel? If I swithched to a 17 on the freewheel side and used the 15 on the fixed side would the chain still have to much difference? I have put on Pasaleas that are 32's and without the fenders they still have plenty of room I like the versatility of this bike. I plan on taking it to the trails in the fall because with the sloping top tube I think I have plenty of clearance. I did change to drop bars. I am sure you will like/love your 9.2.5. Post pictures of your 9.2.5's
 

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The real difference is that in one case you will be spinning circles 1.5cm different in diameter (165 vs 172.5) and in the other only .5 (170 vs 172.5). That might be a big difference for a lot of people. The principle of specificity states that you must practice what it is you want to do. You make the call.

Larry
 

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didn't notice going from 175 to 170

rode 175's on everything [i'm 6'2"] till my first fixie which was 170. - didn't notice. then i went with 175's on my DIY fixie, then to 170's again on my track bike.

all feels the same to me.

i have 180's on my 29er SS which i do notice tho.
 

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I have 172.5s on my road bike, and I had 170s on my fixie when I first got it, but switched to 165s. I noticed the difference, not so much in less pedal strike in the corners as i did in the ability to spin like a madman on the decents. I am running 42X16 as well, and on the decents I often get up to 150 or higher RPMs, and I just couldn't spin that fast with the 170s. Maybe it is just me getting used to spinning, but I felt like the shorter crank made a huge difference. But I don't really notice a difference when I get on the road bike. No pain or oddness. Well, for the first mile every time I coast I flinch, but that is different ;)

Gordon
 

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I know what you mean. I'm 5'8" and can't say I notice a difference moving from 172.5 road to 175 mtb. My current project bike is 170 and I can't say I notice a difference there, either. OTOH, I don't sprint at + 200 RPM. That would be the situation where the different size circles would be most evident. For what I do, I'll take the constant slight leverage advantage of a longer arm vs the occasional high speed sprint advantage of the short arm. I question whether any of it really matters for casual users. Experienced track racers could probably contribute something here.

Larry
 
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