Fitting Cranks To BB

RJWwmb · June 2007

Hi All,

My question is how much of a square bottom bracket should be showing between the frame and crank? I've been tigheting the bolt with a 6" rachet and don't think i'm getting enough leverage as the new chainwheels are not close enough for the front mech.

I've attached a picture to show what i've managed with lots of exertion so far. Should I be aiming to cover the rest of the darker circle area shown?

Thanks, Ryan.
Image Here:
http://img527.imageshack.us/img527/4959/img8261qk0.jpg

RJWwmb · June 2007

Sorry just realised should really be in workshop [:I]

Unknown · June 2007

you may have the wrong crank set for the axel. what was on and what have you fitted? and what is the axel length.

nick
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Unknown · June 2007

nah that doesn't look close enough won't it tighten anymore?

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RJWwmb · June 2007

I'm replacing a basic suntour pff crankset with another. They're not exactly the same in every detail but I hadn't noticed a difference in axel length. I'll try refitting one of the old cranks tomorrow and see if that goes on any easier, thus indicating a difference.

I looked on the parktool site and saw they use a torque wrench which is about 2 foot so was hoping it might just need more leverage.

Thanks for the fast replies and will let you know how I get on.

Unknown · June 2007

so what suntour crank came off? and what crank set is going back on.

and in your picture it looks like it is on as far as it will.

nick
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RJWwmb · June 2007

I've had another look today and attempted to get one of the old cranks back on. It wouldn't go any further than the replacement so I am confident its not that its the wrong part.

I'm sure that they need to go on further so more leverage is needed. I've only got about 6" of wrench so is this unreasonable? PS. I'm not that strong but i've put my 12 stone on it and my mate his on the pedal and struggling.

Unknown · June 2007

That sounds tight enough!! CAn you not adjust the mech a bit more? Could the mech have twisted round a bit?

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RJWwmb · June 2007

I always thought that the mech should fit over the smallest ring when the cable is loose and its currently on the middle. Good idea about the position but I just had a look and am happy with where it is.

I know that they must go on further because of the marks on the axel as well. This maybe a stupid question but they will fit on any way, right? Theres not a certain orientation? I havent seen it mentioned in any guides but might explain a lot.

The gentleman here here has got a huge lever so am still thinking its that!
http://www.parktool.com/images_inc/repair_help/tw21.jpg

Andy B · June 2007

That's a torque wrench, not a huge lever.

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RJWwmb · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Andy_B

That's a torque wrench, not a huge lever.

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Don't mean to be pedantic but it is acting as a large lever [:p]
I'm not sure what torque the pictured part is set to so it may not be producing as much torque as my short wrench though.

RJWwmb · June 2007

Thanks for the assistance all, it turns out they were on far enough once I got enough leverage but the chainset is a different design.

I've started another thread in the proper place this time if anyone can have a look and say which chainset looks normal?
http://www.whatmtb.com/forum/topic.asp?TOPIC_ID=25504

Thanks, Ryan

Fitting Cranks To BB

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