Replacing an old crankset

[John S. Allen]

Hello,, I own a 1997 NWT which I bought refurbished from the factory in 2005. 

The threads of the cranks for the pedals are munged up from repeated installations including an attempt to install pedals on the wrong side. I need to replace these cranks.

Description:

• Square taper
• 74 and 110 mm 5-hole bolt circles.  
• The bike originally came with a single 44T chainring in the middle position and a trouser protector disc in the outer. position.
• The cranks are painted black 
• They bear the lettering Shimano VIA 170 on the back, which is concave. 
• The cranks are very "bow-legged" for extra clearance at the chainstays.
• Unusually, The bolt holes for the 74mm bolt circle are essentially level with the inner face of the crank around the spindle hole.

I installed a replacement left crank, and because it is not as  "bow-legged", it will interfere with and damage the quick release of the rear brake if that is open. 

I tried to install a replacement right crank (Sugino AT) and it would not work because the bolt circles are closer to the bicycle's centerline. 

I see a Shimano crankset on eBay which looks similar but I am not sure -- https://www.ebay.com/itm/389859392083. And it is 175mm, which I don't want.

Can y=anyone supply a crankset, used OK, from a bicycle which has been refurbished with another crankset, or point me to where I might purchase one? If I can't get one as "bowlegged", I'll have to replace the bottom bracket with one that is longer on both sides. That also might be an option. but I'd rather just replace the crankset.

-- 
John S. Allen

CyclingSavvy Instructor
League Cycling instructor
Author, Bicycling Street Smarts
Technical Writer and Editor, sheldonbrown.com

[Vince Mackenzie]

When we built up bikes in the uk. We used to buy shimano rsx triple chainsets. The outer ring was moved to the middle. This worked with a 110mm bb.

Hope this us of some help.

Vince

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[frkrygow]

I'm surprised the pedal threads can't be repaired, maybe by careful use of a tap (starting from the backside). If pedals aren't frequently removed, could that plus some version of Loctite (blue or the even weaker purple) do the job? 

Failing that, I thought that there were Helicoil or similar inserts available. But I admit I never encountered that problem. 

[Walter Lapchynski]

I'd use the tap first, too. A lot of times the issue is the first few threads.

The Helicoil is a great idea, but it would require a significant enlarging of the pedal hole, which ultimately should be done with a mill. That said, it's not a job for your average home mechanic.

Cranks running into linear pull brakes that are open should be expected. I'm a little shocked that there's any crank that would clear them. That said, any replacement crank should do the trick. I think most would probably prefer a crank with less of a Q-factor anyways.

Finally, I'll recommend MKS Ezy pedals as a better solution for travel. The pedal body and axle quick release off a small coupling that stays in the crank. This eliminates the need for a pedal wrench and all but removes the possibility of encountering similar problems. They have a wide array of options, including some quick release ones. And they're fantastic pedals on their own right.

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Walter Lapchynski
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Green Gear Cycling dba Bike Friday

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[Geof Gee]

Maybe play around with alternative bottom brackets to get the crank you already have to work good enough?  It sounds like the old crank was an odd duck.  

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"Sometimes I forget things.  Who I am.  Where I am.  Unimportant things. But I'm not insane. "

[frkrygow]

To clarify my post just a bit: I've never had a stripped thread in a crank arm. I've used Helicoils several times in other cross-threaded devices, always (IIRC) by hand, no milling machine. The process uses special taps that have a non-standard relationship of thread pitch to major diameter. The increase in hole diameter is only about twice the thread depth. 

And there is a Loctite product intended specifically to rebuild bad threads. https://www.napaonline.com/en/p/NCB28654  It can't be as strong as the original aluminum, and I have no experience with it, but if a normal pedal thread tap can salvage enough of the original threads, it may be worth using as reinforcement. 

I second Walter's recommendation for MKS Ezy pedals. I use them and like them. 

[John Thurston]

And keep in mind that if you are willing to wield a wrench, EZY spindles can be swapped into some standard MKS pedals. For example, I wanted the MT-LUX COMPE pedal for my Llama. The product page indicated it was a 'cup and cone' pedal, so I bought the PROMENADE pedal and swapped the spindles between the two sets.

John Thurston
Juneau, Alaska

[robert clark]

I'm still using the cranks the company fit .. but got a suntour grease guard BB to put them on  [JIS  taper]

Rohloff hub chainline  still good.. 

[robert clark]

Saw (Online  Welgo   push button release scheme  for regular pedals )  ?

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