Miche Primato cranks

[JonB]

I have recently switched from a Stronglight crank to a Miche Primato. The R/H side, the chainset, has been fine and a lot 'rounder' than the Stronglight which results in a more even chain tension. When I installed the L/H crank it was extremely close to the bottom bracket shell although it didn't seem to be touching, I did a couple of rides with it, including a 200km and then noticed it was loose. The bolt remained tight and it looked like it had gone too far onto the bottom bracket square taper so that the bolt was just tightening against the end of the bottom bracket. I have since fitted the stronglight L/H crank, which fits fine, but I find it slightly annoying that I have mismatched cranks.

Although I've not removed the bottom bracket I'm sure it's a Shimano 107mm UN (something). I did wonder if I should fit a Miche bottom bracket but this feels a bit of a punt and it looks like I'd also need to buy a Campag tool to fit it which is an added cost.

Any thoughts?

[Tim Hall]

Miche Primato is JIS taper. Is the Stronglight it's replacing JIS or ISO? The crank ending up closer to the bottom bracket would get me looking at bottom bracket taper vs crank taper, as would the almost bottoming out of the crwnk.

I've got a Miche xPress, which is JIS, running on a Shimano something or other, which is ISO without any loosening issues. I did have to be a bit careful to make sure the cranks didn't hit the frame.

[Hot Flatus]

Stringlight is ISO....your SL c/set wont have sat fully down the BB spline because JIS axles are a bit fatter.

Maybe you need a longer BB axle?

[JonB]

Thanks both.
I think the Stronglight was JIS as advertised https://www.probikeshop.com/en/gb/stronglight-track-2000-crankset-165mm/71371.html and the Miche states it is JIS on the box. I had presumed Shimano to be JIS.  I'm not keen on a wider bottom bracket because it will mess with the chainline. The weird thing is that the chainset sits absolutely fine on the bottom bracket, not too near the frame and no loosening or bottoming out problems, I can't help feeling that I've got a duff L/H crank arm

[Hot Flatus]

Ah, I have a 2000 on a bike I haven't ridden for a while (ie a decade) and you are right, it is JIS. Sorry for muddying the waters

[Jonah]

I think this is the same??  I also noticed that both of my Primato's fitted slacker than my Sugino's... 

Not aware of the different measurements before!

BTW I've got a 172.5 L Primato crank arm going spare after a R snapped.  However, you'd need to adjust your leg length aye?

Jonah x

[JonB]

I think this is the same??  I also noticed that both of my Primato's fitted slacker than my Sugino's... 

Not aware of the different measurements before!

BTW I've got a 172.5 L Primato crank arm going spare after a R snapped.  However, you'd need to adjust your leg length aye?

Jonah x

Thanks, Jonah ... that's a kind offer but I'm going to pass on the alternate crank lengths 
So for those interested (can't be that many), I returned from the Brevet Cymru earlier in the year to find the Stronglight L/H crank wobbly loose as I got back to Bristol. At this point I gave up on the combo and invested in a two piece Miche Pistard and matching bottom bracket with outboard bearings.  It's been good apart from some minor clicking out of the saddle and so I might strip it down to see if I can find the source. Part of me thinks I should have spent a bit more and gone with Suginos and square taper but maybe next time.

[LittleWheelsandBig]

Crank manufacturers' tolerances can be quite wide and virtually none of them accurately match ISO or JIS. I mostly run JIS BBs and occasionally ISO cranks. If the cranks have been used for a few years (i.e. have been removed and refitted a few times), even an ISO crank tends to fit acceptably well on a JIS BB.

[rogerzilla]

This is a common problem on shorter BBs.  Some cranks have their inner faces ground out a bit so they tuck inside the BB cups.  Andel singlespeed cranks are definitely ok on a 107mm UN55, but it depends what chainline you want.  They are sold as giving 42mm on a 110.5mm BB, but that's not right - you need a 107mm.

Greasing the tapers can affect chainline by 2mm!  I generally like to grease, having had to cut off seized cranks before, but if you run out of taper then you have to remove them and fit them dry.