Riv Silver brand crank on Crust LB?

[kw]

Hi all,

I'm planning to use a Silver3 crank as a 44/28 double on my Lightning Bolt with a 9 speed cassette. I'm wondering if anyone has this setup and what BB spindle length you're using?

Thanks!

Ken 

[tnort...@gmail.com]

Not exactly an answer to your question.  But I  have accumulated old bb in different sizes to use to "actually " determine the correct chain line. It helps that I work PT in a bike shop and can grab old ones!

Tom

NE Ohio 

[Mark in Beacon]

I would go with what Rivendell says. A 110 bottom bracket will get you a 45mm chainline at the middle ring if you are running it as a triple or with a chain guard outer. I would start around there, maybe try a 107 to move the chainline in a bit for the double, . Call Riv if you are not sure. Doesn't have much to do with the Crust.

[satanas]

Many 110mm BBs (i.e., Shimano) are 3mm longer than 107mm on the LHS, but the same length on the RHS = same chainline.If it was me I'd want to measure the BB before committing to it. YMMV.

Later,

Stephen

[Will Mill]

Hey Ken, 

Short answer: I'd probably go with 110mm BB. 

Longer answer: I ran the Silver1 42/28 on my Lightning Bolt with a 68x107 mm BB and 9-speed cassette... and the chainline and Q-factor were spot on. Your Silver3 (44/28) is a different crank, and people (e.g., Riv Owners bunch) usually seem to run it with about a 110 mm BB, so it may not land in exactly the same place with the same 107 mm spindle.  

Will in NYC

[Kenneth Wiss]

Thanks all! 

I'll start with a 110mm BB and see how that works.

Ken

Brooklyn, NY

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[Ken Freeman]

I intended to share these thoughts with the group earlier, but I’m home caregiver for my wife who is an Alzheimer patient, and keeps me hopping!

Last rewarding fix I did on a bike was to salvage a 1952 Rudge Aero Special.  Identical to the Lenton Sport for 1952, same assembly line, parts list, and parts bins.  Nottingham plant sound them globally in four different branding, depending on where sold. Brands are Raleigh, Rudge and two others not well-known to me.  I think Humber was one of them.

I damaged the original cotter spindle pulling the arms off for overhaul. I ended up able to replace the whole cottered Raleigh Industries steel chainset with a TA 5-vis set of arms and  TA BB parts including BB cups.  I had to search for a 44 or 46 tooth track-width chainring as now used for track.  I found the TA chainset, a 48 tooth Al ring, and a few TA cotterless spindles and some TA bearing cups.

The TA cups threaded into the BB perfectly, with the bearing balls and the TA spindle matching perfectly. A test fit of the and  If the bearing cups thread the frame, place the bearings in the same place as did the original Raleigh Industries parts from 1952, then there is a real good chance the TA set of parts will be a good fit.  So my chain line is 45mm front ring and rear sprocket, my rear dropouts are aligned and their offsets are balanced.  The right pedal offset is 50 mm and the left is 55 for a very small Q factor of 102 mm! 

The alignment also depends on dropout alignment and if the chain stays are aligned nd offset the same.  There may also be spindles which match the TA crank arms but have different length drive side and non-drive side stubs.  This is something to watch out for in a nice old vintage frame like mine.

 

Ken Freeman
Ann Arbor, MI USA

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[Brad]

It may just be my quirks, but I have gone wider than recommended with my Stronglight Impact cranks.  I think they use a related forging.  Here is my rational beyond a bad experience at 107.  Which rear cogs do you ride most often?  That is where your chainline should be.   If you ride the middle cogs front and rear, then great, line up the usual way.  8, 9, 10, 11, etc. cogs the gaps get thinner and the chains more flexible.  see https://www.sheldonbrown.com/cribsheet-spacing.html

A difference of 3mm on the chainline further out is less than the space between cogs.  On a freewheel a difference of 6 is just slightly more than the space between cogs.  

[Dave Johnston]

I like to run setups like this more like single + bailout. Which is to say I plan to use the 44t (39 thru 43t in my case) for the whole range cassette and 98% of the mild terrain around here.  So the chainline on the 44 would be like its a single or middle ring (which it is). I don't set up 28-44 as a double and push it out, with the chainline in between the two. I guess we are talking about 2.5mm so maybe it doesn't matter though for actual shifting performance. 2.5 mm at the chainline would be 5mm more at the bottom bracket if they were symmetric, which they are not. 

Don't forget bottom bracket spacers / shims, for fine tuning.  Shimano BBs seem to be designed for their use, which is why the 110 and 107 have the same right sided spindle protrusion. You use spacers on the right to adjust. I think this use to be common knowledge, but common knowledge is rarer these days.

It is harder to find spacers with the profusion of "standards" these days. Back in the good ole days shops use to have Wheels Manufacturing kits like this: 

https://wheelsmfg.com/products/drivetrain-spacer-kit

[David Johnston]

I'm going through the same issue right now with a crank and new to me old frame with my first 73mm shell. I use the Tom method of just trying different ones.
Attached is a picture of two Shimano UN55s, a 107mm and a 110mm. Notice that both have the same right side protrusion and all the difference is on the left. These are 73mm shells. These are the only 73mm BBsI own so if these don't work I will have to use math.

The reason I mention this is that if Riv is recommending a 110mm, then the only difference when using a UN55 107mm stock is the left crank will move in a little. I thought Sheldon Brown had a crib sheet with measurements but I can't find it.

[David Johnston]

I couldn't find the Shimano Spec sheet but here is an IRD and Tange, which I think follows the Shimano pattern. If anybody has a Shimano specific sizing chart please link or post.

Note: I tried out the two BBs above 107 and 110 and the only thing the 110 did was make the spacing non-symmetric with more crank to chainstay space on the left side than the drive side. This is with an old 90s XTR M900 crankset, your crank may want a non-symmetric BB. The M900 was designed for a Shimano 107 BB.

IRD Chart:

Tange Chart:

[Stephen Poole]

The 110mm UNxx BBs are basically useless IMO. There's no reason why the LH crank should stick out more (unless you have odd biomechanics), but it's often useful for the opposite to happen.

I don't know if *all* 110mm cartridge style BBs follow the Shimano pattern, but haven't seen any that don't - perhaps SKF?

Spacers behind the RH cup are often useful with square taper BBs to make things work, or to minimise Q factor, etc.

If the cranks and chainrings don't touch the stays under load, there's enough clearance - you don't need a lot - and if the chainline is good enough that everything behaves okay I wouldn't worry about it....

Later,

Stephen

[kw]

For what it's worth I ended up using a Shimano 113BB with the Silver3 crank. 

In use it is like Dave said, "I like to run setups like this more like single + bailout. Which is to say I plan to use the 44t (39 thru 43t in my case) for the whole range cassette and 98% of the mild terrain around here.  So the chainline on the 44 would be like its a single or middle ring (which it is)."

[kw]