Cannondale Scalpel help- 1×10 with Rotor cranks?
I have just go hold of a Cannnondale Scalpel frame and am in the process of building it up with a 1×10 drivetrain.
Apologies in advance for the length of this post!
A few things are giving me headaches, the biggest of which is the chainset/ chain guide/ chain line….
What I am trying to get working is:
32T e13 single front ring
e13 direct mount chain guide
Rotor 3D (triple cranks running the single ring in the middle ring position)
Wheelsmfg BB30 to 24mm adapters
Xt/ XTR 11-36 10 speed cassette
With the cranks fitted correctly (wider spacer on the NDS) the 32T chain ring is very close (~2mm) to the chainstay and is far too close to the chain guide (the ring itself rub on the chain guide let alone the chain rubbing). There is no way I could run a bigger than 32T ring. On the plus side, the chainline is nice and the cranks/ pedals are central to the frame as they should be.
As a short term fix prior to taking it to the LBS I swapped the Rotor spacers on the cranks to put both the NDS and DS cranks further towards the DS. While the chain guide no longer rubs, the chainline is poor (not good in the biggest cassette cog) and both pedals are now 5mm over towards the DS (i.e. not central to the frame and lop sided to the DS). This is an issue for me due to knee probems (trust me on this- I have had a lot of fits and put a lot of time in to getting comfortable).
The only other options are:
1) Fit the Rotor cranks correctly but use the outer ring position to mount the chain ring to stop the rubbing on the chain guide. The problem with this is that the chainline is very poor especially in the biggest cog 🙁
2) Add a spacer between the bearings and DS crank to shift the chainring over a little. The issue with this that the axle isn’t long enough for any spacers 🙁
3) Find a chain guide that is closer to the frame. Everything would be good then except for the very small clearance between chain ring and chain stay- I would always be limited to a 32T ring at the very most. I also don’t know if such a chain guide exists.
4) New cranks and chain guide that are known to fit the Scalpel with 1×10. Downside is obviously the cost.
Any ideas how to get a Scalpel running 1×10?
Thank in advance, DanWPosted 4 years ago
I am in Bath so close(ish)
The LBS have been trying to come up with a solution for the past 2 days and have called to say they have filed the chain guide back plate but it still doesn’t offer enough clearance so they have put everything back how I originally had it set up. They didn’t have any solutions for this 😕
I guess most people who run 1×10 on a Scalpel do so with the ring in the outer position on a double crank/ spider which would put the ring between middle and outer on a triple- which is where it looks like it needs to be. The reason I went with the tripe crank on my previous frame was to keep the chainring options open with the 104mm BCD
On the plus side the Scalpel is sitting at 8.6kg with heavy bog standard tubes fitted 😀Posted 4 years ago
Prids, it is 24mm axle Rotor cranks in the BB30 BB so there are currently just the BB30 to standard axle adapters in the bearings and the standard Rotor spacers. The DS crank arm needs to go further out away from the frame but adding spacers isn’t an option as the axle isn’t long enough. The Rotor cranks have a 7.5mm spacer on the DS and a 10mm spacer on the NDS. Just swapping these spacers over has problems as in my original post. I suspect the Rotor 3D+ (BB30) cranks may be easier to get a good fit with more flexibility on washers to choose from…Posted 4 years agoTurnerfan1Member
Had the same issue with a Giant XTC.Ended up putting a 1″ ahead spacer (think about 5mm) between crank and bb.Still enough space on axle for left hand arm.This gave me good chainline and lined up my ethirteen guide perfectly.Was running a 36 but now have a 34 which gives me more clearance.Posted 4 years ago
I have bodged a temporary chain guide/ crank solution (filing the chain guide back plate) but the 32T ring still has just 1mm or less clearance from the chainstay which does not fill me with any confidence.
Foolishly I assumed cranks would be made with sensible chainlines!
The e thirteen XCX is adjustable for chainlines 49-53mm.
e thirteen direct mount tech specs
I measured the Rotor chainline around 49mm and their notes say it is 48.5mm. That seems quite small and most likely the Scalpel frame was never designed for such a small chainline (even if the chainguide should in theory be close to fitting).
Rotor 3D Triple tech specs
I think that is my problem!
Solution? Something with a 50-51mm chainline I think.
Running through the cheapish BB30 options the best seems to be SRAM XX1/ X0 with an Absolute Black Spiderless ring. 51mm chainline, £250 all in, ~510g. Hollowgrams would be nice but will be at least £450-500 even with buying the arms second hand (~495g with the same spiderless chain ring set up).
Does all of that sound correct?
Many thanks again!Posted 4 years ago
I use the same chain guide but with no shims, the chain is perfectly aligned and doesn’t run regardless of gear.
Try crc for the carbon fsa crank with ceramic bb for £150 isn’t quid.
I’m not saying I have the best solution – but resolved the issues you have for very little cash.Posted 4 years ago
The crank is 470 grams without bearings or chainrings.
EDIT: The FSA looks to have a chainline of 50mm for £207 and will be 511g (arms, e thirteen guide ring, alu chain ring bolts)- another good option.
On and on, why do you say it is not necessarily the best solution? Also where is the FSA for sale for £150? Thanks again!Posted 4 years ago
XX1 chainsets have a 49mm chainline (@centreline of sprocket, 46mm to inner face)
XO double states 52mm to inner face, in outer position, chainline will be poor that far out tho.
XO triple states 50mm to inner face, in middle position.
I think tho, you need to accept the frame wont be happy with anything other than 32t.Posted 4 years ago
My Rotor chainline is 48.5. Another mm or 2 will make a big difference.
On and on is using a 36T ring with a 50mm chainline chainset so I think it is more that my current set up is unusually close to the frame.
I swapped the Rotor spacers around to give a 51mm chainline (but pedals shifted towards the drive side) and there was plenty of room for bigger rings while keeping ok chainline to the cassette.
As in my previous post, a 51mm chainline can be acheived on SRAM BB30 cranks with an Absolute Black Spiderless chainring. Absolute Black state the chainline on the 156 versions is just 45mm which ain’t never going to work
XX1 w/ Absolute Black or FSA K-Force Light are looking like the best options…Posted 4 years ago
I say not the best option because you can buy a specialized – re badged
Lightning or hollowgram which can both be used with a direct mount spider. Both will cost £500 plus so the fsa combo I use was bloody good value 🙂
Oh, another option was fibrelite offered to make me a carbon chainring for my fsa slk 3 bolt carbon chainset.Posted 4 years ago
They can make them with any offset BUT they don’t like mud so pretty limited on an MTB
The Lightning MTN crank is 440g without chainrings so lose 30g over the FSA. The Hollowgrams built up with a spiderless Carbon Ti chainring are about 495 all in so again only lose about 15g over the FSA w/ alu bolts/ e13 guide ring. FSA looks like a damn good option and is in keeping with a Cannondale “Factory” theme more so than SRAM cranks.
My Scalpel definitely isn’t intended to be a show bike for Summer mincing so proper robust options only 🙂 I do have a FibreLyte top cap and resevoir caps on my old brakes though 🙂
Cheers!Posted 4 years ago
My Rotor chainline is 48.5.
Have you measured to confirm tho?
Looking at the SRAM specs its inconsistent what a ‘chainline’ is, they state CL for XX1 as 49 to centreline of tooth, all others to back of teeth.
Is yours actually 48.5mm to the centreline of the ring or the back? if not you might already be on ’50mm’ (assuming tooth thickness of 3mm?). Also, depends how other crank manufac measure theirs and to an extent what chainring you have fitted. The teeth on your single-ring might be offset compared to the rotor one which gave ‘48.5mm’Posted 4 years ago
A fair point, and yes I have measured as best I can to confirm my existing chainline. Chainline should always be to the centre of the rings IMO. So, I need a few mm more than I currently have- how the chainline is measured on the new cranks needs to be looked at carefully I agree but with On and on being happy with the FSA/ MRP set up I can be reasonably confident it will work for my too and FSA’s numbers are correct.Posted 4 years ago
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