Trek Rosco 9 / E*Thirteen – need new Chainring, but don’t know whats compatible

I might be a bit thick when it comes to bike mechanics, but I have spent all day today and all day yesterday trying to find out what chainring I need for my Trek Roscoe 9.

I am just looking for the cheapest Steel 30T chainring that is compatible.

The Crankset is E Thirteen Helix.

I am still no closer to finding an answer to when I started. Can anyone provide a direct link to the right one ?

Isn’t it just a E13 Helix chainring you need? Like this one..  https://ethirteen.uk/products/helix-plus-direct-mount-chainring

https://www.starbike.com/en/ethirteen-helix-guidering-directmount-chainring-30t-52-55mm-flip-flop-black/

Helix Steel Direct Mount Chainring

Like this one..

That’s aluminium

Was looking for steel and the price is high at £55… Disapointing if I have to pay this much as my other bike (Turbo Levo) chain rings only cost £20 to replace.

This one says “On Order” with an unknown delivery date. The drive train is worn out and needs to be replaced immediately

https://www.starbike.com/en/ethirteen-helix-guidering-directmount-chainring-30t-52-55mm-flip-flop-black/

Helix Steel Direct Mount Chainring

This one says “On Order” with an unknown delivery date. The drive train is worn out and needs to be replaced immediately

I don’t like to rag on brands, but I’ve unfortunately had nothing but bad experiences with e13 stuff. For that reason, and parts availability, I’d consider looking at replacing both cranks and ring for another brand with better spares availability. Unless the rest of the drivetrain is Shimano, SRAM and the 24mm Race Face cranks seen to have excellent aftermarket parts availability. Shimano rings are more expensive.

Yes it does seem like Trek have shafted the customer by including that E13 crankset which has (so far) seen a lot of difficulty (and in future expense) when it comes to chain ring replacement

Ordering a new Crankset may actually be the best option.

Whenever I have seen an E*Thirteen Chainring, it has been priced anywhere between £55 and £90, with no indication of whether it is compatible with my Cransket.

Apparantly I would also have to buy a special tool for £25 to get chainrings on and off. Making the total cost of replacing this chainring potentially above £100… on a £1300 bike! (Which could be purchased for much less in real terms with Cycle2Work Schemes).

With regards to compatibility, what does Offset mean ? I have seen the terms 3mm offset, 5mm offset, and so on. Which one do I need for the Trek Roscoe 9 ?

Has anyone else on this forum got this bike and managed to actually replace the chainring without getting a new crankset?

The Crankset is E Thirteen Helix

I’ve had E Thirteen cranks on a bike (think they were TRS Race carbon) a few years ago, could never find anywhere with stock of compatible E Thirteen chainrings, steel or aluminium in any size. Tried an Absolute Black oval as they made one that did fit but it wasn’t cheap, and eventually replaced the cranks with XTR’s after a PSA on here

I think Trek have got a lot to answer for, for designing a bike as recently as 2023 where you can’t get a chainring when it wears out (which doesn’t take long!)

The dropper post that came with it was useless, was for the bin after 6 months.

It’s disapointing to see that bikes are still being designed very poorly in some way or another.

It looks like I have no option but to get new Cranks.

How wasteful getting rid of a set of cranks that have no issues with them when it is just because no one does the Chain Ring.

I have never bought Cranks before, is there any compatibility issues I need to be aware of when chosing a set of Cranks ?

The cranks I have at the moment are the E*thirteen Helix, 30T steel ring, 73 mm spindle length, 52 mm chainline, 170 mm length

Shimano 12 Speed drivetrain

Does anyone know if these new cranks are compatible ?

https://www.ebay.co.uk/itm/256488571458?itmmeta=01HWMK2GWWH3VRG8MKA5GD3RTT&hash=item3bb7e90242:g:Xb8AAOSw16ZmJtoY&itmprp=enc%3AAQAJAAAA8AHVNX9Yaxnq1JdMTVtyM3iJkiIJ56lIgqowNGTIwI6xVkST4ui8UISPXcP354FsYxZmPBSMsLhdoyfuR6aSYnUD2nHZSRZMmk%2FkAbWf9EgZx2yjxDnE5ztACCsVqX0%2FyHf%2Fm7NJK2EcgwwxvB2taiLnCVlVnjcsWtAyzA7fTuTiVbMLYJmy11oy06wvGju1600ZephtW4HRJ3Q0%2FPJx0jbO0WgUh0E1JM9l4UFCXXHZPTM9V2Izd5m%2FUb%2FrZEVW02%2BUqSyrzvHT7hCVJ%2BMgg2bPHl5YC5u8NDbhXnIxStNc040Tfmze3JhaUv1GhixIOQ%3D%3D%7Ctkp%3ABk9SR8aOipPlYw

Can’t you just get one from here?

https://ethirteen.eu/cart

If not and you want to go for new cranks the Trek website says it’s a boost frame with a threaded bottom bracket with 73mm shell width. So this should be bsa screw in.

On that basis you could run Shimano ht2 cranks, sram gxp / sram dub, whatever the screw in raceface standard is or something more exotic.

If cheap steel chainrings are important to you then go for sram as you can usually get x sync 2 steel rings for about £20. I’d run a sram chain with their chainrings and a Shimano cassette. The 12 speed Shimano chain doesn’t play nicely with lots of other brand chainrings.  Make sure it’s X01 spec or better on the chain for ultimate longevity.

Arguably Shimano ht2 is a better standard for crank axle / bb with their 24mm axle – although their 12 speed rings are a bit stupid in their construction and seem to fall apart after a while. They should have just made them one piece.

On that linked Shimano crankset if it’s a 52mm chain line it should fit as that’s the chain line specified for your helix crankset. If it’s 55mm chain line it should also fit I believe.

With sram cranks the boost spacing isn’t in the cranks, it’s in the chainring. You’d need a 3mm offset (6mm is non boost / 0mm is fat bike).

Here’s a GX Eagle one on eBay for a similar cost. 170mm arms / 32t chainring (albeit it’s an alloy chainring – but you could replace it with steel if needed).

https://www.ebay.co.uk/itm/256460860302?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=UdTQ5LhWRsm&sssrc=4429486&ssuid=P8vL0CMYTrq&var=&widget_ver=artemis&media=COPY

On both your options you may find you need a new bb – not sure what the Helix uses.

Thanks for the info – I think I will get that Shimano crankset

The BB that came with my bike is a Shimano Hollowtech 2 not an E Thirteen one, so hopefully the new Shimano crankset is compatible with everything on my bike

On that linked Shimano crankset if it’s a 52mm chain line it should fit as that’s the chain line specified for your helix crankset. If it’s 55mm chain line it should also fit I believe.

The eBay web page does not state the chain line but I have found the same pair of cranks on a different website that  says that they have a 53mm chain line – Would this be compatible ?

I think so.

If you’ve got a ht2 bb already then that crank will fit with that fine. Bear in mind that crank has a direct fit chainring and there’s a lock ring tool you need to remove / refit it. Not sure if those cranks will come with it or not.

Okay thanks

Is this the lock ring tool I would need if I got those Cranks ?

https://www.ebay.co.uk/itm/285441248767?chn=ps&_ul=GB&var=587371462963&_trkparms=ispr%3D1&amdata=enc%3A1nF63FCSlRxuLVpEgxDkpLA26&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&mkscid=101&itemid=587371462963_285441248767&targetid=1647205089320&device=c&mktype=pla&googleloc=1007230&poi=&campaignid=21204557927&mkgroupid=169783128948&rlsatarget=aud-1162782600456:pla-1647205089320&abcId=9406817&merchantid=119138145&gad_source=1&gclid=Cj0KCQjwir2xBhC_ARIsAMTXk87KqKQgk9xX2nX_REl9XJM0vZPR6jaOeshnNRvGJmb_-QRqLFDEXsUaAlK1EALw_wcB

Actually ignore that post above, I have just found out that the E Bay purchase comes with the Lock ring tool so I won’t need it

I think you really need to go to a bike shop if you want to get the correct part or parts unless you replace like for like . A steel e13 chainring should last for years unless you do massive miles in bad conditions or are very clumsy .

Not massive miles at all. 1500-1600 miles in 1 year and it has worn out because I let a chain get to nearly 1% stretch according to the chain checker.

Bad conditions yes. It has been a very bad Winter this year.

I know the chainring is worn out because I tried to put a new chain on it and it was very noisy.

I think you really need to go to a bike shop if you want to get the correct part or parts unless you replace like for like

A bike shop would then want the work of replacing the drive train themselves and charge me labour costs for it, when it is something I could easily do myself. They will also have to take the bike off me for a while, and I would have to travel.

It is only finding these parts that I am struggling with. Struggling a very lot

I have never bought Cranks before, is there any compatibility issues I need to be aware of when chosing a set of Cranks ?

Not a compatability issue but the last  Shimano Cranks I bought did not come with a chainring so I’d check on that before ordering.  And Shimano do offset on the actual cranks, not the chainring

SLX cranks available as m7100, m7110 and m7120 are three different width spindles, allowing use of the same chainring for different chainlines

I’d just put the 1% worn chain on it and carry on unless you are having shifting problems.

I bought a Trek Procaliber recently and nearly got a model with E13 cranks and a E13 bb with terrible rep according to the Trek Facebook group. I had budgeted to take it off and sell brand new and replace with Shimano but stock issues meant I ended up getting a lower spec model in the end.