New frame: Longteng RD301-D

[kwantani]

Yes I raised this concern on lack of clearance between downtube and small chainring, when I first got my RD301d. I applied some protective tapes on the downtube/BB area where I think it has a high risk of being scratched should the chain dropped.

Hello
I have just received my Tantan FM301 size 58. Ordered in December and received end of Jan.

Overall pretty satisfied with what i have seen so far and attention to details but i am still building the bike.

However i am very surprised and concerned by the lack of clearance between the frame and the small chainring. The original plan was to fit a Rotor Adlhu crank that i had but i will have to buy a new axle with bigger Q factor (Gravel 24mm axle with 152mm Q). I don't think this bike should be built with a regular road axle (147mm Q for Rotor Aldhu). The issue is coming from the downtube being almost as wide as the BB.

What do you think ?

[Serge_K]

What do you think ?

It either fits, or it doesnt. The chain is always far away from the area where the ring almost meets the frame. As long as this "almost" is more than zero by a sufficient margin to maybe allow for some flex and grit, then no problem. And sometimes you have to use a shim. I had the problem with a non shimano crankset on a velobuild gravel frame, i had to shim it a tiny bit. It just needs to clear the frame, you dont need ample space.

[kwantani]

Existing RD301d users, does your headset rubbing with the upper headtube when turning? Mine does. Plan to grind off the plastic cover spacer that's rubbing with the headtube. If it happened on yours how do you address it?

[Chiyou]

Existing RD301d users, does your headset rubbing with the upper headtube when turning? Mine does. Plan to grind off the plastic cover spacer that's rubbing with the headtube. If it happened on yours how do you address it?

Maybe use a headset shim, something like this? https://shop.fullspeedahead.com/en/spacers/road-mtb/micro-spacer

[julienb]

It either fits, or it doesnt. The chain is always far away from the area where the ring almost meets the frame. As long as this "almost" is more than zero by a sufficient margin to maybe allow for some flex and grit, then no problem. And sometimes you have to use a shim. I had the problem with a non shimano crankset on a velobuild gravel frame, i had to shim it a tiny bit. It just needs to clear the frame, you dont need ample space.

Well, i disagree. There needs to be a minimum gap, at least as wide as a chain width to cope with chain fall off, debris...

And in my case, my power meter does not fit. Hopefully it will with the gravel axle and 3mm worth of spacers.

[kwantani]

Thanks you for the pointer! Q: how much works to install a headset shim like this? Need to re-do all the internal cabling routing over the HS?

Maybe use a headset shim, something like this? https://shop.fullspeedahead.com/en/spacers/road-mtb/micro-spacer

[Chiyou]

I should have been more careful in my advice: chances are that you'll want a C-shaped shim rather than an O-shaped one. See part 04 on this Deda parts diagram as an example (part code HDDCRMS - DCR microspacer).

https://dedaelementi.com/media/catalog/product/attachment//d/c/dcr_headsets.pdf

Hopefully, a C-shim won't require much disassembly; make sure though that the dimensions of the shim match those of your headset.

[maza]

I should have been more careful in my advice: chances are that you'll want a C-shaped shim rather than an O-shaped one. See part 04 on this Deda parts diagram as an example (part code HDDCRMS - DCR microspacer).

https://dedaelementi.com/media/catalog/product/attachment//d/c/dcr_headsets.pdf

Hopefully, a C-shim won't require much disassembly; make sure though that the dimensions of the shim match those of your headset.

Side cutters are great for converting O-shaped things to C-shapes.

[kwantani]

Thanks for clarifying. Yeah C shim seems more straight forward, can just insert it without disassemble the whole HS stack.