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MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 5:20 am
by alcatraz
Hello weenies...
A friend is getting ready for the Taiwan KOM climb and is worried of burning out and having to walk the bike the 27% grades at the end as well as not finishing within the 7h time limit. He likes to spin and just dislikes being out of the saddle.
He's on a wilier running campy veloce 10s with a compact crank 50/34 and a 12-30t cassette. The derailleur is already the longest available thats compatible (medium) and looks to be at the limit on the 30t cog. Not much space to fit even a 32t which isn't available from campy (campy freehub).
To the point. I saw on youtube you can fit an mtb crank on there. The problem is the chainring size. Double chainring cranks are usually maxed at 42/28t and we would like a 46/28 or 46/30. Do you have an idea which common crank can be fitted with such rings and could work on a 10s road bike?
He has a clamp on front derailleur that can be lowered appropriately. I've been looking to get an mtb crank in an appropriate bcd and switch a chainring if needed. What do you think?
Thank you for reading!
/a
MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 5:20 am
by Weenie
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Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 5:58 am
by shimmeD
46/33 on compact 110bcd is definitely doable.
mtb cranks have higher Q-factor, no?
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 6:28 am
by silvalis
Look at those new fsa and praxis sub-compacts.
46/30 and 48/32
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 7:39 am
by Marin
If you really want to fit an MTB crank (higher Q factor but most ppl don't notice) you can get *all* ring sizes from Specialites TA.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 8:23 am
by xeonrs3000
I replaced a Shimano compact with a 46/30 FSA Omega (2017) on my wife's road bike. Only gotcha is that you have to replace the bottom bracket since the FSA has a 19mm spindle, which also implies that there are not a lot of bottom bracket options (only the ones from FSA themselves). They also have a pricier version (SL-K adventure).
Overall we're very happy with it. Much better solution than having to fit a cassette with large gaps between gears.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 8:56 am
by alcatraz
What do you think would happen if you get for example a 3 ring crank like 48/36/24t and take out the 36, put the 48 on it's place and swap out the little one for a 30t (64bcd).
An outer ring being used as a middle ring. How would that work?
/a
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 9:50 am
by silvalis
I think your chainring spacing will be way out.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 10:15 am
by mattr
All the spotfaces on the chainring will be wrong, ring spacing *should* be ok. But chainline might be odd.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 11:24 am
by morganb
Rotor announced a 46/30 chainring set that mounts to their cranks but I have only seen one set in the wild.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 12:13 pm
by Marin
alcatraz wrote:What do you think would happen if you get for example a 3 ring crank like 48/36/24t and take out the 36, put the 48 on it's place and swap out the little one for a 30t (64bcd).
An outer ring being used as a middle ring. How would that work?
/a
I did this on my old CX, riding 26/40 and 30/40 with a FSA Gossamer triple and TA rings. Shifting was *excellent*.
Because of the positive experience, I just did the same for my wife's new (all-)road bike, she now has an FSA SL-K carbon triple crank with the 26/40 combo and an 11-32 in the back.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 12:36 pm
by bikerjulio
I had a Campy 10-speed cross bike that was used on trails. Ended up with a Deore crankset and needed a Deore FD as well. The stock FD will foul the chainstay before being low enough. Everything worked fine.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 2:18 pm
by ooo
Marin wrote:alcatraz wrote:What do you think would happen if you get for example a 3 ring crank like 48/36/24t and take out the 36, put the 48 on it's place and swap out the little one for a 30t (64bcd).
An outer ring being used as a middle ring. How would that work?
/a
I did this on my old CX, riding 26/40 and 30/40 with a FSA Gossamer triple and TA rings. Shifting was *excellent*.
Because of the positive experience, I just did the same for my wife's new (all-)road bike, she now has an FSA SL-K carbon triple crank with the 26/40 combo and an 11-32 in the back.
What was source for 40T chainring?
Was it chainring for big or middle position originally?
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 2:31 pm
by Marin
ooo wrote:What was source for 40T chainring?
Was it chainring for big or middle position originally?
Specialites TA. Middle ring.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 2:42 pm
by jeanjacques
On Rotor crankset, it's possible to change the spider for the MTB one, 110/74 (or 60, Rotor proprietary). You keep the road Q factor, have the possibility to have less than 30t on the inner.
Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 2:42 pm
by Weenie
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starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓ Broad Selection ✓ Worldwide Delivery ✓
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Re: MTB crank on a road bike - 46/30t 46/28t anyone?
Posted: Tue Jul 11, 2017 4:42 pm
by morganb
jeanjacques wrote:On Rotor crankset, it's possible to change the spider for the MTB one, 110/74 (or 60, Rotor proprietary). You keep the road Q factor, have the possibility to have less than 30t on the inner.
Didn't realize they were interchangeable, good to know as I primarily run Rotor cranks due to them offering shorter lengths. On a similar vein TA Specialites cranks allow you to do the same, although they are square taper.