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[Closed] Road chainset on a mountain bike

 Ewan
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Hi all,

I got a small unexpected bonus at work, so I figured I might treat myself to a powermeter on my commuter bike.

My commuter is a hodge podge of old MTB bits hung on a 20 year old raleigh mtrax frame. At the moment it's got SLX cranks + shifters and a 1x9 XT drive chain. The drive train is fairly shagged anyway and undergeared now I've got fitter, so I was thinking of sticking a 105 chainset + 4iii powermeter on it. I'm sure at some point i'll upgrade the whole bike to a cyclecross bike so it makes sense to get something that'll work on both.

So.... does anyone know if an MTB chain will work on a 105 chainset and will a SLX front mech work on a 105 chainset. If not, does anyone know if a front SLX shifter pulls the same amount of cable as a road one (meaning a 105 front mech would work on it).

Thanks! Any other gotchas i've not thought of would be most welcome.


 
Posted : 19/06/2017 7:38 pm
 JoB
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let me just ponder the rationale of putting a powermeter on a commuter bike for a bit and i'll get back to you with some answers


 
Posted : 19/06/2017 7:43 pm
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I used to run a road triple on my mtb, it was the only way to keep up on the chaingangs.
The big ring rubbed the chainstay slightly, but other than that, no issues.


 
Posted : 19/06/2017 7:48 pm
 Ewan
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let me just ponder the rationale of putting a powermeter on a commuter bike for a bit and i'll get back to you with some answers

Why not? I've got one on my proper road bike - I ride my commuter six times a week vs once a week for my proper road bike. It's 25km each way so takes an hour or so... I have to lug a big laptop and clothes to work so not an option to ride my proper road bike.


 
Posted : 19/06/2017 7:49 pm
 JoB
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i apologise, if you feel you're going to gain some valuable use from it then crack on


 
Posted : 19/06/2017 7:52 pm
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SLX shifters unlikely to work with road front mech and SLX front mech unlikely to work with road chainset but you can get a jobbie that will alter pull ratio for you. I would wait until I could get a cx bike full stop and not try the botch


 
Posted : 19/06/2017 8:01 pm
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When I put my chainset on, all I had to do was move the mech up and that was it, it work fine.


 
Posted : 19/06/2017 8:42 pm
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I'm with JoB on this one. Would not spending the money on the \ a commuter bike be better.

Surely you could buy a better commuter bike than your current one instead for the same price as the powermeter?


 
Posted : 19/06/2017 8:47 pm
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I have a rotor power meter crank & Q rings on my BSO full suss i got from tesco, what of it?


 
Posted : 19/06/2017 9:02 pm
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Why are you desperate to train to power? It's not the be all and end all of being fast on a bike. The cx bike first would be a better plan and then a power meter later I would have thought.failing that i suspect clearance for the 50 tooth outer is your main issue.


 
Posted : 19/06/2017 9:24 pm
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MTB possible having a 73mm B&B might be an issue top


 
Posted : 19/06/2017 9:33 pm
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i will buy the mtb cranks if they could be cheap please


 
Posted : 20/06/2017 9:41 am
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Why are you desperate to train to power?

If I could justify the expense, I'd have a PM on the commuter in a shot - it's the bike I probably spend most time riding (depressing as that is) and the ride is consistent and repeated, power data would be totally useful.

Chains are chains; road crank Q factor might bring the pedal a bit close to the chainstays but other than that I can't see a problem.


 
Posted : 20/06/2017 10:21 am
 Ewan
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If I could justify the expense, I'd have a PM on the commuter in a shot - it's the bike I probably spend most time riding (depressing as that is) and the ride is consistent and repeated, power data would be totally useful.

Chains are chains; road crank Q factor might bring the pedal a bit close to the chainstays but other than that I can't see a problem.

My thoughts exactly, a bit of unexpected cash why not treat the commuter as I ride it the most. Although it's an old frame there isn't actually anything wrong with it - the frame is a nice steel thing, the wheels are XT, the drive chain is a mix of XT and SLX, the finishing kit is fine.... It rides nicely - not the lightest but then i'm putting 10kg of panniers on it each day!

Good call on the chain ring issue, I think it'll be ok tho, the frame dates from the time when big rings were in. Will also check the bb width.

The other option would be to look at the shimano CX cranksets - I presume the 5800 left crank arm would work on one of those.


 
Posted : 20/06/2017 12:26 pm
 scud
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Not sure if missing something, why not replace with MTB cranks with power meter?

https://www.bikefast.co.uk/stages-power-meter-shimano-xt-m8000?number=SW10797.2


 
Posted : 20/06/2017 12:38 pm
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I vaguely remember trying to put a spare road chainset on a mtb frame. It didn't go well as the chain stays were chunkier and came out a lot more at the bb. When I tightened up the chainset the inner chainring basically jammed itself against the chain stay. YMMV.


 
Posted : 20/06/2017 1:08 pm
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Plus if you're thinking of 11 speed 105 you're going to need a new free hub.


 
Posted : 20/06/2017 1:08 pm
 Ewan
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Not sure if missing something, why not replace with MTB cranks with power meter?

Principally because Stages seem to be the only people who do MTB cranks and they seem to be very unreliable (both from reports on here and from my mate who has one). My 4iii powermeter was cheaper and hasn't gone wrong.


 
Posted : 20/06/2017 3:01 pm
 Ewan
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Plus if you're thinking of 11 speed 105 you're going to need a new free hub.

Only 105 at the front, XT cassette at the back...


 
Posted : 20/06/2017 3:01 pm
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Depending on chainline and clearance to the chainstay. You might not be able to turn the crank once it's installed.


 
Posted : 20/06/2017 3:33 pm
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I tried to fit an old 2*10 crankset (Campag 52/38) on my 26" hardtail and the rings hit the chainstay.
So I have ended up making an old hybrid a v-brake drop bar commuter.
I have to admit it does roll faster -but I had a powertap on the 26" and am missing not having it.


 
Posted : 20/06/2017 3:41 pm
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you need to check the bb width - if using hollowtech cranks, mtb cranks have a different axle length to road cranks, mtb bb - 73mm, road bb - 68mm.
and if using square taper, you need to check that the cranks or chainrings don't rub against the chain stays.

both were problems i had. had to use mtb cranks with bigger chainrings.


 
Posted : 20/06/2017 3:55 pm
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Buy pedal based one. You won't be locked in then


 
Posted : 21/06/2017 10:37 am
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or a powerpod (i think it works by magic)

https://www.dcrainmaker.com/2016/03/powerpod-depth-review.html


 
Posted : 21/06/2017 11:20 am