Faster MTB - chainring?

[tcdev]

Hi Guys,

A mate of mine has a 2014 Trek Superfly 7 which he uses for both on and off-road, and has zero interest in purchasing a 2nd bike. However, he wants to be able to "go faster" on flat road, ie. he runs out of gears, without losing (much of) his granny gears for any off-road climbing.

Research I've done on these forums seems to indicate that a larger chainring is the way to go. FTR he's running a factory 36/22 crank and 11-36 (10 spd) cassette.

My questions are these (if my assumption is correct):

* Is it possible to just replace the larger chainring, or is he up for a whole new crankset? (I suspect the latter)

* Is it likely that he'll need to adjust/replace either of his derailleurs, or will it depend on what he's got there now and how large he goes?

* Will he require more links in his chain?

* Any suggestions for crankset size given his requirements?

TIA
Regards,
Mark

[mikgit]

Need to find out what the BCD os the crankset/rings are to see if you can get bigger ring that will fit. May be cheaper/easier to get new cranks... 36/22 is onthe small side, just replacing the big ring might mess with shifting with small, might not, bigger jump, replace both?

will have to adjust front mech, probably move it up. Shouldn't have to touch rear

maybe


depends how big,,, there's this 40/28 gain the top end, loose the bottom end
https://www.evanscycles.com/en-au/shima ... t-EV149771

could go triple, gain top end not loose bottom end... just an idea.

[Duck!]

Get a triple. Wider overall gear range, better mid-range, no loss of low range. Will need new front derailleur, longer chain (best just to go a new one) and maybe rear derailleur depending whether current spec is medium or long cage; long is necessary for triple to accommodate the chain length. Some manufacturers spec a long cage with 2x, some fit medium. To check, measure between jockey wheel centres; medium cage will be around 75mm, long cage around 95mm.

[RonK]

However, he wants to be able to "go faster" on flat road, ie. he runs out of gears, without losing (much of) his granny gears for any off-road climbing.

Say What? 36x11@ 90rpm on 29er wheels is a 40kph gear.

Perhaps he should keep his money in his pocket and work on his cadence.

[trailgumby]

I run 26/39 on my Scalpel. Noticed the loss of a granny gear on our steepest longest climbs (20-40%), but learned to deal with it with weight training and hill repeats.

The only time I run out of gears is north of 50km/hr on descents.

I don't believe the lack of interest in another bike. N+1!

[tcdev]

Thanks for the tips, I'll pass them on!

@RonK: 'flat' might mean barely perceptible decline with a tailwind!?!

@trailgumby: normally you'd be right, but in this case, I don't think so.