Just trying to hack together a bike for a mate who's decided to do a sportive with me.

He's got a road bike with 9sp STI shifters (Tiagra I think). It's a 52/39 chainset. I've talked him into buying a compact but I still think he's gonna need a little more in the tank. Just wondering if I can bosh on a spare LX rear mech and cassette and get him some bail out gears?

Triple option is out as he'll need new shifters which starts getting expensive.

I'm running an XT rear mech and casette with an ultegra shifter on my roadrat as a 1X9 and it works fine.

Where is the sportive? As a 39×25 is a fairly low gear for the road.

Why not just MTFU and ride it as it comes?

A perfectly acceptable set up. Your footwear will remain urine free.

The spread of an MTB cassette on a road bike will feel huge – he'll have the bail out gears on the hills (but as sofatester says, 39×25 is pretty 'soft' for most things as it is) but will forever be searching for the right gears on the flat…. IMHO, obv 8)

39×25 isnt easy on steep hills, I recently got a road bike and on the climbs here (13%+) (west Wales) I was standing and grinding up the hills. Its getting easier though 😀

I was waiting for the first MTFU!

It's the Cyclone up in Newcastle. He's getting the miles in but not hills – I've already done the route a couple of times so I think he's in for a couple of shocks halfway round. Suppose even if he gets off and pushes the odd hill he certainly won't be the only one.

I was standing and grinding up the hills. Its getting easier though

Exactly, just get on with it and worry about how steep it was in the pub afterwards.

😀

MTFU when he is new, older or not very fit with an injury…not everyone can be Lance Armstrong!

I'm running 12-25 with 53/39. While I can get uphills it is grinding procedure.

Not good on knees. I'vejust bought a 12-27 cassette and that is all I intend to mod without taking a mountain bike with slicks.

Best thing i can do now is get fit and lose weight -by riding!

I know a guy running a triple and 11-32 with his tourer-he gets over hills easily but when we rode with a racer, no chance the guy on a compact, 12-25 with 3 yrs training sailed off.

I run an XT rear mech on my CX Bike with Ultegra STIs…

I run an XT rear mech on my CX Bike with Ultegra STIs

tick plus one but more of an off road runabout/fugly tourer than a cx racer

one issue is cable adjustment – newer rear mechs don't have a cable adjuster and you get non at front end with most sti's

It's only a mech, there are no laws other than 'does it work?' 34×25 is a pretty amenable gear for hillier rides and shouldn't require too much MTFing U. If you go too big at the back you start having big steps between ratios and lose part of the fun of a close ratio setup. You know his fitness best though.

A very good point antigee. An inline adjuster may be needed.