# Changing gearing on a downhill bike?



## DennisT (Dec 29, 2019)

I have a Santa Cruz V10, which is an awesome bike for downhilling, but not so great for riding to/from the bike park because of the really crappy gearing on the cassette. So I'm wondering if it is possible to change the cassette out for something with a wider gearing range, and if anyone has ever done it.


----------



## DennisT (Dec 29, 2019)

My bike has changed since I posted this. I now have a Trek Session 9, but same problem--crappy gear ratios. But the other day I saw a guy in the line-up with the same year/model bike, but with something like a 10-50 tooth cassette on it. And I had lots of time to eyeball it and ensure that I wasn't seeing things. Unfortunately couldn't leave the line-up to go talk to him. But the point is that someone has done it.

So the cassette on the Session is this one. I figure in order to swap it for something good, I have to be concerned about the cassette width and the mounting option. If the new cassette is thinner (unlikely) then there would be a spacer, but if it's wider, I'm probably SOL.

The SRAM web page isn't really forthcoming on details, and I'm not really into buying every single cassette and returning all but one. So how can I solve this conundrum? Email SRAM? Are they even going to be responsive about something like that? In the computer industry, such questions are handled by drones who have a list of answers and will simply send you the canned response that sounds the closest to what you're asking.

Advice?


----------



## stripes (Sep 6, 2016)

You can change the cassette on any bike. I’m not sure you’d have clearance issues, but I don’t know. I’m not sure a bigger cassette will make your DH bike more pedalable either—you still have 200mm of suspension you’re fighting. And those don’t come with lockouts. 

You most likely with have to change to a longer cage rear derailleur, and possibly a new shifter depending on the amount of speeds or type change.


----------



## macduff (Sep 4, 2012)

In the dim and distant past I did a large cassette swap on a Norco Aurum DH bike (back in the 26" wheel 10spd era). Its the Freehub that mostly dictates what cassette will fit and if yours is SRAM XD then any XD sram 12spd cassette (or 11spd) should fit. The issues are RD capacity and chain growth the DH rear suspension may have. So you will need a long cage RD (and same speed shifter) and probably have to set the chain on the long side but noting your unlikely to be in the big rear cog on a DH run so there is a reduced chance of exceeding the RD/chain length on a full bottom out event, but if you did it could be chain/RD carnage. It will still pedal like a bus as you'll still have a slack seat post angle ((? is that still a thing on DH bikes?) and a low saddle height relative to pedals if thats not bee changed (dropper?!)


----------



## DennisT (Dec 29, 2019)

macduff said:


> In the dim and distant past I did a large cassette swap on a Norco Aurum DH bike (back in the 26" wheel 10spd era). Its the Freehub that mostly dictates what cassette will fit and if yours is SRAM XD then any XD sram 12spd cassette (or 11spd) should fit. The issues are RD capacity and chain growth the DH rear suspension may have. So you will need a long cage RD (and same speed shifter) and probably have to set the chain on the long side but noting your unlikely to be in the big rear cog on a DH run so there is a reduced chance of exceeding the RD/chain length on a full bottom out event, but if you did it could be chain/RD carnage. It will still pedal like a bus as you'll still have a slack seat post angle ((? is that still a thing on DH bikes?) and a low saddle height relative to pedals if thats not bee changed (dropper?!)


I'm looking at the possibility of droppers, but I'm not sure if there's a cable pathway. Wireless droppers are way expensive, even for a gear whore like me.


----------



## macduff (Sep 4, 2012)

I used a reverb external feed post on the Aurum . It did need a perpetual bleed cycle & was a PITA compared to modern cable droppers.


----------



## Nat (Dec 30, 2003)

I wouldn't call it crappy gearing, I'd call it purposeful gearing that matches the intent of the bike you're on. If you just want a lower gear for pedaling to the park then the simplest solution would be a smaller chainring (but then you'd lose out on the top end of the gear range).


----------



## Muddy-Runs (Sep 14, 2018)

The cheapest option would be smaller chainring.


----------



## plummet (Jul 8, 2005)

You answer opie own question...
And that answer is yes. 
Might need to change the derailleur and get s longer chain.


----------



## DennisT (Dec 29, 2019)

Based on my googling, it looks like there are two main issues that can affect whether or not a particular cassette will work. One is the type of hub mount--freehub or cassette. And even with that, there are variations that make them incompatible. The second thing is the width of the hub mount. One video in particular specifies a mount width of 35 mm if you want to have options, vs 30 mm. I don't know how many other widths there might be.

Anyway, unless I want to actually replace my wheel or hub (I don't--that's way too much commitment), I have to find a gearing set that's compatible with my wheel mount, before I can even start to think about derailleurs and shifters and such. I will almost certainly have to replace my chain, but at this point I don't even know which type of chain I'll need so that's way down the road.

The current cassette found here is supposed to be compatible with freehub bodies but not XD driver compatible. That almost means something to me. But there's no info about minimum width required to mount any of the cassettes that I've found, so that part is going to be a crap shoot unless I can find some source of info. I've emailed SRAM support, which hopefully won't be ignored.

Once I have a recommendation for a cassette, I'll buy one and check it out. If it actually fits, then I'll start looking for compatible shifters and chains and such.


----------



## macduff (Sep 4, 2012)

That cassette is for shimano HG style hubs from the link provided 

Fits Shimano/Sram Freehub bodies, NOT XD Driver Compatible
So any big range HG compatible cassette should fit. The SRAM NX 12spd should fit (11-50) but its a cheapo nasty cassette for the bottom end of the factory fitting kit market.


----------



## Nat (Dec 30, 2003)

DennisT said:


> Based on my googling, it looks like there are two main issues that can affect whether or not a particular cassette will work. One is the type of hub mount--freehub or cassette. And even with that, there are variations that make them incompatible. The second thing is the width of the hub mount. One video in particular specifies a mount width of 35 mm if you want to have options, vs 30 mm. I don't know how many other widths there might be.
> 
> Anyway, unless I want to actually replace my wheel or hub (I don't--that's way too much commitment), I have to find a gearing set that's compatible with my wheel mount, before I can even start to think about derailleurs and shifters and such. I will almost certainly have to replace my chain, but at this point I don't even know which type of chain I'll need so that's way down the road.
> 
> ...


Are you _sure_ you want to do this?


----------



## Le Duke (Mar 23, 2009)

No matter the gearing you put on a DH bike it’s still going to pedal like dogshit. 


Sent from my iPhone using Tapatalk


----------



## DennisT (Dec 29, 2019)

Nat said:


> Are you _sure_ you want to do this?


About 80% sure. FWIW, I'll still have the old parts if I end up hating the result. And meanwhile, I get to screw around with modding my bike.


----------



## DennisT (Dec 29, 2019)

Le Duke said:


> No matter the gearing you put on a DH bike it’s still going to pedal like dogshit.


Maybe a little _less_ like dogshit though.


----------



## DennisT (Dec 29, 2019)

Update: I sent an email to SRAM over the weekend and got a very helpful response back today. He basically echoed what @macduff said above, except for the cheapo nasty part  . And that I'll have to replace my shifter, derailleur, chain, and chainring. I didn't realize the chainring would be an issue, but that's why I'm proceeding cautiously with this project.

I'll probably do the actual work over the winter. And my next set of surprises will bel learning what tools I need that I don't have.


----------



## Nat (Dec 30, 2003)

DennisT said:


> Update: I sent an email to SRAM over the weekend and got a very helpful response back today. He basically echoed what @macduff said above, except for the cheapo nasty part  . And that I'll have to replace my shifter, derailleur, chain, and chainring. I didn't realize the chainring would be an issue, but that's why I'm proceeding cautiously with this project.
> 
> I'll probably do the actual work over the winter. And my next set of surprises will bel learning what tools I need that I don't have.


You're _still _sure you want to do this???


----------



## stripes (Sep 6, 2016)

DennisT said:


> Update: I sent an email to SRAM over the weekend and got a very helpful response back today. He basically echoed what @macduff said above, except for the cheapo nasty part  . And that I'll have to replace my shifter, derailleur, chain, and chainring. I didn't realize the chainring would be an issue, but that's why I'm proceeding cautiously with this project.
> 
> I'll probably do the actual work over the winter. And my next set of surprises will bel learning what tools I need that I don't have.


And the next surprise after that is trying to get your suspension working in a way that you’ll be happy pedaling vs dh riding. 

I see an enduro bike in your future.


----------



## Nat (Dec 30, 2003)

stripes said:


> I see an enduro bike in your future.


There it is


----------



## Nat (Dec 30, 2003)

I've been trying to find it online, but I do recall seeing an Intense M29 DH bike with a unicrown and wide range gearing, so it _can _be done with enough money and fiddling.


----------



## dysfunction (Aug 15, 2009)

Nat said:


> I've been trying to find it online, but I do recall seeing an Intense M29 DH bike with a unicrown and wide range gearing, so it can be done with enough money and fiddling.


Everything is possible, for those who can pay.


----------



## Nat (Dec 30, 2003)

dysfunction said:


> Everything is possible, for those who can pay.


I seem to recall that the rider was sponsored by Intense and the bike was set up for a specific event. I’m still looking for the write up.


----------



## stripes (Sep 6, 2016)

dysfunction said:


> Everything is possible, for those who can pay.


You can always rub a little money on the problem 


Sent from my iPhone using Tapatalk


----------



## macduff (Sep 4, 2012)

The items you need to replace for this are all wear and tear parts so normal expense in a bikes lifecycle. Ps chainring swap is as you’ll need a narrow wide ring to help avoid chain drop and fit the chain that matches the cassette cog spec of the new cassette.


----------



## RLTW (5 mo ago)

It’s “eazy-peazy” as my daughter says. I swapped the 9 speed driveline with a 32 tooth cassette to an 11 speed with a 46 tooth cassette (it runs 26” wheels). It was a simple, bolt-on upgrade which took me about an hour. I used an XTR 9000 shifter with an XT 8000 cassette and XT SGS derailleur. I can easily climb to the top of the trails, though it’s not an especially fast climber.


----------

