cadiremar

I'm renovating/upgrading my old Scott hybrid/commuter. I don't actually know how old the bike is, but I think it is more than 10 years old. It originally came with 3x8 Shimano Nexave FD/RD + trigger shifters, and still have those parts.

I want to exchange the rather worn parts with new and shiny stuff. Now for the complicated (and maybe stupid?) part: I want to convert the drivetrain to 2x10. And as I'm currently using a 48/38/28 crankset I want to have a similar big front gearing to keep the top speed, and am therefore looking at using a compact road crankset (50/34) + Shimano 105 front derailer. For the rear I want to use an SRAM X5 rear derailer and a wide-range cassette.

From what I've understood from Sheldon Brown's website, it is no problem with switching between 8/9/10 speed cassettes on Shimano hubs, but I might have missed something in the wealth of information there. If it doesn't work I can simply get a new rear wheel (or hub if I can find someone to rebuild the wheel), so it's not a very big deal.

The real problem comes with the shifters: I'm looking at using SRAM X5 trigger shifters (which of course work with the rear derailer). I've come to understand that SRAM and Shimano MTB front derailers and shifters are interchangeable, but I've not been able to find anything about combining Shimano road front derailers and SRAM MTB trigger shifters.
An alternative is using SRAM SL700 trigger shifters (which also should work with the X5 RD as they both use SRAMs "Exact Actuation"?), but I'm still not sure it will work with the Shimano 105 front derailer.

So to recap and summarize:
Can I put a 10-speed cassette on a 8-speed hub?
Is it possible to combine a Shimano 105 front derailer (road) with SRAM X5 trigger shifters (MTB)?
OR
Combine Shimano 105 front derailer (road) and SRAM X5 rear derailer (MTB) with SRAM SL700 trigger shifters (road)?

(And lastly a disclaimer: I have tried to search as much as possible, but seeing as English isn't my first language and I'm not very well versed in all the specialised terms used in the bike world I might very well have missed much. So feel free to yell at me as I've probably missed something very basic.
I put the thread here rather than the hybrid forum as it is more of a general build question rather than specific for hybrids.
I have also never rebuilt a bike this way before, only changed chain a couple of times and replaced a brake wire or two, so tell me if I might be in over my head with this project.)

Bike Gremlin

Going to 10 speed from 8 speed will make:

1) twice as expensive chain an cassettes, that don't last as long.
2) more cleaning and maintenance of chain, sprockets and derailleur in order for shifting to be flawless

So I'd keep triple up front and just put a tight ratio 8 speed cassette in the back (like 13-25).

Going double and 10 speed makes some sense for racing, but for commuting. On a hybrid bike. Not much.

Of course, it's your money and if it makes you happy - go for it. It will be a nice learning experience. If you set it up nicely, it will give you a very good ride. I ride both 105 10 speed back, triple front road bike, and a 3x8 hybrid/commuter. Both serve their purpouse very well. But 3x8 is the one that sees rain, mud and snow, the one which doesn't hurt when new cassette and chain are due.

blamp28

I'm a big fan of the SRAM stuff and run the X9 on twobikes currently - both with Shimano front detailers. Temper this with the factthat I am still running SRAM’s 9 speed systems and thus they were installed 3 –6 years ago depending on which of my bikes. There may have been changes in thepull ration for the fronts on the newer X series shifters so you will need toverify that.
On my recumbent Tandem, I have a Shimano 105 front derailleurmated up to a SRAM X9 shifter. My mountain bike has an LX front mated up to anX9 shifter. The key is that while the right hand shifter in SRAM’s X seriessystems are setup at a 1:1 pull ratio vs. Shimano’s 2:1, the Left hand shifterswere designed to be compatible with other commercially available products andthus used the 2:1 ratio. I have been told numerous times by various forumposters that these do not work well together but I have thousands of miles of troublefree shifts that say otherwise.

cadiremar

@Slaninar
You have a good point about the wear and tear on a ten speed. I hadn't thought about that, but it makes sense as the parts are thinner.
I actually have no idea about the expected/average lifetime of the chain and cassette (I have not taken very good care of the bike in the past, which is a shame, now that I've begun to ride much more). Though even buying both a new chain and cassette once a month is cheaper than a pass on the intercity buses for a month. (And the wear shouldn't be that hard, even on a ten-speed?)
The bike is/will be stored warm and dry in the basement whenever it's not used, and there is public bike garages near school, so that should also reduce some of the tear on the parts.

The reason I want to switch to a double instead of a triple is that I never use the lowest ring (called a granny ring?), and after some time with the gear calculator from Sheldon Brown I found that by using a 50/36 double I would have about the same ratios/speeds I use now. (Another reason is that I like the looks of doubles. Which is not a very good argument when it comes to rationalizing stuff that are mainly meant to be functional...)
In either case I need to replace the crank/gear rings as many teeth are either worn down or bent out of shape. So now would be a good time if a should change to a double.

About using an eight (or nine) speed rear I thought about it, but figured that by using a 2x10 setup I would have a simpler and more flexible range of gears, which would be a positive thing as I could make many small changes depending in the flow of traffic. But please correct me if I am looking at this from the wrong angle here.

I can see how much of this this looks like I'm trying to rationalize spending lots of money on an old bike, but I value all input.



@blamp28
Thank for the input. I don't have the X9 readily available where I live, but seeing as they are listed as using the same technology as the X5 on SRAMs site there shouldn't be any difference, right?

Bike Gremlin

I change about 2 chains a year. One cassette lasts for 2 to 3 chains. 10s chain is about 40 euros, while a similar quality 8s chain is some 15 euros round here.



Two things to consider.

1) Triple front lets you have the same range of gear-inches, but a lot tighter. You can put a tight 13-25, or even 13-21 cassette on the back and still climb most hills, ride wherever you like. With a double, you'd have to get a wider spaced cassette for that, which isn't so nice on the flats (but nothing too bad of course).

2) Front chainrings on a compact double are really far apart. You have like 14 tooth difference, instead of max 10 tooth difference. This makes it tricky when shifting from small to the big ring (you need to make 3 or more shifts in the back simultaneously). Triple's 38 (or 39) middle chainring is perfect for most flat riding for me. Makes shifting a lot easier, with a really straight chainline as well.


Double is more elegant, simpler however. You won't know until you try, so go for it. You could keep the old parts for a while should you decide to switch back. Not much to loose. Some money and time.


Yes, 10s cassette can give you both a wide range and closely spaced gears. Very nice when working nice. I love it on the road bike.

If the frame and fit of the bike suit you, why change it? It's like an old pair of shoes. Just replace what you feel like replacing. And learn a few more things.

bobotech

I think moving to 10 speed is such an silly waste of money when you have 8 speeds back there. You can easily enough convert the front crank to a double and keep everything else. All you would need to do is remove the crankset and put a new double on and then use the limit screws on the front derailleur to lockout the 3rd position on the existing front shifter.

8 speed stuff is so durable and reliable, I would not upgrade unless you were racing.

On a hybrid? No way.

Change the crankset if you must have a double and adjust limit screws.

blamp28

I might be inclined to agree with what others have saidhere. I'm always looking for an excuse to upgrade a bike but you have toconsider the purpose of the bike when you weigh the value. For a commuter bike,I would be more inclined to keep it in dependable running condition at thelowest reasonable cost(highly subjective). Commuter bikes are exposed to moreinclement weather, potential theft etc. so I would be more inclined to repairrather than upgrade.

That said, if money is not an object, the process can be fun. The X5 shifter isthree speed for the front so you would have to set the limit screws accordinglyand just let the lowest gear position be two clicks since the granny ring willnot be present.

Kimmo

Well, you write a hell of a lot better than a lot of native speakers...
I doubt you do. Modern chainring teeth are intentionally all kinds of shapes, like Hyperglide cog teeth. Measure your chain for wear, for a start - 1/16" extra length over 12" means it's had it. Using a worn chain for a long time will wear out your rings, but evenly - they'll all start to look hooked.

I'll second the 13-21 8spd cassette - with one of these you can stay in the middle ring most of the time (pretty much all the time you're on the flat) and enjoy nice tight ratios, and then your granny ring becomes useful for hills.

If you have an urge to throw money at your bike, get a lighter seat (big difference when you stand on the bike) and lighter tyres and/or rims. That's the best bang for buck.

cadiremar

I think I'm beginning to see things clearer now. And it also seems that you have convinced me to keep the bike as a 3x8, and try out a cassette with a closer gearing.
I'll also have a close look on what parts that are really on their last legs, seems they might be in better condition than I thought, especially based on Kimmos reply.

Thank you all for the suggestions and input.
(I was pleasantly surprised based on my experience with asking newbie questions on forums. Big thumbs up!)