compact chainset

[jpembroke]

I had a compact once on my winter bike but felt like I was going backwards on hills so ended up putting the 53/39 back on. Much prefer a standard double over a 50/34 - I just find the spacing too much. I have a 48/34 on my 'cross bike though and that works really well. I think, on a road bike, a 50/36 would be far more suitable than a 53/39. I really don't know why 50/36 isn't more popular.

 

[Dave5N]

I had a compact once on my winter bike but felt like I was going backwards on hills so ended up putting the 53/39 back on. Much prefer a standard double over a 50/34 - I just find the spacing too much. I have a 48/34 on my 'cross bike though and that works really well. I think, on a road bike, a 50/36 would be far more suitable than a 53/39. I really don't know why 50/36 isn't more popular.

48/34 sounds good for 'cross. What make/model is it?

I have thought of going for a single ring 34 or 36 and get a shorter less likely to fall off chain.

Very rarely I go fast enough to use the big ring much - only one league course is quick enough - and if we have a dry winter I could just swap back.

 

[Smokin Joe]

I wouldn't go anywhere near jejames.co.uk!

Neither would I.

 

[jay clock]

It is all personal. When I cycle I spin my legs like a washing machine on spin. So when I got a new bike with 53-39, the 39 going up steep hills meant I ended up doing 50-60rpm. I changed it to a 50-34 with a 12-27 cassette and now go up the same hills at the same speed but doing 80-100rpm and it suits me fine

 

[jpembroke]

48/34 sounds good for 'cross. What make/model is it?

I have thought of going for a single ring 34 or 36 and get a shorter less likely to fall off chain.

Very rarely I go fast enough to use the big ring much - only one league course is quick enough - and if we have a dry winter I could just swap back.

It's a cheap and cheerful Stronglight Impact (which requires the now much maligned UN53 square taper so definitely not de riguer ). Got it for £48 from Ribble. They're great because the come in 3 different crank lengths (170, 172.5, 175mm and 3 ratios: 48/34, 50/34, and 50/36. Lovely chainset. And yes, 48/34 is ideal for most cross races. I use the 48 quite a lot - perfect for flat and downhills whilst the 34 will get you out of trouble of steep and technical stuff. Definitely recommended.

 

[Dave5N]

Thanks Jamie. Personally I have never had any problems with a square taper BB. Still migh see if I can find a 34 single ring though and swap back if the course is dry.

 

[jpembroke]

I don't think you can expect trouble free riding by just taking off a chainring. If you are going for a single chainring then I'd get something bigger than 34. get a 39 or 40 and then use an MTB cassette on the back (11-28). Using your exisiting chainset, put the single ring on the outer position and then mount a chainguard on the inner position to prevent the chain dropping off. You can also fix a bashring to the right of your chainring to . Also, look in to getting a ramp less chainring i.e. one designed for singlespeed/track as that will also stop the chain unshipping.

 

[Dave5N]

Double bashrings are bad news cos they clog up with mud and leaves and cause chainsuck. 34 might be a bit small but certainly 52 is useless when its soft like this year.

 

[Young Un]

Double bashrings are bad news cos they clog up with mud and leaves and cause chainsuck. 34 might be a bit small but certainly 52 is useless when its soft like this year.

I struggle at times on a 22 but then my bike does weigh a ton

 

[jpembroke]

Double bashrings are bad news cos they clog up with mud and leaves and cause chainsuck. 34 might be a bit small but certainly 52 is useless when its soft like this year.

Chainguards are narrower than bashrings so more suitable for 'cross. If you google it there are websites that recommend how to set up a single chainset for 'cross. One I read suggested an inner chainguard and an outer bashring. I guess you could just go for an outer and inner chainguard. Anyway, I'm happy with a double at the moment but a single chainset certainly does appeal.

 

[jimboalee]

Not so much 'Compact', I had a bike once with a 38 ring to 14 - 28 7 block.
They were a useful range of gears without messing about remembering where the chainring change should happen.
It was my work hack at the time. I did the Castleton Classic Randonnee on it for a laugh. Finished fine.

 

[Pottsy]

I bought a bike with a 50/34 compact chainset and found the 'gap' annoying so I changed the 34 for a 36 (as jpembroke mentions). I feel with a 12-25 on the back this suits me perfectly.

As is mentioned by many though, there isn't a right answer here as local terrain, type of cycling, fitness, bike etc. all have an effect on your requirement.

 

[jimboalee]

When I build a bike from scratch, I tot up its approximate weight from values on weightweenies or Ribble's website.

Lowest gear length is determined from the bike's weight, and highest is determined by 70 cadence at 350 watts; using a reasonable roadload curve.

Rings and sprocket combos are calculated to give a smooth progression of gear lengths between these two extremes.

 

[jpembroke]

Eh? Are you referring to gear inches/gain ratio? Using Sheldon Brown's gear calculator seems a lot simpler to me.