- Anyone using a 50/34 chainset for cyclocross (and why not)
I’ve bought a new groupset for my commuter / cyclocross pit bike / sometimes turbo bike (Its an old Ridley X-bow tat was my first cx bike). Based on recommendataions here I went with Tiagra 4700 (I needed 10sp). Because it was a full groupset it comes with a 50/34 chainset. That’s great for my commuting but less good for cx. Thing is I’ll only use it for cx as a spare/ pit bike when it’s muddy and I can get pit crew (I commute 3-4 days a week most of the year compared to half a doznen days when I’d be using it for cx racing (and some cx training)). Is it worth spending the £60 (less whatever I get for the tiagra chainset) on a 36/46 cx50 chainset? I’d save 100g and get standard cx gearing. I question whether its worth it though – I’ll have more range as is.
So why do people have little differnece between the two front rings for cx.. the only things I can think of is a) easier to shift betwen closer spaced rings if a bit mud-clogged; b) you don’t need the massive range; c) a 50t chainring would be big enough to get in the way when shouldering…
Thoughts? I’ve never noticed needing a bigger range tha 36/46 before.. at the point I start spinning out i’m going downhill at about 50kmh which is quite fast enough for me!!Posted 1 year ago
big chainring looks more pro innit? Aren’t single ring setups popular for cx bikes now anyway? The make more sense than a double for that applicationPosted 1 year ago
you’ll probably get most of 60quid back for the tiagra chainset, chainsets always seem to be fairly expesnive regardless of tier on ebay.Posted 1 year ago
The 34 bit was never a problem. You’ll probably not need the 50 but I wouldn’t have though it would get in the way, it won’t be hugely bigger than a 46t.
I assume finding a 46t is tricky for an asymmetric shimano setup ? Have you looked at spacycles/zepnat/superstarcomponent/sjscycles to see if they have cheaper options.Posted 1 year ago
36/46 is still nowhere near ‘standard’ CX gearing, it’s just what’s been provided on lots of bikes since 110bcd became a thing so has become normalised.
38 or 39 inner with 44 or 46 outer was the king for a long time when 130bcd was the usual unless you ran a single with guards, which was usually a 42.
The reasons for small gaps were pretty much as you say – because it made for fairly easy front shifts in thick mud that were worth 1 or 2 sprockets, the fact that CX takes place within a narrow range of speeds (running pace up to about 25mph), and also because a smaller outer ring allowed you to do the start effort on it and bang up the block rather than risk a full-power front shift halfway down the start straight.
Narrow-wides and 11/12spd pretty much makes a double obsolete for the vast majority of people.Posted 1 year ago
@jonba – yeah I’ve looked everywhere I could think of but the cheapest (and I wasnt sure it was quite right) was £85 – Genuine shimano ones seem only available at Ultegra level for £120!
As its my commuter as well as a spare cx bike (plus 10speed max) I’m not going singlering – especially in wales! I struggle in easiest gear on one of my regular hills at the moment.
If the thick mud is the reason – and I’ll likely only be using it in thick mud I probably will just buy another chainset and hope @joshvegas is right about decent resale!Posted 1 year ago
I’m not a racer but went from sub compact to a 34/50 with a 34t cassette when it wore out. Gear range almost identical, but significantly cheaper than a sub compact drivetrain.Posted 1 year ago
I’ve not done many cx races, only started last season
I’ve a 36/46 x 11-28. I’ve (deliberately) never used the front shifter at all in races (to avoid droppy/snappy chain) so effectively I’m 1×10 but with two sets of ratios, one for hard or flat ground and one for clag or hilly – chosen after the practice laps. Worked fined for me. You might find that 50/34 works in the same way for you (can’t imagine a “typical” course where you’d be switching between the two mid-race)
(I had never imagined a world where one might use the big ring for the starting effort! 😥 )Posted 1 year ago
I found that conditions dictated what gears you needed for a course and unless the course was pan-flat and dry, a 50 ring was near redundant, plus shifting on a 44 or 46 was a lot easier. On really muddy events, I’d often just end up on small ring / big sprocket and leave it there as shifting would usually result in a jammed or shipped chain. I do remember an event in Oxford at the beginning of one season where I was gridded and we started at the far end of a football pitch so we got to gallop the full length of the pitch on our big ring to get the ‘hole shot’ into the woods – just before that there was a slight bank but the lead rider hit it at 20mph, launching himself into the air for a quite spectacularl OTBPosted 1 year ago
I run either a 42t or a 38t single ring with 11-36 11 speed cassette on my CX bike and in those guises it’s been a commuter, a CX racer and monster CX racer and a 200km plus sportive bike.
I don’t see the point of a double, be it a compact or any other style for any of the above if I’m being perfectly honest.Posted 1 year ago
On my good cx bike I’m running 42t and 11-32 11sp. That’s great for hacking around a race course but I don’t think I could make that work for all occasions
@scaredypants – I often think it’s safer to do the reverse if things are getting gunked up badly; just keep it in the middle of the block and shift between the two front rings (rationale being the front mech is stronger).
Anyway- I’ve been given enough ammunition to back up my desire to switch the crankset so job done 😂Posted 1 year ago
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