Carrera TDF Limited Edition 2013 (I think!) - The Wrong Gear?

[Nigelnaturist]

@Dogtrousers great minds and all that.

 

[cyberknight]

It doesn't always work, depends on the rings and cranks.
@johnpenn81 as @Mongoose says the P.C.D. or B.C.D. (Bolt centre diameter), it can be worked out from measuring from centre of one hole to the centre of the next,
and then use this table to work out you B.C.D. most are pretty common 130mm normal double, 110 compact doubles (this is why they are compacts, not the chain ring sizes), you can't fit a ring of less than 38th to a 130mm its why they use the 110mm for the 34th, 74mm BCD is usually used for the inner ring, though Shimano triple use different sizes, my prowheel has a really odd size in that i cant find a size to fit. Campagnolo double is 135mm BCD so it is important to check them.

Indeed, thats what i get for posting after getting home from nights

 

[johnpenn81]

Thanks for your help guys really appreciate it. Just purchased the 38T ring so hopefully it will arrive in time to test it out this weekend. Will see how I shape up and think about the rear cassette after a test run.... Wish me luck

 

[Nigelnaturist]

@johnpenn81
If this is any use to you the gear inch on a 42/52 as it would be on my cassette on the left and with a 38/52 on the right

If you want a specific table let me know your cassette I will do you a couple of tables, there are places on the net also.

 

[Mongoose]

@johnpenn81 If you haven't got your head around gearing yet I have converted Nigel's table into miles per hour for your existing set-up (52/42) and your new set-up (52/38) given a fixed cadence (or rpm in layman's terms) of 80 rpm at the pedals / cranks. For us amateurs I think a cadence of 80 rpm is fairly respectable although this is very much a matter of personal preference. This chat has been mainly about finding the right gearing that enables you to maintain a fairly constant cadence on the flat and on the inclines. I find that at around 80rpm I can keep going for long periods without running short of breath and without having aching muscles. It takes very little to upset this delicate equilibrium which is why correct gearing and a smooth transition between the gears is so important. Hitting the wrong gear at the wrong time can significantly disrupt your rhythm.

As a very rough indicator, in your lowest gear (38/28) when you have the new inner ring you will be doing about 9 mph at 80 rpm and in your highest gear (52/12) you will be doing about 27 mph at 80 rpm. Thinking in terms of cadence and gearing discounts externalities such as hills and wind and only reflects distance travelled by the wheels in relation to revolutions turned at the pedals. I believe the best way to improve performance is by focusing on a comfortable cadence.

View attachment 57349

And all you wanted to know was where you could find a new chainring!

 

[johnpenn81]

@Mongoose @Nigelnaturist Thankyou so much for this guys really appreciate it. To be honest i didnt realise there was so much to learn!!

Good news is I have had the new front ring on and changed the cassette to a 11-28 as per your suggestions. Took the bike out for a long ride yesterday and the gearing is now perfect. Hit a couple of hills with steep section in the dales where is gets up to 15-17% for a few hundred metres and i could actually turn the pedals over now.

Really makes a big difference to the enjoyment factor of a ride when you know you have made it to the top of a climb on the bike and not had to get off and push. Big thanks to you both for all your help.

My wife also sends her regards as I had been talking her into letting me ditch the TDF & spend a £1200 on a bike with better performance. Think i have everything I need now for a while yet

 

[Mongoose]

@Mongoose @Nigelnaturist Thankyou so much for this guys really appreciate it. To be honest i didnt realise there was so much to learn!!

Good news is I have had the new front ring on and changed the cassette to a 11-28 as per your suggestions. Took the bike out for a long ride yesterday and the gearing is now perfect. Hit a couple of hills with steep section in the dales where is gets up to 15-17% for a few hundred metres and i could actually turn the pedals over now.

Really makes a big difference to the enjoyment factor of a ride when you know you have made it to the top of a climb on the bike and not had to get off and push. Big thanks to you both for all your help.

My wife also sends her regards as I had been talking her into letting me ditch the TDF & spend a £1200 on a bike with better performance. Think i have everything I need now for a while yet

Delighted it has made the difference for you. I hope a few more TDF owners struggling with the 42T inner ring pick up on this thread and realise how simple and inexpensive it is to address the problem. No need to abandon them or sell them or be put off cycling.

Done 225 miles now with the new setup on my TDF and really enjoying it. I hope the weather holds.

 

[Nigelnaturist]

As @Mongoose says @johnpenn81 glad you have a bike you enjoy riding,

I have a Viking that weighs in with bottles saddle bag and mudguards at 13.5Kg's ( I weighed it yesterday), it some times is heavier if I am doing errands rack and panniers, so gearing is everything to me, I am never going to be very fast on it, but hold my own reasonable well on some strava segments with bikes weighing much less, I was going to say about cost, but totted it up the other day and to get them same bike with the same level of kit I would be looking over £1,000 (It cost £300 in 2008), I am fortunate in that its a triple so I have further options on low gearing, this means I can have a closer grouped cassette for instance your 38x28 at 35.7" I can get on a 26x19=36", I currently have a 12-27, so my 38 ring is very similar to yours, and I find i get around most things around here on it, that doesn't mean i wouldn't drop to the 26th as it gives me better option whilst spinning up hill as it stand right down to a 26x27=25.3", I am looking however to change this to a 12-25 (27-109") so the rear ratios are much closer, even toying with the idea of a 12-13-14-15-16-17-18-19-21-23 on the 50/38/26 giving me a range of 29"-109" almost the same as my 52/40/30 on a 12-27 had 29-114" but with really close ratios on the rear, I hate that 17-19 jump.

 

[cyberknight]

Tongue in cheek mode engage ............


MTFU , when i was in my twenties i rode a gas pipe bike 52/42 with a 13-19 block !,

exit mode.
Hurt like hell on hills mind .

 

[Big_Dave]

Tongue in cheek mode engage ............


MTFU , when i was in my twenties i rode a gas pipe bike 52/42 with a 13-19 block !,

exit mode.
Hurt like hell on hills mind .

I had an old Peugeot gas pipe 10sp racer in my early teens to go to school on, and go into Chesterfield for my Saturday job, it was soo heavy, my 12sp Viscount was light as a feather in comparison

 

[Nigelnaturist]

Tongue in cheek mode engage ............


MTFU , when i was in my twenties i rode a gas pipe bike 52/42 with a 13-19 block !,

exit mode.
Hurt like hell on hills mind .

In my late teens I had a Gitane can't remember the rear, same front as it was pretty standard, but I am not in my teens and I have better choices how I want to gear the bike, I may well end up with a 12-23 cassette, pretty much the gearing on this 50/38/26 as was on my 52/40/30 12-27 just better geared on the 50 and 38 with the option should it be needed, remember my bike can weigh up to 20Kg's and maybe more with the rack and panniers.

 

[Mongoose]

Currently the Halfords website says the TDF should be fitted with:
OVERVIEW

The Carrera TDF has had a serious dressing down. The model prior to this had the Prowheel 52/42T chainset at the front and SRAM 12/26T 8 speed cassette at the back with Shimano Claris 16 speed gear shifters. The front chainset with a 42T inner ring may have been ill-conceived but, on this version, with small tweaks to the front and back gearing, you could get a lot of bike for not much money. This is not the case with the latest version with the spec you have detailed. It may boast a 50/34T compact double chainset but, at the very least, it has taken a step back with a smaller range of gears and inferior gear shifters. Also, in my experience, the 50/34T arrangement up front is a hard one to manage comfortably with such a big step (16T) between the two front rings.

 

[cyberknight]

Which is why changed my compacts to 50/36 , works a treat .

 

[mattwenn]

Been reading this with interest..... I've got a TDF 52/42.... hills are not nice... legs burn and I'm already in bottom gear!!

I'm going to have a read tonight at home and decide what 'treat' I get myself along with a set of 105 wheels to make the bike lighter.

 

[cyberknight]

Been reading this with interest..... I've got a TDF 52/42.... hills are not nice... legs burn and I'm already in bottom gear!!

I'm going to have a read tonight at home and decide what 'treat' I get myself along with a set of 105 wheels to make the bike lighter.

Nice, they will make the bike a little lighter (maybe 1lb )and go for it if you can but the weight saving will only help slightly and a more effective upgrade will be a gearing change, a quick method would be a longer cage rear mech, wider range cassette + chain or as already stated above a new BB and compact chainset .