New bike supplied with better crankset but in the wrong ratio? Thoughts please.

WillBurnett

Hi all.

I should quickly say I'm a newbie who knows little about bikes - getting back into it after a 20 year break!

I used to have an old heavy cheap mountain bike but found I used it mainly on roads, with a little light off-road track use thrown in, and so I thought a hybrid might suit my style better. I want to enjoy leisure cycling not make it a chore or a sport.

I just bought a new Boardman MX Comp from Halfords. They assembled it for me. When I picked it up they told me that the crank it had been supplied with was bent but that they had put a better quality one on for me instead. I took their word on this and took the bike.

I like the bike a lot - but I was surprised that even on mild hills I seemed to be hitting the bottom gear quickly (yes I'm out of practice too) and not getting ratios even as low as my ancient battered 18sp mountain bike.

It should come with a SRAM via Centro 48/32T

It has been fitted with a SRAM Rival 46/36T

Now I can't find a price for an over the counter SRAM via Centro crankset, I guess it's only available with the bike. But I don't doubt Halfords' claim that the SRAM Rival is the better, higher quality set. However it's clearly a narrower ratio and presumably explains why the gear range isn't as wide as I hoped?

I am sure I'll be within my rights to require that the replace the crankset with the one that it should have had - if I want to. So at last I come to my question!

Do you think that I'm going to notice a big difference in gearing, especially low-range for steep hills and tracks, by swapping from the 46/36 to the 48/32 it should have come with - or do you think it's only a small difference and perhaps I'm better off keeping the supplied SRAM Rival 46/36 because it's potentially a higher quality crankset that is better in other ways that I maybe don't appreciate yet?!

Thanks for any advice on this.

Cheers
Will

cougie

If you've just started then you will get stronger anyway.

What's the cassette on the back ? They may be able to swap that to get you the lower gear ?

Realistically whatever gearing you have on you'll always use the lowest one and wish you had lower.

daniel_b

Hi Will,

looks like the rear is a 11\36, so technically a 36\36 is still a pretty small gear.

Your average road bike will likely have a 34\32 as the smallest gear, so (without checking it using a calculator) would not have thought that is that much different in terms of the smallest gear, and you likely have a slightly smaller gear.
The SRAM Rival chainset, seems to be circa £100 on it's own, so am fairly sure they are telling the truth that it is an upgrade.

One other option, could be to ask if they could swap just the smaller cog to a 34 or a 32 I guess?
Not sure if they will have the stock to achieve that - IF they do, be cheeky and ask if you can keep the 36, as you may want to swap to that when you get fitter.

bendertherobot

It's certainly an upgrade and, to some extent, a better mix overall. Stick with it. It's got a pretty easy low gear for hills. Arguably the loss of some 'speed' at the top end is more niggling but given the purpose, I'd not worry too much about that.

imposter2.0

I'd be a bit concerned that the original crank/chainset was 'bent' - it requires a hell of a force to bend a crank, the kind of force which would almost certainly show damage elsewhere too. I would be doubtful about halfords' explanation and I would ask to see the 'bent' crank which was removed..

WillBurnett

Hi everyone. Thanks for the thoughts and advice - much appreciated. It's pretty encouraging so I think I'll give it a go with this set - though I'll check out that suggestion of possibly changing just the inner cog if I still feel I need it.

To answer one of the previous questions - as far as I know they left the rear cassette as it is normally supplied with this bike - so going on Halfords' own specs, that would be a SRAM, PG-1030, 10-SPD, 11-36T

Cheers all.
Will

svetty

A 36:36 as a bottom gear is really pretty friendly and as you've definitely got an upgrade on the crankset I'd say you're a winner here

imposter2.0

oxoman wrote:

As to it being bent, probably manufacturing fault from new

Unlikely - aside from the question of how a crank would have come out 'bent' from an otherwise perfectly-reliable casting process, a bent crank would not have got past SRAM's QC.

WillBurnett

I "believe" it's assembled by Halfords (I had the option of having the unassembled bike delivered to me but decided I didn't trust myself with that at this newbe stage). So it might be that the crank wasn't yet in the frame and dropped / bashed / run over by some clumsy Halfords guy prior to assembly perhaps? All I can say is that I can't "see" any signs of bends, scrapes or impacts on the frame - and things like discs running silently through the calipers and smooth gear shifts all seem to be fine so I guess I have to trust them on this. Thanks for the heads up about that though.

imposter2.0

WillBurnett wrote:

I "believe" it's assembled by Halfords (I had the option of having the unassembled bike delivered to me but decided I didn't trust myself with that at this newbe stage). So it might be that the crank wasn't yet in the frame and dropped / bashed / run over by some clumsy Halfords guy prior to assembly perhaps? All I can say is that I can't "see" any signs of bends, scrapes or impacts on the frame - and things like discs running silently through the calipers and smooth gear shifts all seem to be fine so I guess I have to trust them on this. Thanks for the heads up about that though.

Halfords don't build up the bikes from components. Mostly, bikes are 99% factory assembled before being boxed, leaving just the front wheel, seatpost to be fitted and maybe the bars to be straightened.

N0bodyOfTheGoat

13Kg is a fair weight bike to drag up hills, depending upon their gradient and length, roughly that is the weight of my Voodoo in 29er mode versus my 9Kg Cube.

Over the winter. I've often done hill reps on the Voodoo, but the times are nowhere near those of the Cube... But at least with my 24/38T chainrings and 11-30T cassette I'm often using no easier a gear than 24/20, which leaves me three easier gears to select if needs be (handy for doing multiple Dell Road climbs peaking at ~20%).

If you need a wider gear range, go back to Halfords ASAP and tell them, asking for them to change the 11-36 cassette for an 11-40 (presuming the rear mech will run an 11-40). But if you can climb your typical worst hill at ~80+rpm cadence in your lowest gear, stick with it, your power will improve with practice.

Edit: Larger chainring corrected to a more normal mountain bike compact size! :oops:

daniel_b

24/28??

WillBurnett

NitrousOxide wrote:

If you need a wider gear range, go back to Halfords ASAP and tell them, asking for them to change the 11-36 cassette for an 11-40 (presuming the rear mech will run an 11-40). But if you can climb your typical worst hill at ~80+rpm cadence in your lowest gear, stick with it, your power will improve with practice.

I have no idea yet what my cadence is - I've literally taken it out twice - and hadn't ridden once for about two years prior to that. But I do appreciate the suggestions. I guess I need to get a bit more practice in before making that judgement! Cheers

WillBurnett

Imposter wrote:

Halfords don't build up the bikes from components. Mostly, bikes are 99% factory assembled before being boxed, leaving just the front wheel, seatpost to be fitted and maybe the bars to be straightened.

Yeah, that sounds pretty much more what I'd imagine them doing. Oh well, not much more I can say if I can't see any other problem and got a crank upgrade I guess I have to trust them. Cheers